Abstract.
Dementia is characterized by a decline in memory, language, problem-solving and in other cognitive domains that affect a person’s ability to perform everyday activities and social functioning. It is consistently agreed that cognitive impairment is an important risk factor for developing functional disabilities in patients with dementia. Functional status can be conceptualized as the ability to perform self-care, self- maintenance and physical activity. A person with dementia usually requires help with more complex tasks, such as managing bills and finances, or simply maintaining a household. Good functional performance is fundamental for elderly people to maintain independency and avoid institutionalization. The purpose of this review is to describe functional changes in demented patients, evaluating the variability in subgroups of dementias.
Key words:
activities of daily living (ADLs); dementia; functional abilities; instrumental activities of daily living (IADLs)
Resumo.
Demência é caracterizada por declínio na memória, linguagem, resolução de problemas e de outros domínios cognitivos que afetam a capacidade de realização de atividades cotidianas e atividades sociais. É consensual que o comprometimento cognitivo é um importante fator de risco para o desenvolvimento de incapacidades funcionais em pacientes com demência. O status funcional pode ser conceituado como a capacidade de realizar autocuidado, automanutenção e atividade física. Uma pessoa com demência geralmente requer ajuda para tarefas mais complexas, como gerenciar contas e finanças, ou simplesmente realizar atividades domésticas. Um bom desempenho funcional é fundamental para que os idosos mantenham a independência e evitem a institucionalização. O objetivo desta revisão é delinear alterações funcionais em pacientes com demência, valorizando os subgrupos variados de demências.
Palavras-chave:
atividades da vida diária (AVD); demência; habilidades funcionais; atividades instrumentais da vida diária (AIVD)
Dementia constitutes a multifactorial process11 Cipriani G, Borin G. Understanding dementia in the sociocultural context: a review. Int J Soc Psychiatry. 2015;61(2):198-204. that is always associated with cognitive decline and impaired functioning. As the disease progresses, people living with dementia experience, in addition to impaired cognitive functions, gradual dysfunction and loss of individual autonomies. Besides decline in memory and/or other cognitive domains, the criteria for diagnosis of dementia require loss of functional reserve and pejoration in functional status.22 American Psychiatric Association. Diagnostic and statistical manual of mental disorders (DSM-5). Washington, D.C: American Psychiatric Association;2013. An important quality of life component from elderly people’s perspective is functional indepen dence. When older people show functional loss, they experience a variety of negative outcomes, such as higher rates of use of hospital services, institutionalization, and increased risk of death.33 Brown RT, Diaz-Ramirez LG, Boscardin WJ, Lee SJ, Williams BA, Steinman MA. Association of Functional Impairment in Middle Age With Hospitalization, Nursing Home Admission, and Death. JAMA Intern Med. 2019;179(5):668-75. The progression of healthy aging to dementia must be considered a continuum, both in terms of the slow manifestation of the impairment of cognitive functions, as well as functional limitation.44 Lindbergh CA, Dishman RK, Miller LS. Functional disability in mild cognitive impairment: a systematic review and meta-analysis. Neuropsychol Rev. 2016; 26:129-59. Originally, mild cognitive impairment (MCI) was considered a condition in which someone has minor cognitive decline, not severe enough to interfere significantly with daily life and function. As a result, some authors proposed introducing minor functional disability among the criteria for diagnosing MCI.55 Winblad B, Palmer K, Kivipelto M, Jelic V, Fratiglioni L, Wahlund LO, et al. Mild cognitive impairment beyond controversies, towards a consensus: report of the International Working Group on Mild Cognitive Impairment. J Intern Med 2004;256:240-6. However, many years can separate the onset of disease, perceived only through mild impairments in everyday living, the evolution from the date of clinical diagnosis and the earliest functional deficits as patients advance to mild dementia, are often difficult to characterize.66 Morris JC. Revised criteria for mild cognitive impairment may compromise the diagnosis of Alzheimer disease dementia. Arch Neurol. 2012; 69(6):700-8. Furthermore, there are age and gender differences in functional limitations. Subjects with a low level of formal education can show early deficits in cognitive performances, as well as functional abilities.77 Mograbi DC, Faria Cde A, Fichman HC, Paradela EM, Lourenço RA. Relationship between activities of daily living and cognitive ability in a sample of older adults with heterogeneous educational level. Ann Indian Acad Neurol. 2014;17(1):71-6. Data regarding differences in functional limitations by dementia subtype are limited and conflicting. The aim of this literature review is to describe functional disabilities in dementia and to understand the individual variability of limitations in the heterogeneity of the disease.
METHODS
A literature review (Cochrane Library and PubMed databases) was carried out (only upper time limit: 2019) on daily functioning and dementia. We retrieved: 207 articles by using the search terms “activities of daily living” and “dementia”; 47 articles using the terms “instrumental activities of daily living” and “dementia”; 18 articles using the terms “daily functioning” and “dementia”; and 21 articles using the terms “functional abilities” and “dementia”. Publications found through this indexed search were reviewed and manually screened to identify relevant studies. We manually added relevant articles identified through other sources (i.e. Google Scholar and key journals). At the end of the process, 81 articles and chapters of books were included in our qualitative evidence synthesis.
FUNCTIONAL ASSESSMENT: ACTIVITIES OF DAILY LIVING AND INSTRUMENTAL ACTIVITIES OF DAILY LIVING
Useful screening techniques or instruments can provide valuable clinical and psychosocial information and can expedite the efficient assessment of patients once they are routinely utilized. Therefore, the assessment of functional disability and its severity must be carried out through measurement scales both in the general population and in dementia.88 De Lepeleire J, Aertgeerts B, Umbach I, Pattyn P, Tamsin F, Nestor L, et al. The diagnostic value of IADL evaluation in the detection of dementia in general practice. Aging Mental Health. 2004;8(1):52-7.,99 Barberger-Gateau P, Commenges D, Gagnon M, Letenneur L, Sauvel C, Dartigues JF. Instrumental activities of daily living as a screening tool for cognitive impairment and dementia in elderly community dwellers. J Am Geriatr Soc. 1992;40(11):1129-34. The instruments for assessing functional ability are divided into two levels, from the more basic (Activities of Daily Living - ADLs) to the more advanced activities necessary for self-care (Instrumental Activities of Daily Living IADLs). The activities that fall into the category of ADLs, involve all tasks that are needed to be performed in order for the patient to survive comfortably: mobility, toilet and bathing/continence, personal hygiene, dressing, and feeding; IADLs, on the other hand, are more complex than ADLs. They include transportation, shopping, preparing meals, managing households, managing finances, using communication devices, and managing medication. Performance of basic and instrumental activities of daily living depends upon the integrity of different cognitive (e.g., reasoning, planning), motor (e.g., balance, dexterity), and perceptual (including sensory) functions. Nevertheless, at present there is no “gold standard” available for ADL and IADL assessment in dementia, despite the fact that functional decline is an essential part of the diagnostic criteria for dementia.1010 Pérès K, Helmer C, Amieva H, Orgogozo JM, Rouch I, Dartigues JF, et al. Natural history of decline in instrumental activities of daily living performance over the 10 years preceding the clinical diagnosis of dementia: a prospective population based study. J Am Geriatr Soc 2008;56:37-44.,1111 Sikkes SAM, de Lange-de Klerk ESM, Pijnenburg YAL, Scheltens P, Uitdehaag BMJ. A systematic review of instrumental activities of daily living scales in dementia: room for improvement. J Neurol Neurosurg Psychiatry 2009;80:7-12. In clinical practice, information about everyday activities is typically ascertained by asking a patient or his/her caregiver to report everyday functioning. It has been suggested that family caregivers who are depressed and feel burdened may be inaccurate and underestimate the patient’s actual functional capacity.1212 Loewenstein DA, Argüelles S, Bravo M, Freeman RQ, Argüelles T, Acevedo A, Eisdorfer C. Caregivers judgements of the functional abilities of the Alzheimer's disease patient a comparison of proxy reports and objective measures. J Gerontol B Psychol Sci Soc Sci. 2001;56(2): P78-84. According to Loewenstein et al.,1212 Loewenstein DA, Argüelles S, Bravo M, Freeman RQ, Argüelles T, Acevedo A, Eisdorfer C. Caregivers judgements of the functional abilities of the Alzheimer's disease patient a comparison of proxy reports and objective measures. J Gerontol B Psychol Sci Soc Sci. 2001;56(2): P78-84. caregivers significantly overestimate the ability of impaired dementia patients to tell time, identify currency, make change for a purchase, and utilize eating utensils. The selection of a functional assessment instrument typically depends upon the severity of the dementia population being evaluated. Many assessment tools are available to help the clinician detect and monitor improvement in IADLs and ADLs in the elderly. The Katz ADL Index1313 Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged. The index of ADL: a standardized measure of biological and psychosocial function. JAMA. 1963;185:914-9. was first developed in an effort to find a way to assess function and how it changes over time in the elderly. It is an ordinal index designed to assess physical functioning using a dichotomous rating (dependent/independent) of six ADLs in hierarchical order of decreasing difficulty as follows: bathing, dressing, toileting, transferring, continence, and feeding, rated on a scale of independence. An appropriate instrument for assessing independent living skills was developed by Lawton and Brody in 1969 to assess the more complex ADLs necessary for living in the community: eight domains of function for women (ability to telephone, shopping, food preparation, housekeeping, laundry, mode of transportation, responsibility for own medication, ability to handle finances), but only five for men (food preparation, housekeeping, and laundry were excluded).1414 Lawton MP, Brody E. Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist 1969;9:179-86. The administration time of the Lawton IADL is 10-15 minutes and it is easy to administer. The patient or a knowledgeable family member or caregiver may provide answers. The higher the score, the greater the person’s abilities. A summary score ranges from 0 (low function, dependent) to 8 (high function, independent) for women, and 0 through 5 for men. As the items of the Lawton IADL scale conform to a formal hierarchy, the most “difficult” items such as “shopping” and “food preparation” can act as sensitive indicators of impending disability in the other activities.1515 McGrory S, Shenkin SD, Austin EJ, Starr JM. Lawton IADL scale in dementia: can item response theory make it more informative? Age Ageing. 2014;43(4):491-5. Fields et al.1616 Fields JA, Machulda M, Aakre J, Ivnik RJ, Boeve BF, Knopman DS, et al. Utility of the DRS for predicting problems in day-to-day functioning. Clin Neuropsychol. 2010;24(7):1167-80. found that when using a caregiver-report measure, problems in bathing and grooming appeared first, whereas eating was the last to be affected. Elderly aged 80 or older are more than twice as likely to have limitations than those aged 65 to 74. The impairment of individual activities develops sequentially (i.e., housework, transportation, shopping, meal preparation, finances).1717 Ikeda Y, Ogawa N, Yoshiura K, Han G, Maruta M, Hotta M, et al. Instrumental Activities of Daily Living: The Processes Involved in and Performance of These Activities by Japanese Community-Dwelling Older Adults with Subjective Memory Complaints. Int J Environ Res Public Health. 2019;16(14). pii: E2617. IADL impairment is reported to develop earlier in dementia and has a higher prevalence, and stronger correlations with cognition than ADL,1818 Royall DR, Lauterbach EC, Kaufer D, Malloy P, Coburn KL, Black KJ. The cognitive correlates of functional status: a review from the Committee on Research of the American Neuropsychiatric Association. J Neuropsychiatry Clin Neurosci. 2007 Summer;19(3):249-65. whereas basic ADL declines are often not present until later dementia stages.1919 West S, Mc Cue R., Golden C. Does memory predict decline in activities of daily living in older adults with Alzheimer's disease? Arch Assess Psychol. 2012;2(1):32-43. One study demonstrated that diminishing IADLs predicted a clinical diagnosis of dementia 10 years beforehand and suggested it as an early screening tool.1010 Pérès K, Helmer C, Amieva H, Orgogozo JM, Rouch I, Dartigues JF, et al. Natural history of decline in instrumental activities of daily living performance over the 10 years preceding the clinical diagnosis of dementia: a prospective population based study. J Am Geriatr Soc 2008;56:37-44. Among all ADLs, bathing impairment may be associated with the highest risk of future institutionalization.2020 Fong JH, Mitchell OS, Koh BS. Disaggregating activities of daily living limitations for predicting nursing home admission. Health Serv Res. 2015;50(2):560-78.
RELATIONSHIP BETWEEN FUNCTIONAL IMPAIRMENT AND COGNITIVE DECLINE
Cognition is a term referring to the mental processes involved in gaining knowledge and comprehension. These processes include thinking, knowing, remembering, judging and problem-solving. These cognitive domains are closely associated with the ability to perform everyday functions.2121 Yu STM, Yu ML, Brown T. Association between older adults' functional performance and their scores on the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Irish Journal of Occupational Therapy. 2018;46(1):4-23. Longitudinal studies of persons at risk for dementia have demonstrated the initial clinical presentation of the disease is one in which there are cognitive deficits measurable with performance-based tests, but with no evident deficit in activities of daily living. According to anecdotal reports, many of those with poor performances on mental status examinations may exhibit an essentially normal life. For this reason, it is essential to establish the degree of correlation between performance on a cognitive test and ability to function in daily life. While functional assessment typically addresses specific content areas, neuropsychological assessment normally focuses on patterns of relatively impaired and preserved generic, cognitive, perceptual, and motor abilities, such as language, memory, spatial ability, problem-solving ability, and perceptual-motor skills. The relationship between these two domains is complex, since a particular functional content area usually involves a number of the specific skills typically evaluated by neuropsychological tests. Neuropsychological assessment can be a reasonably good predictor of those activities of daily living that place relatively heavy demands on reasoning, memory, and related intellectual abilities. Executive function2222 Boyle PA, Malloy PF, Salloway S, Cahn-Weiner DA, Cohen R, Cummings JL. Executive cognitive dysfunction and apathy predict functional impairment in Alzheimer's disease. Am J Geriatr Psychiatry. 2003;11(2):214-21. and memory have been shown to have specific relationships to functional limitations. Individuals with marked executive dysfunction are likely to have significant difficulty carrying out such complex tasks as managing a complicated medication regimen, preparing a meal involving multiple ingredients and steps, or balancing a check-book.2323 de Paula JJ, Malloy-Diniz LF. Executive functions as predictors of functional performance in mild Alzheimer's dementia and mild cognitive impairment elderly. Estud. psicol. (Natal). 2013; 18:117-24. Barberger-Gateau et al.99 Barberger-Gateau P, Commenges D, Gagnon M, Letenneur L, Sauvel C, Dartigues JF. Instrumental activities of daily living as a screening tool for cognitive impairment and dementia in elderly community dwellers. J Am Geriatr Soc. 1992;40(11):1129-34. performed a study identifying which IADL items are more specifically related to cognitive impairment as assessed by the MMSE, in a representative sample of French elderly community dwellers. The authors affirmed that, when age, sex, educational level, and all Lawton’s scale items are simultaneously taken into account, only items A (telephone), G (medication) and H (budget), plus F (transportation) for women, are significant. More recently, Brown et al.2424 Brown TG, Joliffe L, Fielding L. Is the Mini Mental Status Examination (MMSE) Associated with Inpatients' Functional Performance? Phys Occup Ther Geriatr. 2014;32(3):228-40. investigated whether the MMSE was associated with functional performance as measured by the Functional Independence Measure (FIM)2525 Hamilton BB, Granger CV, Sherwin FS, Zielezny M, Tashman JS. A uniform national data system for medical rehabilitation. In: Fuhrer JM, ed. Rehabilitation outcomes: Analysis and measurement. Baltimore, MD: Brookes; 1987:137-47. (the FIM is an 18-item, clinician-reported scale that assesses function in six areas including self-care, continence, mobility, transfers, communication, and cognition). The MMSE scores derived for inpatients with suspected dementia were significantly associated with the inpatients’ total FIM and cognition subscale scores. The Short Portable Mental Status Questionnaire (SPMSQ),2626 Pfeiffer E. A short portable mental status questionnaire for the assessment of organic brain deficit in elderly patients. J Am Geriatr Soc. 1975;23(10):433-41. a mental status test that emphasizes memory, orientation, and calculation, was deemed an inadequate predictor of self-care capacity in nursing home patients.2727 Winograd CH. Mental status tests and the capacity for self-care. J Am Geriatr Soc. 1984;32(1):49-55. A strong association was found between the MMSE and the Disability Assessment for Dementia (DAD),2828 GélinasI, Gauthier L, McIntyre M, et al. Development of a functional measure for persons with Alzheimer's disease: the Disability Assessment for Dementia. Am J Occup Ther. 1999;53(5):471-81. in particular DAD total score.2929 Zucchella C, Bartolo M, Bernini S, Picascia M, Malinverni P, Sinforiani E. Modeling Alzheimer Disease Through Functional Independence and Participation. Alzheimer Dis Assoc Disord. 2017;31(3):218-24. There was an association between functional status and visuospatial performances among AD samples.3030 Jefferson AL, Barakat LP, Giovannetti T, Paul RH, Glosser G. Object perception impairments predict instrumental activities of daily living dependence in Alzheimer's disease. J Clin Exp Neuropsychol. 2006; 28(6):884-97. A significant and specific relationship was found between measures of visual object form discrimination and the adequacy of performance of IADLs that require visual processing; no similar relations emerged between other visual perceptual abilities and IADLs.3131 Glosser G, Gallo J, Duda N, de Vries JJ, Clark CM, Grossman M. Visual perceptual functions predict instrumental activities of daily living in patients with dementia. Neuropsychiatry Neuropsychol Behav Neurol. 2002;15(3):198-206. Damage to the frontal lobe, the prefrontal cortex in particular, was associated with problems in successful completion of goal-directed behaviour and with a variety of neuropsychiatric syndromes: Instrumental Activities of Daily Living (IADLs) such as using transportation, managing financial matters, and organizing a household require the planning strategy and adjustment capacities of the dorsolateral prefrontal cortex.3232 Marshall GA, Rentz DM, Frey MT, Locascio JJ, Johnson KA, Sperling RA et al. Executive function and instrumental activities of daily living in mild cognitive impairment and Alzheimer's disease. Alzheimers Dement. 2001;7(3):300-8. Executive dysfunction serves as a predictor of IADL impairment both in dementia and, in general, in geriatric patients.3333 Bell-McGinty S, Podell K, Franzen M, Baird A, Williams M. Standard measures of executive function in predicting IADLs in older adults. Int. J. Geriat Psych. 2002;17(9):828-34. Abilities that fall under executive function include goal planning, initiating and executing actions, multitasking, switching between tasks, monitoring, and inhibiting habitual behaviours when presented with unexpected events.3434 Boyle PA, Cahn-Weiner D. Assessment and prediction of functional impairment in vascular dementia. Expert Rev Neurother. 2004;4(1): 109-14. Mariani et al. affirmed that performance of tasks such as shopping and medication management, is mainly related to more severe cognitive dysfunction and lower executive abilities, supporting the connection between executive function, global cognition, and IADLs.3535 Mariani E, Monastero R, Ercolani S, Rinaldi P, Mangialasche F, Costanzi E, et al. Influence of comorbidity and cognitive status on instrumental activities of daily living in amnestic mild cognitive impairment: results from the ReGAl project. Int J Geriatr Psychiatry. 2008;23(5):523-30. Mayo et al.3636 Mayo AM, Wallhagen M, Cooper BA, Mehta K, Ross L, Miller B. The relationship between functional status and judgment/problem solving among individuals with dementia. Int J Geriatr Psychiatry. 2013;28(5):514-21. hypothesized that there is a relationship between judgment/problem solving and functional status: findings showed that cognition moderated a strong relationship between functional status and judgment/problem solving among individuals with dementia, with lower reported functional performance predicting poorer judgment/problem solving.
RELATIONSHIPS BETWEEN FUNCTIONAL DECLINE AND BEHAVIOURAL DISTURBANCE
Performance on cognitive testing predicts only a modest proportion of the variance in functional abilities in persons with cognitive impairment, indicating that other variables also predict function. Behavioural disturbances, such as apathy,3737 Cipriani G, Lucetti C, Danti S, Nuti A. Apathy and dementia. Nosology, assessment and management. J Nerv Ment Dis. 2014;202(10):718-24. depression,3838 Cipriani G, L Lucetti, C Carlesi, S Danti, A Nuti. Depression and dementia. A review. Eur Geriatr Med 2015:5;479-86. and delusions,3939 Cipriani G, Danti S, Vedovello M, Nuti A, Lucetti C. Understanding delusion in dementia: a review. Geriatr Gerontol Int. 2014;14(1):32-9. are frequent bothersome characteristics of people living with dementia that increase with disease severity. Additional problem behaviours among late-stage dementia patients include wandering,4040 Cipriani G, Lucetti C, Nuti A, Danti S. Wandering and dementia. Psychogeriatrics. 2014;14(2):135-42. disruptive vocalizations,4141 Cipriani G, Vedovello M, Ulivi M, Nuti A, Lucetti C. Repetitive and stereotypic phenomena and dementia. Am J Alzheimers Dis Other Demen. 2013;28(3):223-7. and inappropriate sexual behaviours.4242 Cipriani G, Ulivi M, Danti S, Lucetti C, Nuti A. Sexual disinhibition and dementia. Psycho geriatrics. 2016;16(2):145-53. An understanding of which neuropsychiatric symptoms are most strongly associated with functional disability may encourage health care providers and loved ones to vigilantly monitor for their presence and aggressively treat these symptoms to reduce their potentially modifiable effects on function. One study strongly indicated the close relationship between behavioural and functional impairment, especially for IADLs that deteriorate in the early stages of the disease and are hierarchically more complex than ADLs.4343 Norton LE, Malloy PF, Salloway S. The impact of behavioral symptoms on activities of daily living in patients with dementia. Am J Geriatr Psychiatry. 2001 Winter;9(1):41-8. Given the consistent associations between behavioural disturbances and functional disability, researchers have attempted to determine their relative strengths in predicting everyday functioning in persons with cognitive impairment.4444 Zawacki TM, Grace J, Paul R, Moser DJ, Ott BR, Gordon N, Cohen RA. Behavioral problems as predictors of functional abilities of vascular dementia patients. J Neuropsychiatry Clin Neurosci. 2002;14(3):296-302. The development and severity of behavioural disorders are not always correlated with poor cognitive symptoms and functional disability; changes in behaviour may be determined by other factors, such as the variety of clinical signs and symptoms of dementia, personality traits of patients, the social support required and available, and the capacity to manage stress of caregiver.4545 Desai AK, Grossberg GT, Sheth DN. Activities of daily living in patients with dementia: clinical relevance, methods of assessment and effects of treatment. CNS Drugs. 2004;18(13):853-75. Associations have been reported between behavioural disturbance and ADLs, such as toileting and hygiene,4646 Lechowski L, Dieudonné B, Tortrat D, Teillet L, Robert PH, Benoit M, et al. Role of behavioural disturbance in the loss of autonomy for activities of daily living in Alzheimer patients. Int J Geriatr Psychiatry. 2003; 18(11):977-82. and IADLs, such as managing medications and finances.4444 Zawacki TM, Grace J, Paul R, Moser DJ, Ott BR, Gordon N, Cohen RA. Behavioral problems as predictors of functional abilities of vascular dementia patients. J Neuropsychiatry Clin Neurosci. 2002;14(3):296-302. Different types of neuro-behavioural changes have been associated with functional disability.4747 Moheb N, Mendez MF, Kremen SA, Teng E. Executive Dysfunction and Behavioral Symptoms Are Associated with Deficits in Instrumental Activities of Daily Living in Frontotemporal Dementia. Dement Geriatr Cogn Disord. 2017;43(1-2):89-99. Some features of apathy and depression overlap. In persons with cognitive impairment, apathy may be more common than depression, which is characterized by guilt, sad mood, hopelessness and poor self-concept. Apathy is characterized by loss of interest, social withdrawal, and generally decreased motivation, initiation, and persistence in the absence of low mood or depressive thought patterns. Apathy has been associated with impairments in planning, initiating and executing IADLs,4343 Norton LE, Malloy PF, Salloway S. The impact of behavioral symptoms on activities of daily living in patients with dementia. Am J Geriatr Psychiatry. 2001 Winter;9(1):41-8. while depression was only associated with impaired initiation and planning. Depression has been shown to be a strong predictor of functional difficulty.4848 Ormel J, Rijsdijk FV, Sullivan M, van Sonderen E, Kempen GI. Temporal and reciprocal relationship between IADL/ADL disability and depressive symptoms in late life. J Gerontol B Psychol Sci Soc Sci. 2002; 57(4):P338-47. Depression reduction was associated with benefits to non-mood outcomes of importance to patients who had dementia and their caregivers.4949 Lyketsos CG, Del Campo L, Steinberg M, Miles Q, Steele CD, Munro C, et al. Treating depression in Alzheimer disease: efficacy and safety of sertraline therapy, and the benefits of depression reduction: the DIADS. Arch Gen Psychiatry. 2003;60(7):737-46. The most striking benefit involved ADLs, with stabilization, and perhaps some reversal of ADL decline. Anxiety and aberrant motor disturbance may also be an important risk factor for functional disability.5050 Tekin S, Fairbanks LA, O'Connor S, Rosenberg S, Cummings JL. Activities of daily living in Alzheimer's disease: neuropsychiatric, cognitive, and medical illness influences. Am J Geriatr Psychiatry 2001;9:81-6.
ALZHEIMER’S DISEASE
Alzheimer’s disease (AD) is an age-related progressive neurodegenerative disorder representing the most common form of dementia, that ultimately leads to death due to complications of the disease or to age-related mortality. Its prevalence increases exponentially between the age of 65 and 85 years.5151 Hort J, O'Brien JT, Gainotti G, Pirttila T, Popescu BO, Rektorova I, et al. EFNS guidelines for the diagnosis and management of Alzheimer's disease. Eur J Neurol 2010;17:1236-1248. The diagnosis of AD requires that patients display both cognitive and functional deterioration. There is robust evidence and consensus that the onset of the symptoms of AD is so insidious that neither family nor patient can pinpoint the exact date of onset. It is now clear that there is continuum from psychosomatic individuals, to those with MCI, to patients with dementia, and that the pathological hallmarks of the disease are present years before cognitive symptoms are recognized.5252 Sperling RA, Aisen PS, Beckett LA, Bennett DA, Craft S, Fetagan AM, et al. Toward defining the preclinical stages of Alzheimer's disease: Recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011;7:280-92.,5353 Bateman RJ, Xiong C, Benzinger TL, Fagan AM, Goate A, Fox NC, et al. Clinical and biomarker changes in dominantly inherited Alzheimer's disease. N Engl J Med 2012;367:795-804. Functional impairment is a core symptom of AD, significantly impacting the quality of life of persons with AD as well as of their family members and caregivers.2929 Zucchella C, Bartolo M, Bernini S, Picascia M, Malinverni P, Sinforiani E. Modeling Alzheimer Disease Through Functional Independence and Participation. Alzheimer Dis Assoc Disord. 2017;31(3):218-24. Data support the concept that decline in cognition is later reflected in functional deficits.5454 Zahodne LB, Manly JJ, MacKay-Brandt A, Stern Y. Cognitive declines precede and predict functional declines in aging and Alzheimer's disease. PLoS One. 2013;8:e73645. Researchers have studied the temporal relationship of cognitive deficit and functional impairment in AD. The correlation observed supports the hypothesis that, as disease progresses, cognition becomes more clearly related to function and the two measures become more strongly associated. IADLs, specifically finance and medications or outings, are the first to decline with memory deterioration and evolving of behavioural changes; decline in ADLs follows when, gradually, dementia progresses and becomes severe and executive dysfunction becomes evident.5555 Gure TR, Kabeto MU, Plassman BL, Piette JD, Langa KM. Differences in functional impairment across subtypes of dementia. J Gerontol A Biol Sci Med Sci. 2010;65(4):434-41.
Furthermore, IADLs requiring higher neuropsychological functioning seem to be more severely affected than ADLs.5656 Snyder PJ, Kahle-Wrobleski K, Brannan S, Miller DS, Schindler RJ, DeSanti S, et al. Assessing cognition and function in Alzheimer's disease clinical trials: do we have the right tools? Alzheimers Dement. 2014;10(6): 853-60. Observations suggest that the influence of poor cognitive function on impairments in everyday activities becomes more significant as the disease progresses from MCI to the early symptoms of dementia, and then to the severe form of AD, with the magnitude of correlations depending on the complexity of the functional task.5757 Liu-Seifert H, Siemers E, Selzler K, Sundell K, Aisen P, Cummings J, et al. Correlation between Cognition and Function across the Spectrum of Alzheimer's Disease. J Prev Alzheimers Dis. 2016;3(3):138-44.,5858 Liu-Seifert H, Siemers E, Sundell K, Mynderse M, Cummings J, Mohs R, et al. Analysis of the Relationship of Cognitive Impairment and Functional Impairment in Mild Alzheimer's Disease in EXPEDITION 3. J Prev Alzheimers Dis. 2018;5(3):184-7.
FRONTOTEMPORAL DEMENTIA
Frontotemporal dementia (FTD) was first described by Arnold Pick (1851-1924), a Czech psychiatrist, neurologist and neuropathologist, in 1892. It covers a wide range of different conditions, representing a group of neurodegenerative dementias affecting the frontal and/or temporal lobes relatively selectively, even in later stages of the disease. It is most often diagnosed between the ages of 45 and 65. Therefore, FTD has a substantially greater impact on work, family, and economic burden faced by families than AD. There are three subtypes of FTD: the behavioural-variant FTD (bvFTD), the most common presentation of the three variants, characterized by behaviour changes, emotional blunting, loss of empathy, and personality decline, progressive non-fluent aphasia (PNFA) characterized by agrammatism, effortful speech, alexia, and agraphia, semantic dementia (SD) with loss of semantic knowledge and inability to match certain words with their images or meanings.5959 Cipriani G, Carlesi C, Lucetti C, Danti S, Nuti A. Eating Behaviors and Dietary Changes in Patients With Dementia. Am J Alzheimers Dis Other Demen. 2016;31(8):706-16. FTD impinges markedly on everyday function, but studies evaluating functional status in the course of FTD are sparse. Functional difficulties depend on the clinical subtype of dementia and its severity. These differences are recognizable even after controlling for age, education, and disease duration.6060 Mioshi E, Kipps CM, Dawson K, Mitchell J, Graham A, Hodges JR. Activities of daily living in frontotemporal dementia and Alzheimer disease. Neurology. 2007;68(24):2077-84. The bvFTD patients proved the most impaired group and this deficit was particularly evident in ADLs. The PNFA group, despite being the least impaired overall, had subtle, but definite, problems beyond language-based IADLs. Similarly, the SD group was not only affected in language-based activities, but impairment extended to IADLs, such as “leisure and house chores,” “going on an outing,” and “meal preparation.” It should be highlighted that bvFTD may sometimes have a catastrophic effect on ADLs, which may not be reflected in cognitive test scores.6161 Larner AJ, Hancock PR. Activities of daily living in frontotemporal dementia and Alzheimer disease. Neurology. 2008;70(8):658. Patients with SD remain relatively independent in everyday tasks for a much longer period of time, in line with a much more protracted disease progression.6262 Mioshi E, Hodges JR. Rate of change of functional abilities in frontotemporal dementia. Dement Geriatr Cogn Disord 2009;28:419-26. With worsening of the disease, functional outcomes become similar in all FTD variants.6363 O'Connor CM, Clemson L, Hornberger M, Leyton CE, Hodges JR, Piguet O, et al. Longitudinal change in everyday function and behavioral symptoms in frontotemporal dementia. Neurol Clin Pract. 2016;6(5):419-28. Stereotypical behaviour and ADL decline are associated with disability in patients with bvFTD.6363 O'Connor CM, Clemson L, Hornberger M, Leyton CE, Hodges JR, Piguet O, et al. Longitudinal change in everyday function and behavioral symptoms in frontotemporal dementia. Neurol Clin Pract. 2016;6(5):419-28. However, little is known about the rate of deterioration of functional activities in FTD patients over a 12-month period and if the decline is associated with changes on general tests of cognitive function.6262 Mioshi E, Hodges JR. Rate of change of functional abilities in frontotemporal dementia. Dement Geriatr Cogn Disord 2009;28:419-26. The rate of deterioration for bvFTD and PNFA patients are more marked than those reported in studies of AD patients, whereas SD patients decline at a similar rate to AD.6464 Feldman H, Sauter A, Donald A, Gelinas I, Gauthier S, Torfs K, et al. The disability severity Alzheimer disease. Alzheimer Dis Assoc Disord 2001;15:89-95.,6565 Suh GH, Ju YS, Yeon BK, Shah A. A longitudinal study of Alzheimer's disease: rates of cognitive and functional decline. Int J Geriatr Psychiatry 2004;19:817-24. Some authors have investigated the relationship between emotion and social skills assessed by ADL scales.6666 Kipps CM, Mioshi E, Hodges JR. Emotion, social functioning and activities of daily living in frontotemporal dementia. Neurocase. 2009;15(3): 182-9. In fact, decision-making may be affected by the inability to use emotional cues to bias behaviour in social situations. The researchers demonstrated that the ability to perform ADLs is independent of impaired emotion in FTD.
DEMENTIA WITH LEWY BODIES
Dementia with Lewy bodies (DLB) is a progressive, degenerative dementia of unknown aetiology and complex clinical picture. Fluctuating cognitive function is a relatively specific feature of a person with DLB; other clinical features are recurrent visual hallucinations, behavioural problems, extrapyramidal symptoms (typically including rigidity, bradykinesia, and gait instability), and changes in autonomic body functions, such as blood pressure control, temperature regulation, and bladder and bowel function.6767 Varanese S, Perfetti B, Monaco D, Thomas A, Bonanni L, Tiraboschi P, et al. Fluctuating cognition and different cognitive and behavioural profiles in Parkinson's disease with dementia: comparison of dementia with Lewy bodies and Alzheimer's disease. J Neurol. 2010;257:1004-11. It is characterized by cellular inclusions called Lewy bodies in the cytoplasm of cortical neurons, the limbic system and brainstem structures. Lewy bodies are abnormal, eosinophilic spherical structures, resulting in neuronal cytoplasmic inclusions composed of aggregates of alpha-synuclein, a synaptic protein. Little is known about how much individual cognitive, behavioural and motor problems influence functional performance in patients suffering from DLB. In the elderly with motor disorders, functional impairment is particularly significant, especially for continence and walking6868 Richards M, Touchon J, Ledesert B, Ritchie K. Mild extrapyramidal signs and functional impairment in ageing. Int J Geriatr Psychiatry. 2002;17(2):150-3. (up to 75% of DLB patients are reported to have extrapyramidal motor symptoms during the illness). Differences in functional changes between people with DLB and AD tend to manifest in the early stages of the diseases, whereas these difference tend to disappear in advanced stages. According to Stavitsky et al.,6969 Stavitsky K , Brickman AM, Scarmeas N, Torgan RL, Tang MX, Albert M, Brandt J, Blacker D, Stern Y. The progression of cognition, psychiatric symptoms, and functional abilities in dementia with Lewy bodies and Alzheimer disease. Arch Neurol. 2006;63(10):1450-6. at first evaluation, patients with DLB were significantly more impaired on measures of ADL and showed greater dependence on caregivers, but functional changes over time were similar in the two groups. Similarly, another study found no differences in the frequency of development of severe functional impairment between patients with AD and those with DLB.7070 Lopez OL, Wisniewski S, Hamilton RL, Becker JT, Kaufer DI, DeKosky ST. Predictors of progression in patients with AD and Lewy bodies. Neurology. 2000;54:1774-9. In DLB, motor disability best predicts IADL ratings, with severity of cognitive impairment adding predictive value.7171 Poletti M, Emre M, Bonuccelli U. (2011). Mild cognitive impairment and cognitive reserve in Parkinson's disease. Parkinsonism Relat Disord. 2011;17(8):579-86. An explanation is that motor disability in DLB serves as a proxy for the general integrity of the basal ganglia, and cognitive impairment associated with basal ganglia dysfunction (e.g., executive dysfunction) contributes to the IADL deficits in DLB.
PARKINSON’S DISEASE DEMENTIA
Parkinson’s disease (PD) is a long-term, progressive, degenerative nervous system disorder that affects a wide range of functions. It is generally accepted that the main pathological feature of this condition is damaged dopaminergic nigrostriatal pathways with decreased concentration of dopamine in the compact zone of the substantia nigra. Resting tremor is the most common clinical feature. Bradykinesia, rigidity and postural instability are often detectable. It is now recognized that PD is much more than a motor disorder. In the course of the illness, autonomic symptoms, anxiety, mood disorder and cognitive changes are often observed.7171 Poletti M, Emre M, Bonuccelli U. (2011). Mild cognitive impairment and cognitive reserve in Parkinson's disease. Parkinsonism Relat Disord. 2011;17(8):579-86. PD patients may have deficits in multiple cognitive areas from the initial stages of the disease progressing ranging from subtle symptoms (mild cognitive impairment in PD - PD-MCI) to clear cognitive alterations (PD dementia - PDD). PDD has been increasingly better recognized, probably because persons with PD survive for longer than before owing to modern treatment. Different cognitive profiles may exist within PD, but cognitive deficits associated with PD mainly involve executive functions, memory, attention and visuo-spatial functions, but other cognitive functions may also be impaired, often as a secondary consequence of the primary executive disorder.7272 Miura K, Matsui M, Takashima S, Tanaka K. Neuropsychological Characteristics and Their Association with Higher-Level Functional Capacity in Parkinson's Disease. Dement Geriatr Cogn Dis Extra. 2015;5(2):271-84. The aetiology of dementia in PD has not yet been fully established. The rate of early disability in PD patients is associated with declining cognitive function.7373 Foster ER. Instrumental activities of daily living performance among people with Parkinson's disease without dementia. Am J Occup Ther. 2014;68(3):353-62. We know that dysfunction in everyday activities occurs early in the course of the disease and its detection is important for patients to fully understand their substantial difficulties in daily life. For example, people with PD show compromise in housekeeping, managing money, and preparing meals.7474 Shulman LM, Gruber-Baldini AL, Anderson KE, Vaughan CG, Reich SG, Fishman PS, et al. The evolution of disability in Parkinson disease. Mov Disord. 2008;23(6):790-6. While it has been well documented that the extrapyramidal syndrome is associated with impairment in basic ADLs,7575 McKeith IG, Rowan E, Askew K, Naidu A, Allan L, Barnett N, et al. More severe functional impairment in dementia with Lewy bodies than Alzheimer's disease is related to extrapyramidal motor dysfunction. Am J Geriatr Psychiatry 2006;14:582-8.,7676 Bronnick K, Ehrt U, Emre M, De Deyn PP, Nesnes K, Tekin S, et al. Attentional deficits affect activities of daily living in dementia-associated with Parkinson's disease. J Neurol Neurosurg Psychiatry. 2006;77:1136-42. Rasovska and Rektorova also observed highly significant correlations between IADL and functional disability.7777 Rasovska H, Rektorova I. Instrumental activities of daily living in Parkinson's disease dementia as compared with Alzheimer's disease: Relationship to motor disability and cognitive deficits: A pilot study. J Neurol Sci. 2011 Nov 15;310(1-2):279-82. Axial non-dopaminergic symptoms (such as postural instability and gait difficulty) influence IADLs; this is more evident in PDD patients than in persons suffering from PD without dementia.7777 Rasovska H, Rektorova I. Instrumental activities of daily living in Parkinson's disease dementia as compared with Alzheimer's disease: Relationship to motor disability and cognitive deficits: A pilot study. J Neurol Sci. 2011 Nov 15;310(1-2):279-82. However, a recent study demonstrated that cognitive deficits contribute to a greater functional decline in ADL performance.7878 Chen JH, Hong CT, Wu D, Chi WC, Yen CF, Liao HF, et al. Dementia-Related Functional Disability in Moderate to Advanced Parkinson's Disease: Assessment Using the World Health Organization Disability Assessment Schedule 2.0. Int J Environ Res Public Health. 2019;16(12). pii:E2230. More specific to PD than AD is impairment of executive functions as the hallmark feature of cognitive dysfunction.7979 Sabbagh MN, Lahti T, Connor DJ, Caviness JN, Shill H, Vedders L, et al. Functional Ability Correlates with Cognitive Impairment in Parkinson's Disease and Alzheimer's Disease. Dement Geriatr Cogn Disord. 2007;24(5):327-34. Patients with PD showing executive impairment scored lower on instrumental self-maintenance, the use of new devices, and life management compared to those not presenting executive function impairments.7373 Foster ER. Instrumental activities of daily living performance among people with Parkinson's disease without dementia. Am J Occup Ther. 2014;68(3):353-62. Financial capacity represents a cognitive set of knowledge and skills that has a special characteristic as an IADL. It correlates poorly with motor function and is usually clearly compromised in persons with PDD.8080 Martin RC, Triebel KL, Kennedy RE, Nicholas AP, Watts RL, Stover NP, et al. Impaired financial abilities in Parkinson's disease patients with mild cognitive impairment and dementia. Parkinsonism Relat Disord. 2013;19(11):986-90. Disability in IADLs is particularly correlated with PD duration.7979 Sabbagh MN, Lahti T, Connor DJ, Caviness JN, Shill H, Vedders L, et al. Functional Ability Correlates with Cognitive Impairment in Parkinson's Disease and Alzheimer's Disease. Dement Geriatr Cogn Disord. 2007;24(5):327-34.
PROGRESSIVE SUPRANUCLEAR PALSY
Steele, Richardson and Olszewski first described progressive supranuclear palsy (PSP). It is an uncommon degenerative neurological disorder representing the most common form of atypical parkinsonian syndrome. It is a debilitating disease. Symptoms usually emerge at50-60 years of age, with onset ranging from the early forties to late eighties. PSP symptoms include progressive, early-onset postural instability, frequent (unexplained) falls, impaired eye movement (vertical supranuclear gaze palsy), axial (involving neck or trunk) rigidity and speech/swallowing difficulties. Clinically, the presence or absence of functional impairment may dictate a diagnosis of dementia or MCI, respectively.8181 Petersen RC, Doody R, Kurz A, Mohs RC, Morris JC, Rabins PV, et al. Current concepts in mild cognitive impairment. Arch Neurol 2001;58: 1985-92. Affected individuals frequently experience personality changes and memory and executive attention deficits.8282 Kertesz A, McMonagle P. Behavior and cognition in corticobasal degeneration and progressive supranuclear palsy. J Neurol Sci. 2010;289 (1-2):138-43. Mood and behavioural changes may occur. People with PSP may become irritable, depressed or apathetic; they may also become more impulsive in their decision-making.8383 Yatabe Y, Hashimoto M, Kaneda K, Honda K, Ogawa Y, Yuuki S, et al. Neuropsychiatric symptoms of progressive supranuclear palsy in a dementia clinic. Psychogeriatrics. 20;11(1):54-9. Functional disability is high in patients with early-stage PSP.8484 Duff K, Gerstenecker A, Litvan I; investigators and coordinators of the ENGENE-PSP Study Group. Functional impairment in progressive supranuclear palsy. Neurology. 2013;80(4):380-4. Duff et al.8484 Duff K, Gerstenecker A, Litvan I; investigators and coordinators of the ENGENE-PSP Study Group. Functional impairment in progressive supranuclear palsy. Neurology. 2013;80(4):380-4. examined functional profiles of patients with early-stage PSP: 100% of the participants in their study underperformed on all scales, suggesting at least some functional disability.
HUNTINGTON’S DISEASE
Huntington’s disease (HD), sometimes called Huntington’s chorea, is an incurable, lethal, genetically inherited neurodegenerative disorder caused by an expansion of a repeating cytosine-adenine-guanine (CAG) triplet series in the huntingtin gene on the short arm of chromosome 4, resulting in impairment of multiple domains. The illness is characterized by motor, cognitive, and psychiatric symptoms, which begin insidiously and progress over many years, until the death of the individual. It is thought that the variability in disease severity and rate of progression among people with HD is linked to the genetic mutation causing the disease. Patients and their families note the progression of the disease in different ways, as symptoms are present at different times from person to person; however, it is difficult to divide physical and mental traits.8585 Ross CA, Pantelyat A, Kogan J, Brandt J. Determinants of functional disability in Huntington's disease: role of cognitive and motor dysfunction. Mov Disord. 2014;29(11):1351-8. The cognitive deficits can precede the appearance of motor symptoms by as much as 20 years, although they most often emerge in the 10 years leading up to clinical diagnosis of the disease. Because the disease affects the frontal lobes of the brain, planning ability, judgment and decision-making are affected; memory appears especially affected, with problems occurring for both verbal and non-verbal memory; motor functions are disrupted, which interferes with speech and coordination.8585 Ross CA, Pantelyat A, Kogan J, Brandt J. Determinants of functional disability in Huntington's disease: role of cognitive and motor dysfunction. Mov Disord. 2014;29(11):1351-8. Individuals with mildly deteriorating conditions may be able to carry on their ‘normal’ life for many years and continue to function well in their job and with hobbies and activities, but at some point they will become disabled and need help to carry out activities of daily living. The most common functional declines show relationships with behavioural changes, motor functioning, and cognitive deficits. In particular, the latter deficits are responsible for functional losses in managing finances, working performance and driving.8686 Beglinger LJ, O'Rourke JJ, Wang C, Langbehn DR, Duff K, Paulsen JS; Huntington Study Group Investigators. Earliest functional declines in Huntington disease. Psychiatry Res. 2010;178(2):414-8. Certain changes in cognitive abilities are characteristic of HD and can significantly affect the lives of individuals with the disease. For example, cognitive changes may affect the ability of a person with HD to work, manage a household or properly care for him or herself regardless of motor impairment.8787 Hamilton JM, Salmon DP, Corey-Bloom J, Gamst A, Paulsen JS, Jerkins S, et al. Behavioural abnormalities contribute to functional decline in Huntington's disease. J Neurol Neurosurg Psychiatry. 2003;74(1):120-2. Furthermore, in the early stages of HD (duration 0 to 5 years), cognitive deterioration is considered an important factor that determines the loss of functional ability.8888 Marder K, Zhao H, Myers RH, Cudkowicz M, Kayson E, Kieburtz K, et al. Huntington Study Group. Rate of functional decline in Huntington's disease. Neurology. 2000;54(2):452-8. The role of emotional changes needs further elucidation. Regarding neuropsychological performance and depressive symptomatology, these are considered predictive factors of functional disability.8686 Beglinger LJ, O'Rourke JJ, Wang C, Langbehn DR, Duff K, Paulsen JS; Huntington Study Group Investigators. Earliest functional declines in Huntington disease. Psychiatry Res. 2010;178(2):414-8. Behavioural problems associated with the disease are thought to contribute significantly to dysautonomia in daily functions: the significant loss of motivation, absence of initiative, and irascibility present in some Huntington’s chorea individuals may affect their ability to perform basic activities of daily living, even if cognitive and motor functioning remain intact.8787 Hamilton JM, Salmon DP, Corey-Bloom J, Gamst A, Paulsen JS, Jerkins S, et al. Behavioural abnormalities contribute to functional decline in Huntington's disease. J Neurol Neurosurg Psychiatry. 2003;74(1):120-2.
VASCULAR DEMENTIA
Vascular dementia (VaD) is an umbrella term for a group of conditions that recognize vascular brain damage of ischemic, haemorrhagic, or hypoxic type as a common pathophysiological event. Its prevalence increases exponentially with age and its risk doubles every 5.3 years. Clinical3737 Cipriani G, Lucetti C, Danti S, Nuti A. Apathy and dementia. Nosology, assessment and management. J Nerv Ment Dis. 2014;202(10):718-24. manifestation may be cortical or subcortical. Cortical manifestations include cognitive and behavioural symptoms, with or without sensory or motor deficits. Subcortical VaD patients have sensory and motor deficits, gait disorders, dysphagia, dysarthria, extrapyramidal signs, urinary incontinence, emotional lability, impairment of attention and executive function with slowing of information processing. Frequently, small infarcts remain clinically “silent”, producing no apparent symptoms, while larger infarcts are more likely to produce impairment. This is especially true for subcortical white matter ischemic events, which may not produce cognitive dysfunction until a particular threshold has been exceeded.8989 Paul RH, Cohen RA, Ott BR, Zawacki T, Moser DJ, Davis J, et al. Cognitive and functional status in two subtypes of vascular dementia. Neuro Rehabilitation. 2000;15(3):199-205. There is limited information on functional limitations in VaD. This fact may, in part, be due to the clinical heterogeneity in subgroups of patients.3434 Boyle PA, Cahn-Weiner D. Assessment and prediction of functional impairment in vascular dementia. Expert Rev Neurother. 2004;4(1): 109-14. Functional status among people with VaD is often conditioned by sensory and motor deficits, but other underlying factors such as perceptual and mood changes, apathy, and even urinary incontinence, have a negative impact on both ADLs and IADLs. In addition, the co-presence of other diseases such as diabetes, peripheral arteriopathies, and heart failure further reduces functional capacity in VaD patients.5555 Gure TR, Kabeto MU, Plassman BL, Piette JD, Langa KM. Differences in functional impairment across subtypes of dementia. J Gerontol A Biol Sci Med Sci. 2010;65(4):434-41. Therefore, it is not easy to ascertain the main origin of disability in everyday functioning. Individuals with VaD have significant limitations in ADLs (eating, toileting, and transferring) and in IADLs (grocery shopping and cooking).5555 Gure TR, Kabeto MU, Plassman BL, Piette JD, Langa KM. Differences in functional impairment across subtypes of dementia. J Gerontol A Biol Sci Med Sci. 2010;65(4):434-41. IADLs are typically affected at earlier stages with worsening of memory and the development of behavioural disturbances, followed by a progressive decline in ADLs as executive function becomes more affected at later stages of the dementia.1010 Pérès K, Helmer C, Amieva H, Orgogozo JM, Rouch I, Dartigues JF, et al. Natural history of decline in instrumental activities of daily living performance over the 10 years preceding the clinical diagnosis of dementia: a prospective population based study. J Am Geriatr Soc 2008;56:37-44. People suffering from VaD present functional impairment that differs from that presented by AD patients. However, in the scientific literature, there are data that contradict this assertion; in fact, some authors claim that the rate of progression of ADL deficits in VaD is slower than in AD, but that the impairment is qualitatively similar.3434 Boyle PA, Cahn-Weiner D. Assessment and prediction of functional impairment in vascular dementia. Expert Rev Neurother. 2004;4(1): 109-14. Researchers have observed worse performance in almost all variables of both ADLs and IADLs in patients with subcortical ischemic vascular disease compared to those with AD: the fully adjusted model indicated that patients with subcortical ischemic vascular disease had worse performance in toilet use among ADLs and in laundry and ability to handle finances among IADLs than patients with AD.9090 Tu,MC, Huang, CF, Lo CP, Yu Y., Huang WH, Deng JF et al. Comparisons of Daily Functional Performance and Relevant Factors in Patients with Alzheimer's Disease and Subcortical Ischemic Vascular Disease. Neuropsychiatry (London). 2018;8(2):557-69. Associations between specific cognitive domains and functional disability have been studied and show that executive functions consistently predict everyday functioning in cognitively impaired older adults with VaD. This is especially true for IADL dysfunction in patients with VaD due to small vessel disease.9191 Libon DL, Bogdanoff B, Swenson R, Hurka R, Bonavita J, Skalina S, et al. Neuropsychological profiles associated with subcortical white matter alterations and Parkinson's disease: implications for the diagnosis of dementia. Arch Clin Neuropsychol. 2011,16(1);19-32.,9292 Royall DR, Roman DC. Differentiation of vascular dementia from Alzheimer's disease on neuropsychological tests. Neurology. 2000;55(4):604-6. Given the consistency of reports indicating frequent and prominent executive dysfunction among patients with VaD allied to the increasing evidence of its functional significance, evaluations of executive abilities are recommended for VaD patients, particularly those with VaD due to small vessel disease.3434 Boyle PA, Cahn-Weiner D. Assessment and prediction of functional impairment in vascular dementia. Expert Rev Neurother. 2004;4(1): 109-14. Jefferson, et al.9393 Jefferson AL, Cahn-Weiner D, Boyle P, Paul RH, Moser DJ, Gordon N, et al. Cognitive predictors of functional decline in vascular dementia. Int J Geriatr Psychiatry. 2006;21(8):752-4. highlight the impact of executive processes on functional performance, such as using means of transport or managing money. Tasks such as cooking, housekeeping and managing finances are the most vulnerable to cognitive decline. Disturbances in ADLs may be considered unidimensional, but their clinical repercussion might vary according to the hierarchy or importance of the function affected. Changes in executive functioning and memory over a one-year period were predictive of IADL and ADL changes.9393 Jefferson AL, Cahn-Weiner D, Boyle P, Paul RH, Moser DJ, Gordon N, et al. Cognitive predictors of functional decline in vascular dementia. Int J Geriatr Psychiatry. 2006;21(8):752-4. Functional impairment is more severely impaired among those subjects with both cortical infarcts and white matter ischemia, but the differences were largely quantitative rather than qualitative. This finding was not observed for both basic and instrumental activities, as significant group differences were evident only on the more complex instrumental behaviours such as managing money and shopping.8989 Paul RH, Cohen RA, Ott BR, Zawacki T, Moser DJ, Davis J, et al. Cognitive and functional status in two subtypes of vascular dementia. Neuro Rehabilitation. 2000;15(3):199-205.
CONCLUSIONS
Dementia goes beyond cognitive impairment, also encompassing functional disability. With disease worsening, physical, cognitive and clinical problems accumulate and the pattern of loss follows a distinct progression. The first areas requiring external support in functional status are the IADLs and, over time, there is a need for support in performing ADLs. Expected functional decline may be an even more important issue for families than cognitive decline. Cognitive impairment is a condition with a high impact on the aetiology of disability, independently of other clinical variables, while impairment in functions of daily living worsens with clinical stage of dementia. However, data indicate that disability is significantly affected by comorbidity. Behavioural symptoms also play a role in deteriorating function. Executive function is a high complexity cognitive domain which comprises several functions required for the efficient execution of a cognitive process, enabling active retrieval of the information stored in long-term memory. A correlation between dysexecutive syndrome and poor functional status has been observed. Furthermore, it is clear that executive functioning measures are able to predict functional outcome. Knowing the stages of functional decline in dementia can help clinicians to make decisions regarding patients, considering that dementia affects each patient differently. It is important to make the necessary lifestyle adaptations, while remaining flexible about meeting needs as they evolve. Clinicians should be able to assess functional performance, where this information is integral to understanding health and for the optimal provision of clinical care and implementation of individual measures of rehabilitation designed to improve executive function.9494 Martyr A, Clare L. Executive function and activities of daily living in Alzheimer's disease: a correlational meta-analysis. Dement Geriatr Cogn Disord. 2012;33(2-3):189-203.
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This study was conducted at the Versilia Hospital, Neurology Unit, Lido di Camaiore (Lu), Italy.
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Publication Dates
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Publication in this collection
12 June 2020 -
Date of issue
Apr-Jun 2020
History
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Received
25 Oct 2019 -
Accepted
13 Apr 2020