Dementia among older adults living in long-term care facilities: an epidemiological study

ABSTRACT Institutionalization has been associated with social isolation, psychological and cognitive changes, and decreased levels of physical activity in older adults. Objectives: The aim of this study was to estimate the prevalence of dementia, mild cognitive impairment (MCI), and functional dependence in older adults dwelling in two different Brazilian long-term care facilities (LTCFs). Methods: This is a cross-sectional study with 185 older people of both sexes, aged 60 years or over, residing in two LTCFs in the city of Montes Claros-MG, Brazil. The diagnosis of MCI and dementia was performed using the Diagnostic and Statistical Manual of Mental Disorders. Results: Prevalence rates of dementia, MCI, and functional dependence in institutionalized older participants were 62.3, 15.1, and 78.9%, respectively. There was a significant reduction of the Mini-Mental State Examination scores according to the increase of the institutionalization period in LCTFs and the age of older adults (p<0.001). Conclusions: Prevalence of dementia and functional dependence of older adults residing in LTCFs exhibited higher rates compared to the other older population worldwide. A higher institutionalization period is related to a greater cognitive decline.


INTRODUCTION
T he number of people with dementia worldwide was estimated to be more than 47 million in 2015. In 2030, it is estimated that there will be more than 75 million people with dementia, reaching 135 million in 2050. 1 In Brazil, the prevalence of dementia varies from 5.1 to 19% in people aged 60 and over. 2 With the population aging, family insufficiency and the difficulties of older adults' caregivers also emerge, increasing the number of individuals residing in long-term care facilities (LTCFs) for older adults. 3 Among the various reasons that lead older persons to be institutionalized, the limitation to perform activities of daily living (ADL), the onset of cognitive impairment, neurodegenerative diseases, neuropsychological disorders, and caregiver burden are the most common. 4,5 In addition, institutionalization itself has been associated with social isolation, psychological and cognitive changes, and decreased levels of physical activity in older adults. [6][7][8] Furthermore, the decreased general stimuli and family distancing contribute to a possible increase in the prevalence of dementia in LTCFs. 3 Therefore, this study aimed to estimate the prevalence of dementia, mild cognitive impairment (MCI), and functional dependence in older adults living in Brazilian LTCFs.

Study design and participants
This is a cross-sectional study conducted from January 2018 to October 2019 following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. 9 The sample comprised 185 institutionalized older persons from two LTCFs in Montes Claros, Minas Gerais, Brazil ( Figure 1). Older men and women aged ≥60 years were recruited. Individuals with severe visual and auditory deficits were excluded from cognitive assessment and determination of the prevalence of dementia. However, these individuals were kept in the study for analysis of functional dependence. The manager of each LCTF signed a consent form on behalf of participants in the present study because most of the institutionalized older adults had the manager as the representative signer. However, participants who were able to sign the consent form were advised to do that. This study was approved by the Research Ethics Committee (No. 2.398.863/2017).   Edition (DSM-V). 10 The Mini-Mental State Examination (MMSE) was used to detect cognitive impairment. 11 The maximum score is 30 points and the cutoff point is given according to schooling. 12 MMSE was used to replace Montreal Cognitive Assessment (MoCA). This replacement was chosen due to very low educational level of the participants and to the fact that MoCA presents assessment items that are not part of the routine of institutionalized older adults.

Functional dependence assessment
The Barthel index was used to assess older adults' functional dependence. It is an instrument widely used for the assessment of functional independence and mobility. 13 The Barthel Index assesses basic ADL and measures functional dependence for personal care, mobility, transferences, and eliminations. Each item is scored according to the individual's performance. An overall score is formed by assigning points to each category. The score ranges from 0 to 100, in five-point intervals, and the higher scores indicate greater independence. 14 The Barthel index cutoff points are 90-100 independent; 60-89 slightly dependent; 40-59 moderately dependent; 20-39 severely dependent; and <20 completely dependent. 15 Data analysis Descriptive statistics are displayed as measures of central tendency, dispersion, and frequencies. Continuous variables were presented with n, mean, standard deviation, minimum and maximum. Categorical variables were presented with valid absolute and relative frequencies.
Data normality was verified through the Kolmogorov-Smirnov test. For each statistical test performed, the conceptual assumptions were verified and assumed.
Multiple linear regression and multinomial logistic regression were conducted to identify the associations between continuous and categorical variables, respectively. Nonparametric correlations were also performed through the Spearman test between continuous variables and cross-tabulation with Pearson's χ 2 test for categorical variables. All analyses were established at the level p≤0.05, performed in the IBM SPSS ® version 24 software.

RESULTS
Demographic data and sample characterization are shown in Table Table 2).
The multinomial logistic regression model showed an association between altered cognition and total functional dependence (OR=6.21; p=0.01, adjusted for sex and age). Although age was significantly associated with total functional dependence (OR=1.07, p=0.01) and moderate functional dependence (OR=1.06, p=0.04), this result is not very significant (Table 3). In addition, women were almost 2.5 times more likely to have dementia than men (OR=2.41; p=0.03).
Language was the MMSE field that most correlated with the overall global cognition score (Rho=0.89, n=146, p<0.01). The best performance in the MMSE was correlated to the best performance in the Barthel index (Rho=0.45, n=157, p<0.01). Temporal orientation was the MMSE field that most correlated with Barthel (Rho=0.39, n=146, p<0.01). Transference was the Barthel item that most correlated with the general functionality score (Rho=0.87, n=174, p<0.01). The variable food was the Barthel index item that most correlated with MMSE (Rho=0.47, n=146, p<0.01).

DISCUSSION
This study identified a 62.3% prevalence of dementia in institutionalized older adults. Furthermore, there was an association between altered cognition and total functional dependence and the institutionalization period. The prevalence of dementia herein shown is greater than that found in a recent meta-analysis, 16 which showed that 53% of institutionalized older adults were  diagnosed with dementia, considering data obtained worldwide. On the other hand, the observed prevalence of dementia in the noninstitutionalized older adults in Brazil ranges from 5.1 to 19%. 2 Social isolation, loss of contact with the family, low cognitive stimulation, and decreased physical activity contribute to the high prevalence of dementia in LTCFs. 3 Such data displays a worrying reality, which denotes a high cost for health promotion in LTCFs, in addition to inadequate health, with a propensity to increase the morbidity and mortality rates of institutionalized older adults.
In this study, a low mean of the Barthel index was observed and presented an institutionalized population with many functional impairments. According to the study by Ang et al., 17 functional decline is common in LTCFs. The risk factors are age, dementia, and other diseases in institutionalized older adults, such as stroke and urinary incontinence. The level of dependency is a risk factor for older adults to remain institutionalized. Evidence points that cognitive decline affects the functional state. 18 As noted in this study, the risk of total functional dependence is more than 60 times higher in the older population with impaired cognition. The prevention of functional decline may be possible through better management of dementia, falls, and chronic medical conditions, as well as the implementation of rehabilitation and quality care in LTCFs. 17 The MMSE decreased according to the institutionalization period, with a decrease of 0.2 points per month (2.4 points per year), which corroborates the study by Harmand et al., 18 who found that the institutionalization of older adults was significantly associated with a decrease of 2.8 points in the MMSE score, with a greater increase in cognitive decline after institutionalization and a decrease of 0.2 points per year. Considering that dementia itself is a predictor of institutionalization, older adults with dementia have a higher tendency of being institutionalized than older people with mild dementia/cognitive decline. 19 Certain components of dementia, such as severity and functional impairment, make older adults more susceptible to institutionalization. 20 Furthermore, it appears that certain conditions exist in LTCFs, but not yet fully elucidated, which predispose older adults to cognitive decline. Institutionalization could have negative physical and psychological effects on older persons. Another possible element of cognitive decline is the lack of cognitively stimulating activities and physical exercise. In addition, family commitment and participation in social activities, which do not often occur in LTCFs, provide protective effects on older adults' cognition. 21 Furthermore, the influence of age on dementia is widely described in the literature and it is known that the prevalence of dementia doubles every 5 years in individuals aged between 65 and 85 years, although these data are from non-institutionalized individuals. 22 Older women showed an increased risk of dementia compared to male individuals in the present study. According to the study by Zhang et al., 23 such a higher prevalence of dementia may be due to longer life expectancy in women. In addition, the higher frequency of low schooling in females may also explain the higher risk of dementia in this group.
Language and food were the fields that most correlated with the mental state of institutionalized older adults, while temporal orientation and transference were the fields that most correlated with the functional profile. Thus, it is assumed that the evaluation of these fields could be used for a simplified screening to check the mental status and functionality of older adults living in LTCFs.
Our study presents some limitations. Other tests, such as MoCA and Pfeffer, are more used to assess cognition and functional dependence in the general older population. However, such instruments do not apply to the reality of LTCFs. Therefore, the MMSE and Barthel index were applied as they provide a more similar approach to the reality of institutionalized older people, although they are not being used as a gold standard for the diagnosis of dementia. The differential diagnosis of the causes of dementia syndromes is difficult to run in LTCFs, due to the absence of companions who deeply know the clinical history of the older adults, the incomplete and not detailed medical records, the lack of complementary exams, and the high frequency of advanced dementia. We limited the diagnosis of people with dementia and non-dementia, without detailing those who have a primary neurodegenerative disease (e.g., Alzheimer's disease), acquired processes (e.g., stroke), and even potentially reversible diseases (e.g., normal pressure hydrocephalus, neurosyphilis, vitamin deficit, depression, and delirium). Moreover, not having a cognitive assessment at the time of institutionalization makes it difficult to understand how the older adults' cognition evolves over time in the institution, making it impossible to compare the current cognitive status with cognition on the admission to the LTCF. The majority of Brazilian LTCFs are philanthropic. They receive low or no government support and remain to provide their services supported by donations. These institutions have few workers in their staff and a lack of highly specialized health professionals. However, they resist and survive to keep offering an important service to the community. Additionally, making associations and correlations between variables becomes a challenge, considering the heterogeneous environment of the LTCFs, in which older individuals have different comorbidities, in addition to different social, psychological, and cultural conditions. Finally, subjects were Brazilian citizens, thus belonging to a specific sociocultural context. It this sense, prevents from generalizing results to other countries, characterized by different healthcare and welfare systems, and different family organization.
The prevalence of dementia, MCI, and functional dependence was 62.3, 15.1, and 78.9%, respectively. Institutionalization time might be one of the risk factors for further cognitive decline in older adults. Thus, there is a need for actions at LTCFs, which include measures to improve socialization, cognitive stimulation, physical exercise, rehabilitation, treatment of comorbidities, and adequate management of dementias.