Association between religiosity and functional capacity in older adults : a systematic review

Objective: To verify the association between religiosity and functional capacity in the elderly. Method: a systematic review of literature in the SciELO, Lilacs, MEDLINE/ PubMed and the portal of CAPES Journals databases was performed. The descriptors were selected through the list of Descriptors in Health Sciences (Decs) and Medical Subject Headings (Mesh). Original articles in Portuguese and English, published between 2007 Palavras-chave: Idoso. Religião. Espiritualidade. Atividades Diárias. http://dx.doi.org/10.1590/1981-22562017020.170088


INTRODUCTION
The development of a long-lived population has revealed the importance of understanding human aging which, despite being a process characterized by physical and biological alterations, also causes changes in the psychological, relational and social dimensions 1 .
Since the World Health Organization (WHO) recognized the psychosocial dimensions of health and quality of life, certain aspects have begun to be considered in the evaluation and promotion of health 2 .In the elderly population, one of these aspects is religiosity, which has a variety of implications for the health/disease process 3 .
Religiosity is how much an individual believes, follows, and practices a religion.It can be practiced publicly, in an organized (participation in a church or temple) or non-organized (participation in activities outside a religious institution) manner, and/or intrinsically 4 (prayers and orisons, readings, meditations).
The relationship between the different aspects of religiosity and health in the elderly is of gerontological interest.Some studies have already described the association between religious practice and mortality and physical and mental health 5,6 .In the elderly, it should be considered that physical and mental health is closely linked to functional capacity, a new and important paradigm in health and aging 7 .
The functional capacity of the elderly can be understood as the ability to perform, with autonomy and independence, the basic activities of daily living (BADL), linked to self-care, and instrumental activities of daily living (IADL) related to an independent life in the community 7 .
While a decline in functional capacity is accepted with advancing age, maintaining independence facilitates the life of the elderly person within the family and social environment 8 .The frequency and intensity of this decline vary greatly, and are associated with gender, cognition, educational level, general health conditions and use of medications 9,10 .
Psychosocial aspects also play an important role in this process and have been described as factors associated with functional capacity.According to Kagawa and Corrente 7 , quality of life, self-knowledge and participation in the community influence the performance of BADL and IADL.For Nogueira et al. 10 , non-socialization and a more negative selfperception of health are positively associated with reduced functional capacity.
Considering the importance of functional capacity as an indicator of health for the elderly and religiosity as a psycho-sociocultural dimension of great significance in the daily life of such individuals, it is useful to research and understand the benefits that this dimension can offer to the elderly.The objective of this article, therefore, was to verify the association between religiosity and functional capacity in the elderly through a systematic review of articles related to the theme.

METHODS
A systematic review of literature was carried out based on the following guiding question: What is the association between religiosity and functional capacity in the elderly?The search for articles was carried out in April 2017 in the SciELO, Lilacs, MEDLINE/ PubMed and CAPES Periodicals Portal databases.
Descriptors in Portuguese and English were used in the article search.These were divided into two categories: category 1) elderly (idoso), functionality ( funcionalidade), disability (incapacidade), activities of daily living (atividades de vida diária) and day to day activities; and category 2) religion (religião) and spirituality (espiritualidade).Each term in category 1 was combined with a category 2 term (of the same language), using the Boolean operator "AND", until all combinations had been made.The descriptors were selected from the lists of the Descriptors in Health Sciences (Decs) and the Medical Subject Headings (Mesh).
Original articles in Portuguese and English, published between 2007 and 2017, with a sample composed of elderly individuals aged 60 years or older, were included.Systematic or integrative reviews, case studies, validation of scales studies, dissertations and theses, and studies on religious social support were excluded, as were articles that included elderly and non-elderly adults in their samples.
The article searches and selection process was performed by two independent reviewers with a third evaluator requested in cases of disagreement.After consulting the databases, duplicate studies from more than one database were excluded.Analysis by title and subsequently abstract was carried out, which allowed the exclusion of further studies.The selected studies were read in full and included in the review in accordance with the inclusion and exclusion criteria.An active manual search of the references of the included studies was also performed.
The data were extracted and input into a standard form, adapted from the Cochrane Collaboration 11 .

RESULTS
Although the initial search using the descriptors identified 280 articles, only six were included in this systematic review.The methods used and the excluded articles are summarized in Figure 1.
Among the included studies, only one was qualitative 3 and the others were quantitative.Two articles had a cross-sectional design 12,13 , three were longitudinal [14][15][16] and one was an observational ethnographic study 3 .Five studies [12][13][14][15][16] were conducted in the United States and only one was carried out in Brazil 3 (Chart 1).The samples of the studies were varied.Three articles [14][15][16] were conducted with American elderly persons living in the community, one with diabetic rural elderly persons from different ethnic groups (American, African American and white) 13 , one with institutionalized Hispanic elderly persons (of Mexican origin) who had suffered a stroke 12 and one with elderly Brazilians registered with a Basic Health Unit 3 .
In two articles 12,15 the authors included in the evaluation of functional capacity, as well as the analysis of daily activities, the evaluation of aspects of mobility, such as lower limb strength and gait.
All six articles indicated a significant association between the religiosity and functional capacity of the elderly, revealing its beneficial and protective influence on functionality.Religiosity was associated with functional capacity in three different forms: coping with disability 3 , improved functional capacity 13,14 and delayed functional decline 12,15,16 .Different aspects of religiosity displayed an association with functional capacity, such as: participation in religious activities [12][13][14][15] , a position of religious leadership 16 and religious beliefs and traditions 3 .
In three articles [13][14][15] , the positive association of religiosity with functional capacity was linked only to public religious activities, whether organized or non-organized, and not intrinsic religious practices such as prayers and readings.

DISCUSSION
Religiosity positively affects physical and mental health, promoting successful aging 17 .Many elderly persons attribute a special value to religiosity in relation to the improvement of their condition, considering that it contributes to quality of life, wellbeing, and social and psychological integration 1 .In addition, one study 3 included in this review identified an association between religiosity and coping with disability, meaning that it is a valuable resource for the acceptance of common losses in aging, such as the loss of functional independence 18 .
According to Santos et al. 3 , coping responses are alternatives where the negative element is controlled.Religious beliefs and behaviors therefore help the elderly to cope with the suffering experienced in functional dependence, and serve to facilitate problem solving and prevent or alleviate negative emotional consequences.
In the coping process, the individual plays an active role, using religious resources as an aid to reduce anxiety, increase hope, and broaden the meaning of existence.Religious involvement can provide an increased sense of purpose and meaning in life, which is associated with a greater capacity to respond positively to the demands of everyday life.In addition, meditations and prayers enable the mind to focus on other things, diverting thought away from problems and afflictions 18,19 .
The spiritual support of people in the religious community is also a positive resource for coping with the effects of functional disability, as it provides the elderly with a manner of restructuring physical health problems by helping them find meaning in the face of such adversity.A study of 583 elderly Americans showed that those with a high level of spiritual support had gains in personal control when dealing with functional dependence 20 .
Other authors identified greater social support 21 and more positive forms of religious coping 22 in individuals with religious leadership roles, which in this review was associated with a slower functional decline 16 .According to Hayward and Krause 16 , religious leadership can contribute to successful aging by providing a sense of purpose and positive selfimage; in addition, the personal value generated by group leadership provides the motivation to engage in healthier behavior in order to remain active in the role, and potentially reduces the stress and depression associated with a loss of roles, thereby reducing their impact on physical health.
The association between religiosity and improved functional capacity described in two articles included in this review 13,14 is corroborated by the findings of a previous review 17 that showed benefits of religiosity in the physical and functional evolution of hospitalized elderly persons, as well as a positive correlation between spirituality and functionality in adults in rehabilitation.In contrast, the study by Santos and Abdala 18 , which evaluated the relationship between religiosity and the dimensions of healthrelated quality of life among the elderly, did not find any association between religiosity and the "functional capacity" dimension.
Moraes and Souza 19 , however, found that elderly persons whose personal beliefs gave more meaning to life had up to a tenfold greater chance of experiencing a successful aging process.According to Luccheti et al. 17 , religiosity is one of the determining factors of successful aging, which encompasses high physical functioning and the absence of functional disability.It can therefore be inferred that religiosity, by positively influencing successful aging 20 , also influences the improvement of functional capacity.
Other benefits to the elderly have been attributed directly to religiosity, such as a reduced fear of falling 21 , a lower prevalence and slower evolution of neuropsychiatric diseases 17 , and greater adherence to medical treatments and preventive care 22 , which also contributes to better functional capacity 23,24 .
The association between religiosity and the delay in functional decline identified in some of the studies 12,15,16 in this review can be justified by the fact that elderly people with religious beliefs are more likely to adopt healthy habits and reduce alcohol and cigarette intake 1,25 , which makes them less exposed to risk factors for chronic diseases that anticipate the loss of functionality, such as diabetes 26 , arterial hypertension, heart and lung diseases 27 , thus delaying functional decline.Ratifying this idea, studies have already shown a lower index of cardiovascular diseases 28 and depression 29 among the elderly who engage in religious and spiritual activities.Thus, religiosity seems to protect the elderly against chronic diseases that accelerate functional decline.
Four articles [12][13][14][15] included in this review identified an association between participation in religious activities and a better performance in BADL and IADL.Corroborating our findings, previous studies have shown that religiosity is closely linked to factors such as community participation, socialization and well-being 17,30 and these factors have previously been associated with a better performance in BADL and IADL 7,31 .This suggests that by producing such psychosocial benefits among the elderly, religiosity contributes to greater independence in daily activities.
While participating in social and leisure activities themselves also provides these psychosocial benefits 32 , religiosity goes further than social participation as it is associated with intrinsic religious practice 13,15 .Some authors 33,34 have identified the benefits of intrinsic practices such as prayer and meditation in coping with chronic diseases and pain, generating feelings of well-being and relaxation.Another study 4 found that a higher level of intrinsic religiosity was associated with an improved mental component and quality of life in the elderly.However, although intrinsic religiosity brings benefits to aspects associated with functionality 21,24,35 , three studies [13][14][15] found no association between functional capacity and intrinsic religious practice.
A possible hypothesis for the non-association of intrinsic religiosity with functional capacity may be the fact that elderly persons who describe a greater participation in intrinsic religious practices are those with inferior functionality, as functional decline intensifies with increasing age.There is then a tendency to reduce participation in formal religious activities, due to physical and functional limitations.To compensate for non-attendance at church, temples and organized events, the elderly individuals end up spending more time on intrinsic religious activities 18 .
The association between the greater frequency of intrinsic religious practices and functional decline, together with the association between intrinsic religiosity and functional capacity, remain unclear, however.Comparative studies of the functionality of elderly people who attend religious activities and those who frequent social activities are also necessary to clarify whether both activities have the same effect on the functional capacity of the elderly.
This study presents certain limitations, such as the scarcity of Brazilian articles, meaning that the analysis is largely based on samples of American elderly persons.Another limitation to be considered is that there was no standardization in the instruments of the evaluation of religiosity, which may result in different interpretations of the term "religiosity" by different authors.This article does not consider a specific type of religion, but rather the benefits of religious activities for functional capacity.

CONCLUSION
Based on this review, it can be concluded that religiosity is associated with improved functional capacity, delayed functional decline and more effective coping with disability.
Religious beliefs and traditions, participation in religious activities, and leadership performance were aspects of religiosity that were associated with functional capacity.
Despite generating well-being among the elderly, the association of intrinsic religiosity with functional capacity is still unclear.
More studies are therefore needed to clarify the real association between functional capacity and intrinsic religiosity, as well as a greater appreciation of religious aspects by all professionals who deal directly with the elderly, so that the psychosocial dimension is considered in the care of this population and the principle of integrality in the Unified Health System is respected.
Summary of studies selected for review.Brasília, Distrito Federal, 2017.
to be continued Chart 1.