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The objective of this study was to examine how the effect of depressive symptoms on cognitive function is modified by church attendance.
We used a sample of 2759 older Mexican Americans. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) at baseline, 2, 5, 7, and 11 years of follow-up. Church attendance was dichotomized as frequent attendance (e.g., going to church at least once a month) versus infrequent attendance (e.g., never or several times a year). Depressive symptoms were assessed by the Center for Epidemiologic Studies Depression Scale (CES-D; score ≥16 vs <16). General linear mixed models with time-dependent covariates were used to explore cognitive change at follow-up.
In unadjusted models, infrequent church attendees had a greater decline in MMSE scores (drop of 0.151 points more each year, standard error [SF] = 0.02, p < .001) compared to frequent church attendees; participants having CES-D scores ≥16 also had greater declines in MMSE scores (drop of 0.132 points more each year, SE = 0.03, p < .001) compared to participants with CES-D score <16 at follow-up. In fully adjusted models, a significant Church attendance × CES-D × Time interaction (p = .001) indicated that, among participants with CES-D scores ≥16, infrequent church attendees had greater decline in MMSE scores (drop of 0.236 points more each year, SE = 0.05, p < .001) compared to frequent church attendees at follow-up.
Church attendance appears to be beneficial for maintaining cognitive function of older persons. Church attendance moderates the impact of clinically relevant depressive symptoms on subsequent cognitive function.
MAINTENANCE of cognitive function in old age has been linked to multiple factors: exercise, good nutrition, education, and participation in social or leisure activities (1–4). For example, Verghese and colleagues (1) reported that highly educated persons were less likely to develop dementia than were less educated persons; compared to persons with high school education or less, those with college education reported greater participation in doing crossword puzzles and playing musical instruments, activities found to be significantly associated with lower risk of developing dementia after 5 years of follow-up.
Involvement in religious activity has also been associated with better cognitive function (5–8). Hill and colleagues (8) reported that older Mexican Americans who attend church monthly, weekly, and more than weekly tend to exhibit slower rates of cognitive decline than those who do not attend church. Using data from the New Haven Established Populations for Epidemiologic Studies of the Elderly (EPESE), Van Ness and Kasl (6) found that, compared with those who attend church less than once per week, those who attend church once per week or more exhibited reduced odds of cognitive dysfunction over 3 years. In contrast, depressive symptoms have been reported to be associated with a decline in cognitive function (9–12). Nevertheless, little is known about how involvements in religious activities interact with depressive symptoms to influence cognitive function in the elderly population. Because religious involvement can provide meaning, purpose, and hope in later life, and religious attendance may promote social interaction and stimulation, it may help to moderate the effects of depression on cognition with aging.
To extend the earlier work of Hill and colleagues (8) who used data from four waves of the Hispanic EPESE, the purpose of this study is to assess the potential influence of church attendance on the relationship between depressive symptoms and cognitive function, using data from five waves of the Hispanic EPESE.
Data are from the Hispanic EPESE, a population-based study of 3050 noninstitutionalized Mexican Americans 65 years old or older (83% response rate) residing in five Southwestern states: Texas, California, New Mexico, Colorado, and Arizona. Sampling and data collection are described elsewhere (13). Persons with severe visual impairment (n = 291) were excluded from this analysis. The present study used baseline data (1993–1994; n = 2759) and the data obtained from the 2-year follow-up (1995–1996; n = 2225), the 5-year follow-up (1998–1999; n = 1822), the 7-year follow-up (2000–2001; n = 1561), and the 11-year follow-up (2004–2005; n = 1091). Over the 11-year follow-up, 473 participants refused or were lost to follow-up and 1411 were confirmed dead through the National Death Index file and from reports from participants’ relatives. After complete description of the study to the participants, written informed consent was obtained for all interviews.
The outcome was cognitive status measured by the Mini-Mental State Examination (MMSE) (14) scores from baseline to 2, 5, 7, and 11 years later. MMSE was used as continuous (range 0–30).
The two main variables of interest in this analysis were church attendance and depressive symptoms, and were measured at baseline and at 2, 5, 7, and 11 years later. Church attendance was assessed by the question “How often do you go to church or religious services? 1—never or almost never; 2—several times a year; 3—once or twice a month; 4—almost every week; or 5—more than once a week.” Church attendance was dichotomized as infrequent attendance (never or almost never, several times a year, or once/twice a month) versus frequent attendance (almost every week or more than once a week). We dichotomized church attendance in that way because, compared with group 5, group 4 did not have a statistically significant difference on MMSE scores at follow-up (adjusted slope = –0.02, p = .70), but the other groups had statistically significantly lower MMSE scores (group 3 =–0.18, p = .006; group 2 =–0.21, p = .001, and group 1 =–0.27, p < .001).
Depressive symptoms were measured by using the Center for Epidemiologic Studies Depression Scale (CES-D) (15). Scores range from 0 to 60, where higher scores indicate increased depressive symptoms. The conventional cut point of 16 was used to classify respondents as “depressed” or as having clinically relevant depressive symptoms versus “non-depressed” (15).
Sociodemographic variables examined were age, gender, marital status, living arrangements, and education. In all waves, medical conditions were assessed with a series of questions asking the respondents if they had ever been told by a doctor that they had diabetes, heart attack, stroke, and/or hypertension. Corrected bilateral near vision acuity was measured by having participants hold cards at least 7 inches from their eyes and asking them to read the numbers (three sizes: 7, 10, and 23 points) (16). Participants unable to read the 23-point size were excluded. Participants who could only read the 10- or 23-point size were considered to have near vision impairment, and participants who could read the 7-point size were considered to have adequate near vision. Corrected bilateral distant vision was measured using a modified Snellen test (Es at 4 m) (16). Participants unable to read Es ≥20/200 (functional blindness) were excluded. Those who could only read Es ≥20/60 were considered to have distant vision impairment, and participants who could read ≤20/40 were considered to have adequate distant vision. Hearing was assessed using the 10-item Hearing Handicap Inventory for the Elderly-Screening version (HHIE-S) (17) (scores 0–40), where higher scores indicate more difficulties with hearing. The HHIE-S was used as continuous variable. Near vision, distant vision, and hearing were used only at baseline because the measures changed in the other waves.
In all waves, functional status was assessed by seven items from a modified version of the Katz Activities of Daily Living (ADL) scale (18). ADLs included walking across a small room, bathing, grooming, dressing, eating, transferring from a bed to a chair, and using the toilet. ADL score (range 0–7) was used as continuous variable.
We examined sociodemographic and health characteristics at baseline for participants stratified by categories of church attendance (frequent vs infrequent) using the chisquare test for categorical variables and the t test or the Wilcoxon rank-sum test for continuous variables. To test whether church attendance (frequent vs infrequent) or depressive symptoms (CES-D <16 vs ≥16) were associated with cognitive function decline, and whether church attendance and depressive symptoms have an interaction effect on cognitive function over time, we fitted unadjusted and adjusted general linear mixed models using the MIXED procedure in SAS. We used these models for longitudinal analysis of the multi-wave Hispanic EPESE data set as this analytic approach accounts for unbalanced data (e.g., missing data), modeling of covariance structure, modeling the trajectory of cognition change, and incorporated with time-dependent covariates (19,20). For example, some sociodemographic characteristics and medical conditions may change over time and could subsequently affect cognitive function. In addition, participants with at least one follow-up through the five waves of data collected, contributed to the longitudinal calculations.
In longitudinal multivariate analysis, the time-dependent effects (measured at all five waves) of church attendance, depressive symptoms, marital status, living arrangements, medical conditions, and functional status along with the fixed effects (measured at baseline) of age, gender, education, and sensory measures (near and distant vision, hearing) on cognitive function were examined over 11 years of follow-up. All analyses were performed using the SAS System for Windows (version 9.1; SAS Institute, Inc., Cary, NC), and significance level was set at p < .05, two-tailed.
Of an initial baseline sample of 3050 participants, 291 met the criteria for severe visual impairment (who were blind [n = 45], who could only read >23 points for near vision [n = 207], or >20/200 for distant vision [n = 39]), and were excluded resulting in a study sample of 2759 participants. Participants excluded for severe vision problems were more likely to be older, unmarried, less educated, depressed, disabled, an infrequent church attendee, or to report stroke than were those who remained in the study.
The distribution at baseline, 2, 5, 7, and 11 years for frequent church attendees was 49%, 49%, 50%, 48%, and 57%; for having clinically relevant depressive symptoms (CES-D ≥16) it was 23%, 14%, 17%, 13%, and 20%. Table 1 presents baseline characteristics of participants overall and by church attendance categories. Frequent church attendees were more likely to be younger, female, and more educated; to have near or distant vision impairments; and to have more ADL limitations compared to infrequent church attendees. In addition, frequent church attendees were less likely to report diabetes, heart attack, and stroke compared to infrequent church attendees.
Figure 1 presents unadjusted means in MMSE scores (with 95% confidence intervals) by church attendance and depressive symptoms categories measured at baseline and at follow-up. Frequent church attendees had significantly higher MMSE scores compared to infrequent church attendees at baseline (p = .010) and at follow-up (all p < .001); the slopes of decline were steeper for infrequent church attendees than for frequent church attendees (drop of 0.151 points more each year, standard error [SE] = 0.02, p < .001). Participants with CES-D ≥16 had significantly lower MMSE scores than participants with CES-D <16 at baseline and at follow-up (all p < .001); the slopes of MMSE decline were steeper for participants with CES-D ≥16 (drop of 0.132 points more each year, SE = 0.03, p < .001) compared to participants with CES-D <16.
Figure 2 presents unadjusted means (with 95% confidence intervals) in MMSE scores by combined categories of church attendance and depressive symptoms measured at baseline and at follow-up. Participants who were frequent church attendees had higher mean MMSE scores than those who were infrequent church attendees; the difference was small at baseline and wider at 11 years of follow-up, especially among those who had clinically relevant depressive symptoms. For example, the mean MMSE scores among participants with CES-D < 16 at baseline were 25.8 for frequent church attendees and 25.2 (p = .003) for infrequent church attendees; at 11 years were 22.0 for frequent and 20.4 (p < .001) for infrequent church attendees. Whereas the mean MMSE scores among participants with CES-D ≥16 at baseline were 24.3 for frequent church attendees and 24.5 (p = .58) for infrequent church attendees, at 11 years they were 20.6 for frequent and 17.4 (p < .001) for infrequent church attendees.
Table 2 shows the adjusted mixed models predicting MMSE scores over the 11-year follow-up as a function of church attendance, depressive symptoms, and other characteristics, along with the interaction terms. Variable time is testing the slope of MMSE scores over time. The term for the interaction between the predictor variable and time represents the longitudinal effect of the baseline measure of that variable on the annual rate of decline in performance of the MMSE (e.g., for two-way interactions, a negative sign preceding the estimate indicates decline in MMSE scores over time). Infrequent church attendees had a greater decline in MMSE scores (drop of 0.059 points more each year, SE = 0.02, p = .013) compared to frequent church attendees through 11 years of follow-up (interaction of Church attendance × Time). Also, participants with CESD ≥16 had a greater decline in MMSE scores (drop of 0.152 points more each year, SE = 0.06, p < .001) compared to participants with CESD < 16 through 11 years of follow-up (interaction of Depression × Time). A significant church attendance × CES-D × Time interaction effect was found (p = .001) and showed that the slopes of decline (per year) of the MMSE scores were –0.452 (SE = 0.02) for those who were not depressed (CESD <16) and were infrequent church attendees, –0.392 (SE = 0.02) for those who were not depressed (CESD < 16) and were frequent church attendees, –0.604 (SE = 0.03) for those who were depressed (CESD ≥16) and were infrequent church attendees, and –0.368 (SE = 0.04) for those who were depressed (CESD ≥16) and were frequent church attendees. Then, among participants with CES-D ≥16, infrequent church attendees had a greater decline in MMSE scores (drop of 0.236 points more each year, SE = 0.05, p < .001) compared to frequent church attendees. Additional analysis using CES-D as a continuous variable (total score) showed a significant Church attendance × CES-D × Time interaction effect (p < .001) indicating a similar trend, thus, among participants with higher CES-D scores, those who were infrequent church attendees had a greater decline in MMSE scores compared to frequent church attendees.
We examined the relationship between church attendance and depression on cognitive functioning among older Mexican Americans. We found that infrequent church attendance was associated with greater cognitive decline over time. We also found that participants having clinically relevant depressive symptoms (CES-D ≥16) had a greater decline in MMSE scores over time compared to participants having no clinically relevant depressive symptoms (CES-D <16). In addition, we found a significant interaction effect between church attendance and depressive symptoms on cognitive decline over time, finding that, among those with depression, the inverse relationship between church attendance and cognitive function was particularly strong. Those associations were significant after adjustment for demographics, sensory measures, comorbidities, and functional status.
Other studies have found associations between religious involvement and cognitive function. A study of 850 hospitalized male veterans found religious coping positively correlated with better cognitive function (5). Pargament and colleagues (21) found that improvements in cognitive status were predicted by seeking support from clergy or church members and active religious surrender. In another study, Koenig and colleagues (7) found that cognitive function was better in those individuals more involved in private religious activities such as prayer or Bible study and those who observers rated as more spiritual or religious. Finally, Hill and colleagues (8), using an approach different from that of our study (linear growth curve models) reported that religious attendance was associated with less cognitive decline in older Mexican Americans projected from baseline to 7 years later.
Involvement in religious activity has been postulated to affect cognitive performance by increasing intellectually stimulating activities and, subsequently, leading to a maintenance of brain reserve (1,22). Religious coping activities such as prayer or scripture reading may lead to better cognitive functioning, or perhaps inversely, better cognitive function may facilitate private religious activities (given the highly cognitive nature of such practices) (7). Other studies have shown that sensory stimuli along with social and leisure activities are associated with a lower risk of developing dementia in older people (1,22). Such stimulation may have beneficial effects on neuronal development (e.g., new synapses), function (e.g., DNA repair), and survival (23,24). By contrast, lack of cerebral stimulation or sensory impairment has a deleterious effect on brain function by producing cerebral atrophy and intellectual decline (23–25). In addition, church attendees engage in healthier lifestyles that can protect cognitive function (26).
The central finding in our study was that church attendance may preserve cognitive functioning among depressed Mexican American older adults. Depressive symptoms have been reported as a risk factor for cognitive decline (9–12), and church attendance has been reported to be associated with fewer depressive symptoms (27); however, the interaction effect of depression with church attendance on cognition has not been reported before in the literature. According to our data, religious involvement seems to be important in maintaining cognitive function over time for older individuals with clinically relevant depressive symptoms.
There is rationale to help explain the benefits of church attendance on cognitive functioning among depressed Mexican American older adults. First, church attendance, as a unique form of social engagement, may influence cognitive functioning among depressed individuals by social connections and activities, providing a dynamic and rich environment that requires the mobilization of cognitive faculties, which, in turn, inhibits the deterioration of cognitive performance in old age (6,28), presumably through the maintenance of dense neocortical synapses in the brain.
Second, church attendance may buffer the impact of stress or illness on cognitive functioning among those persons who are depressed. For example, one type of church support, emotional support from fellow church members, tends to reduce the impact of financial strain on self-rated health in older people (29). In addition, older frequent church attendees may develop a more close personal relationship with God leading to better health because being closer to God helps them feel more optimistic and more hopeful (30). Older people who are optimistic and hopeful tend to cope more effectively with stressful life events and illness, and enjoy better health (30–33). Because patients who frequently use religion to cope with stress have the lowest level of cognitive symptoms of depression (such as loss of interest, social withdrawal, hopelessness, and poor self-esteem), and because cognitive symptoms of depression are often less responsive to pharmacotherapy than somatic symptoms, religious coping is an important potential cognitive therapy treatment in elderly patients who may experience frequent milder depression linked to their declining health status (34).
Third, we know that serum cortisol levels are increased in patients with depression, particularly more severe depression (35,36). We also know that high serum cortisol may affect cognitive functioning, based on work in both animal studies and humans (37–39). Religious attendance, through social support and social interaction, may reduce the elevations in cortisol that are seen in the depressed, and therefore reduce the negative impact that depression has on cognitive function. In addition to the social support and interactions, religious sermons, hymns, and corporate prayer may give depressed people hope and a sense of meaning, which also helps to moderate the severity of the depression (even while depression at some level may continue to persist, although not at the level that would cause an increase in cortisol level). However, studies are needed to see if this mechanism is actually true, and this would involve measuring religious attendance, depression, cortisol levels, and cognitive functioning. Finally, church attendance, as a form of religious meditation, might improve executive functions such as manipulation of information in the verbal working memory or attention span and visuomotor speed among those persons who are depressed (40).
This study has limitations. First, we did not have the same sensory measures after the baseline evaluation so sensory measures could not be examined as time-dependent, resulting in a potential underestimation of their effect. Second, church attendance may be a marker of health and other factors that we did not measure. Third, one cannot prove causality from an observational study, although the order of change documented in this study is relevant because it suggests more than simple correlation. Nevertheless, an important contribution of this study is the potential benefit of church attendance on cognitive functioning for depressed individuals, a population in which cognitive changes with depression are not well understood. Also, the findings in this study remained significant after controlling for time-dependent covariates likely to affect cognitive functioning.
Our results over 11 years of follow-up showed that infrequent church attendance and depressive symptoms predict cognitive decline in older Mexican Americans independent of other health factors, including visual, hearing, and functional impairment. We also showed a mediation effect of church attendance on the relationship between depressive symptoms and cognitive function, where the effect of church attendance appears to buffer the negative impact of depressive symptoms on cognitive function. Further research is needed to investigate the effect of other religious practices on the rate of cognitive decline with age.
This study was supported in part by Grant P50 CA105631 (University of Texas Medical Branch Center for Population Health and Health Disparities) funded by the National Institutes of Health, National Cancer Institute, and Grant AG10939 (Hispanic Established Populations for Epidemiologic Studies of the Elderly) funded by the National Institute on Aging.