Depression in the elderly

Context A history of depression may increase risk for developing Alzheimer disease (AD) later in life. Clarifying this relation might improve understanding of risk factors for and disease mechanisms in AD. Objective To systematically review and complete a meta-analysis on the relation of depression and AD. Data sources We conducted electronic bibliographic searches of MEDLINE, PsychLit, EMBASE, and BIOSIS using search terms sensitive to studies of etiology combined with searches on terms related to depression and AD and reviewed reference lists of articles. Study selection Studies with data contrasting depressed vs nondepressed patients who did and did not later develop AD were included. Studies that related continuous measures of depression and cognitive status were excluded. Data extraction Numerical data were independently extracted by 3 reviewers. They also rated studies on a scale that assessed quality indicators for observational studies. Data on the interval between observation of depression and the diagnosis of AD were collected when available. Data synthesis Meta-analytic evaluation with random-effects models resulted in pooled odds ratios of 2.03 (95% confidence interval, 1.73-2.38) for case-control and of 1.90 (95% confidence interval, 1.55-2.33) for cohort studies. Findings of increased risk were robust to sensitivity analyses. Interval between diagnoses of depression and AD was positively related to increased risk of developing AD, suggesting that rather than a prodrome, depression may be a risk factor for AD. Conclusions A history of depression may confer an increased risk for later developing AD. This relation may reflect an independent risk factor for the disease.

https://jamanetwork.com/journals/jamapsychiatry/articlepdf/209578/yoa50281.pdf

Depression and Risk for Alzheimer Disease: Systematic Review, Meta-analysis, and Metaregression Analysis

In this monograph, we ask whether various kinds of intellectual, physical, and social activities produce cognitive enrichment effects-that is, whether they improve cognitive performance at different points of the adult life span, with a particular emphasis on old age. We begin with a theoretical framework that emphasizes the potential of behavior to influence levels of cognitive functioning. According to this framework, the undeniable presence of age-related decline in cognition does not invalidate the view that behavior can enhance cognitive functioning. Instead, the course of normal aging shapes a zone of possible functioning, which reflects person-specific endowments and age-related constraints. Individuals influence whether they function in the higher or lower ranges of this zone by engaging in or refraining from beneficial intellectual, physical, and social activities. From this point of view, the potential for positive change, or plasticity, is maintained in adult cognition. It is an argument that is supported by newer research in neuroscience showing neural plasticity in various aspects of central nervous system functioning, neurochemistry, and architecture. This view of human potential contrasts with static conceptions of cognition in old age, according to which decline in abilities is fixed and individuals cannot slow its course. Furthermore, any understanding of cognition as it occurs in everyday life must make a distinction between basic cognitive mechanisms and skills (such as working-memory capacity) and the functional use of cognition to achieve goals in specific situations. In practice, knowledge and expertise are critical for effective functioning, and the available evidence suggests that older adults effectively employ specific knowledge and expertise and can gain new knowledge when it is required. We conclude that, on balance, the available evidence favors the hypothesis that maintaining an intellectually engaged and physically active lifestyle promotes successful cognitive aging. First, cognitive-training studies have demonstrated that older adults can improve cognitive functioning when provided with intensive training in strategies that promote thinking and remembering. The early training literature suggested little transfer of function from specifically trained skills to new cognitive tasks; learning was highly specific to the cognitive processes targeted by training. Recently, however, a new generation of studies suggests that providing structured experience in situations demanding executive coordination of skills-such as complex video games, task-switching paradigms, and divided attention tasks-train strategic control over cognition that does show transfer to different task environments. These studies suggest that there is considerable reserve potential in older adults' cognition that can be enhanced through training. Second, a considerable number of studies indicate that maintaining a lifestyle that is intellectually stimulating predicts better maintenance of cognitive skills and is associated with a reduced risk of developing Alzheimer's disease in late life. Our review focuses on longitudinal evidence of a connection between an active lifestyle and enhanced cognition, because such evidence admits fewer rival explanations of observed effects (or lack of effects) than does cross-sectional evidence. The longitudinal evidence consistently shows that engaging in intellectually stimulating activities is associated with better cognitive functioning at later points in time. Other studies show that meaningful social engagement is also predictive of better maintenance of cognitive functioning in old age. These longitudinal findings are also open to important rival explanations, but overall, the available evidence suggests that activities can postpone decline, attenuate decline, or provide prosthetic benefit in the face of normative cognitive decline, while at the same time indicating that late-life cognitive changes can result in curtailment of activities. Given the complexity of the dynamic reciprocal relationships between stimulating activities and cognitive function in old age, additional research will be needed to address the extent to which observed effects validate a causal influence of an intellectually engaged lifestyle on cognition. Nevertheless, the hypothesis that an active lifestyle that requires cognitive effort has long-term benefits for older adults' cognition is at least consistent with the available data. Furthermore, new intervention research that involves multimodal interventions focusing on goal-directed action requiring cognition (such as reading to children) and social interaction will help to address whether an active lifestyle enhances cognitive function. Third, there is a parallel literature suggesting that physical activity, and aerobic exercise in particular, enhances older adults' cognitive function. Unlike the literature on an active lifestyle, there is already an impressive array of work with humans and animal populations showing that exercise interventions have substantial benefits for cognitive function, particularly for aspects of fluid intelligence and executive function. Recent neuroscience research on this topic indicates that exercise has substantial effects on brain morphology and function, representing a plausible brain substrate for the observed effects of aerobic exercise and other activities on cognition. Our review identifies a number of areas where additional research is needed to address critical questions. For example, there is considerable epidemiological evidence that stress and chronic psychological distress are negatively associated with changes in cognition. In contrast, less is known about how positive attributes, such as self-efficacy, a sense of control, and a sense of meaning in life, might contribute to preservation of cognitive function in old age. It is well known that certain personality characteristics such as conscientiousness predict adherence to an exercise regimen, but we do not know whether these attributes are also relevant to predicting maintenance of cognitive function or effective compensation for cognitive decline when it occurs. Likewise, more information is needed on the factors that encourage maintenance of an active lifestyle in old age in the face of elevated risk for physiological decline, mechanical wear and tear on the body, and incidence of diseases with disabling consequences, and whether efforts to maintain an active lifestyle are associated with successful aging, both in terms of cognitive function and psychological and emotional well-being. We also discuss briefly some interesting issues for society and public policy regarding cognitive-enrichment effects. For example, should efforts to enhance cognitive function be included as part of a general prevention model for enhancing health and vitality in old age? We also comment on the recent trend of business marketing interventions claimed to build brain power and prevent age-related cognitive decline, and the desirability of direct research evidence to back claims of effectiveness for specific products.

/pdf/enrichment-effects-on-adult-cognitive-development-can-the-57xv8ecx2m.pdf

Enrichment Effects on Adult Cognitive Development: Can the Functional Capacity of Older Adults Be Preserved and Enhanced?

GUSKIEWICZ, K. M., S. W. MARSHALL, J. BAILES, M. MCCREA, H. P. HARDING JR, A. MATTHEWS, J. R. MIHALIK, and R. C. CANTU. Recurrent Concussion and Risk of Depression in Retired Professional Football Players. Med. Sci. Sports Exerc., Vol. 39, No. 6, pp. 903–909, 2007. Purpose: The purpose of our study was to investigate the association between prior head injury and the likelihood of being diagnosed with clinical depression among retired professional football players with prior head injury exposure. Methods: A general health questionnaire, including information about prior injuries, the SF-36 (Short Form 36), and other markers for depression, was completed by 2552 retired professional football players with an average age of 53.8 (T 13.4) yr and an average professional football-playing career of 6.6 (T 3.6) yr. A second questionnaire focusing on mild cognitive impairment (MCI)-related issues was completed by a subset of 758 retired professional football players (50 yr and older). Results: Two hundred sixty-nine (11.1%) of all respondents reported having prior or current diagnosis of clinical depression. There was an association between recurrent concussion and diagnosis of lifetime depression (W 2 = 71.21, df =2 ,P G 0.005), suggesting that the prevalence increases with increasing concussion history. Compared with retired players with no history of concussion, retired players reporting three or more previous concussions (24.4%) were three times more likely to be diagnosed with depression; those with a history of one or two previous concussions (36.3%) were 1.5 times more likely to be diagnosed with depression. The analyses controlled for age, number of years since retirement, number of years played, physical component score on the SF-36, and diagnosed comorbidities such as osteoarthritis, coronary heart disease, stroke, cancer, and diabetes. Conclusion: Our findings suggest a possible link between recurrent sport-related concussion and increased risk of clinical depression. The findings emphasize the importance of understanding potential

/pdf/recurrent-concussion-and-risk-of-depression-in-retired-4ovi6639t8.pdf

Recurrent concussion and risk of depression in retired professional football players.

Background 

Late-life depression may increase the risk of incident dementia, in particular of Alzheimer’s disease and vascular dementia.

Aims 

To conduct a systematic review and meta-analysis to evaluate the risk of incident all-cause dementia, Alzheimer’s disease and vascular dementia in individuals with late-life depression in population-based prospective studies.

Method 

A total of 23 studies were included in the meta-analysis. We used the generic inverse variance method with a random-effects model to calculate the pooled risk of dementia, Alzheimer’s disease and vascular dementia in older adults with late-life depression.

Results 

Late-life depression was associated with a significant risk of all-cause dementia (1.85, 95% CI 1.67-2.04, P <0.001), Alzheimer’s disease (1.65, 95% CI 1.42-1.92, P <0.001) and vascular dementia (2.52, 95% CI 1.77-3.59, P <0.001). Subgroup analysis, based on five studies, showed that the risk of vascular dementia was significantly higher than for Alzheimer’s disease ( P = 0.03).

Conclusions 

Late-life depression is associated with an increased risk for all-cause dementia, vascular dementia and Alzheimer’s disease. The present results suggest that it will be valuable to design clinical trials to investigate the effect of late-life depression prevention on risk of dementia, in particular vascular dementia and Alzheimer’s disease.

/pdf/late-life-depression-and-risk-of-vascular-dementia-and-4w0f4639md.pdf

Late-life depression and risk of vascular dementia and Alzheimer’s disease: systematic review and meta-analysis of community-based cohort studies

Background: It remains unclear whether depression increases the risk for dementia in the elderly. We evaluated the relationship between depressed mood at baseline and the incidence of dementia, particularly Alzheimer's disease, in the elderly living in the community. Methods: A total of 1070 elderly individuals, aged 60 years or older, were identified as part of a registry for dementia in the Washington Heights community of North Manhattan, NY. In a prospective, longitudinal design with follow-up for 1 to 5 years, annual physician evaluation and neuropsychological testing were used to assess levels of cognitive impairment and to diagnose dementia. Depressive symptoms were evaluated with the 17-item Hamilton Rating Scale for Depression. Based on clinical considerations and a validity study, a positive score for the depressed mood item was used in statistical analyses. To confirm the results, the total Hamilton Rating Scale for Depression score was also evaluated as the "depression" variable. Results: Of the 1070 subjects, 218 met criteria for dementia at baseline evaluation. In the 852 subjects without dementia, depressed mood was more common in individuals with greater cognitive impairment. In a follow-up study of 478 of these subjects without dementia (mean±SD, 2.54±1.12 years of follow-up), the effect of baseline depressed mood on the end-point diagnosis of dementia (93% had possible or probable Alzheimer's disease) was evaluated in a Cox proportional hazards model. Depressed mood at baseline was associated with an increased risk of incident dementia (relative risk, 2.94; 95% confidence interval, 1.76 to 4.91;P Conclusions: Depressed mood moderately increased the risk of developing dementia, primarily Alzheimer's disease. Whether depressed mood is a very early manifestation of Alzheimer's disease, or increases susceptibility through another mechanism, remains to be determined.

/pdf/depressed-mood-and-the-incidence-of-alzheimer-s-disease-in-xmk0acx0fd.pdf

Stuart Taylor

Papers

Depressed mood and the incidence of Alzheimer's disease in the elderly living in the community.