Systematic review of health behavioral risks and cognitive health in older adults

Background: An increasing body of evidence suggests that health behaviors may protect against cognitive impairment and dementia. The purpose of this study was to summarize the current evidence on health behavioral factors predicting cognitive health through a systematic review of the published literature. Methods: PubMed, Embase, and PsycINFO databases were searched for studies on community representative samples aged 65 and older, with prospective cohort design and multivariate analysis. The outcome - cognitive health - was defined as a continuum of cognitive function ranging from cognitive decline to impairment and dementia, and health behaviors included physical activity, smoking, alcohol drinking, body mass index, and diet and nutrition. Results: Of 12,105 abstracts identified, 690 relevant full-texts were reviewed. The final yield amounted to 115 articles of which 37 studies were chosen that met the highest standards of quality. Leisure time physical activity, even of moderate level, showed protective effects against dementia, whereas smoking elevated the risk of Alzheimer's disease. Moderate alcohol consumption tended to be protective against cognitive decline and dementia, but nondrinkers and frequent drinkers exhibited a higher risk for dementia and cognitive impairment. Midlife obesity had an adverse effect on cognitive function in later life. Analysis showed vegetable and fish consumption to be of benefit, whereas, persons consuming a diet high in saturated fat had an increased dementia risk. Conclusion: The review demonstrates accumulating evidence supporting health behavioral effects in reducing the risk of cognitive decline and dementia. Results indicate potential benefits of healthy lifestyles in protecting cognitive health in later life.