Revitalizing the aged brain

Cognitive leisure activities and future risk of cognitive impairment and dementia: systematic review and meta-analysis

BACKGROUND

As life expectancies continue to rise, modifiable lifestyle factors that may prevent cognitive decline and dementia in later life become increasingly important in order to maintain quality of life in old age.

METHODS

Five meta-analyses were conducted on data from papers identified in a systematic review. Studies were grouped according to outcomes (dementia, cognitive impairment including amnestic Mild Cognitive Impairment (aMCI), Mild Cognitive Impairment (MCI), and cognitive decline) and output (risk (RR), odds (OR), or hazard ratios (HR)).

RESULTS

Nineteen studies met our inclusion criteria and quality assessments. Four of five meta-analyses showed significant associations between participation in cognitive leisure activities and reduced risk of cognitive impairment (OR = 0.69, 95% CI: 0.56-0.85) and dementia (HR = 0.58, 95% CI: 0.46-0.74; RR = 0.61, 95% CI: 0.42-0.90; OR = 0.78, 95% CI: 0.67-0.90). However, one pooled analysis of cognitive impairment studies did not reach significance (HR = 0.85, 95% CI: 0.71-1.02). Mentally stimulating leisure activities were significantly associated with later life cognition (β = 0.11, p = 0.05), better memory (β = 0.20, 95% CI: 0.11-0.29), speed of processing (β = 0.37, 95% CI: 0.29-0.45), and executive functioning (β = 0.23, 95% CI: 0.15-0.29), and less decline in overall cognition (β = -0.23, p < 0.01), language (β = -0.11, p < 0.05), and executive functioning (β = -0.13, p < 0.05). Activities were also shown to reduce rate of cognitive decline (estimate = 0.03, SE = 0.01, p = 0.00).

CONCLUSIONS

There is increasing evidence that participation in cognitively stimulating leisure activities may contribute to a reduction of risk of dementia and cognitive impairment in later life. Promoting involvement in such activities across lifespan could be an important focus for primary prevention strategies for governments and health services.

Could androgens maintain specific domains of mental health in aging men by preserving hippocampal neurogenesis?

Interest surrounds the role of sex-hormones in regulating brain function outside of reproductive behaviour. Declining androgen production in aging males has been associated with cognitive impairment, depression and increased risk of developing Alzheimer's disease. Indication for testosterone replacement therapy is based on biochemically determined low circulating testosterone combined with manifest symptoms. However, which aspects of age-related cognitive decline are attributable to low circulating testosterone remain ambiguous. Studies examining cognition in aging men receiving testosterone replacement therapy have yielded equivocal results. The exact role of testosterone in maintaining cognitive function and the underlying neural mechanisms are largely unknown, though it would appear to be domain specific. Clarity in this area will provide clinical direction toward addressing an increasing healthcare burden of mental health decline coincident with increasing longevity. The premise that androgens contribute to maintaining aspects of mental health in aging men by preserving hippocampal neurogenesis will be used as a forum in this review to discuss current knowledge and the need for further studies to better define testosterone replacement strategies for aging male health.

Physical activity and cognitive function in individuals over 60 years of age: a systematic review

BACKGROUND

It is unclear whether physical activity in later life is beneficial for maintenance of cognitive function. We performed a systematic review examining the effects of exercise on cognitive function in older individuals, and present possible mechanisms whereby physical activity may improve cognition.

METHODS

Sources consisted of PubMed, Medline, CINAHL, the Cochrane Controlled Trials Register, and the University of Washington, School of Medicine Library Database, with a search conducted on August 15, 2012 for publications limited to the English language starting January 1, 2000. Randomized controlled trials including at least 30 participants and lasting at least 6 months, and all observational studies including a minimum of 100 participants for one year, were evaluated. All subjects included were at least 60 years of age.

RESULTS

Twenty-seven studies met the inclusion criteria. Twenty-six studies reported a positive correlation between physical activity and maintenance or enhancement of cognitive function. Five studies reported a dose-response relationship between physical activity and cognition. One study showed a nonsignificant correlation.

CONCLUSION

The preponderance of evidence suggests that physical activity is beneficial for cognitive function in the elderly. However, the majority of the evidence is of medium quality with a moderate risk of bias. Larger randomized controlled trials are needed to clarify the association between exercise and cognitive function and to determine which types of exercise have the greatest benefit on specific cognitive domains. Despite these caveats, the current evidence suggests that physical activity may help to improve cognitive function and, consequently, delay the progression of cognitive impairment in the elderly.