Brain reserve and the prevention of dementia

Purpose of review To evaluate and synthesize recent evidence linking mental activity and dementia risk, which commonly invokes 'brain reserve' as the mediating construct. Recent findings Brain reserve has acquired several interpretations; however, the most reliable and practical definition focuses at the behavioural level by assessing frequency and range of participation in complex mental activities. Epidemiological research suggests a clear and consistent link of high brain reserve with reduced dementia risk. Furthermore, emerging clinical trials of cognitive exercise suggest that it may be effective for the prevention of longitudinal cognitive and functional decline. Recent animal studies implicate several mechanisms, including disease-dependent and disease-independent compensatory pathways. Summary Given the precipitous forecasts for dementia over the coming decades, effective preventive strategies are of utmost importance. Findings from brain reserve studies now meet many of the formal criteria for causal agency between complex mental activity and reduced dementia risk. Key clinical trials are therefore under way to test these claims and results are keenly awaited.