Background: Research on the potential effects of cognitive intervention in healthy elderly has been motivated by (1) the apparent effectiveness of cognitive rehabilitation in Alzheimer's disease (AD) patients; (2) the face validity of bolstering skills eventually burdened by disease; (3) interest in low-cost/noninvasive methods of preventing or delaying onset of disease; (4) the epidemiologic research suggesting protective effects of educational attainment and lifelong participation in cognitively stimulating activities; (5) the burgeoning industry of brain training products and requisite media attention; and (6) the aging world population.
Methods: We performed a systematic review with meta-analytic techniques to analyze randomized controlled trials of cognitive interventions in healthy elderly.
Results: The weighted mean effect size (Cohen's d) of cognitive intervention across all outcome measures after training was .16 (95% confidence interval, .138 to .186). The existing literature is limited by a lack of consensus on what constitutes the most effective type of cognitive training, insufficient follow-up times, a lack of matched active controls, and few outcome measures showing changes in daily functioning, global cognitive skills, or progression to early AD.
Conclusions: Our review was limited by a small, heterogeneous, and methodologically limited literature. Within this literature, we found no evidence that structured cognitive intervention programs delay or slow progression to AD in healthy elderly. Further work that accounts for the limitations of past efforts and subsequent clear and unbiased reporting to the public of the state and progress of research on this topic will help the elderly make informed decisions about a range of potential preventive lifestyle measures including cognitive intervention.