The clinical significance of cognition-focused interventions for cognitively impaired older adults: a systematic review of randomized controlled trials

Background: Cognitive stimulation, training or rehabilitation can achieve modest, skill-specific gains in cognitively healthy older adults. With regard to the limited efficacy of currently available anti-dementia drugs it is crucial to investigate whether such treatments also provide clinically meaningful benefits to cognitively impaired older individuals. Methods: We conducted a systematic review of randomized controlled trials evaluating cognition-focused interventions in participants with mild cognitive impairment or dementia. Meta-analytic strategies were used to calculate effect sizes. Results: Cognition-focused interventions confer small and inconsistent effects on trained cognitive skills which, according to some studies, translate into gains on general cognitive ability. Instruments measuring such effects such as the Mini-Mental State Examination (MMSE) or the Alzheimer's Disease Assessment Scale, cognitive part (ADAS-Cog) show standardized mean differences of 0.20 and 0.30, respectively, which are comparable with those of current antidementia drug treatments. However, convincing evidence of clinical significance was only obtained from single trials in terms of delay of cognitive decline, improvement in activities of daily living, or enhanced attainment of personally relevant goals. Conclusions: The potential of cognition-focused interventions has probably been obscured by the methodological inconsistencies and limitations of the clinical studies conducted thus far. Further randomized controlled trials on the efficacy of these treatment modalities are required using optimized and consistent methods. Emphasis should be placed on tailoring interventions to individual needs and resources while maintaining a high level of standardization, on implementing newly acquired skills and strategies in the everyday context, on appropriate treatment duration, and on including person-centered outcomes.