Background: Normal aging is associated with changes in cognitive function that are non-pathological and are not necessarily indicative of future neurocognitive disease. Low cognitive and brain reserve and limited cognitive stimulation are associated with increased risk of dementia. Emerging evidence now suggests that subtle cognitive changes, detectable years before criteria for mild cognitive impairment are met, may be predictive of future dementia. Important for intervention and reduction in disease risk, research also suggests that engaging in stimulating mental activity throughout adulthood builds cognitive and brain reserve and reduces dementia risk. Therefore, midlife (defined here as 40 to 65 years) may be a suitable time to introduce cognitive interventions for maintaining cognitive function and, in the longer term, possibly preventing or delaying the onset of clinical dementia.
Objectives: To evaluate the effects of computerised cognitive training interventions lasting at least 12 weeks for maintaining or improving cognitive function in cognitively healthy people in midlife.
Search methods: We searched up to 31 March 2018 in ALOIS (www.medicine.ox.ac.uk/alois), the specialised register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG). We ran additional searches in MEDLINE, Embase, PsycINFO, CINAHL, ClinicalTrials.gov, and the WHO Portal/ICTRP at www.apps.who.int/trialsearch, to ensure that the search was as comprehensive and as up-to-date as possible, to identify published, unpublished, and ongoing trials.
Selection criteria: We included randomised controlled trials (RCTs) or quasi-RCTs, published or unpublished, reported in any language. Participants were cognitively healthy people between 40 and 65 years of age (80% of study population within this age range). Experimental interventions adhered to the following criteria: intervention was any form of interactive computerised cognitive intervention - including computer exercises, computer games, mobile devices, gaming console, and virtual reality - that involved repeated practice on standardised exercises of specified cognitive domain(s) for the purpose of enhancing cognitive function; duration of the intervention was at least 12 weeks; cognitive outcomes were measured; and cognitive training interventions were compared with active or inactive control interventions.
Data collection and analysis: For preliminary screening of search results, we used a 'crowd' method to identify RCTs. At least two review authors working independently screened remaining citations against inclusion criteria; independently extracted data; and assessed the quality of the included trial, using the Cochrane risk of bias assessment tool. We used GRADE to describe the overall quality of the evidence.
Main results: We identified one eligible study that examined the effect of computerised cognitive training (CCT) in 6742 participants over 50 years of age, with training and follow-up duration of six months. We considered the study to be at high risk of attrition bias and the overall quality of the evidence to be low.Researchers provided no data on our primary outcome. Results indicate that there may be a small advantage for the CCT group for executive function (mean difference (MD) -1.57, 95% confidence interval (CI) -1.85 to -1.29; participants = 3994; low-quality evidence) and a very small advantage for the control group for working memory (MD 0.09, 95% CI 0.03 to 0.15; participants = 5831; low-quality evidence). The intervention may have had little or no effect on episodic memory (MD -0.03, 95% CI -0.10 to 0.04; participants = 3090; low-quality evidence).
Authors' conclusions: We found low-quality evidence from only one study. We are unable to determine whether computerised cognitive training is effective in maintaining global cognitive function among healthy adults in midlife. We strongly recommend that high-quality studies be undertaken to investigate the effectiveness and acceptability of cognitive training in midlife, using interventions that last long enough that they may have enduring effects on cognitive and brain reserve, and with investigators following up long enough to assess effects on clinically important outcomes in later life.