The terms 'cognition' and 'cognitive function' describe all of the mental activities related to thinking, learning, remembering, and communicating. There are normal changes in cognition with aging. There are also diseases that affect cognition, principally dementia, which becomes increasingly common with increasing age from about 65 years onwards. Researchers have showed a great deal of interest in trying to prevent cognitive decline and dementia. It is known that being mentally active throughout life is associated with lower risk of dementia. Therefore, it has been suggested that encouraging mental activity might be an effective way of maintaining good cognitive function as people age. Cognitive training comprises a set of standardised tasks intended to 'exercise the brain' in various ways. Programmes of cognitive training are often delivered by computers or mobile technology, so that people can do this training on their own at home. Increasingly, these are available as commercial packages that are advertised to the general public. We wanted to know whether computerised cognitive training (CCT) is an effective way for people aged 65 and older to maintain good cognitive function as they age.
What we did
We searched the medical literature up to 15 March 2018 for trials that compared the cognitive function of people aged 65 or older who had taken part in computerised cognitive training lasting at least three months against a control group that had not done so. All participants should have been cognitively healthy at the start of the trials. For the comparison to be as fair as possible, it should have been decided randomly whether participants were in the cognitive training group or in the control group. We were primarily interested in overall measures of cognition. The choice of three months for the intervention was somewhat arbitrary, but we thought it unlikely that shorter periods of training could have long-lasting effects.
What we found
We found eight trials with a total of 1183 participants to include in the review. Four trials provided CCT for three months. The longest duration of training was six months. We compared CCT with other activities, such as watching educational videos, and with no activity at all. We looked for effects on overall cognitive function and on specific cognitive functions, such as memory and thinking speed. All of the studies had some design problems, which could have biased the results. Results show a lot of inconsistency between different trials. Overall, we thought the quality of the evidence found was low or very low. This means that we cannot be confident in the results, and that more research might well find something different. We either were unable to comment or found no evidence of an effect of CCT on overall cognitive function or on most of the specific cognitive functions that we examined. The longest trial also found that compared to doing nothing, completing six months of CCT may have had a beneficial effect on memory. None of the trials reported effects on quality of life or on daily activities, and none reported harmful effects of training.
It is not yet possible to say for certain whether or not computerised cognitive training can help older people to maintain good cognitive function. Although we excluded very short trials (< 3 months) from this review, the trials that we found were still quite short for examining long-term effects as people age. We think it is important to do more research to find out whether longer periods of training work better, and whether training can produce lasting effects.
We found little evidence from the included studies to suggest that 12 or more weeks of CCT improves cognition in healthy older adults. However, our limited confidence in the results reflects the overall quality of the evidence. Inconsistency between trials was a major limitation. In five of the eight trials, the duration of intervention was just three months. The possibility that longer periods of training could be beneficial remains to be more fully explored.
Increasing age is associated with a natural decline in cognitive function and is also the greatest risk factor for dementia. Cognitive decline and dementia are significant threats to independence and quality of life in older adults. Therefore, identifying interventions that help to maintain cognitive function in older adults or to reduce the risk of dementia is a research priority. Cognitive training uses repeated practice on standardised exercises targeting one or more cognitive domains and is intended to maintain optimum cognitive function. This review examines the effect of computerised cognitive training interventions lasting at least 12 weeks on the cognitive function of healthy adults aged 65 or older.
To evaluate the effects of computerised cognitive training interventions lasting at least 12 weeks for the maintenance or improvement of cognitive function in cognitively healthy people in late life.
We searched to 31 March 2018 in ALOIS (www.medicine.ox.ac.uk/alois) and performed additional searches of MEDLINE, Embase, PsycINFO, CINAHL, ClinicalTrials.gov, and the WHO Portal/ICTRP (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.
We included randomised controlled trials (RCTs) and quasi-RCTs, published or unpublished, reported in any language. Participants were cognitively healthy people, and at least 80% of the study population had to be aged 65 or older. 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.
We performed preliminary screening of search results using a 'crowdsourcing' method to identify RCTs. At least two review authors working independently screened the remaining citations against inclusion criteria. At least two review authors also independently extracted data and assessed the risk of bias of included RCTs. Where appropriate, we synthesised data in random-effect meta-analyses, comparing computerised cognitive training (CCT) separately with active and inactive controls. We expressed treatment effects as standardised mean differences (SMDs) with 95% confidence intervals (CIs). We used GRADE methods to describe the overall quality of the evidence for each outcome.
We identified eight RCTs with a total of 1183 participants. Researchers provided interventions over 12 to 26 weeks; in five trials, the duration of intervention was 12 or 13 weeks. The included studies had a moderate risk of bias. Review authors noted a lot of inconsistency between trial results. The overall quality of evidence was low or very low for all outcomes.
We compared CCT first against active control interventions, such as watching educational videos. Because of the very low quality of the evidence, we were unable to determine any effect of CCT on our primary outcome of global cognitive function or on secondary outcomes of episodic memory, speed of processing, executive function, and working memory.
We also compared CCT versus inactive control (no interventions). Negative SMDs favour CCT over control. We found no studies on our primary outcome of global cognitive function. In terms of our secondary outcomes, trial results suggest slight improvement in episodic memory (mean difference (MD) -0.90, 95% confidence interval (CI) -1.73 to -0.07; 150 participants; 1 study; low-quality evidence) and no effect on executive function (SMD -0.08, 95% CI -0.31 to 0.15; 292 participants; 2 studies; low-quality evidence), working memory (MD -0.08, 95% CI -0.43 to 0.27; 60 participants; 1 study; low-quality evidence), or verbal fluency (MD -0.11, 95% CI -1.58 to 1.36; 150 participants; 1 study; low-quality evidence). We could not determine any effects on speed of processing at trial endpoints because the evidence was of very low quality.
We found no evidence on quality of life, activities of daily living, or adverse effects in either comparison.