Meta-Analyses of Brain Training for Over 50s: A Review

Scientific interest in brain training designed to maintain or improve cognitive functions in the aging brain has been rapidly increasing over the last decade. Numerous studies have shown that neuroplastic change in brain connectivity and function is considerable up to very old age (1, 2, 3, 4).

In this review I will be reviewing the peer-reviewed literature I will be reviewing brain training for over 50s. I will be finding evidence-based answers to the following questions:

  • Does brain training for over 50s work, or is it just a placebo effect?
  • What kind of brain training is effective?
  • What kinds of benefits are there, and do they apply to real life (everyday cognitive tasks)?
  • Are the benefits of brain training any better than having mentally stimulating hobbies such as playing a musical instrument or playing chess?
  • Which are effective brain training apps on the market?

I will be reviewing the latest meta-analyses, not individual studies to ensure we can be confident in my answers to these questions.

Some Useful Definitions

For those without training in experimental design, here are some useful definitions that will equip you to understood some of the more technical content of this review, and help you evaluate it for yourself.

Experiments / Randomized Control Trials involve randomly assigning participants in the study to receive one of a number of cognitive interventions. One of these interventions is the computerized cognitive training (brain training) program. One of these interventions is the standard of comparison or control. The control may be an active control (e.g. playing a simple game or doing cross-words for the same duration as the brain training), or a passive control where there is no intervention at all.

Peer-reviewed journal articles.  These are published articles of randomized control trials (studies) on brain training that have been submitted to the scrutiny of experts in the same field, and judged to acceptable for publication.

Meta-analyses systematically assess all peer-reviewed studies meeting adequate standards of experimental design and relevance criteria for a particular type of brain training. A meta-analysis uses a statistical approach to combine the results from multiple trials to improve estimates of the size of the effect and resolve uncertainty when reports disagree – for example when one study concludes there is an effect and another study does not. It can also correct for publication bias – the tendency to only publish reports when there is a positive result. A meta-analysis, compared to a single peer-reviewed journal article, enables us to draw much stronger conclusions about the effectiveness of brain training interventions.

If there is statistical significance in a brain training study, it means that the difference in tested outcomes such as average IQ score between training group and the control group is very unlikely (p < 0.05) to have occurred by chance. If the study is well-designed, this gives us confidence that the difference in IQ scores between the brain training and placebo group is due to the training itself, and not some fluke.

The effect size is a measure of the magnitude of the outcome difference between the two groupswhich can be measured in standardized scores. Effect size is typically measured in  ‘standard deviation’ units (g). When  SD = 1.0, this is equivalent to 15 points in a standardized IQ test. If SD = 0.5 this would be 7.5 points. And so on. As a reference, antidepressant drugs typically have an effect size (compared to placebo) of 0.3 – 0.5 – i.e. 4.5 – 7.5 points.

Does brain training work or is it a placebo effect?

Julia Karbach and Paul Verhaeghen (2014) analysed 49 brain training studies with over 60s (average age 69). Many of these individual studies also hand a young adults brain training group doing the same exercises (average age 22.4), allowing for a comparison.

There was essentially no difference between younger and older participants. Overall, there were clear brain training benefits, with:

  • Significant and large improvements in the trained (target) tasks. The raw gain is ~0.9 SD (14 points); gain after subtracting the effects of active control treatment is ~0.5 SD (7.5 points).
  • Significant and quite large  ‘near-transfer’ gains on abilities such as working memory or executive control. The raw gain is ~0.5 SD (7.5 points). The gain after subtracting the effects of control treatment, is ~0.3 SD (4.5 points).
  • Significant but smaller ‘far-transfer’ gains on abilities such as IQ (called ‘far transfer’ because these abilities not directly related to the training exercise). The raw gain is ~0.4 SD (6 points). After subtracting the effects of control treatment the effect is ~0.2 SD (3 points).
brain training effect sizes

Average effect sizes for two types of brain training. From Karbach and Verhaeghen (2014)

In Michelle Kelly and colleagues’ (2014) meta-analysis of brain training for over 50s they analysed 31 randomized controlled trials with 1806 participants. They concluded:

cognitive training significantly improved performance on measures of recognition, on composite measures of cognitive function, and on executive measures of working memory, and processing speed compared to active controls. Consistent with our findings, previous reviews have reported significant intervention effects for cognitive training versus active controls on cognition, particularly on measures of executive functioning (Reijnders et al., 2012; Tardif and Simard, 2011). Larger effect sizes have been reported for executive measures of reasoning and processing speed compared to measures of memory (Papp et al., 2009).

Effect sizes in their study ranged from 0.47 (~7.5 points) to 0.82 (~12.5 points) – which are sizeable effect estimates. (There was no statistical correction for publication bias in this study and these are comparable to the Karbach and Verhaeghen estimates.)

In this meta-analysis the effects of training were found to last between 3 and 6 months after the training period in nine out of ten cognitive training interventions.

More recently, Amit Lampit and colleagues (Nov 2014) investigated the effects of ≥ 4 h of brain training on performance in neuropsychological tests in older adults (60 years and older) without dementia or other cognitive impairment. They analysed fifty-two studies encompassing 4,885 participants. In line with the other meta-analyses, they found that brain training was statistically significant with an effect size of 0.22 SD = ~3.5 points. 

This relatively small effect size is an estimate of the net training gain after subtracting the cognitive gains of active controls. It i not the raw gain which is much higher.

The latest meta-analysis by Kate Laver and colleagues (2015) has also concluded that brain training improves memory, speed of information processing and visuospatial skills in older adults.

So we can conclude from the meta-analyses that brain training for older adults is effective in improving cognitive functioning with benefits that apply in day-to-day life.


What kind of brain training works?

For some quick definitions, working memory is our ‘mental workspace’ that stores and processes task-relevant information.  It is the interface between the current focus of attention and long-term memories. Working memory training such as the dual n-back targets this capacity. Multi-domain training trainings multiple cognitive skills such as you find in Lumosity. Attention training is also called ‘cognitive control’ training, and trains attention control.

Executive functioning – also known as cognitive control – is the ability to manage attention, goal focus and cognitive processes. ‘Attention training’ is an example of executive functioning.

Karbach and Verhaeghen (2014) found there was little difference between the efficacy of executive function training and working memory training as shown in this figure from their meta-analysis.


executive training vs working memory training

Lampit and colleagues (Nov 2014)  found there was no difference between types of brain training, although in terms of effect size, attention (executive functioning/control) training and video game training had the largest effects. They also found that group-based training was more effective than home training in isolation, possibly due to better supervision.

type of training

From Lampit et al (2014)


Lampit and colleagues
 found that training between 5 and 20 hours in total was as effective as training more than 20 hours in total, and that it was best to do 1 to 3 sessions a week. Half an hour training time sufficed.

The average number of brain training sessions in the Karbach and Verhaeghen (2014) meta-analysis was 9 and the total training time was 10 hours spread over 24 days.

What kinds of benefits are there from brain training?

Karbach and Verhaeghen (2014) found the following cognitive abilities benefited from brain training.

older adults

.
Fluid intelligence is a measure of IQ and there was a clear benefit to IQ.

Kelly and colleagues’ (2014) found that compared to active controls, brain training improved performance in:

  • working memory 
  • processing speed
  • recognition memory

Compared to passive (no intervention) controls, brain training improved performance in:

  • memory (face-name recall and immediate recall)
  • learning (paired associates learning)
  • self-report ratings of cognitive function

The effect sizes for active control and passive controls are of this meta-analysis are shown below:

brain training for over 50s

The meta-analysis by Laver and colleagues (2015) concludes that brain training improves:

  • memory
  • speed of information processing
  • visuospatial skills

How does brain training compare to other mentally stimulating activities?

Kelly and her colleagues (2014) also meta-analysed studies looking at the effects of more general mental stimulation for over 50s such as reading, playing music or playing chess.

Significant intervention effects were reported for mental stimulation versus no intervention controls in 4 out of 8 measures of memory, 9 out of 17 measures of executive function, and on 1 out of 3 composite measures of cognitive function. They conclude:

Overall, our review shows that mental stimulation might benefit cognitive function of older adults, but these results are not consistent across trials.

The authors suggest that mental stimulation might operate by maintaining cognitive function over time, as opposed to immediately improving performance such as you see with computerized cognitive training.

Effective brain training apps on the market

Working Memory and Executive Control Training Apps

A free app resource for dual n-back is Brain Workshop. This provides variations of the dual n-back.

My own i9 working memory and executive functioning brain training software implements a combination of working memory training (e.g. n-back) and executive function training. (e.g. interference control and task-switching for cognitive flexibility). This can be found at this website.

I am happy to provide this software for free for any research or education related projects.

The company CogMed also provides working memory training tools.

References

Karbach, J., & Verhaeghen, P. (2014). Making working memory work: A meta-analysis of executive-control and working memory training in older adults. Psychological Science, 25, 2027–2037. Full article.

Kelly, M. E., Loughrey, D., Lawlor, B. A., Robertson, I. H., Walsh, C., & Brennan, S. (2014). The impact of cognitive training and mental stimulation on cognitive and everyday functioning of healthy older adults: a systematic review and meta-analysis. Ageing Research Reviews, 15, 28–43. Full article.

Lampit, A., Hallock, H., & Valenzuela, M. (2014). Computerized Cognitive Training in Cognitively Healthy Older Adults: A Systematic Review and Meta-Analysis of Effect Modifiers. PLoS Medicine, 11(11). Full article.

Laver, K., Hamilton, C., & McCluskey, A. (2015). Computerised cognitive training programs improved the cognitive performance of healthy older adults on some cognitive tests including memory, speed of information processing and visuospatial skills. Australian Occupational Therapy Journal, 62(3), 223–224. Abstract.

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