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Further evidence that exercise is effective in improving cognition

By Nicole MacKee
Regular physical exercise of at least moderate intensity can help to boost cognitive function in the over-50s, regardless of baseline cognitive status, say Australian researchers.

In a systematic review and meta-analysis published in the British Journal of Sports Medicine, researchers analysed 39 randomised controlled trials of supervised physical exercise interventions in community-dwelling adults aged 50 years and over.

Of the modalities evaluated, aerobic training, resistance training, multicomponent training (combining both aerobic and resistance training in the one intervention) and tai chi were similarly effective – with an overall standardised mean difference (SMD) of 0.29. No significant effect was found with yoga.

Cognitive gains were shown when moderate-to-vigorous exercise of 45 to 60 minutes’ duration was undertaken on two to seven days per week for four to 26 weeks or more. By contrast, low intensity exercise was not effective.

Professor Maria Fiatarone Singh, John Sutton Chair of Exercise and Sports Science at the University of Sydney, said the review provided further evidence that exercise was effective in improving cognition.

‘We don’t have any drugs that prevent dementia, so it’s good to know that there is a treatment that can be used either to prevent cognitive decline or improve cognition in people who already have mild cognitive impairment,’ she said, adding that other reviews had also shown exercise to be effective at more advanced stages of cognitive decline, including dementia.

Professor Fiatarone Singh said the dose–response effect seen in the review – with benefits only at moderate or high intensity – added to the evidence that exercise worked ‘like a drug’, rather than through a mechanism such as increased socialisation or attention from research staff, as all participants were exposed to these elements. She said the study reinforced the importance of resistance training in addressing cognitive decline, with this modality significantly improving executive function (SMD, 0.49), memory (SMD, 0.54) and working memory (SMD, 0.49).

‘Resistance training was the only significant exercise modality when they looked at specific cognitive domains like executive function or memory, and it needs to be done at moderate-to-high intensity,’ Professor Fiatarone Singh told Medicine Today.

Although the researchers concluded that exercise programs with components of both aerobic- and resistance-type training should be recommended for cognitive benefit, Professor Fiatarone Singh pointed out that the results of this meta-analysis indicated statistically similar benefits on overall cognition for isolated aerobic or resistance training, or combined aerobic and resistance training, as well as tai chi. Therefore, she said, either combined or isolated training may be prescribed if the intended outcome is improved cognition, which allows for flexibility when individuals may not be able to do both kinds of exercise due to comorbidities.

‘Besides simplicity, there are other reasons to advocate this approach. Evidence from other studies suggests that when you combine resistance and aerobic training in the one session, the benefits of either may be reduced,’ Professor Fiatarone Singh said.
Br J Sports Med 2017; 0: 1-9. doi:10.1136/bjsports-2016-096587.

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