Physical exercise can improve cognitive function in adults over 50 years of age

Northey JM, Cherbuin N, Pumpa KL, et al. Exercise interventions for cognitive function in adults older than 50: A systematic review with meta-analysis Br J Sports Med. 2018;52:154-160.

Review question

What is the effect of supervised physical exercise on cognitive function in adults over 50 years of age? How does exercise type, duration, frequency, intensity, and length effect cognitive function? How do initial cognitive status (i.e. the presence or absence of mild cognitive impairment) and study design impact the outcome?   

Background

As adults age, cognitive function declines. Physical exercise has emerged as a promising way to reduce cognitive decline and the occurrence of related diseases such as dementia. However, past analyses and systematic reviews have shown conflicting results on the relationship between physical exercise and cognitive function. New research needs to assess the impact of exercise type, duration, intensity and frequency, as well as alternative forms of exercise to determine if physical exercise impacts cognitive function, and if so, what combination of physical exercise is associated with the greatest impact.              

How the review was done

This is a systematic review of 39 randomized controlled trials published between 1989 and 2016, with a meta-analysis of 36 of the trials.

• Participants were men and women over the age of 50 with/without/unclear mild cognitive impairment, who lived in the community.
• Study participants completed supervised exercise programs of various types: (aerobic, resistance training, multicomponent training, tai chi, or yoga); durations (short (≤45 min), medium (>45 to ≤60 min), or long (>60 min); frequencies (low (≤2x/week), medium (3–4x/week), or high (5-7x/week); intensities (low, moderate, or high) and lengths (short (4-12 weeks), medium (13-26 weeks), or long (>26 weeks)).
• Researchers measured change in cognitive function – this included global cognition, attention, executive function, working memory, and memory.
• Results were compared to people in control groups who either maintained their current lifestyle or participated in sham exercises, educational approaches (e.g. health lectures), or social group meetings.
• The evidence included in the review was of moderate quality.

What the researchers found

Overall, adults over 50 years of age who participated in supervised physical exercise – aerobic exercise, resistance training, multicomponent training, or tai chi – experienced improved cognitive function, regardless of the presence or absence of mild cognitive impairment. Yoga did not have an effect on cognitive function. Improvements occurred for attention, executive function, memory, and working memory, but not global cognition. However, the effect varied depending on the type of exercise and the type of cognition assessed. Resistance training was effective for improved executive function, memory, and working memory, while tai chi was effective for working memory only. Exercise lasting >45 min to ≤60 minutes at or above moderate intensity was associated with cognitive benefits. Meanwhile, low (≤2x/week), medium (3-4x/week) and high (5-7x/week) exercise frequencies and conducting exercise in the short to long term (2 - >26 weeks) all produced positive effects.

Conclusion

Regardless of cognitive status, supervised physical exercise can improve cognitive function in adults over 50. Exercise programs consisting of aerobic exercise and resistance training, occurring as frequently as possible within the week, and where exercise duration is at least 45 mins and intensity is at least moderate may be of benefit.