Over the years, there has been much research on the potential cognitive benefits of exercise on mental performance in older adults. Overall, results have been inconclusive, but a new review takes a fresh look at the data.
As we age, our cognitive prowess tends to take a hit. Finding a way to halt or reduce this decline would make a huge difference to billions of lives.
One potential intervention is exercise, and many researchers have attempted to prove whether or not it can stave off age-related mental decline and neurodegenerative conditions.
Early research and meta-analyses demonstrated strong, positive results. Over recent years, however, published reviews on the topic have not reported such strong effects.
A fresh look at aging and the brain
According to the authors of the current paper, recently published reviews and meta-analyses have been inconclusive due to their restrictive inclusion criteria. For instance, some focused on just one type of exercise, while others limited their literature search to a narrow date range. The latest review is published this week in the British Journal of Sports Medicine.
The new analysis casts its net wide, looking at aerobic exercise, resistance training (such as weights), multicomponent exercise (including both resistance and aerobic training), tai chi, and yoga.
To fully assess the impact of these interventions, they looked at a raft of cognitive parameters. These include:
1. Brain capacity - global cognition
2. Attention - sustained alertness, including speed of information processing
3. Executive function - including goal-oriented behaviors
4. Memory - storage and retrieval
5.Working memory - the part of short-term memory that deals with immediate conscious perceptual and language processing
The team's analysis showed that exercise improved the brain power of people aged 50 and older, regardless of their current brain health.
The results suggested that aerobic exercise enhanced cognitive abilities, while resistance training had a positive influence on executive function, memory, and working memory. According to the researchers, the results were strong enough to recommend prescribing both exercise types to bolster brain health in over 50s.
The next question asks how much exercise is needed. According to the analysis, a session of moderate to vigorous intensity lasting between 45 and 60 minutes was beneficial to brain health. In fact, any frequency had positive effects. The authors conclude that:
"The findings suggest that an exercise program with components of both aerobic and resistance type training, of at least moderate intensity and at least 45 minutes per session, on as many days of the week as possible, is beneficial to cognitive function in adults aged over 50 years."
Interestingly, tai chi was also found to improve cognitive capabilities. This is important because, as a low-impact exercise, it can be carried out by people who could not physically cope with more intense regimes. However, the authors point out that this conclusion was based on only a small number of studies, making the finding less robust.
How exercise might reduce cognitive decline
Although there is a great deal of debate on this topic, scientists believe that there are a number of ways that exercise could help to stave off dementia and other degenerative neurological conditions.
According to the authors of the study, these include the promotion of neurogenesis (growth of new nervous tissue), angiogenesis (growth of new blood vessels), synaptic plasticity (the ability of synapses to strengthen or weaken over time), decreased pro-inflammatory processes, and reduced cellular damage due to oxidative stress.
Although the results will be widely heralded as positive, the authors note certain limitations to the study. For example, the analysis was limited to studies that looked at supervised exercise, and only those that were published in the English language.
If physical exercise really can stave off cognitive decline, it will benefit the population at large. This type of intervention can, of course, be cost effective or even free. If it has large-scale benefits, it could be a simple way of improving the lives of millions of older adults.
Even though the cognitive benefits may be small, the physical benefits of exercise are well established - so it is a win-win situation either way.