Exercise for brain health

We’ve know for a long time that exercise has significant, measurable effects on the function of our heart, lungs, and blood vessels, and that regular exercise helps to maintain good general health. In recent years, however, research has shown that regular exercise can have specific effects on the function and health of the brain, in addition to these general health benefits. This interaction between physical activity and the brain will be the focus of this video. So, what can exercise do for your brain? First, it enhances cognitive functions, including attention and learning and memory. These improvements have been seen both in cognitively impaired and in healthy people and have been measured even after a single bout of exercise.

For example, in young healthy adults, high intensity aerobic exercise is reported to improve learning and working memory. However, resistance, or an anaerobic exercise, does not seem to confer these same benefits, suggesting that exercise induced enhancement and brain function is likely to be dependent on the type of exercise taken, the intensity, and the duration, as well as the physical fitness of the exerciser. Certainly, short bouts of exercise can converse some cognitive advantage, at least in the short term, since we don’t yet know how long lasting these effects are. Still, this research underlines why it is so important for school going children or adults in education to exercise regularly, as the physical benefits can translate into cognitive benefits.

Excitingly, we are now beginning to understand the biology underlying the effects of exercise on the brain. Exercise can enhance brain blood flow, the growth of new synapses, which are the connections between neurons, and even the number of new neurons born within the brain via a process called adult neurogenesis. A protein called BDNF, brain derived neurotrophic factor, is consistently linked with the brain enhancing affects of exercise, and many laboratories worldwide are assessing how this protein may mediate the effects of exercise on the brain.

Every human will experience some form of physical and mental decline in old age, but for many this can progress from mild cognitive impairment to vascular dementia, Alzheimer’s disease, and other forms of dementia that impair, or even destroy, quality of life and the ability to live independently. The link between a healthy lifestyle and a healthy old age is indisputable, and exercise is a key element of this relationship. Elderly persons who undertake regular physical activity show decreased incidence of cognitive impairment and dementia. This is strong evidence of the neuroprotective effects of exercise. However, exercise can be used as a treatment for those with existing cognitive impairment.

The trend emerging from many studies is that mild to moderate aerobic exercise is of benefit to patients with mild cognitive impairment, dementia, and Alzheimer’s disease. However, because of the varying protocols used in different studies, differences in type and frequency of exercise, and length of exercise programme, and the differing health status of participants, no consensus has yet been reached on the most effective exercise programme to use. Systematic reviews of the available data show that at the very least, some exercise is better than none, and that exercise with a mainly aerobic component is of greatest benefit, especially when outcomes, such as progression of cognitive symptoms and performance of activities of daily living are considered.

For patients who are physically able to do so, the best outcomes fit well with the general physical activity guidelines. That is moderate intensity exercise, such as brisk walking for at least 30 minutes on 5 days per week. The well-known motor symptoms that characterise Parkinson’s disease are often accompanied by cognitive impairment. Despite the motor impairments suffered by many Parkinson’s disease patients, many retain the ability to participate in exercise activity, in some cases resulting in a measurable cognitive benefit. A regime as simple as regular walking can improve motor function, cognition, and general quality of life. Depression and its accompanying cognitive impairment may present as a primary psychiatric disorder or may be co-morbid with conditions such as Alzheimer’s disease, Parkinson’s disease, or schizophrenia.

Promisingly, there is a vast and growing literature on the potential benefits of exercise in the prevention and treatment of depression. Indeed, the UK National Institute for Health and Clinical Excellence recommends structured exercise three times per week for 10 to 14 weeks for the treatment of mild to moderate depression. Unfortunately, depression is often associated with low levels of physical activity and lower cardiorespiratory fitness, and motivation to exercise and adherence to exercise programmes can be an obstacle to its use as a treatment tool. The same confines exist for patients with schizophrenia, a major psychiatric disorder whose negative symptoms include cognitive impairments affecting memory, executive functioning, and attention.

Treatment with anti-psychotic medication is, of course, the most effective treatment for the positive symptoms of this disorder, such as hallucinations, but exercise interventions, including treadmill running and yoga as an adjunct to pharmacotherapy and psychotherapy have been shown to improve cognitive function and mood in these patients. For patients with mental health disorders, tailoring the physical activity to the patient’s needs is key, taking into account their current level of activity, their motivation, and their willingness to interact with others in a social context. This is likely to be more important than the type of exercise undertaken, whether aerobic or resistance.

For patients who are very sedentary, it may be necessary to gradually build up daily physical activity before engaging in a specific exercise regime, allowing patients to build confidence as well as fitness. The overall benefits of exercise to anyone’s sense of well-being, achievement, and fulfilment cannot be underestimated. The physical changes brought by regular activity are complemented by these important effects on mental health and well-being. But to really develop exercise as a neurotherapeutic, we need more evidence. Thankfully, the results of more and more studies on the effects of exercise on brain function in healthy people and patients of different ages are being published and made available for study.

As a community of scientists, clinicians, patients, and those generally interested in exercise, this evidence base will help us generate better, more accurate guidelines for the prescription of exercise, specifically to target brain health.