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Could resistance training help improve cognitive abilities? Image credit: Stereo Shot/Stocksy.
  • Exercise is known to improve cognition in older adults and reduce the risk of dementia.
  • The mechanism behind this is not well understood and the majority of research is into the effect of aerobic exercise, designed to increase heart and breath rate.
  • Researchers from Brazil have now looked at the impact of resistance training, such as using weights, on cognition in male mouse models.

Being physically active is already understood to be linked to improved bone and muscle health, reduced risk of disease and obesity, and improved brain health, according to the Centers for Disease Control and Prevention (CDC).

Physical activity is linked with improved cognition in children, adolescents, and adults according to the World Health Organization (WHO), and there are links between higher levels of physical activity and lower levels of dementia in older adults.

Exercise has been shown to improve cognition in older adults both in clinical trials and in reviews of the available evidence.

This may well be because exercise has an anti-inflammatory effect. In older adults, this could be due to the release of substances known as myokines, which are released from the muscles when they contract.

This means that the beneficial effects of exercise could also be seen with resistance training as well as aerobic exercise.

The relationship between cognitive health and resistance training was investigated by a team of Brazilian scientists affiliated with the Federal University of São Paulo, Brazil, and the University of São Paulo, Brazil, who looked at the impact of resistance exercise on male mice.

The results of this study appear in Frontiers of Science.

To carry out their study, researchers use a mouse model which had a mutation responsible for a buildup of beta-amyloid plaques in the brain. Beta-amyloid plaques are often associated with the development of dementia.

One group of mice with the mutation and a control group did no exercise, while a third group of mice, which did have the mutation, were trained to carry out an exercise regime that mimicked resistance training in humans.

The exercise regime involved the mice climbing a ladder over 1 meter tall, sloped at an angle of 80 degrees, with loads attached to their tails corresponding to 75%, 90%, and 100% of their body weight.

Postmortems were carried out on the mice to observe beta-amyloid plaque formation.

The researchers found that not only did the mice that had carried out resistance exercise over 4 weeks have fewer amyloid plaques on the hippocampus — a region of the brain often affected in Alzheimer’s disease — but they also had a higher number of a type of immune cell called microglial cells, that help to clear these plaques.

Nancy Mitchell, a registered nurse working in geriatric care who was not involved in the research, told Medical News Today: “According to this study, resistance training may aid in preventing or controlling Alzheimer’s disease by regulating the formation of the protein deposits (or plaques) on the hippocampus — the part of the brain which controls memory and some thought processing.“

“The study is promising, for now, but still lacks human-based results. Mice studies are merely one of the first steps in any medical investigation. Until we see tangible results on how resistance training impacts the cognitive health of adults in the early and developing stages of Alzheimer’s, there’s still much more to be explored.”

– Nancy Mitchell

Results also showed that resistance training reduced stress. After 4 weeks of exercise, blood was taken from the mice and tested for corticosterone, the hormone in mice equivalent to cortisol in humans.

High levels of cortisol have been linked to a higher risk of Alzheimer’s in humans. However, while corticosterone and cortisol can be released in response to exercise, levels of this hormone were found to be normal in the study mice.

Prof. Henning Ulrich, a professor of biochemistry at the University of São Paulo, and corresponding author of the paper told MNT that this was a surprising finding:

“We wanted to investigate whether this type of exercise would have any stressful effect, and to our surprise, what we found that, not only was it not stressful, but it reduced stress compared to the sedentary group! And more importantly, exercise was also able to reduce beta-amyloid levels in the hippocampus, and in another study by our group, neuroinflammation was also reduced by decreasing levels of anti-inflammatory cytokines.”

Before postmortem, mice were observed to see if they were agitated or restless by taking measurements of their movements, as being agitated is a symptom of Alzheimer’s disease.

Researchers found that mice that had undergone resistance training moved less around their space, suggesting they were less agitated.

While the results demonstrate a potential role for resistance training in mouse models of Alzheimer’s, it should be noted that the mice in which the study was carried out were all male.

They were also 6–7 months old, that is, adult but not representative of an older population. Prof. Ulrich said: “We are preparing new experimental groups with female animals and the idea is to compare the results of males and females.”

He said he and his colleagues also hoped the experiments could be carried out with younger mice.

“We have already started an exercise protocol with younger animals, before the onset of the first symptoms, to see if we can prevent the rapid advance, or slow the progression of the disease when starting physical activity in young people,“ Prof. Ulrich told us. “This is similar to a young person who practices regular physical activity and continues to do so at an older age.”

Furthermore, some research had also started in humans, he said:

“In addition, in collaboration with another research group from UNIFESP, we have begun to investigate the effect of resistance exercise in patients with mild cognitive impairment. The work is already in progress, and we hope to be able to show positive results soon as well.”

Dr. Sumeet Kumar, a geneticist and Parkinson’s disease researcher told MNT in an email that “[t]here’s an increasing amount of data that highlights the positive impact of physical activity on preventing Alzheimer’s disease.”

”Research indicates that active individuals are at a lower risk of developing this disease compared to inactive ones,” he added.

Dr. Kumar pointed to a review showing that the majority of research in this area was into the effect of aerobic exercise including tai chi and yoga.

The reasons why exercise has this effect on older adults’ brain health are unclear, but current understanding suggests the beneficial effects seen are due to improved growth and differentiation of nerve cells in the brain, reduced inflammation, improved function of blood vessels, and hormonal regulation.