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How does exercise protect brain health? New research sheds light. Suhaimi Abdullah/NurPhoto via Getty Images
  • Existing studies show that exercise helps protect brain cells through mechanisms that researchers don’t yet fully understand.
  • Researchers know that exercise increased cerebral glucose metabolism, which correlates with improved brain function.
  • Studies show that exercise affects insulin resistance and has a complex relationship with body mass index (BMI) levels.
  • A new study suggests that exercise plays a role in maintaining insulin levels and BMI, which may help prevent dementia by protecting gray matter volume in the brain.

A new study examines the mechanisms involved in the relationship between exercise and brain health.

Previous research had shown that greater gray matter volume may help protect against dementia by improving brain function.

The new study shows that insulin resistance and BMI mediate the relationship between larger and smaller brain gray matter volumes (the part of the brain involved in processing information).

The research is published in the April 2022 online issue of Neurologythe medical journal of the American Academy of Neurology.

The corresponding author of the study was Dr Géraldine Poisnel, of the Inserm Regional Research Center, in Caen, Normandy, France.

The study involved 134 people with an average age of 69 who had no memory problems. Participants completed a physical activity survey covering the past 12 months. They also had brain scans to measure glucose metabolism and brain volume.

Glucose metabolism in the brain provides fuel for the brain by generating adenosine 5′-triphosphate (ATP) – a key molecule for maintaining the health of neurons and other cells. ATP is also essential for generating neurotransmitters. Reduced glucose metabolism in the brain can be seen in people with dementia.

Gray matter development peaks with age 2–3 years. It begins to decrease thereafter in certain areas of the brain, but the density of gray matter increases. From an evolutionary point of view, the greater processing capacity of the human brain and its development are due to this increase in density.

In certain studieslarger total brain volume, estimated by magnetic resonance imaging (MRI), has a weak correlation with higher intelligence in men and a very weak correlation in women with the ability to perform well on intelligence tests.

In contrast, the deterioration of brain tissue and the loss of volume contribute significantly to the decline in cognitive abilities later in life.

In the new study, the researchers included 134 people with an average age of 69 who had no memory problems. Participants completed a physical activity survey covering the past 12 months. They also had brain scans to measure glucose metabolism and brain volume.

In the new study, the researchers gathered information on cardiovascular risk factors, including BMI and insulin levels, as well as cholesterol, blood pressure and other factors.

Researchers have examined the relationship between insulin and cardiovascular disease. Insulin-induced metabolic abnormalities increase the risk of cardiovascular complications, which in turn affect brain function.

The researchers found that insulin levels and BMI did not affect glucose metabolism in the brain.

Research has shown that the amount of amyloid plaque in the brain that contributes to Alzheimer’s disease was not affected by exercise.

Medical News Today contacted Dr. Raeanne Moore, associate assistant professor of psychiatry at UCSD in La Jolla, California.

Dr. Moore, who was not involved in the study, was asked about the results of the study. She shared with DTM:

“This study adds to the growing body of research on the positive benefits of staying active on brain health, particularly as we age.”

“[T]there is an urgent need to identify markers of cognitive decline,” added Dr. Moore. “Decreased insulin levels and weight loss are modifiable factors that can be improved with healthy diet and exercise.”

She added: “It was not surprising that higher physical activity was not associated with the amount of amyloid plaque people had in their brains. There is growing evidence that vascular risk factors on cognitive function are mediated by the amount of tau pathology in the brain and not by amyloid load.

DTM also spoke with Dr. Sheldon Zablow, assistant professor of medicine at the University of California San Diego School of Medicine in La Jolla, California. Dr. Zablow shared his comments on this study:

“Exercise has often been referred to as food for the brain, with numerous studies showing the benefits of exercise in improving brain health and reducing the risk of dementia.”

“This current research study indicates that physical activity improves cognitive brain function by reducing BMI and improving insulin metabolism. Improved weight control may limit the rate of brain volume loss, a known risk factor for dementia.

“This study will help physicians reinforce the importance of regular exercise in lowering BMI as an inexpensive way to limit cognitive decline.”

– Dr. Zablow

Dr. Moore’s closing remarks were: “The literature clearly demonstrates that cardiovascular risk factors are associated with cognitive decline and the risk of Alzheimer’s disease and related dementias.”

“Studies looking at subtle brain changes before the development of dementia are critical to optimizing brain health and avoiding cognitive decline.”

“Strengths of this study include a sample of cognitively normal older adults and the use of multimodal imaging methods to explore the role of CVD risk factors in the association between physical activity and neuroimaging. biomarkerssaid Dr. Moore.

“[T]his methodology may advance the field by helping to identify important risk markers for cognitive decline.

“A limitation to the study was the use of a self-report of physical activity […] which the authors acknowledged as a limitation. Self-reported physical activity is subject to hindsight bias, and objective tools for measuring physical activity, such as fitness trackers, are more accurate.

“These findings that insulin and BMI fully mediated the relationship between physical activity and whole-brain gray matter volume—and in particular hippocampal gray matter volume—provide further evidence that the targeting these modifiable CVD risk factors could improve brain health.”