Exercise key to stalling dementia

Exercise prevents the development of dementia and Alzheimer’s disease.

A study in the Journal of Neuroscience has given a clue to the benefit of exercise in the brains of older people.

Exercise prevents the development of dementia and Alzheimer’s disease, research has found.

Scientists have developed an increasing understanding of the links between exercise and neuro­-degenerative disease and cognitive ageing in recent years, but exactly how exercise had a protective effect had been unknown. Now a study in the Journal of Neuroscience has given a clue to the benefit of exercise in the brains of older people.

The key appears to lie in exercise’s ability to decrease immune cell activation and consequent reduced inflammation in the brain, the study has indicated.

The brain’s immune cells, microglia, activate to clear debris and foreign invaders from the brain but too much activation can trigger inflammation, damage neurons and disrupt brain signalling.

Scientists have previously ­observed that exercise helped to reduce aberrant activation of the microglia in animals, but the link had not been established until now in humans.

Scientists from the Memory and Ageing Centre in the department of neurology at the University of California Rush Memory and Ageing Project studied the activity levels of 167 older people for 10 days and then tested their cognitive function. They also examined microglia activation and Alzheimer’s disease in post-­mortem brain tissue analyses.

Greater physical activity was linked to lower microglial activation, particularly in an area of the brain known as the inferior temporal gyrus, the region hit hardest by Alzheimer’s disease.

Not only was decreased microglial activation observed in all older adults following exercise, but physical activity had a more pronounced effect on brain inflammation in people with more severe Alzheimer’s disease pathology. “Our data suggests that reduced microglial activation may be a meaningful pathway linking physical activity to age-related brain health in humans, and adults who stand to clinically benefit most from physical ­activity may be those with ­Alzheimer’s disease-related microglial activation,” the authors of the paper said.

“Given the role for microglia guiding brain ageing and neuro-degeneration and the casual relationship between physical activity and microglial homeostasis in animals, an in-depth understanding of this relationship in humans is needed.”