An image of the human brain.
(photo credit: REUTERS)
There is growing medical evidence that exercise slows down the aging of the brain and can reduce the risk of Alzheimer’s disease and other dementias by about half, according to Prof. Nir Giladi, chief of neurology at Tel Aviv Sourasky Medical Center.
Speaking Tuesday at a Tel Aviv University international conference on the effects of exercise on health – especially that of the brain – he said the modern, sedentary way of life has resulted in less body movement.
However, long-term epidemiological and physical studies show that exercise can minimize pain and improve memory, concentration and mood, as well as reduce the risk of cognitive damage, stroke, Parkinson’s disease and depression.
The connection between exercise and brain function was first disclosed in animal studies two decades ago, said Giladi. The brains of rats that ran on a wheel for three months had many more neurons and synapses for conveying electric signals, showing that exercise causes these to multiply, he said.
“These findings flew in the face of the belief that [in people] over the age of 30, the neurons decline irreversibly,” he said. “Today we know that the adult brain has many stem cells that, when stimulated, can differentiate and turn into ripe neurons that know how to create synapses.”
The neurologist added that for some unknown reason, the best potential for differentiation exists in brain regions responsible for memory.
Exercise promotes the secretion of trophic factors – including brain-derived neurotrophic factors, which encourage the growth of stem cells that can become adult nerve cells, he explained. These factors activate genes responsible for the development of stem cells in the hippocampus and other brain regions involved in memory, storage and processing of data. They are available in large quantities during a baby’s first years, when the brain develops at a rapid pace, but the amounts decline during adolescence and aging.
The greater the amount, the more the brain grows and holds more nerve cells, especially in the hippocampus, he said. Exerting the muscles activates genes that encourage the muscle cells – and apparently others – to create proteins that increase the synthesis of trophic factors.
“This is why those who exercise regularly look [younger] and have younger brain function – and their cells are more protected from diseases, trauma and natural aging.”
Giladi said it is best to do aerobic exercise (causing the heart and lungs to exert themselves) along with non-aerobic exercise (strengthening one’s muscles) at least three times a week. Even for those who only begin exercise in adulthood, after the cognitive decline has begun, the physical activity will slow down the rate of decline.
A 2011 study published in the journal PNAS, using MRI to see the effect of regular exercise on the brain, showed that the brains of healthy 75-year-olds who performed physical activity at least three times a week declined more slowly in the regions responsible for memory, concentration, planning, initiative and management abilities. The same thing emerged from studies of teenagers, Giladi said.
Exercise influences the brain cells in deciding which genes will function and contribute, and which will be neutralized. This process thus falls under epigenetics, in which the environment actually affects the genes, the neurologist said.
In addition, he went on, exercise increases the supply of blood to the organs, including the brain, and encourages the growth of alternate blood vessels to take over functions from clogged vessels.
Giladi bemoaned that many Israelis don’t exercise regularly. An average of 150 to 300 minutes per week – half aerobic and half non-aerobic – can improve the abilities of the brain and protect it from disease, he said.