Physical exercise protects brain health in older adults
An international research team has shed light on the biological processes involved in the beneficial effect of physical exercise on cognitive abilities and mental health. As published in the journal Alzheimer’s and dementiathe team found that exercise increases levels of certain proteins known to enhance communication between brain cells across synapses, which may be a key factor in keeping dementia at bay.
In order to support healthy brain aging in older adults, various lifestyle changes are generally recommended, such as adopting a more balanced diet, boosting routine cognitive activities, and spending more time in physical exercise. This recommendation is based on epidemiological observations which support that physical activity is associated with a lower incidence of Alzheimer’s disease and other dementias, and it is estimated that sedentary lifestyles may account for more than four million cases of dementia each year.
“Several clinical trials in which moderate physical exercise was included as a therapy showed a positive effect on both cognition and cortical thickness,” noted study co-author Alfredo Ramos-Miguel, researcher at the University of the Basque Country. Additionally, preclinical studies in animal models have suggested that physical exercise may improve cognitive abilities by increasing synaptogenesis, i.e. the generation of new neural connections. But according to Ramos-Miguel, “the difficulty of performing molecular studies in the human brain limits the possibilities of finding the biological mechanisms that mediate the beneficial effects of physical exercise on mental and cognitive health during aging”.
To establish the anatomo-pathological and molecular bases of cognitive and psychomotor decline, the Memory and Aging Project (MAP) of the Rush Alzheimer’s Disease Center has been conducting since 1997 a longitudinal study with volunteers who agree to undergo periodic cognitive and psychomotor assessments and to donate their organs for scientific purposes after their death. This makes it possible to directly correlate daily habits and health states with structural and functional alterations in participants’ brains.
The latest publication of this project presents the results of 404 people whose physical activity was monitored with a wristwatch or wristband activity meters for an average of 3.5 years ante-mortem. After death, samples were taken from up to 12 brain areas critical for cognitive and psychomotor skills; quantitative and functional analyzes of eight synaptic proteins were performed on these samples, and a comprehensive histopathological evaluation, which examines 10 neuropathologies associated with aging, was performed.
The results confirmed that higher levels of daily physical activity are associated at all levels with an enrichment in the quantity and functionality of all synaptic proteins analyzed. This association was more pronounced in brain regions related to motor control, such as the caudate nucleus and putamen. Moreover, the relationship between physical exercise and synaptic density was independent of both the neuropathological load found in the same brain areas and the presence of pathologies affecting motor skills, indicating that physical activity can be beneficial for all. elderly person regardless of their state of health. Actigraphy data also indicated that the beneficial effects of physical exercise are highly volatile, as participants with a high physical routine in early life who discontinued this habit in the last two years of life had synaptic densities similar to those seen in more sedentary participants.
“This study shows, for the first time in humans, that physical exercise, even at advanced age, contributes either to promoting the processes of synaptogenesis or to increasing synaptic resilience against the deleterious effects of neuropathological lesions”, said Ramos-Miguel.
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