Researchers have found that regular aerobic exercise not only improves physical health but also improves cognitive functioning, which might protect against Alzheimer's disease.
"This study is a significant step toward developing an exercise prescription that protects the brain against Alzheimer's disease, even among people who were previously sedentary," said lead investigator Ozioma C Okonkwo from the University of Wisconsin in the US.
For the study, published in the journal Brain Plasticity, researchers investigated 23 cognitively normal, relatively young older adults with a family history or genetic risk for Alzheimer's. All patients had a sedentary lifestyle.
They underwent a battery of assessments, including cardiorespiratory fitness testing, measurement of daily physical activity, brain glucose metabolism imaging (a measure of neuronal health), and cognitive function tests.
Half of the participants were randomly assigned to receive information about maintaining an active lifestyle but no further intervention.
The other half participated in a moderate-intensity treadmill training program with a personal trainer, three times per week for 26 weeks.
Improved cardiorespiratory fitness associated with increased brain glucose
Compared to the participants maintaining their usual level of physical activity, individuals assigned to the active training program improved their cardiorespiratory fitness, spent less time sedentary after the training program ended, and performed better on cognitive tests of executive functioning (but not episodic memory).
Executive function, an aspect of cognition that is known to decline with the progression of Alzheimer's, comprises the mental processes enabling individuals to plan, focus attention, remember instructions, and juggle multiple tasks successfully.
The participants' improved cardiorespiratory fitness was associated with increased brain glucose metabolism in the posterior cingulate cortex, an area of the brain linked to Alzheimer's.
This research shows that a lifestyle behaviour -- regular aerobic exercise -- can potentially enhance brain and cognitive functions that are particularly sensitive to the disease.
"The findings are especially relevant to individuals who are at a higher risk due to family history or genetic predisposition," Okonkwo said.