Aerobic exercise could give older adults a boost in brainpower, according to a recent review of studies from the Netherlands.
"Aerobic physical exercises that improve cardiovascular fitness also help boost cognitive processing speed, motor function and visual and auditory attention in healthy older people," said lead review author Maaike Angevaren.
Around age 50, even healthy older adults begin to experience mild declines in cognition, such as occasional memory lapses and reduced ability to pay attention. Convincing evidence shows that regular exercise contributes to healthy aging, but could the types of exercise a person does influence his or her cognitive fitness?
Angevaren and her colleagues at the University of Applied Sciences, in Utrecht, evaluated 11 randomized controlled trials, comprising about 670 adults ages 55 and older, which examined the effects of aerobic exercise on areas of cognition including cognitive processing speed, memory and attention.
Nine studies took place in the United States; one occurred in France and another in Sweden.
Aerobic exercise involves continuous, rhythmic activity that strengthens the heart and lungs and improves respiratory endurance. In the studies included in this review, participants exercised aerobically between two and seven days a week for several weeks - three months on average - and underwent fitness and cognitive function tests.
The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Not surprisingly, eight of the 11 included studies found that participation in aerobic exercise programs increased participants' VO2 max, an indicator of respiratory endurance, by 14 percent.
Improvements in cardiorespiratory fitness coincided with improvements in cognitive function - especially motor function, cognitive speed and auditory and visual attention - when participants were compared to a group of non-exercising adults or adults in a yoga- or strength-based program.
So how does sweating to the oldies affect brain function?
"Improvements in cognition as a result of improvements in cardiovascular fitness are being explained by improvements in cerebral blood flow, leading to increased brain metabolism which, in turn, stimulates the production of neurotransmitters and formation of new synapses," Angevaren aid.
"At the same time, improved cardiovascular fitness could lead to a decline in cardiovascular disease [which is] proven to negatively affect cognition," she said.
Despite the positive mental health benefits that seem to be associated with aerobic activity, researchers could not confirm that aerobic activity specifically is necessary for cognitive improvement, Angevaren said.
For example, when researchers left non-exercisers out of the equation and examined test scores of adults who did any type of exercise - including aerobic activity, strength training or flexibility programs - they found no significant differences for nine of the 11 cognitive functions measured.
"It needs to be established whether the same effects can be achieved with any type of physical exercise," including exercise bouts of greater intensity or longer duration, Angevaren said.
Based on the individual studies and their overall analysis, the authors have made a clear case in concluding that physical activities benefit cognitive function in older adults, said Sarah Laditka, associate professor in the Arnold School of Public Health at the University of South Carolina. She was not affiliated with the review.
"At the same time, they pointed out a number of considerations that readers need to keep in mind," Laditka said. For example, in many of the studies, the sample size was small, and the cognitive tests used to assess participants varied widely from study to study.
In addition, "it's clear that the longer-term effects of aerobic physical activity on cognition are not known and that needs to be studied," Laditka said.
However, although relatively few randomized controlled trials exist that investigate the cognitive affects of aerobic activity on cognition, "there are an increasing number of epidemiological studies which indicate very positive benefits of regular physical activity on cognitive health," Laditka said.
"The takeaway message to me as a gerontologist is that increasingly there is an association between physical activity - broadly defined - and cognitive health. That would speak in favor of encouraging older people and people of all ages to engage in regular physical activity," Laditka said.