September 3, 2008
Improving physical conditioning isn't the only reason to work out. More research suggests mental benefits from exercise.
Adults with memory problems who participated in a home-based physical activity program experienced a modest improvement in their thought processes compared with those who did not participate in the program, according to a study in the September 3 issue of JAMA.
As the world population ages, the number of older adults living with Alzheimer disease is estimated to increase from the current 26.6 million to 106.2 million by 2050.
"If illness onset could be delayed by 12 months, 9.2 million fewer cases of AD would occur worldwide," the authors conclude. "For this reason, attempts have been made to identify individuals who are at increased risk of AD and to test interventions that might delay the progression of early symptoms to full-blown dementia."
Researchers from the University of Melbourne, Australia, conducted a randomized controlled trial to test whether a physical activity intervention would reduce the rate of cognitive decline among 138 adults age 50 years and older at increased risk of dementia.
The participants, who reported memory problems but did not meet criteria for dementia, were randomly allocated to an education and usual care group or to a 24-week home-based program of physical activity.
The idea was to encourage participants to perform at least 150 minutes of moderate-intensity physical activity per week in three 50-minute sessions. The most frequently recommended type of activity was walking.
The intervention resulted in 142 minutes more physical activity per week or 20 minutes per day than with usual care. Cognitive function was assessed with the Alzheimer Disease Assessment ScaleCognitive Subscale over 18 months.
The researchers found that by the end of the study, participants in the exercise group had better ADAS-Cog scores and delayed recall than those in the usual care control group. They also had lower Clinical Dementia Rating scores.
The benefits of physical activity were apparent after 6 months and persisted for at least another 12 months after the intervention had been discontinued.
"The average improvement of 0.69 points on the ADAS-Cog score compared with the usual care control group at 18 months is small but potentially important when one considers the relatively modest amount of physical activity undertaken by participants in the study," the authors write.
"Unlike medication, which was found to have no significant effect on mild cognitive impairment at 36 months," they conclude, "physical activity has the advantage of health benefits that are not confined to cognitive function alone, as suggested by findings on depression, quality of life, falls, cardiovascular function, and disability."
