BOSTON — MONDAY, July 15, 2013 (MedPage Today) — Physical activities may help to protect against the deleterious influence of age on memory in people at high risk of mild cognitive impairment (MCI) and Alzheimer's disease, researchers reported here.
Cognitive tests of immediate memory remained relatively stable in people who regularly exercised, while declining in people who exercised less, Dorothy Edwards, PhD, of the University of Wisconsin in Madison, and colleagues reported at the Alzheimer's Association International Conference.
On cognitive tests of speed and flexibility, even the high exercisers saw some drop in scores, "but the decline was much much greater in the lower exercisers, she told MedPage Today.
Moreover, imaging tests showed that the negative effects of age on memory on hippocampal volume were much weaker in the high exercise group, Edwards said. "This was particularly true in the left hippocampus, which is where we usually first see early changes indicative of MCI and Alzheimer's disease," she said.
"Exercise did not prevent the loss of memory associated with age in high-risk people, but it did ameliorate age-associated hippocampal atrophy associated loss of memory," she said.
Previous research has shown that physical exercise stimulates hippocampal neurogenesis and that an inactive lifestyle is associated with brain changes associated with Alzheimer's disease.
"But none have looked at a preclinical population at high familial risk of MCI and Alzheimer's," Edwards said. "That's what makes these findings so important."
Maria Carrillo, PhD, vice president of medical and scientific relations at the Alzheimer's Association, agreed. "The benefits of exercise on protecting cognition is something we will be hearing a lot about at this year's meeting," she said.
"We already know that exercise is important in terms of all sorts of health measures. Now it appears that over time, it also had benefits in preserving memory and other aspects of cognition, even in high-risk people," she added.
The study involved 317 people who were enrolled in the Wisconsin Registry for Alzheimer's Prevention (WRAP) study, a longitudinal cohort of people with a family history of Alzheimer's.
Participants filled out an exercise questionnaire and then were divided into two groups depending on how much exercise they performed each week, further scaled according to intensity.
Overall, 79 people were classified as having low exercise status, corresponding to less than 7.6 metabolic equivalents of task (METs) per hour/week; the other 238, who performed at least 7.7 MET per hour/week were in the higher exercise group.
Baseline factors that differed significantly between the two groups were:
- Age: Mean of 60 for high exercisers versus 34 for lower exercisers
- Body mass index: Mean of 27.1 kg/m2 for high exercise group versus 30.6 kg/m2 for the low group
- IQ: Mean of 114.8 in the high group versus 112.4 in the low group
Six cognition tests were performed. Exercise had no impact on scores on four of the tests — verbal learning and memory, working memory, visual learning and memory and story recall.
The next step is to try to figure out why exercise seems to have a protective effect. "Is it through effects on cardiovascular health, or through certain brain growth factors, for example?" Edwards said.
"Further longitudinal analysis will help us to clarify whether these effects hold prospectively as well as provide information on the extent to which midlife participation in physical activities protects against the development of [Alzheimer's] and related disorders in later life," she said.