Aerobic Exercise for the Older Brain

RESEARCH UPDATE

Animal research and observation studies in humans point to an association between exercise-particularly aerobic cardiovascular exercise-and enhanced brain health that may reduce the risk of dementia or slow its progression. Given that there are no disease-modifying or preventive therapies for Alzheimer disease (AD), exploration of the impact of aerobic exercise on dementia has become a popular avenue of research. Recent findings from researchers affiliated with the University of Kansas in Kansas City suggest that aerobic exercise helps improve functional ability and reduce hippocampal atrophy in early-stage AD.¹

The researchers conducted a pilot study to assess the effect of 6 months of supervised aerobic exercise on memory, executive function, functional ability, and depression in 68 adults (average age, 73 years) with a diagnosis of mild cognitive impairment or probable AD. Secondary outcomes included cardiovascular fitness and impact on brain structure.

The registered randomized controlled clinical trial was dubbed ADEPT (Alzheimer’s Disease Exercise Program Trial). It compared the effects of 2½ hours per week of aerobic exercise versus nonaerobic stretching and toning exercise.

Aerobic vs nonaerobic exercise

Participants randomized to the aerobic therapy group were supervised to gradually increase weekly exercise duration to 150 minutes per week, per the Physical Activity Guidelines for Americans, with the target heart rate gradually increasing from 40% - 55% to 60% - 75%.² The control group engaged in nonaerobic exercises that rotated weekly and included core strengthening, use of resistance bands, tai chi, and yoga.

Neuropsychological tests and surveys were conducted at baseline and at 13 and 26 weeks to assess memory (Logical Memory and Free and Cued Selective Reminding Test); executive function (Digit Span, Category Fluency, D-KEFS Confirmed Correct and Free Card Sorting, Letter Number Sequencing, and Stroop Color-Word Interference); functional ability (Disability Assessment for Dementia); and depressive symptoms (Cornell Scale for Depression in Dementia). Cardiorespiratory fitness testing (highest oxygen consumption attained [peak VO₂] and the 6-minute walk test) and brain structure evaluation (magnetic resonance imaging of bilateral hippocampal volume and total gray matter) were performed at baseline and at 26 weeks.

Improved functional ability

Although the primary outcomes regarding memory, executive function, and depressive symptoms were not met, aerobic exercise was associated with a modest but statistically significant gain in functional ability compared with nonaerobic stretching and toning (P = .02). Disability Assessment for Dementia scores increased 1.5 points for the aerobic group but decreased by 4.5 points for the nonaerobic exercise group. Change in cardiorespiratory fitness, as measured by change in peak VO₂, positively correlated with change in memory performance (P = .003). A positive change (P = .03) in bilateral hippocampal volume also was seen.

The bottom line

The researchers noted that the intervention had a meaningful effect on sustained independence. They concluded that their research supports previously published findings on the role of cardiovascular fitness in dementia risk prevention and that regular, supervised aerobic exercise that meets the Physical Activity Guidelines for Americans (2½ hours per week) can help increase functional ability and enhance brain structure in older adults in cognitive decline.

References:

1. Morris JK, Vidoni ED, Johnson DK, et al. Aerobic exercise for Alzheimer’s disease: a randomized controlled pilot trial. PLoS One. 2017;12:e0170547.

2. Office of Disease Prevention and Health Promotion. Department of Health and Human Services. Physical Activity Guidelines for Americans. https://health.gov/paguidelines/guidelines/. Accessed February 20, 2017.