A year of moderate-to-vigorous aerobic exercise reduced MRI-based measures of brain aging. Digest
Brain aging begins long before memory problems appear, but researchers still debate when lifestyle changes can measurably influence brain structure. A randomized clinical trial tested whether an aerobic exercise program that matches common activity recommendations can alter an MRI-derived estimate of brain aging in early and midlife adults.
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Researchers enrolled 130 generally healthy adults ages 26 to 58 who reported low levels of structured physical activity. They randomized participants to either 12 months of moderate-to-vigorous aerobic exercise, targeting 150 minutes per week with two supervised sessions plus home workouts, or to a health information control condition. The study assessed brain-predicted age difference (brain-PAD), defined as the gap between a person's chronological age and an age estimate generated from structural magnetic resonance imaging (MRI). The team also measured cardiorespiratory fitness using peak oxygen uptake (VO2peak), and examined potential mediators at baseline and 12 months: body mass index, body fat and waist measures, blood pressure, and plasma brain-derived neurotrophic factor (BDNF, a protein that helps support nerve cell health and communication).
- At the start of the study, participants with higher VO2peak tended to have a lower brain-PAD, meaning their brains appeared younger relative to their age.
- After 12 months, brain-PAD decreased by about 0.6 years in the exercise group. The control group showed no clear change, even though the brain-PAD was slightly higher at the end of the year.
- The exercise program improved VO2peak relative to control, consistent with a training-related gain in cardiorespiratory fitness.
- Changes in fitness, body composition, blood pressure, or BDNF did not explain why the estimated brain age shifted.
These results support the idea that sustained aerobic exercise in early and midlife can influence brain aging, even when standard cardiometabolic measures remain stable. Improvements in processes not captured here, such as inflammatory signaling, neurovascular function (how blood vessels support brain tissue), mitochondrial adaptations, or metabolic shifts, could contribute to better brain aging.
Larger trials that test other biological pathways, more time points, and more diverse risk profiles will be needed to clarify who benefits most and through which physiological routes. In this clip, Dr. Axel Montagne highlights how 90% of our brain vasculature is tiny blood vessels - without exercise, they collapse, and neurons die.