Aerobic exercise can improve cognition and increase cortical thickness in older adults. In this randomized, community-based clinical trial, researchers examined whether aerobic exercise can affect cognitive performance in younger adults. At baseline, 132 adults aged 20 to 67 (mean, about 40) were cognitively normal with below-average fitness. All participants were randomized into an aerobic exercise or a stretching/toning condition, exercising for 40 to 55 minutes four times a week for 6 months.

Outcomes included aerobic capacity (maximum oxygen uptake), cognitive performance, body-mass index (BMI), and cortical thickness. Aerobic exercise (but not stretching and toning) was associated with increased aerobic capacity, decreased BMI, and increased left middle frontal cortical thickness. Improvement in executive function was also seen in the aerobic exercise condition, especially with increasing age and in those without an apolipoprotein E ℇ4 allele.