Aerobic fitness and cognitive function in midlife: an association mediated by plasma insulin

Insulin resistance in midlife increases the risk of dementia in late-life. In contrast, habitual aerobic exercise is an established strategy to ameliorate insulin resistance which may translate into better cognitive outcome. To determine the role of plasma insulin in mediating the relation between cardiorespiratory fitness and cognitive function, fifty-eight adults completed assessments of plasma insulin levels, maximal oxygen consumption (VO 2 max), and neuropsychological test performance. Endurance-trained subjects demonstrated better cognitive outcome (total composite z-score: 0.21 ± 0.08 versus −0.26 ± 0.10, P = 0.001) and lower concentrations of plasma insulin (12.6 ± 0.6 versus 21.3 ± 1.5 ulU/mL, P