title: Aerobic fitness and cognitive function in midlife: an association mediated by plasma insulin.
abstract: 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 (VO2max), 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 < 0.001) than sedentary subjects. Greater VO2max was significantly associated with higher memory performance (β = 0.37, P = 0.01) and lower plasma insulin levels (β = -0.68, P < 0.001). The significant association between VO2max and memory performance was abolished when the indirect effect of plasma insulin was statistically removed (β = 0.24, P = 0.19). Fitness-related cognitive enhancement may be mediated, at least in part, by plasma insulin levels.
authors.affiliation: Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tarumi
authors.forename: Mitzi M
authors.initials: MM
authors.lastname: Gonzales
authors.forename: Bennett
authors.initials: B
authors.lastname: Fallow
authors.forename: Nantinee
authors.initials: N
authors.lastname: Nualnim
authors.forename: Jeongseok
authors.initials: J
authors.lastname: Lee
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tanaka
authors.forename: Andreana P
authors.initials: AP
authors.lastname: Haley
mesh_terms: D003071:Cognition / Q000502:physiology*; D015444:Exercise / Q000502:physiology* / Q000523:psychology; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*
chemical_list: D007328:Insulin