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. Purpose To determine the role of plasma insulin in mediating the relation between cardiorespiratory fitness and cognitive function. Methods Fifty-eight adults completed assessments of plasma insulin levels, maximal oxygen consumption (VO2max), and neuropsychological test performance. Results 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). Conclusion Fitness-related cognitive enhancement may be mediated, at least in part, by plasma insulin levels.

The Role of Chronic Physical Activity in Alleviating the Detrimental Relationship of Childhood Obesity on Brain and Cognition

“…Importantly, research has indicated the mediating role of insulin resistance on the relationship between aerobic fitness and memory. That is, increased aerobic fitness may favor memory performance via decreased insulin resistance (Tarumi et al, 2013). This finding has been expanded by a study showing close relationships between increased aerobic fitness, increased insulin sensitivity, and greater cortical thickness in the frontal lobes in adolescent children, with higher insulin sensitivity showing stronger association with frontal cortical thickness (Ross et al, 2015).…”

Vascular Functions and Brain Integrity in Midlife: Effects of Obesity and Metabolic Syndrome

“…The cardiovascular benefits of aerobic exercise are well known [46] and fitness training has been associated with cognitive enhancement in nondemented older adults [47]. Our own research has demonstrated that fitness-related benefits on neuronal viability [48], cerebral perfusion [49], and cognitive function [50] are evident as early as midlife. However, it is still unclear whether this benefit is simply due to prevention of other risk factors (e.g., reductions in blood pressure), or whether exercise can reverse the negative effects of aging on the brain.…”

Associations of midlife fitness and obesity profiles with cognitive function

“…Although there are fewer studies in middle age (Adamo et al., 2020; Malmstrom et al., 2005), similar associations have been demonstrated. For example, in middle age, weaker grip strength was cross‐sectionally associated with lower executive function, global cognition and verbal fluency (Adamo et al., 2020; Malmstrom et al., 2005), and lower CRF was associated with lower global cognition and memory (Tarumi et al., 2013). The mechanisms underpinning these relationships are uncertain.…”

“…This relationship is likely driven by vascular disease (Kivipelto et al., 2005), physical inactivity and pro‐inflammatory markers released from adipose tissue (Craft, 2009). However, collectively, these studies have mainly considered strength, obesity and CRF independently (Adamo et al., 2020; Dahl et al., 2013; Malmstrom et al., 2005; Tarumi et al., 2013) and included small sample sizes ( n < 60) (Adamo et al., 2020; Tarumi et al., 2013).…”