Astaxanthin Supplementation Preserves Cognitive Markers of Executive Function Following Mental Fatigue in Females

Mental fatigue (MF) is a psychobiological state caused by prolonged periods of demanding cognitive activity, often characterized by impairments to cognitive performance. Astaxanthin (AX) is a naturally occurring antioxidant that can cross the blood-brain barrier and may preserve cognition when presented with a MF challenge. As yet, no studies have yet been conducted in an all-female cohort. This is the first study to investigate 4-weeks of AX supplementation on markers of cognitive performance (reaction time (RT), speed, and responses correct per second (RCS), visual analog scale of mental exertion (VAS-E)) following acute MF. Twenty-five recreationally active female subjects (AX: n  = 13, PLA: n  = 12) completed a battery of cognitive tasks (psychomotor vigilance test (PVT), task-switching (TS), and incongruent flanker (IF)) pre-post supplementation with either AX (12 mg/day) or a placebo (PLA). Following supplementation, PLA exhibited no differences on VAS-E or in any task after MF ( p  > 0.05). However, AX significantly improved RT (TS: ~200 ms; IF: ~50 ms), speed (TS: +20%; IF: +11%), and RCS (TS: pre, 1.04 ± 0.25 vs. post, 1.29 ± 0.24 correct·s; IF: pre, 1.79 ± 0.27 vs. post, 1.97 ± 0.29 correct·s)( p  < 0.05), although no differences were observed in the PVT variables ( p  > 0.05). These findings suggest that AX supplementation may preserve executive functions, such as cognitive flexibility and inhibitory control, under conditions of acute MF but may not influence basic attentional processes in college-age females. These findings have implications for populations where MF is known to occur (i.e., athletes and students), and suggest that dietary supplementation with AX may serve as a potent strategy for mitigating MF.