Mental Fatigability and Heart Rate Variability in Mild Cognitive Impairment

Objectives Adaptive physiological stress regulation is rarely studied in mild cognitive impairment (MCI). Here we targeted mental fatigability (MF) as a determinant of altered high frequency heart rate variability (HF-HRV) reactivity in individuals with MCI, and examined frontobasal ganglia circuitry as a neural basis supporting the link between MF and HF-HRV reactivity. Methods We measured mental fatigability and HF-HRV during a 60-minute cognitive stress protocol in 19 individuals with MCI. HF-HRV responses were modeled using a quadratic equation. Resting state functional connectivity of intra- and inter-network frontobasal ganglia circuitry was assessed using blood-oxygen-level-dependent magnetic resonance imaging among seven of the participants. Results Lower MF was associated with faster and greater rebound in U-shape HF-HRV reactivity, which linked to a stronger connectivity between right middle frontal gyrus and left putamen. Conclusions Results suggest that MF may contribute to abnormal physiological stress regulation in MCI, and fronto basal ganglia circuitry may support the link.