Differential macro- and microvascular function responses to acute mental stress in healthy young men

Acute mental stress (MS) can impair macrovascular function, causing increased arterial stiffness and endothelial dysfunction; however, its effect on microvascular function remains largely unclear. This study examined the impact of acute MS on microvascular function using near-infrared spectroscopy combined with vascular occlusion testing (NIRS-VOT). Seventeen healthy young men underwent two experimental trials with a randomized crossover design: control (CON) and MS trials. In the MS trial, the participants performed a 5-min MS task, whereas those in the CON trial remained quiet at rest for the same duration. Arterial stiffness was assessed using the cardio-ankle vascular index (CAVI). NIRS-VOT was conducted on the forearm, and the upslope of tissue oxygen saturation (StO₂) during the first 10 s after cuff release was used as an index of microvascular function. These measurements were obtained before (pre) and 30 min after (post) the task. The MS trial resulted in a significant increase (P < 0.05) in CAVI (pre: 6.0 ± 0.5 unit, post: 6.3 ± 0.6 unit), whereas no significant change was observed in the CON trial (pre: 6.0 ± 0.4 unit, post: 6.0 ± 0.5 unit). The StO₂ upslope did not change significantly in either the CON (pre: 2.65 ± 0.99%/s, post: 2.72 ± 1.07%/s) or MS (pre: 2.64 ± 0.82%/s, post: 2.62 ± 0.70%/s) trial. The findings of this study demonstrate that acute MS increases arterial stiffness while having a limited impact on microvascular function, suggesting differential macro- and microvascular reactivity to acute MS.