Abstract
Forearm vascular conductance (FVC) increases in response to mental stress (verbal mental arithmetic) in young people. However, the effect of healthy aging and mental stress on FVC is unknown. In this study, we tested the hypothesis that FVC and cutaneous vascular conductance (CVC) would be attenuated in older adults compared to young adults. In 13 young (27 ± 1 year) and 11 older (62 ± 1 year) subjects, we quantified heart rate (HR), mean arterial pressure (MAP), FVC (Doppler ultrasound), and CVC (laser Doppler flowmetry) in response to a 3-min bout of mental stress in the supine posture. Changes from baseline were compared between groups and physiological variables were also correlated. Older adults had a blunted HR response to mental stress (Δ = 7 ± 2 vs. 14 ± 2 beats/min) but ΔMAP was comparable between groups (Δ = 11 ± 2 mmHg vs. 9 ± 1). During the third minute of mental stress, the %ΔFVC (-2 ± 5 vs. 31 ± 12%) and %ΔCVC (2 ± 6 vs. 31 ± 15%) were both impaired in older adults compared to young subjects. There was no relationship between ΔHR and %ΔCVC in either group, but there was a positive relationship between ΔHR and %ΔFVC in both young subjects (R = 0.610, P < 0.027) and older subjects (R = 0.615, P < 0.044), such that larger tachycardia was associated with higher forearm vasodilation. These data indicate that older adults have impaired forearm vasodilation in response to mental stress.