The diagnostic value of endothelial function as a potential sensor of fatigue in health

Yoshiko Ohno^1,2, Teruto Hashiguchi¹, Ryuichi Maenosono¹, Hidetoshi Yamashita³, Yukio Taira³, Kazufumi Minowa³, Yoshihito Yamashita³, Yuko Kato³, Ko-ichi Kawahara¹, Ikuro Maruyama¹

¹Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima City, Kagoshima Prefecture, Japan; ²Department of Community Health Nursing/Nursing Informatics, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima City, Kagoshima Prefecture, Japan; ³Kagoshima Seikyo General Hospital, Kagoshima City, Kagoshima Prefecture, Japan

Purpose: Many epidemiological research studies have shown that vital exhaustion and psychosocial factors are associated with the occurrence of cerebrocardiovascular disease (CCVD). Fatigue is thought to induce endothelial dysfunction and may be linked to the occurrence of CCVD; however, no studies have investigated this potential link. We studied to determine the effect of fatigue on endothelial function in healthy subjects with no traditional CCVD risk factors or potential confounding factors to be controlled.

Subjects and methods: Peripheral arterial tonometry (PAT) was used to evaluate endothelial function. The influence of the following parameters on endothelial function was analyzed in 74 office workers without traditional CCVD risk factors at health check-ups: endothelial function before and after work, subjective fatigue, lifestyle factors such as sleeping time, and psychosocial factors such as depression and social support.

Results: Twenty-five subjects (33.8%) had low endothelial function; reactive hyperemia (RH)-PAT index <1.67, even though no abnormalities were reported in the health check-ups. There was no significant difference in endothelial function before versus after labor. Of note, endothelial function was associated with the individual’s level of subjective fatigue (t = 2.98, P = 0.008) and showed a daily fluctuation, sometimes to a pathological degree (<1.67).

Conclusion: We showed that, even in healthy people, endothelial function fluctuates diurnally, with an interaction between the individual’s cognitive fatigue and the environment, sometimes to a pathological degree. Based on these findings, we suggest that endothelial function is an objective assessment tool of fatigue in healthy individuals.

Keywords: cerebrocardiovascular disease, endothelial dysfunction, subjective fatigue, flow-mediated dilatation, health education, reactive hyperemia peripheral arterial tonometry