Evidence of the moderating role of hair cortisol and hair cortisone in the relationship between work stress and depression symptoms among Chinese fishermen

Background Stress plays an important role in the pathogenesis of depression through functional changes to the hypothalamic-pituitary-adrenal (HPA) axis, a key output of which is the stress hormone cortisol. But the precise relationship between HPA axis activity and depression remains unclear, in part because mostly cortisol measurement only provides reflect acute or short-term fluctuations. In this study, hair cortisol and its metabolite cortisone were measured in a prospective, pre and post follow-up study of working stress and depressive symptoms in Chinese fishermen. We evaluated HPA activity, work stress, and depression symptoms before and after fishing to determine whether cortisol and cortisone in hair can moderate the work stress and depression symptoms of Chinese fishermen. Methods Hair cortisol, hair cortisone, work stress, and depression were measured in Chinese fishermen (n=229; age 16–65) before and after 1–3 months at sea. A week after the fishermen returned, they provided 2–4 cm hair segments closest to the scalp. We measured hair cortisol and hair cortisone using high-performance liquid chromatography–tandem mass spectrometry. Results The work stress and hair cortisol of fishermen before fishing were significantly higher than those after fishing, while hair cortisone was lower. There was no significant difference in depressive symptoms. Fishermen with low hair cortisol or high hair cortisone were more likely to show depressive symptoms after experiencing stress, and were less likely to show depressive symptoms when faced with lower levels of work stress, consistent with the differential susceptibility model. Limitations The assumption of an average hair growth of 1 cm/month may cause time overlap between pre- and post-fishing, and time error between the hormone data and questionnaire collection. The present study evaluated only two observation points. The use of self-report scales may affect interpretability of the results. Finally, the study used a limited sample of marine fishermen working out of a single location in Hainan province, China. Conclusions Hair cortisol and hair cortisone appear to have a moderating role in the relationship between work stress and depressive symptoms among fishermen, which fits with the differential susceptibility model of depression. However, their mechanisms of moderation are not the same, which may reflect the complexity of physiological indicators.