Theory of mind and hair cortisol in healthy young adults: the moderating effects of childhood trauma

Background: Experiences of negative social interactions and childhood trauma (CT) can lead to aberrant hypothalamic–pituitary–adrenal functions. Poor theory of mind (ToM) ability is related to increased social stress levels; however, studies on the relationship between ToM and cortisol remain scarce. Objective: This study aimed to evaluate the relationship between ToM and the hair cortisol concentration (HCC) in healthy young adults considering the moderating role of CT. Method: A total of 206 healthy young adults were divided into two groups based on an experience of moderate-to-severe childhood trauma (CT+ and CT–). To determine whether CT moderated the relationship between ToM and HCC, moderation analysis was conducted controlling for age, sex, years of education, and scores of perceived stress, depression, and anxiety. Results: CT+ individuals reported higher subjective stress perception and depressive symptoms than CT– individuals, whereas anxiety-related symptoms, ToM, and HCC were not different between the groups. The experience of CT significantly moderated the relationship between ToM and HCC. The association between poorer ToM ability and higher HCC was significant only in CT+ group. Conclusion: CT is a moderator of the association between ToM and HCC, indicating the importance of CT in social cognition and the stress response.