How hair keeps track: Associations between hair concentrations of psychoactive substances and steroid hormones in a large cohort sample of young adults in Switzerland

Cortisol and cortisone are frequently used as physiological stress markers in neuropsychiatric research, with growing interest also in the role of testosterone. Recently, these steroid hormones are increasingly measured via hair sampling to provide a window into cumulative exposure. However, studies investigating steroid hormones in hair largely ignore the potential effects of psychoactive substances so far, although animal models suggest a knock-on effect of psychoactive substances on the hypothalamic–pituitary–adrenal axis stress response. Determining response to stress is important because higher levels of stress are associated with increased physical illness, worsening mental health and premature mortality. This project aims to assess the association between steroid hormones and a number of substances such as cannabinoids, stimulants, MDMA, and opioids in hair. We expected higher concentrations of cocaine, cannabis, and MDMA to be associated with higher levels of cortisol in hair.

Data was drawn from a large representative sample of 20-year olds (n=1002). Multiple regression models were used to assess associations between steroid hormones, potential covariates, and psychoactive substances in hair. Median splits were used to divide participants into: no, low, and high concentrations of each substance.

Preliminary results show an association between both low (β=.29, 95%CI=0.02-0.34, p=0.026) and high concentrations of cannabinoids (β=.40, 95%CI=0.10-0.40, p=0.001) with higher levels of hair cortisol. High cocaine concentrations were associated with higher levels of cortisol (β=.0.31, 95% CI=0.01–0.60, p=0.040). Testosterone levels were not associated with substance concentrations in hair.

The use of cannabis and cocaine was clearly associated with higher hair cortisol levels. These results suggest that substance use should be considered when interpreting hair levels of corticosteroids in large samples.