Psychosocial correlates of cortisol levels in fingernails among middle-aged workers.

It was recently suggested that cortisol levels in fingernails reflect cumulative hormone exposure over a relatively long period. This exploratory study cross-sectionally investigated the relationships between fingernail cortisol level and psychosocial stress in a sample of middle-aged workers (94 men and 29 women). The participants were asked to grow their fingernails for ∼2 weeks and then provide fingernail samples from every digit by using nail clippers. Further, they completed questionnaires for assessment of exposure to psychosocial stress in the past (stressful life events in the workplace in the previous year; e.g. change to a different line of work) and in the present (job stress and perceived stress). Results of a regression analysis adjusting for the effects of demographic variables showed that experience of stressful life events, but not job stress and perceived stress, was associated with elevated fingernail cortisol level. These findings indicate the potential of fingernail samples to retrospectively reflect individual differences in cortisol levels related to past psychosocial stress.