Pre-treatment waking cortisol response and vulnerability to interferon α induced depression

Depressive disorder is a common consequence of interferon α treatment. An understanding of the aetiological processes involved is evolving. HPA axis abnormalities are clearly described in community depressive disorder and represent vulnerability to depression development. We explored whether pre-treatment HPA axis abnormalities influence depression emergence during interferon α treatment. We examined waking HPA axis response via salivary cortisol sampling in 44 non-depressed, chronic hepatitis C infected patients due to commence standard interferon α treatment. Hamilton depression scales and the structured clinical interview for DSM-IV major depressive disorder status were administered monthly during treatment. Major depressive disorder developed in 26 of 44 subjects during interferon-α treatment. The pre-treatment waking cortisol response over 1 h was significantly greater in the subsequent switch to depression group (F=4.23, p=0.046). The waking cortisol response pre-treatment with interferon α appears greater in those subsequently switching to depressive disorder during treatment. This waking response may join other vulnerability factors for depression emergence in this group. This model could prove a valuable tool in understanding non-iatrogenic depressive disorder in the general population and notably the role of cytokines.