Menstrual cycle effects on the dexamethasone suppression test in major depression.

Patients with major depressive disorder (MDD) fiequently exhibit dysregulation of the hypothalamo-pituitary-adrenal (HPA) axis reflected in elevated basal cortisol levels as well as resistance to feedback inhibition, which is typically manifested by resistance to suppression by dexamethasone (Carroll et al 1981; Stokes and Sikes 1988). Alterations in and interactions between the HPA and hypothalamo-pituitary-gonadal (HPG) axes in MDD have also been documented (Rubin and Poland 1984; McEwen 1987). Systematic fluctuations of gonadal steroid levels through the menstrual cycle have been well described (Yen 1980), with maximal estrogen activity in the periovulatory phase and maximal progesterone activity in the early to mid-luteal phase. In view of the interactions between the HPG and HPA axes, the relationship between premenstrual syndrome and mood disorders (Endicott et al 1985; Rubinow et al 1985; Mortola et al 1989; Graze et al 1990), and the systematic menstrual oscillations in gonadal steroid activity, it would be important to evaluate possible menstrual effects on HPA function. Early studies in this regard have failed to find differences in cortisol secretory parameters between the follicular and luteal phase (Haskett et al 1984;