Sex-related differences in the relationships between self-rated depression and biological markers

Gender-related differences in self-reported depression, in biological factors putatively related to depression and in the associations between severity of illness and biological factors were investigated. To this end the Zung Self-Rating Depression Scale (SDS), the ratio L-tryptophan/valine + leucine (L-TRP/CAA) and basal cortisol in serum at 8 a.m. were determined in 51 depressed inpatients undergoing a dexamethasone suppression test (DST). In the total study group no significant relationships were established between severity of illness and either of the biological markers. In women, SDS correlated significantly (P less than 0.01) negatively with the ratio L-TRP/CAA and positively with post-dexamethasone cortisol (P less than 0.01). In men these relationships tended to be inverted. The differences in the two sexes between these correlation coefficients were significant (P less than 0.01). These gender-related differences in the relationships between self-reported depression and the biological variables could be explained by differential psychoneuroendocrine and psychobiochemical responses. Future work on the severity of illnesses in terms of biological factors must take into account these differential responses between depressed males and females.