The dexamethasone suppression test and thyroid stimulating hormone response to TRH in RDC schizoaffective patients.

The dexamethasone suppression test (DST) brought to light significantly more non-suppression of cortisol secretion in RDC schizoaffectives of the depressed (89%) and of the manic type (67%) than in RDC schizophrenia (25%). However, only in the RDC endogenous depressives, whose pathological DST rate was 57%, was the thyroid stimulating hormone (TSH) response to thyrotrophin releasing hormone (TRH) found to be significantly "blunted". It is suggested that the DST results can be interpreted as partially validating DSM-III's wide major affective disorder since this concept also encompasses all cases with mood-incongruent psychotic features. Furthermore, it is hypothesized that the coupling of DST non-suppression and TSH "blunting" may be important for defining a valid depressive subgroup within these extended clinical boundaries for affective illness.