Dexamethasone suppression test and familial subtypes of unipolar depression

We have studied the suppression of plasma cortisol after dexamethasone (1 mg) and the peak post-dexamethasone cortisol values in 84 hospitalized patients with a diagnosis of primary unipolar depression. The non-suppressor responses in the three familial subgroups (Winokur) were: 11/22 in familial pure depressive disorder (FPDD), 21/49 in sporadic depressive disease (SDD) and 1/13 in depression spectrum disease (DSD) (FPDD vs. SDD, p less than 0.05; SDD vs. DSD, p less than 0.05). When considering the peak post-dexamethasone cortisol value, or the 8.30-9.00-hour values, the results in the DSD group were lower than in the other two groups (p less than 0.05). These results suggest a different behaviour of DSD as compared with FPDD and SDD.