DEXAMETHASONE RESPONSE, THYROTROPIN-RELEASING-HORMONE STIMULATION, RAPID EYE-MOVEMENT LATENCY, AND SUBTYPES OF DEPRESSION

Most prior studies of mood disorders have used a single laboratory tes t to assist in differential diagnosis, prediction of treatment respons e, and prediction of relapse. This study compared three laboratory mea sures in a combined in- and outpatient sample of depressed patients. D examethasone suppression test (DST) nonsuppression occurred in 46% of patients with endogenous major depression, in 15% with nonendogenous m ajor depression, and in 56% with bipolar, depressed phase disorder A b lunted thyrotropin-releasing hormone stimulation test (TRH-ST) occurre d in 25% of patients with endogenous, 10% with nonendogenous, and 44% with bipolar, depressed phase disorder, Reduced REM latency was found in 65% of endogenous major depressions, in 34% of nonendogenous major depressions, and in 53% of bipolar, depressed phase disorders. Fifty-o ne percent of those with reduced REM latency also evidenced DST nonsup pression. When the endogenous major depression and bipolar, depressed phase groups were combined 28% had no laboratory abnormality whereas 8 % evidenced all three. These findings suggest that 1) endogenous/nonen dogenous unipolar groups are distinguished by all three laboratory tes ts; 2) most patients with a blunted TRH-ST also evidence DST nonsuppre ssion; and 3) one half of patients with reduced REM latency evidence D ST nonsuppression. Sensitivity is greatest and specificity is lowest f or REM latency, followed by the DST and then the TRH-ST. (C) 1997 Soci ety of Biological Psychiatry.