The dexamethasone suppression test in patients with mood disorders.
BACKGROUND
This study was undertaken to (1) determine whether the endogenous/nonendogenous mood disorder dichotomy is validated by the dexamethasone suppression test (DST); (2) determine whether other subtyping schemes (unipolar/bipolar, DSM-III melancholic/nonmelancholic, Winokur's family history subtypes) relate to the DST; (3) evaluate the relative contributions of symptom severity, weight loss, and other factors to DST status; and (4) assess the relative sensitivity of various post-dexamethasone cortisol determinations in the detection of dexamethasone nonsuppression.


METHODS
487 consecutive adult inpatients (N = 131) and outpatients (N = 356) with unipolar (N = 422) or bipolar disorder (N = 65) underwent the 1.0-mg DST. Nonsuppression was defined as at least one post-dexamethasone cortisol measurement > 4.0 micrograms/dL.


RESULTS
Nonsuppression occurred in 27% of all patients with major depression and 43% of all bipolar depressed phase patients. For outpatients, dexamethasone nonsuppression occurred in 35.2% of subjects with endogenous (unipolar + bipolar; N = 145) and 9.0% of those with nonendogenous (unipolar only; N = 211) depressions (single 4 p.m. post-dexamethasone cortisol). For inpatients, dexamethasone nonsuppression was found in 61.5% of subjects with endogenous (N = 104) and 18.5% of those with nonendogenous (N = 27) depressions (three post-dexamethasone cortisol determinations). For the inpatient and outpatient sample together, the DST had a sensitivity of 46.2% and a specificity of 89.9% in differentiating endogenous from nonendogenous major depressive episodes. Weight loss, gender, and symptom severity added little to the endogenous/nonendogenous dichotomy. The Research Diagnostic Criteria (RDC) primary/secondary and Winokur and colleagues' family history subtypes for unipolar depression were not strongly validated by the DST. The 4 p.m. and 11 p.m. samples together detected 91.0% of those inpatients with abnormal three-sample DST results. The 8 a.m. sample alone detected 30% of those, the 4 p.m. sample alone detected 67%, and the 11 p.m. sample alone detected 62%.


CONCLUSIONS
The RDC endogenous/nonendogenous dichotomy was validated by the DST.
Rush
A J
AJ
Mental Health Clinical Research Center, University of Texas, Southwestern Medical Center at Dallas, USA.
Giles
D E
DE
Schlesser
M A
MA
Orsulak
P J
PJ
Parker
C R
CR
Weissenburger
J E
JE
Crowley
G T
GT
Khatami
M
M
Vasavada
N
N
D000328:Adult; D000553:Ambulatory Care; D001714:Bipolar Disorder / Q000097:blood / Q000175:diagnosis; D002940:Circadian Rhythm; D003866:Depressive Disorder / Q000097:blood / Q000175:diagnosis*; D003907:Dexamethasone; D003937:Diagnosis, Differential; D005260:Female; D006760:Hospitalization; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D011569:Psychiatric Status Rating Scales; D015203:Reproducibility of Results; D012720:Severity of Illness Index
D003907:Dexamethasone; D006854:Hydrocortisone