Study of the diagnostic value of the dexamethasone suppression test in endogenous depression

Plasma corticosterone is increased and correlated with brain acetylcholine in physostigmine- but not in neostigmine-treated rats

Rats were given intraperitoneal injections of physostigmine (PHYSO), neostigmine (NEO) or saline (SAL). Either 15 or 30 min later the number and intensity of observable cholinomimetic effects (OCE) was determined, plasma was collected for corticosterone (Cst) measurement, and the cerebral cortex, striatum, hippocampus and hypothalamus were removed after microwave treatment for the measurement of tissue acetylcholine (ACh) and choline (Ch) concentrations. Plasma Cst correlated with the number of OCEs at both 15 and 30 min in both NEO- and PHYSO-treated animals. Although the number and intensity of OCE were the same in NEO- and PHYSO-treated animals 15 min after injection, plasma Cst was significantly higher in the PHYSO-treated group. ACh levels in the cortex were also increased in PHYSO- compared with NEO-treated animals 15 min after injection. Ch levels remained unchanged. Plasma Cst correlated positively with ACh levels in the cortex and striatum in PHYSO-treated rats both 15 and 30 min after injection. These data support the involvement of central cholinergic mechanisms in the regulation of the HPA axis.

Plasma postdexamethasone cortisol levels in schizoaffective disorder

The degree of hypothalamic-pituitary-adrenal (HPA) axis dysregulation in depressed patients with schizoaffective disorder was compared to that seen in patients with major depressive disorder with and without delusional features. The frequency of nonsuppression to dexamethasone was similar for all three diagnostic groups. Maximum postdexamethasone plasma cortisol was greater for delusional depressives, but did not differ between patients with major depressive and schizoaffective disorders. Modest correlations were found between postdexamethasone plasma cortisol levels, severity of illness, age, and recent weight loss, for patients with both major depressive disorder and delusional depression. For schizoaffective patients, associations between postdexamethasone plasma cortisol levels and various measures of severity of illness, but not age and recent weight loss, were found. Although HPA axis dysregulation occurs more frequently in all three of the studied diagnostic groups than in normal individuals, factors contributing to this dysregulation may be qualitatively different for schizoaffective patients.

The effect of diagnosis and age on the DST: a metaanalytic approach

The authors present new data on the results of the pretreatment Dexamethasone Suppression Test (DST) in 164 drug-free inpatients, as well as on the effects of age on postdexamethasone cortisol values. Nonsuppression rates were 18% in schizophrenic patients (n = 44), versus 46% in patients with a major depression (n = 56). In addition, a significant correlation was found between age and the 4:00 PM postdexamethasone cortisol value among the depressed patients (r = 0.33). The authors then applied a metaanalysis to summarize 25 other studies that have addressed the schizophrenia/major depression dichotomy as it relates to the DST outcome. Nonsuppression rates were consistently different in schizophrenic patients (19%) when compared to patients with a major depression (51%) or normal controls (7%). These differences were highly significant as measured by the Mantel-Haenszel chi-square statistic. A metaanalysis applied to a series of correlations obtained from 14 other studies reporting an age/postdexamethasone cortisol relationship in affective patients indicated a modest, but significant correlation (r = 0.24) in a total of 1284 patients (p less than 1 x 10(-8)).

The relationship between age and post-dexamethasone cortisol: a test of three hypotheses

Previous studies report that DST nonsuppressors are older than normal suppressors. Data are presented on 188 primary unipolar major depressive inpatients and 35 healthy controls. In males, age appeared to correlate positively with post-dexamethasone cortisols in depressed patients and normal controls, although mean levels were higher in depressives. Female controls showed no consistent relationship between age and post-dexamethasone cortisol. A positive relationship did exist for depressed women. However, the association disappeared when age-of-onset was entered into the model, suggesting that in females early onset may identify a subtype of depression with normal DST suppression.

Response to the dexamethasone suppression test in schizoaffective disorder, depressed type

Response to the dexamethasone suppression test (DST) was tested in 20 patients fulfilling the Research Diagnostic Criteria (RDC) for schizoaffective disorder, depressed type, and in 52 patients meeting RDC for major depressive disorder. Non-suppression was observed in 25% of the schizodepressives and in 40.4% of the depressives. No significant difference between suppressor and non-suppressor schizodepressives was found with respect to demographic, historical and clinical variables. These results do not support the usefulness of the DST for the identification of a homogeneous subtype of schizoaffective disorders.

Multisteroid analysis after DST in depressed patients--a controlled study

111 consecutively admitted in-patients with a depressive syndrome received a dexamethasone suppression test (DST) after all known factors which might confound the test results had been carefully excluded. Plasma concentrations of cortisol, corticosterone and dexamethasone were compared with several diagnostic evaluations (RDC, DSM-III, ICD-9) in a controlled study. The positive predictive value of nonsuppressed corticosteroid levels was only moderate for each diagnostic category. Diagnostic specificities were 84.6% for major depression, endogenous subtype (RDC), 71.2% for melancholia (DSM-III) and 86.8% for endogenous depression (IDC-9) when using a post-DST cortisol value above 50 ng/ml (5 micrograms/dl) as the referent value to define DST nonsuppression. Combined determination of cortisol and corticosterone as an index of dexamethasone-induced suppression raised the sensitivity rate considerably at the cost of the predictive value for major diagnostic categories. Dexamethasone plasma levels were reciprocally correlated with cortisol levels and neglect of samples with low plasma dexamethasone contents improved the diagnostic performance for endogenous depression according to RDC and ICD-9, but not for DSM-III melancholia. Although it would be speculative to suppose that the observed low dexamethasone levels are involved in DST nonsuppression, the present findings emphasize that multisteroid analysis which includes dexamethasone is important in future studies designed to explore the clinical utility of the DST.

The dexamethasone suppression test in schizo-affective depression

The dexamethasone suppression test (DST) was performed on 30 patients fulfilling RDC or Kendell criteria for schizo-affective depression. Symptoms characteristic of depression or schizophrenia were noted, and the severity of psychosis and the severity and endogenicity of depression were assessed. Ratings of severity were repeated at 2-month follow-up. Ten of the 30 subjects were DST non-suppressors, but no clear differences in symptoms, severity of illness or outcome between suppressors and non-suppressors emerged. Thus, although schizo-affective depression is associated with an increased frequency of HPA axis abnormality as assessed by the DST, this test does not clarify the status of schizo-affective depression in the classification of psychiatric illness.