The dexamethasone suppression test in depressed and non-depressed geriatric medical inpatients

State specificity of DST abnormalities in geriatric depression

Pre-treatment and posttreatment dexamethasone suppression test (DST) results in physically healthy elderly major depressives without dementia demonstrated an association between treatment and DST normalization. Sixty percent of subjects were nonsuppressors at baseline compared to 17% after intensive treatment. DST results normalized in 75% of initial nonsuppressors; none of the initial suppressors converted to nonsuppression. A strong correlation between clinical improvement and decreases in afternoon cortisol levels was identified. Initial suppression status did not influence this association. There was a nonsignificant trend for very high (> 15 micrograms/dl) afternoon cortisol levels to be associated with delusional depression. The advantage of using continuous rather than categorical measures to assess the relationship between reversal of depression and DST results is discussed.

Biological studies of dysthymia

Dysthymic disorder (DD) is a chronic subsyndromal depressive condition that has generated increasing interest since its formal introduction into the psychiatric nomenclature in 1980. Although DD was included among the affective disorders in DSM-III, this classification was controversial. Some clinical and family studies support an association between DD and major depression disorder (MDD), but there has been little additional research firmly establishing the diagnostic validity of DD or clarifying its relation to MDD and to personality disorders. In this article, the literature on the biology of DD is reviewed. Studies of rapid eye movement (REM) latency, electrodermal activity, and the thyroid axis show similarities between DD and MDD, but the findings are mixed. Other investigations, including the Dexamethasone Suppression Test (DST), catecholamines, and several other electroencephalogram (EEG) sleep variables, show more consistent differences between DD and MDD. These findings suggest that DD manifests primarily trait characteristics of depression, thus differentiating it from the state characteristics of MDD. The methodological problems and implications of these studies, and suggestions for future research, are discussed.

Use of the dexamethasone suppression test in an inpatient setting: a replication and new findings

The dexamethasone suppression test (DST) was administered to 131 depressed and 109 nondepressed psychiatric inpatients. The depressed patients were categorized according to DSM-III as minor depression, major depression without melancholia, and major depression with melancholia and/or with psychotic features. The nondepressed patients were stratified over several DSM-III subcategories. DST nonsuppression was nonspecific for major depression: the mean post-dexamethasone cortisol value and the number of nonsuppressors were not significantly different between the major depressives and the nondepressed psychiatric controls. Within the depressive sample the DST was a significant (p less than 0.01) discriminator between major and minor depression. Postdexamethasone plasma greater than or equal to 3.5 micrograms/dl at 0800h was the most sensitive (39%) and specific (94%) criterion; cortisol values at 1600h and 2300h showed no significant discriminating power for major vs. minor depression. The diagnostic utility of the DST thus appears to be limited to confirming the diagnosis of major depression, once the clinical diagnosis of depression is made. There was no significant influence of age or gender on postdexamethasone cortisol values.

Results of dexamethasone suppression test in early Alzheimer dementia

The frequency of an abnormal response to the Dexamethasone Suppression Test (DST) was examined in 24 non-depressed patients in the early stages of Alzheimer dementia. Results were compared with those obtained in 51 geriatric medical inpatients: 15 with major depression, 18 with dysthymic disorder and 18 normal controls. As an abnormal lack of suppression was found in 9 demented patients, in 9 with major depression, 1 with dysthymic disorder and in 2 the normal controls, it appears that DST alone is not useful in distinguishing dementia, even in its early stages, from major depression. In our experience abnormal DST results in demented patients were unrelated to mood.

The dexamethasone suppression test in dementia

The dexamethasone suppression test (DST) was performed on 13 patients with multi-infarct dementia (MID), 5 patients with primary degenerative dementia (PDD) and 18 elderly controls. Abnormal lack of suppression was found in 7 demented patients (3 with PDD, 1 mild and 2 severe, and 4 with MID, 1 mild and 3 severe), and in 2 of the controls. Only one demented patient was depressed. The value of DST in the differential diagnosis of dementia from the major depressive disorders is discussed.