The dexamethasone suppression test in depressed outpatients and normal control subjects

In contrast to a recently published report by Amsterdam and associates, the authors noted a higher frequency of abnormal dexamethasone suppression test results in 88 outpatients with primary depression (particularly the endogenous subtype) than in 49 normal controls.     

The effect of age on dexamethasone suppression test results in alcoholic patients

The authors studied the effects of age, liver function, mean corpuscular volume, and major depression on cortisol concentrations following the dexamethasone suppression test in 31 alcoholics. Only age was significantly correlated with cortisol levels, and it appeared to be an independent effect.     

Effect of weekly testing on dexamethasone suppression test results in normal subjects

Four weekly repetitions of the overnight dexamethasone suppression test (DST) in each of 10 healthy volunteers yielded plasma cortisol levels that were consistently suppressed. These results suggest that unlike some dynamic tests of hypothalamic-pituitary functioning, the DST does not produce false-positive results due to weekly repetition. This finding is of interest because previous research has demonstrated that a subgroup of melancholic initial nonsuppressors continue to resist cortisol suppression despite apparent clinical improvement. The present findings do not support the hypothesis that continued nonsuppression in clinically improved patients is an artifact of serial testing.     

The dexamethasone suppression test: a study in a normal population

One hundred healthy, non-depressed volunteers were given a standard dexamethasone suppression test (DST) to determine the appropriate criterion values of plasma cortisol to define suppression or nonsuppression. By radioimmunoassay (RIA) of cortisol, the criterion value for 5% nonsuppression was plasma cortisol greater than 187 nmol/l, and for suppression less than 153 nmol/l, with an indeterminate range between these values. Use of the widely accepted pre-determined criterion value of 138 nmol/l gave a significantly greater frequency of nonsuppression. Values of cortisol measured by two RIAs in a subset of 43 volunteers were not equivalent. With the experimentally determined criterion value, no significant differences between nonsuppressors and suppressors were found for any measured physical or psychological parameters. Women taking oral contraceptives had significantly higher plasma cortisol pre-dexamethasone and post-dexamethasone. Their exclusion did not alter the calculated criterion value for the remainder, but their separately estimated criterion value was significantly higher. Caution should be exercised when classifying the DST status of women on oral contraceptives, particularly when values are at the lower end of the nonsuppressor range. Determination of a separate normal range for them may be warranted.     

Age and cortisol suppression by dexamethasone in normal subjects

A study of 60 healthy volunteers ranging from 19-88 yr of age found nonsuppression rare (5%) and confirmed that the dexamethasone suppression test (DST) of the reactivity of the hypophyseal-pituitary-adrenal axis to negative feedback inhibition requires 0800 h plasma dexamethasone (DEX) levels in excess of 220 ng/dl. All of the subjects with inadequate DEX levels (N = 3) were older than 50 yr of age as were the nonsuppressors (N = 3); two of the three nonsuppressors had inadequate DEX concentrations. Thus, DST may be more often invalid in elders than in younger adults because of inadequate plasma dexamethasone (DEX) concentration, indicating that plasma DEX levels should be assayed concomitantly with DST in elders.     

The effect of serum dexamethasone concentrations in the dexamethasone suppression test

Serum dexamethasone and cortisol concentrations were measured in a sample of 98 psychiatric inpatients during the course of the 1-mg oral overnight Dexamethasone Suppression Test (DST). Suppressors were found to have significantly higher serum dexamethasone concentrations than nonsuppressors at each time of sampling (8:00 AM, 4:00 PM, and 11:00 PM). There was a significant inverse curvilinear relationship between serum dexamethasone and cortisol concentrations at each sample time. Although serum dexamethasone concentration was a potent determinant of postdexamethasone serum cortisol concentration, there were still significantly higher serum concentrations of cortisol in patients with major depression compared with patients with other disorders when dexamethasone concentrations were statistically controlled. By taking serum dexamethasone concentrations into account in defining DST suppression status, a modest increase in diagnostic specificity was achieved, but no substantial change in sensitivity.     

The dexamethasone suppression test: importance of dexamethasone concentrations

Plasma dexamethasone concentrations and cortisol response to dexamethasone were measured in 29 normal healthy volunteers, 23 depressed patients, and 10 patients with anorexia nervosa at 4:00 PM postdexamethasone. In each of the 3 groups, nonsuppressors had lower dexamethasone concentrations than suppressors. Of the subjects with plasma dexamethasone at or below 0.7 ng/ml, a significantly higher proportion (48%) were nonsuppressors compared to the proportion above 0.7 ng/ml (14%), all of whom were patients. Plasma dexamethasone concentrations in a subgroup of depressed nonsuppressors were high (mean 1.35 ng/ml), whereas the remainder were low (0.42 ng/ml) and were similar to the normal nonsuppressors (0.35 ng/ml), suggesting different mechanisms for nonsuppression in the subgroups. Plasma dexamethasone concentrations were similar in nonendogenous and endogenous depressives, in men and women, and in medicated and drug-free patients. None of the variables of age, weight, history of weight loss, Hamilton depression rating score, predexamethasone cortisol, or postdexamethasone cortisol were significantly correlated with plasma dexamethasone, except for body weight and a history of weight loss in the depressed group only. Mean plasma dexamethasone concentrations increased significantly from week 1 to week 2 in 7 depressed patients, whereas plasma cortisol decreased; however, the relationship between dexamethasone and cortisol varied considerably for individual patients.     

The effect of stress on the dexamethasone suppression test

The dexamethasone suppression test (DST) was studied in 40 presurgical subjects and 20 controls. Cortisol plasma concentrations were measured before and after a nocturnal dose of 1 mg dexamethasone. Nineteen of the 40 patients (47.5%) failed to show a suppression of plasma cortisol after dexamethasone. Nonsuppression on the DST was associated with a significantly higher baseline plasma cortisol concentration. Another putative indicator of emotional stress, the level of acute anxiety, was also studied. There was a significant difference in the level of acute anxiety among suppressors, nonsuppressors, and controls--the level of anxiety in nonsuppressors being significantly higher than in controls. It is concluded that stress associated with a physical danger can be a cause of nonsuppression on the DST.     

The effect of anticonvulsants on the dexamethasone suppression test

Rates of non-suppression on the DST were compared in 19 psychiatric inpatients and anticonvulsants and 38 psychiatric inpatients not on anticonvulsants who were matched for age, sex, and diagnosis. Patients on anticonvulsants had a significantly higher rate of nonsuppression.     

Dexamethasone suppression test: use of two different dexamethasone doses

The endocrinologic methods used in the dexamethasone suppression test (DST) for depression were examined, by employing two different doses of dexamethasone (0.5 or 1.0 mg) at 11 p.m. Nonsuppression to the 1.0 mg DST (plasma cortisol criterion value of 5 micrograms/dl) was seen in 33% of major depressives and in 15% of schizophrenics. A similar result was obtained with the 0.5 mg DST when 12 micrograms/dl was employed as the plasma cortisol criterion value. Plasma cortisol levels 33 hours postdexamethasone did not distinguish between major depressives and schizophrenics.     

A comparison of the cortisol suppression index and the dexamethasone suppression test

The cortisol suppression index (CSI) (the ratio of pre- to postdexamethasone serum cortisol concentrations) was compared to the dexamethasone suppression test (DST) in endogenously depressed DST suppressors (N = 20) and nonsuppressors (N = 21) and in normal controls (N = 23). The 8 a.m. CSI detected 17.1% and 31.7% of endogenous depressives at the 4.0 and 6.0 thresholds; for the 4 p.m. CSI, rates were 48.8% and 65.9%. The 4 p.m. CSI produced 17.4% and 39.1% false positives in normal controls at the two thresholds, whereas the false positive rate for the DST was 4.3%. These data suggest that the CSI is not as specific as the standard DST for the detection of endogenous depression.     

The dexamethasone suppression test in bulimia

Nineteen (35%) of 55 women with bulimia failed to exhibit cortisol suppression after dexamethasone administration. Although there was no statistically significant difference between suppressors and nonsuppressors on any clinical variable, there was a higher frequency of major depression among nonsuppressors.     

The dexamethasone suppression test in depression

The DST does appear to be abnormal in a sizable subgroup of patients with major depressive disorder, particularly those characterized as "endogenomorphic" or "melancholic." At present the available data seem clear in indicating this abnormality is significantly less common in normal controls and patients without affective illness. The test holds considerable promise in helping to define new subgroups of depressed individuals for further study. In terms of its ability to predict treatment response to an adequate course of somatic therapy, the test does not appear to be of value, and the clinician should still be guided by the clinical presentation and history in initiating or choosing between various somatic treatments. With further attention to issues of diagnosis and DST methodology this strategy could help in addressing questions of differential diagnosis in potential "variants" of affective illness and providing a better understanding of the pathophysiology of depression.     

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.

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Sommario Il test di soppressione al desametazone (DST) è stato applicato a 13 pazienti con demenza multi-infartuale (MID), a 5 pazienti affetti da demenza degenerativa primaria (PDD), e a 18 controlli (anziani). Una nonsoppressione è stata ritrovata in 7 pazienti affetti da demenza (3 di tipo PDD, in 1 caso di grado moderato ed in 2 casi severo, e 4 di tipo MID, in 1 caso moderato ed in 3 casi severo). Solo uno dei pazienti affetti da demenza si presentava contemporaneamente affetto da depressione. Viene discussa l’utilità del DST nel giudizio diagnostico-differenziale tra la demenza ed il disturbo depressivo maggiore.

     

The effect of benzodiazepine withdrawal on the dexamethasone suppression test

Recent studies of the dexamethasone suppression test (DST) suggest lack of specificity for the diagnosis of melancholia. An earlier study showed that high doses of benzodiazepines lead to DST normalisation in depressed patients. This present study examines the effect of benzodiazepine withdrawal on the DST in a middle aged, non-depressed group. Forty-eight volunteers from a double blind placebo-controlled trial of triazolam 0.5 mg and lormetazepam 2 mg all suppressed normally when given the DST on the sixth day of withdrawal following 25 days of drug.     

The dexamethasone suppression test: interaction of diagnosis, sex, and age in psychiatric inpatients

A group of 277 semiconsecutive psychiatric inpatients manifesting a depressive affect underwent an overnight 1 mg dexamethasone suppression test (DST) and a semistructured diagnostic interview according to DSM-III criteria. For major depressive syndromes (major depression with and without psychosis, bipolar depressed) the sensitivity of the DST was 63.9%, specificity 73.0%, and diagnostic confidence 72.3%. Additionally, a significant interaction between age and baseline cortisol values and nonsuppression rates was found in depressed males but not in nondepressed males nor in depressed and nondepressed females. The authors discuss the implications of these findings.