Mean 14.00-17.00 h plasma cortisol concentration and its relationship to the 1 mg-dexamethasone suppression response in depressives and controls

Cortisol and the Dexamethasone Suppression Test as a Biomarker for Melancholic Depression: A Narrative Review

The dexamethasone suppression test (DST) assesses the functionality of the HPA axis and can be regarded as the first potential biomarker in psychiatry. In 1981, a group of researchers at the University of Michigan published a groundbreaking paper regarding its use for diagnosing melancholic depression, reporting a diagnostic sensitivity of 67% and a specificity of 95%. While this study generated much enthusiasm and high expectations in the field of biological psychiatry, subsequent studies produced equivocal results, leading to the test being rejected by the American Psychiatric Association. The scientific reasons leading to the rise and fall of the DST are assessed in this review, suggestions are provided as to how the original test can be improved, and its potential applications in clinical psychiatry are discussed. An improved, standardized, and validated version of the DST would be a biologically meaningful and useful biomarker in psychiatry, providing a tool for clinicians caring for depressed patients in the areas of diagnosis, treatment, and prognosis, and predicting the risk of suicide. Additionally, such a test could be a crucial part in the generation of biologically homogenous patient cohorts, necessary for the successful development of new psychotropic medications.

Discrimination between patients with melancholic depression and healthy controls: comparison between 24-h cortisol profiles, the DST and the Dex/CRH test

Diurnal (24-h) cortisol profiles were compared to DST and Dex/CRH test outcomes with regard to their discriminative power in depressive disorder. With regard to several statistical measures (effect sizes, area under the curve) we found 24-h cortisol profiles to better discriminate between healthy controls and inpatients with the melancholic subtype of depression compared to the DST and Dex/CRH test. In search of a shortened time interval we found the 2-h time window 1000-1200 h of the cortisol profile to be the one with the highest sensitivity (83.3%) and specificity (87.9%). The specificity of the DST was 93.3% and somewhat higher than that of the cortisol profiles and the Dex/CRH test (87.9% and 78.8.%, respectively). However, the sensitivity of the DST was very low (30.8%), in fact similar to that of the Dex/CRH test (30.8%), but much lower than that of the 1000-1200 h interval (83.3%). The assessment of cortisol in plasma is an easy to perform, cost-saving method for the evaluation of the HPA system activity, which may have a series of clinical and scientific implications for the depressive disorder.

Dexamethasone nonsuppression in transgenic mice expressing antisense RNA to the glucocorticoid receptor

Transgenic mice with impaired glucocorticoid receptor (GR) function produced by partially knocking out GR gene expression with antisense RNA were treated with increasing dosages of dexamethasone. In these mice, ten-fold higher dexamethasone dosages were required to induce full suppression of plasma corticosterone than in normal mice. This relative dexamethasone insensitivity adds to the evidence that these transgenic mice could serve as an appropriate model to study the negative feedback disturbance of the hypothalamic-pituitary-adrenocortical system in affective disorders.

Elevated levels of acute phase plasma proteins in major depression

Levels of acute phase and other plasma proteins were measured in 21 men with major depression, 28 men with alcohol dependence, and 12 men who acted as controls. The depressed men had significantly elevated levels of the acute phase proteins, haptoglobin and alpha-1-antichymotrypsin, and of immunoglobulin G. The elevations in haptoglobin and alpha-1-antichymotrypsin were highly correlated with each other, and were correlated with the severity of depression and negatively correlated with the thyroid stimulating hormone response to thyrotropin. The alcoholic men had elevated haptoglobin levels, but significantly decreased levels of immunoglobulin G. These findings provide further evidence for an inflammatory response during depression.

Depression, natural killer cell activity, and cortisol secretion

Natural killer (NK) cell activity was evaluated in 34 ambulatory patients with Major Depressive Disorder (MDD) and 21 healthy controls. No mean differences between the groups were found. However, female depressives (n = 19) exhibited higher NK activity than female controls (n = 14). The relationship between cortisol secretion and NK activity was examined using an integrated cortisol value derived from multiple blood samples taken between 1:00 and 4:00 PM. This comprehensive assessment of cortisol secretion circumvents spurious "single stick" cortisol values and provides a more accurate determination of hypercortisolemia than the dexamethasone suppression test. NK activity in depressives with cortisol hypersecretion (greater than 11 micrograms/dl) (n = 7) was no different than NK activity in depressives and controls with normal cortisol secretion. Furthermore, there was no correlation between cortisol secretion and NK activity in any of the groups. These results indicate that decreased NK activity is not a consistent finding in MDD and cannot be predicted by the presence of hypercortisolemia in these patients.

Psychiatric implications of altered limbic-hypothalamic-pituitary-adrenocortical activity

Hormones of the limbic-hypothalamic-pituitary-adrenocortical (LHPA) system are much involved in central nervous system regulation. The major LHPA neuropeptides, corticotropin-releasing hormone (CRH), vasopressin (AVP) and corticotropin (ACTH) do not only coordinate the neuroendocrine response to stress, but also induce behavioral adaptation. Transcription and post-translational processing of these neuropeptides is regulated by corticosteroids secreted from the adrenal cortex after stimulation by ACTH and other proopiomelanocortin derived peptides. These steroids play a key role as regulators of cell development, homeostatic maintenance and adaptation to environmental challenges. They execute vitally important actions through genomic effects resulting in altered gene expression and nongenomic effects leading to altered neuronal excitability. Since excessive secretory activity of this particular neuroendocrine system is part of an acute stress response or depressive symptom pattern, there is good reason to suspect that central actions of these steroids and peptides are involved in pathophysiology determining the clinical phenotype, drug response and relapse liability. This overview summarizes the clinical neuroendocrine investigations of the author and his collaborators, while they worked at the Department of Psychiatry in Mainz. The major conclusions from this work were: (1) aberrant hormonal responses to challenges with dexamethasone, ACTH or CRH are reflecting altered brain physiology in affective illness and related disorders; (2) hormones of the LHPA axis influence also nonendocrine behavioral systems such as sleep EEG; (3) physiologically significant interactions exist between LHPA hormones, the thyroid, growth hormone, gonadal and other neuroendocrine systems; (4) hormones of the LHPA axis constitute a bidirectional link between immunoregulation and brain activity; and (5) future psychiatric research topics such as molecular genetics of affective disorders, familial risk studies, drug response analysis and neurobiology of aging will benefit from extended knowledge of neural corticosteroid effects at a clinical, cellular, and molecular level.

Computerized brain tomography measures compared with spontaneous and suppressed plasma cortisol levels in major depression

We determined brain density and ventricular measurements with computerized tomography (CT) in 33 depressed patients and compared the results with basal plasma cortisol and its suppressibility by dexamethasone. Mean plasma cortisol was positively related to elevated ventricular brain ratio (VBR). No association could be found between dexamethasone suppression test (DST) status and VBR or any other CT parameter. Elevated plasma cortisol levels and increased VBRs were positively correlated with total scores on the Brief Psychiatric Rating Scale, the Global Assessment Scale and the Bech-Rafaelsen Melancholia Scale, but they were not significantly correlated with total score on the Hamilton Anxiety Scale.

Past and present strategies of research on the HPA-axis in psychiatry

Hypercortisolism in depression has been extensively studied during the last three decades. The main hypothesis regarding origin and clinical relevance of this phenomenon, however, has changed significantly. Up to the mid-seventies hypercortisolism was conceived as consequence of stress modified by the degree of unconscious defense mechanisms in different forms of depressive or non-depressive psychiatric disorders. At the end of the seventies this point of view changed considerably. Hypercortisolism was regarded as a biological statemarker of the endogenous subtype of depression with clinical differential-diagnostic relevance. An abnormal dexamethasone suppression test (DST) was assumed to be the best indication of increased activation of the cortisol system. These conclusions turned out to be wrong. DST results are not specific for melancholia and the test seems to be of limited value for measuring the function of the HPA-axis. Intervening variables, such as weight loss, drug and alcohol withdrawal or situational stress, influence the test results significantly, independent of the nosological classification. Additionally, interindividual differences in the susceptibility of the HPA-axis may decisively influence the the activation of the HPA-axis as well in healthy subjects under stress as in psychiatric patients.

Salivary cortisol hypersecretion in juvenile depression

Thirty depressed inpatients aged 7-16 yrs were compared for salivary hypercortisolism with a control group of 16 inpatients of mixed diagnosis matched for age and sex. Four cortisol samples were taken over a 48 hr period: 8 a.m. and 11 p.m. on the first day; then, with 1 mg of dexamethasone given immediately after the second sample, at 4 p.m. and 11 p.m. on the second day. All except the 8 a.m. value were significantly greater (P less than 0.03) in the depressed group. A 4 nmol/l cutoff for the 4 p.m. sample gave 48% sensitivity and 91% specificity for discriminating depressed cases (P = 0.03). The results indicate that the salivary method for estimating cortisol levels in children and adolescents with depression warrants further study.

TRH: behavioral and endocrine effects in man

1. The tripeptide TRH exerts a spectrum of biological activities in both animals and man. Some of these activities have been extensively studied, particularly in psychiatric patients. 2. Behaviorally, TRH appears to increase the sense of well-being, motivation, relaxation, and coping capacity in both normal subjects and patients with psychiatric and neurologic disease. These effects are not disease-specific; attempts to use TRH as a treatment tool have thus been disappointing. 3. Endocrinologically, administration of TRH stimulates the response of TSH; this response has been reported to be blunted in approximately 30% of patients with major depression. However, TSH blunting is not specific for depression, it has also been observed in a variety of other psychiatric conditions. 4. The relevance of these effects for psychiatry in general, and for psychoneuroendocrinology especially, is discussed in this review.

Dexamethasone suppression test and the response to antidepressant depending on their central monoaminergic action in major depression

After 1 mg DST, 25 major depressive patients (DSM-III) received at random either a specific inhibitor of noradrenaline reuptake (Maprotiline) or an inhibitor of serotonin reuptake (Indalpine or Citalopram). After at least 3 weeks of treatment, no difference was found in treatment response between suppressors and non suppressors. This study is unable to confirm the usefulness of the DST in selection of treatment according to its central activity on serotonin or noradrenaline-reuptake.

Weight loss, cortisol levels, and dexamethasone suppression in major depressive disorder

Appetite and/or weight loss are integral, albeit not necessary, symptoms of depression. We explored the contribution of diminished appetite and/or weight loss ascertained by history to the hypothalamic-pituitary-adrenocortical (HPA) axis dysregulation in 120 patients with primary major depressive disorder. Significant positive relationship for both appetite and weight loss with cortisol levels in plasma and cerebrospinal fluid (CSF) were observed. Plasma cortisol levels were consistently higher in patients who noted both appetite and weight loss as opposed to patients without appetite or weight loss. Depressed patients with weight loss showed higher rates of dexamethasone-nonsuppression. Age and severity of depression influenced but did not eliminate the significance of the findings, suggesting that weight loss accounts in part for the HPA-axis function changes observed in depression.

The relationship of the dexamethasone suppression test (1 mg and 2 mg) to basal plasma cortisol levels in endogenous depression

The 1 mg and 2 mg dexamethasone suppression tests (DST) were evaluated in two groups of endogenously depressed patients (n = 39 and n = 30, respectively) who also had a 1300-1600 hr basal cortisol assessment. Non-suppressors (on both DSTs) had significantly higher basal plasma cortisol levels and thus were significantly associated with relative cortisol hypersecretion. However, there was only a partial overlap between DST response and basal plasma cortisol, with a large variation of cortisol levels among non-suppressors. The 2 mg DST appears to be more specific for cortisol hypersecretion than the 1 mg DST. If cortisol hypersecretion is to be identified, neither the 1 mg or 2 mg DST is an adequate assessment nor a substitute for a basal cortisol assessment.

Hypothalamic-pituitary-adrenal-cortical activity in anorexia nervosa and bulimia

We studied hypothalamic-pituitary-adrenal-cortical (HPA) activity in nine underweight women with anorexia nervosa, 12 women of normal body weight with bulimia, and nine control subjects. The measures of HPA activity were the pattern of plasma cortisol secretion over 24 hr and the responses of plasma cortisol to dexamethasone suppression and to low dose ACTH stimulation. The patients with anorexia nervosa had significantly elevated 24 hr concentrations of plasma cortisol compared to the controls and showed significantly less cortisol suppression following dexamethasone. There was no difference between patients with anorexia nervosa and controls in the rise in plasma cortisol following ACTH. On most measures of HPA activity, the normal weight patients with bulimia were indistinguishable from the controls. These results suggest that HPA activity is normal in most patients of normal body weight with bulimia and that the psychological and behavioral disturbances common to both anorexia nervosa and bulimia are, in the absence of significant weight loss, insufficient to produce major alterations in HPA activity.

Computed tomography in affective disorders. Part II. Brain density

The attenuation values of brain density were investigated in 53 patients with affective disorder and 53 individually age- and sex-matched controls by computed tomography (CT). Asymmetry of density distribution, with higher values in most regions of the left hemisphere, was found in patients as well as in controls. Patients tended to display higher attenuation values than controls. In patients, an association between higher density of the parenchyma and smaller ventricular size was observed, but not in controls. Corresponding greater density in patients, compared to controls, was found in those subgroups (women, nonpsychotics, and bipolars) that did not differ in ventricle size from controls. Comparisons within subgroups of patients revealed lower attenuation values in psychotic than in nonpsychotic subjects, lower values in men than in women, lower values in lithium-treated than in non-lithium-treated patients, and lower values in unipolar than in bipolar patients. No differences were observed between older and younger patients or Dexamethasone Suppression Test (DST) normal versus DST-abnormal patients. No correlations between age and density were obtained in patients and controls.

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 plasma dexamethasone variable in depression: test-retest studies and early biophase kinetics

A dexamethasone suppression test (DST) was performed in 45 patients during depressive illness and after recovery. Thirty-one samples from patients in whom plasma cortisol was resistant to the suppressive action of dexamethasone contained significantly lower mean (+/- SD) concentrations of the test drug (0.63 +/- 0.39 ng/ml vs 1.10 +/- 0.53 ng/ml) during illness than after recovery and normalization of the DST. In a control group of 14 patients who exhibited adequate DST suppression during the depressive state and after recovery, the dexamethasone concentrations were unchanged (1.54 +/- 0.91 ng/ml vs. 1.30 +/- 0.92 ng/ml). To investigate further the influence of bioavailability or pharmacokinetics of the test drug on DST results, we conducted a catheter study during sleep in 11 endogenously depressed patients who received an oral 1.5 mg dose of dexamethasone at 11 p.m. The half-life of dexamethasone was markedly lower in five DST nonsuppressors (t1/2 = 160 +/- 33 minutes) than in six DST suppressors (t1/2 = 422 +/- 172 minutes). These preliminary results indicate that metabolism of dexamethasone should be controlled in studies evaluating the clinical utility of the DST.

Dexamethasone suppression test as a simple measure of stress?

Non-suppression of cortisol by dexamethasone has been described as a biological marker of a diagnostic subgroup of depressed patients. This paper presents the hypothesis that the degree of non-suppression is a variable that reflects the quantity of stress or distress experienced by the patient rather than relating to a specific diagnosis. Such a quantitative measure of stress would be valuable for research in general medicine as well as in psychiatry. Testing of this postulate should apply a more precise interpretation of endocrine principles than has been applied to the dexamethasone suppression test to date.

ACTH, cortisol, and corticosterone output after ovine corticotropin-releasing factor challenge during depression and after recovery

Synthetic ovine corticotropin releasing factor (o-CRF) was administered as an intravenous bolus (100 micrograms) to eight patients suffering from a major depressive disorder, endogenous subtype. All patients showed inadequately suppressed cortisol levels after 1 mg dexamethasone. After clinical remission and normalized dexamethasone responses, these patients were reinvestigated with o-CRF stimulation. The mean adrenocorticotropic hormone (ACTH) release from the pituitary corticotroph cells was indiscriminate at both test sessions. Cortisol and corticosterone output after o-CRF tended to be higher during depression than after recovery. The o-CRF-induced increments observed with corticosterone were more marked in comparison with cortisol. Within the limitations of the current protocol, our preliminary data lend support to the view that an increased pituitary ACTH reserve or adrenocortical steroid reserve is not likely to be responsible for the defective pituitary-adrenal regulation in some dexamethasone-resistant depressives.