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

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

Patterns of DST positivity in remitted affective disorders

BACKGROUND

While the Dexamethasone Suppression Test (DST) has been extensively used in cross-sectional observations of patients with major affective disorders, studies have tended to ignore the longitudinal application of the DST in patients stabilized on long-term prophylactic medication.

METHODS

Monthly DST's were performed on 19 patients, 16 with bipolar disorder and 3 with recurrent major depression. All cases had an excellent response to lithium treatment, and family history positive for bipolar disorder. The average duration of observation was 4 years.

RESULTS

All patients remained clinically stable throughout the period of observation. Eleven patients showed intermittent DST positivity ranging from 10% to 60% of tests, and 2 patients exhibited no positivity. Six patients had fewer than 10% positive DST's. Females showed significantly higher positivity than males. The frequency of positivity did not correlate with current age, age of illness onset, duration of illness, duration of lithium treatment, or season. The risk of primary affective disorders in first-degree relatives was also unrelated to the frequency of positivity.

CONCLUSIONS

While the highly selected and small sample population limits generalizability, our observations suggest that clinically sufficient lithium prophylaxis does not automatically prevent intermittent HPA dysregulation. We hope that a better understanding of this phenomenon will offer new approaches to the long-term management of mood disorders.

The periodicities in and biometeorological relationships with bed occupancy of an acute psychiatric ward in Antwerp, Belgium

Recently, some investigators have established a seasonal pattern in normal human psychology, physiology and behaviour, and in the incidence of psychiatric psychopathology. In an attempt to elucidate the chronopsy and meteotropism in the latter, we have examined the chronograms of, and the biometeorological relationships to bed occupancy of the psychiatric ward of the Antwerp University Hospital during three consecutive calendar years (1987-1989). Weather data for the vicinity were provided by a local meteorological station and comprise mean atmospheric pressure, air temperature, relative humidity, wind speed and minutes of sunlight and precipitation/day. The number of psychiatric beds occupied during the study period exhibited a significant seasonal variation. Peaks in bed occupancy were observed in March and November, with lows in August. An important part of the variability in the number of beds occupied could be explained by the composite effects of weather variables of the preceding weeks. Our results suggest that short-term fluctuations in atmospheric activity may dictate some of the periodicities in psychiatric psychopathology.

Adrenocorticotropin hormone, beta-endorphin and cortisol responses to oCRF in melancholic patients

Several authors have reported attenuated adrenocorticotropin hormone (ACTH) responses to corticotropin releasing factor (CRF) administration in melancholic patients as compared with healthy controls. In order to explore the integrity of the hypothalamic-pituitary-adrenal (HPA)-axis in melancholics, we examined the following parameters in 98 subjects: the ACTH; beta-endorphin; and cortisol responses to ovine CRF (oCRF) (100 micrograms/i.v.); and the postdexamethasone cortisol values. We found significant lower CRF-induced ACTH responses in melancholic patients as opposed to healthy controls and minor depressives, while major depressives occupied an intermediate position. The psychopathological correlates of the blunted CRF-induced ACTH responses were feelings of worthlessness, self-reproach, or excessive guilt. The CRF-stimulated beta-endorphin and cortisol response did not differ between the study samples. Higher baseline plasma cortisol was associated with attenuated CRF-induced ACTH responses, but these effects were not pertinent to melancholia. There were no relationships between the disordered oCRF test results, and postdexamethasone cortisol values, age, body size, sex and severity of illness. The diagnostic power of the oCRF and the dexamethasone suppression test for melancholia is enhanced when both test results are combined.

Abnormal pituitary function during melancholia: reduced alpha-melanocyte-stimulating hormone secretion and increased intact ACTH non-suppression

In order to investigate pituitary alpha-melanocyte-stimulating hormone (alpha-MSH), intact (1-39 structure) adrenocorticotropic hormone (ACTH), and adrenal cortisol secretion, we measured 8 a.m. plasma levels of those hormones before and after administration of 1 mg dexamethasone in 39 depressed inpatients and 10 healthy controls. We found a significantly lower baseline alpha-MSH secretion in melancholic patients as opposed to healthy controls. There were no significant relations between alpha-MSH secretion on the one hand and ACTH or cortisol secretion on the other. Dexamethasone did not affect the 8 a.m. alpha-MSH circulating levels. The post-dexamethasone intact ACTH and cortisol values were significantly higher in melancholics as compared with healthy, minor and simple major depressed subjects. ACTH non-suppression was defined as post-dexamethasone intact ACTH greater than or equal to 12 pg/ml. ACTH non-suppression was found to be more sensitive (70%) and specific (100%) for melancholia than cortisol non-suppression. By means of pathway analysis we have established that cortisol non-suppression during a severe depression is completely determined by an augmented ACTH escape from suppression by dexamethasone. It is concluded that the assay of post-dexamethasone intact ACTH could, in the future, replace post-dexamethasone cortisol determination.

A multivariate study of simultaneous escape from suppression by dexamethasone of urinary free cortisol, plasma cortisol, adrenocorticotropic hormone and beta-endorphin in melancholic patients

To investigate the relationships between pre- and postdexamethasone hypothalamic-pituitary-adrenal (HPA) axis functioning in depression, we measured the levels of baseline and postdexamethasone urinary free cortisol (UFC), plasma cortisol, adrenocorticotropic hormone (ACTH) and beta-endorphin. We found that dexamethasone significantly suppressed all hormone levels. All 4 postdexamethasone hormones--but not their baseline levels--were significantly higher in melancholic subjects than in minor and simple major depressives. We have accumulated evidence that the melancholic and minor depression groups form discrete classes in postdexamethasone HPA axis hormone levels; this supports the biological heterogeneity hypothesis of melancholia. We found that a combination of the postdexamethasone UFC and beta-endorphin values yielded the most significant diagnostic tool for melancholia. Our results suggest that the measurements of both hormones may constitute the most accurate index reflecting the HPA axis escape from suppression by dexamethasone in melancholia. By means of pathway analysis, we determined the causal relationships between age, dexamethasone circulating levels, diagnostic depression classification and the various baseline and postdexamethasone hormone values.

L-5-hydroxytryptophan stimulated cortisol escape from dexamethasone suppression in melancholic patients

The dexamethasone suppression test (DST) was carried out in 62 depressed patients. At 0800 the postdexamethasone cortisol values were determined and 125 mg L-5-hydroxytryptophan (L-5-HTP) was administered. The second cortisol sample at 0930 revealed a significant enhancing effect for L-5-HTP on the postdexamethasone cortisol values in melancholic patients, whereas no effects were detected in minor depressives. Our results show that L-5-HTP converts some DST suppressors into nonsuppressors, whereas the escape from dexamethasone in some nonsuppressors is markedly stimulated. The L-5-HTP-stimulated 0930 postdexamethasone cortisol values performed markedly better than the 0800 DST results: at a cut-off value of greater than or equal to 5 micrograms/dl the sensitivity for melancholia increased from 46% to 68%, and the specificity remained unchanged (96%).

A revised interpretation of postdexamethasone ACTH and cortisol findings in unipolar depressed females

Baseline 8 a.m. adrenocorticotropic hormone (ACTH) and cortisol levels and the postdexamethasone ACTH/cortisol values at 8 a.m. and 4 p.m. were determined in 86 depressed females diagnosed using DSM-III criteria. Postdexamethasone ACTH and cortisol values were significantly correlated with their baseline levels. We have shown that regression analysis should be used to assess dexamethasone-induced changes as the residual ACTH and cortisol responses, with the relative effects of the baseline data on the hormone responses being partialed out. The residual ACTH and cortisol values were significantly increased in the most severely depressed females as compared to minor depressives. The residual ACTH responses were markedly correlated with the residual cortisol responses. Cortisol nonsuppression during a depressive episode appeared to be determined by an augmented ACTH escape from dexamethasone suppression. The residual ACTH and cortisol responses could prove to be the most sensitive reflection of the disorder in the negative feedback by dexamethasone on the pituitary. In clinical practice, the ratio ln (postdexamethasone ACTH): ln (basal ACTH) can be used, since this ratio is linearly correlated with the residual ACTH responses.

Prediction of the DST results in depressives by means of urinary-free cortisol excretion, dexamethasone levels, and age

This study investigates the relationships between cortisol escape from suppression by dexamethasone during a depressive episode, and the baseline activity of the hypothalamic-pituitary-adrenal (HPA) axis, circulating dexamethasone levels, and age. To this end, we measured urinary-free cortisol (UFC) excretion in 24-hr urine samples and the 8 AM cortisol and dexamethasone levels after administration of 1 mg dexamethasone in 50 depressive patients. We found that up to 54% of the variance in the postdexamethasone cortisol values could be explained by the multiple regression on UFC, age, and dexamethasone levels. By utilizing these three parameters, the dexamethasone suppression test (DST) nonsuppressor/suppressor state was correctly identified in 92% of the subjects. It was shown that an important part of the variance in postdexamethasone cortisol is actually background variance, irrelevant to depression and produced by the cumulative effects of the three aforementioned parameters. Only a small part (less than 20%) of the variance in postdexamethasone cortisol is determined by the actual depressive state. It was concluded that (1) baseline hypersecretion of cortisol, (2) decrements in the bioavailability of the test substance, (3) increasing age, and (4) the depressive state per se--all of which are cumulative--contribute independently to cortisol escape from suppression by 1 mg dexamethasone.

The relationships between the cortisol responses to dexamethasone and to L-5-HTP, and the availability of L-tryptophan in depressed females

In order to investigate the relationships between the hypothalamic-pituitary-adrenal (HPA)-axis activity, the central serotonergic neurotransmission, and the peripheral metabolism of l-tryptophan (L-TRP), the authors measured the following: the postdexamethasone cortisol values, the cortisol responses to 125 mg 5-hydroxy-L-tryptophan (L-5-HTP) orally, and the total L-TRP/competing amino acids (CAA) ratio in 64 depressed females. Severely depressed females showed significantly lower values for L-TRP/CAA, significantly higher postdexamethasone cortisol values, and cortisol responses to L-5-HTP as compared with minor depressives. Dexamethasone nonsuppressors showed significantly lower L-TRP/CAA values as compared with suppressors. The cortisol responses to dexamethasone were significantly and negatively correlated with the availability of L-TRP. The cortisol responses to L-5-HTP were not related to either the availability of L-TRP or to the postdexamethasone cortisol values.

An augmented escape of beta-endorphins to suppression by dexamethasone in severely depressed patients

Baseline beta-endorphin and cortisol levels and their responses to 1 mg dexamethasone were measured in 11 healthy controls and in 35 depressed patients, categorized according to the DSM-III. Dexamethasone significantly suppressed beta-endorphin levels. Depressed patients with melancholia/psychotic features exhibited significantly increased post-dexamethasone beta-endorphin levels compared with healthy controls, minor and simple major depressives; the baseline beta-endorphin levels did not differ between those study samples. Post-dexamethasone beta-endorphin and cortisol values were found to be significantly and positively correlated. Accordingly, cortisol non-suppressors showed significantly higher post-dexamethasone beta-endorphin levels. Post-dexamethasone beta-endorphin may be the most sensitive and specific reflection of the disorder in negative feedback exerted by dexamethasone in depression.