Plasma dexamethasone concentrations and the dexamethasone suppression test

Assessment of plasma dexamethasone levels after 1-mg dexamethasone suppression test in adults with obesity

BACKGROUND

The 1-mg overnight dexamethasone suppression test is the most frequently used screening test for Cushing's syndrome. It has been proposed that people with obesity may have insufficient plasma dexamethasone levels for the test which may result in false positives. We sought to compare the plasma dexamethasone levels after 1-mg dexamethasone suppression test in healthy obese participants and in optimal-weight participants.

METHODS

A total of 30 optimal-weight participants (BMI ≤ 25 kg/m2 ) and 62 obese participants (BMI > 25 kg/m2 ) were enroled in the study. Obese participants were further divided into class 1 (25-29.9 kg/m2 ) and class 2 (>30 kg/m2 ). After a standard overnight 1-mg dexamethasone suppression test, blood samples were obtained for serum cortisol and plasma dexamethasone levels. Plasma dexamethasone levels were quantified using liquid chromatography - mass spectrometry (LC-MS/MS).

RESULTS

No significant difference in plasma dexamethasone levels were found between obese and optimal-weight participants (3.31 ± 1.35 vs. 2.82 ± 1.11 nmol/L, mean ± SD; p = .09 respectively). There were also no correlations found between sex, BMI, body surface area and plasma dexamethasone levels. There was also no significant difference in the proportion of participants who achieved a plasma dexamethasone level >3.3 nmol/L in comparison between obesity class 1, obesity class 2, and optimal-weight groups.

CONCLUSION

Our results suggest that obesity does not affect plasma dexamethasone levels. However, dexamethasone measurement may still be helpful in patients who are being investigated for Cushing's syndrome and suspected to have a false-positive DST.

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.

A glucocorticoid receptor agonist improves post-weaning growth performance in segregated early-weaned pigs

While beneficial for sow reproductive efficiency and biosecurity, segregated early weaning (SEW) leads to a systemic immune response that adversely affects the digestive physiology and post-weaning growth of pigs. Two experiments were conducted to evaluate the effects of a glucocorticoid receptor agonist (GA) on growth performance, measures of immune function and intestinal integrity of SEW pigs. In both experiments, pigs were fed corn-soybean meal-based starter diets. In the first experiment, 48 pigs (initial BW 4.8 ± 0.7 kg) were weaned at 21 ± 1 days and randomly assigned to three GA treatment groups: 0, 0.2 and 0.6 mg GA/kg of BW injected intramuscularly. Treatments were administered one day before weaning. Pigs in the 0 mg GA group received sterile saline in place of GA. Body weight was measured daily from one day before to 7 days post-weaning, and then weekly until 28 days post-weaning. Piglets treated with 0.2 mg GA had a higher BW than piglets in other treatment groups during the 28-day course of the study (P <0.02). To further explore the mechanisms behind this result, a second experiment was performed in which a total of 18 gilts (BW 5.6 ± 0.85 kg) were randomly assigned into three treatment groups: suckling plus saline (UWS), weaned treated with GA (WGA; 0.2 mg GA/kg BW) and weaned plus saline (CON). Treatments were administered one day before and 3 days post-weaning. The WGA and CON groups were weaned at 23 ± 2 days, while the UWS group remained with sow for the duration of the study. Body weight was measured daily and blood plasma was collected at 0, 1, 4 and 5 days post-weaning. All gilts were euthanized 5 days after weaning and jejunum samples were collected for mucosal scrapings, histomorphological analysis and gene expression analysis. Plasma levels of interleukin-1β (IL-1β) and haptoglobin were lower in WGA pigs compared with CON (P <0.02), while plasma total antioxidant capacity was higher in WGA pigs compared with both CON and UWS groups (P <0.01). Relative to CON, GA downregulated IL-18 gene expression in the jejunum, as assessed by both tissue homogenate and mucosal scrapings, but it upregulated claudin-IV gene expression only in the tissue homogenate (P <0.01). These results suggest that GA treatment improves the growth performance of SEW pigs in part by mitigating the negative effects of systemic inflammation. However, the effect of GA on barrier integrity requires further investigation.

Dexamethasone promotes granulocyte mobilization by prolonging the half-life of granulocyte-colony-stimulating factor in healthy donors for granulocyte transfusions

BACKGROUND

Granulocyte transfusion (GTX) is a potential approach to correcting neutropenia and relieving the increased risk of infection in patients who are refractory to antibiotics. To mobilize enough granulocytes for transfusion, healthy donors are premedicated with granulocyte-colony-stimulating factor (G-CSF) and dexamethasone. Granulocytes have a short circulatory half-life. Consequently, patients need to receive GTX every other day to keep circulating granulocyte counts at an acceptable level. We investigated whether plasma from premedicated donors was capable of prolonging neutrophil survival and, if so, which factor could be held responsible.

STUDY DESIGN AND METHODS

The effects of plasma from G-CSF/dexamethasone-treated donors on neutrophil survival were assessed by annexin-V, CD16. and CXCR4 staining and nuclear morphology. We isolated an albumin-bound protein using α-chymotrypsin and albumin-depletion and further characterized it using protein analysis. The effects of dexamethasone and G-CSF were assessed using mifepristone and G-CSF-neutralizing antibody. G-CSF plasma concentrations were determined by Western blot and Luminex analyses.

RESULTS

G-CSF/dexamethasone plasma contained a survival-promoting factor for at least 2 days. This factor was recognized as an albumin-associated protein and was identified as G-CSF itself, which was surprising considering its reported half-life of only 4.5 hours. Compared with coadministration of dexamethasone, administration of G-CSF alone to the same GTX donors led to a faster decline in circulating G-CSF levels, whereas dexamethasone itself did not induce any G-CSF, demonstrating a role for dexamethasone in increasing G-CSF half-life.

CONCLUSION

Dexamethasone increases granulocyte yield upon coadministration with G-CSF by extending G-CSF half-life. This observation might also be exploited in the coadministration of dexamethasone with other recombinant proteins to modulate their half-life.

Dynamics of salivary cortisol in chronic kidney disease patients at stages 1 through 4

CONTEXT

End-stage renal disease has been associated with derangement of the HPA function. The dynamics of this axis in early stages of renal disease (CKD) has not been assessed.

OBJECTIVES

To evaluate in patients with CKD at stages 1-4 (KDOQI): the diurnal variation of salivary cortisol; the suppressibility of cortisol in saliva and serum after an overnight oral 1 mg dexamethasone suppression test (1 mg DST) with simultaneous measurement of circulating dexamethasone.

DESIGN AND METHODS

80 CKD outpatients and 40 healthy subjects were included. All CKD collected whole saliva at 08·00 and 23·00 h (SAF23 ) on two nonconsecutive days. Thereafter at 08·00 h, following 1 mg DST, saliva and blood were obtained. Salivary and serum cortisol as well as CBG were assessed by RIA, dexamethasone by ELISA and serum free cortisol was calculated.

RESULTS

SAF23 correlated negatively with glomerular filtration rate (GFR). The fraction of free cortisol in serum and saliva after 1 mg DST, correlated positively and significantly in both patients with CKD and healthy subjects (r: 0·86 and r: 0·85, respectively; P < 0·0001 for both). Ten percent of CKD with GFR < 90 ml/min/1·73 m(2) had false positive results unrelated to dexamethasone and CBG concentrations.

CONCLUSIONS

False positive responses to 1 mg DST were associated with GFR < 90 ml/min/1·73 m(2) . This could not be ascribed to either defects in dexamethasone absorption or CBG concentrations. Higher dexamethasone doses were necessary to achieve adequate HPA suppression. Salivary cortisol was useful to assess circadian cortisol levels and feed-back regulation in CKD.

Time-dependent effects of dexamethasone plasma concentrations on glucocorticoid receptor challenge tests

Glucocorticoid challenge tests such as the dexamethasone suppression test (DST) and the combined dexamethasone/corticotropin-releasing hormone (dex-CRH) test are considered to be able to sensitively measure hypothalamic-pituitary-adrenal (HPA) axis activity in stress-related psychiatric and endocrine disorders. We used mass-spectrometry to assess the relationship of plasma dexamethasone concentrations and the outcome of these tests in two independent cohorts. Dexamethasone concentrations were measured after oral ingestion of 1.5mg dexamethasone in two cohorts that underwent a standard (dexamethasone at 23:00h) as well as modified (18:00h) DST and dex-CRH test. The first study population was a case/control cohort of 105 depressed patients and 133 controls in which peripheral blood mRNA expression was also measured. The second was a cohort of 261 depressed patients that underwent a standard dex-CRH test at baseline and after 12 weeks' treatment with cognitive-behavioral therapy or antidepressants. Dexamethasone concentrations explained significant proportions of the variance in the DST in both the first (24.6%) and the second (5.2%) cohort. Dexamethasone concentrations explained a higher proportion of the variance in the dex-CRH test readouts, with 41.9% of the cortisol area under the curve (AUC) in the first sample and 24.7% in the second sample. In contrast to these strong effects at later time points, dexamethasone concentrations did not impact cortisol or ACTH concentrations or mRNA expression 3hours after ingestion. In the second sample, dexamethasone concentrations at baseline and week 12 were highly correlated, independent of treatment type and response status. Importantly, a case/control effect in the Dex-CRH test was only apparent when controlling for dexamethasone concentrations. Our results suggest that the incorporation of plasma dexamethasone concentration or measures of earlier endocrine read-outs may help to improve the assessment of endocrine dysfunction in depression.

A review of hypothalamic-pituitary-adrenal axis function in chronic fatigue syndrome

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been found in a high proportion of chronic fatigue syndrome (CFS) patients and includes enhanced corticosteroid-induced negative feedback, basal hypocortisolism, attenuated diurnal variation, and a reduced responsivity to challenge. A putative causal role for genetic profile, childhood trauma, and oxidative stress has been considered. In addition, the impact of gender is demonstrated by the increased frequency of HPA axis dysregulation in females. Despite the temporal relationship, it is not yet established whether the endocrine dysregulation is causal, consequent, or an epiphenomenon of the disorder. Nonetheless, given the interindividual variation in the effectiveness of existing biological and psychological treatments, the need for novel treatment strategies such as those which target the HPA axis is clear.

Escitalopram alters gene expression and HPA axis reactivity in rats following chronic overexpression of corticotropin-releasing factor from the central amygdala

We have previously demonstrated that viral-mediated overexpression of corticotropin-releasing factor (CRF) within the central nucleus of the amygdala (CeA) reproduces many of the behavioral and endocrine consequences of chronic stress. The present experiment sought to determine whether administration of the selective serotonin reuptake inhibitor (SSRI) escitalopram reverses the adverse effects of CeA CRF overexpression. In a 2×2 design, adult male rats received bilateral infusions of a control lentivirus or a lentivirus in which a portion of the CRF promoter is used to drive increased expression of CRF peptide. Four weeks later, rats were then implanted with an Alzet minipump to deliver vehicle or 10mg/kg/day escitalopram for a 4-week period of time. The defensive withdrawal (DW) test of anxiety and the sucrose-preference test (SPT) of anhedonia were performed both before and after pump implantation. Additional post-implant behavioral tests included the elevated plus maze (EPM) and social interaction (SI) test. Following completion of behavioral testing, the dexamethasone/CRF test was performed to assess HPA axis reactivity. Brains were collected and expression of HPA axis-relevant transcripts were measured using in situ hybridization. Amygdalar CRF overexpression increased anxiety-like behavior in the DW test at week eight, which was only partially prevented by escitalopram. In both CRF-overexpressing and control groups, escitalopram decreased hippocampal CRF expression while increasing hypothalamic and hippocampal expression of the glucocorticoid receptor (GR). These gene expression changes were associated with a significant decrease in HPA axis reactivity in rats treated with escitalopram. Interestingly, escitalopram increased the rate of weight gain only in rats overexpressing CRF. Overall these data support our hypothesis that amygdalar CRF is critical in anxiety-like behavior; because the antidepressant was unable to reverse behavioral manifestations of CeA CRF-OE. This may be a potential animal model to study treatment-resistant psychopathologies.

The DEX/CRH test for major depression: a potentially useful diagnostic test

The dexamethasone/corticotropin-releasing hormone (DEX/CRH) test has been proposed as a potential diagnostic test for major depressive disorder (MDD). A previously proposed four-step approach assesses the stage of development for a biological finding into a clinically useful diagnostic test. Using this approach, we evaluated the progress of the DEX/CRH test using meta-analysis as a part of step 1. A literature review identified 15 studies of the DEX/CRH test in patients with MDD and healthy controls. Meta-analysis estimated the effect size, heterogeneity, and confidence intervals using random effects models. Studies consistent with any step of the four-step approach were identified, and their characteristics were presented. Eleven studies reported significantly higher cortisol levels with the DEX/CRH test in patients with MDD, compared with the healthy controls (step 1). Eight eligible studies were included in meta-analysis, and had an effect size of 1.34 (95% confidence interval: 0.70-1.97). Most studies were step-1 studies (comparison of patients and healthy controls), and no step-4 studies (multicenter trials) were found. This review emphasizes that despite appearing as a promising test, the DEX/CRH has not been adequately studied for the required stages of development into a clinically useful laboratory test. Particularly, additional step-3 and step-4 studies are necessary.

Association between posttest dexamethasone and cortisol concentrations in the 1 mg overnight dexamethasone suppression test

It has been suggested that comparison of posttest dexamethasone and cortisol concentrations may improve the evaluation of the dexamethasone suppression test (DST) for Cushing's syndrome. In particular, this would be reasonable if posttest cortisol differs by dexamethasone levels within the range that is usually attained in the DST. Using fractional polynomial regression, we therefore studied the association between posttest 0800 h dexamethasone and cortisol levels in 53 subjects without Cushing's syndrome who were tested with the 1 mg overnight DST. Plasma dexamethasone was associated with plasma cortisol (P<0.001), and the regression line suggested a strong negative association related to dexamethasone levels <5 nmol/l. However, among the 94% of subjects with plasma dexamethasone >5.0 nmol/l, there was no association between dexamethasone and cortisol levels (P=0.55). In conclusion, subjects tested with the 1 mg overnight DST usually attain an 0800 h plasma dexamethasone >5 nmol/l, and plasma cortisol does not differ by plasma dexamethasone in these subjects. This suggests that routine comparison of dexamethasone and cortisol levels may not be a useful approach to improve the performance of the 1 mg DST. However, dexamethasone measurements may identify subjects with inadequately low plasma dexamethasone and may therefore be of value when retesting subjects with possibly false-positive DST results.

Pathophysiology of hypercortisolism in depression: pituitary and adrenal responses to low glucocorticoid feedback

OBJECTIVE

To test three theories of hypercortisolemia in depression-hypothalamic overdrive, impaired glucocorticoid feedback, or autonomous cortisol production.

METHOD

We applied an overnight low-cortisol feedback strategy by administering metyrapone to hypercortisolemic depressed in-patients and control subjects.

RESULTS

Under metyrapone, the increases of plasma adrenocorticotropic hormone (ACTH) concentrations and of basal and pulsatile ACTH secretion were not exaggerated in hypercortisolemic depressed patients compared with control subjects. ACTH approximate entropy (ApEn) did not differ at baseline or under metyrapone. Thus, neither hypothalamic overdrive nor irregular ACTH secretion was seen. We did not detect impaired cortisol feedback: the ACTH response was not reduced, and ApEn measures that are sensitive to feedback changes were comparable in both groups. Metyrapone disrupted cortisol secretory regularity in depressed and control subjects. On the baseline day, basal cortisol secretion was significantly increased and was highly irregular (high ApEn), and ACTH-cortisol cross-ApEn was markedly elevated in high-cortisol patients.

CONCLUSION

Classical feed-forward overdrive and impaired feedback theories of hypercortisolemia in depression were not supported. Depressive hypercortisolemia may result from alternative pathophysiological mechanisms involving irregular basal hypersecretion of cortisol, associated with adrenal enlargement, possibly through splanchnic sympathetic activation of the adrenal cortex.

Pharmacokinetics, pharmacodynamics, and comparative bioavailability of single, oral 2-mg doses of dexamethasone liquid and tablet formulations: a randomized, controlled, crossover study in healthy adult volunteers

BACKGROUND

Dexamethasone is a glucocorticoid used widely worldwide for immunosuppressive treatment, allergies, bronchiolitis, and croup, among others. For children, liquid formulations are especially suitable because, compared with other dosage forms, both exact dosing and proper intake are facilitated.

OBJECTIVE

The objective was to evaluate the pharmacokinetics, pharmacodynamics, and comparative bioavailability of a commercial liquid oral dexamethasone formulation intended for pediatric use relative to those of a tablet.

METHODS

In a randomized, controlled, crossover study in 24 healthy adult volunteers, we administered single doses of the liquid and tablet formulation, containing 2 mg of dexamethasone each. Blood samples were taken up to 24 hours postdose. Quantification was carried out using a validated specific and sensitive high-pressure liquid chromatography with UV detector method. Noncompartmental pharmacokinetic parameters were compared between treatments according to European Medicines Agency (EMA) bioequivalence guidelines. For AUC(0-t) and C(max), the 90% CI for the ratio of the test and reference products should be contained within the predetermined acceptance interval of 80% to 125%. As a pharmacodynamic variable, we measured suppression of endogenous cortisol (predose and postdose).

RESULTS

Both preparations showed similar pharmacokinetic and pharmacodynamic profiles but high between-subject variability of pharmacokinetic key parameters and endogenous cortisol concentrations (>30%). Mean AUC(0-t), AUC(0-∞), and C(max) were 37.8 ng/mL/h, 46.0 ng/mL/h, and 9.35 ng/mL, respectively, for the liquid and 41.3 ng/mL/h, 48.1 ng/mL/h, and 9.17 ng/mL, respectively, for the tablet formulation. T(max) was 0.89 hour (liquid) and 0.97 hour (tablet). The point estimates and 90% CIs for AUC(0-t), AUC(0-∞), and C(max) ratios (liquid vs tablet) were 91.42% (82.05%-101.86%), 95.72% (84.46%-108.5%), and 102.04% (86.94%-119.76%), respectively. Thus, point estimates and 90% CIs were within the bioequivalence range of 80% to 125% for all relevant parameters, including the pharmacodynamic parameter AUEC (area under the effect curve).

CONCLUSIONS

This single-dose study suggests that the test and reference products met the EMA regulatory criteria to assume bioequivalence in these fasting healthy male and female volunteers. German Register of Clinical Trials registration number: DRKS00000785.

Effects of a cognitive stress challenge on myocardial perfusion and plasma cortisol in coronary heart disease patients with depression

Although it is well established that coronary heart disease (CHD) patients with depression exhibit increased mortality compared with equally ill cardiac patients without depression, the mechanisms mediating this effect remain obscure. Depression is characterized by vulnerability to stress and heightened stress responsiveness, and stress can theoretically act through several biological pathways to contribute to excess mortality from CHD. Mechanisms connecting stress, depression and cardiovascular mortality have not been previously explored in detail. The purpose of this study was to assess the effects of stress and depression on myocardial perfusion and plasma cortisol concentrations in CHD patients. Patients with CHD with and without depression (n = 28) underwent single photon emission computed tomography imaging of myocardial perfusion at rest and during a stressful cognitive challenge. Severity of ischaemia was measured by summing perfusion defect scores across myocardial segments and subtracting out rest from stress scores. Plasma cortisol concentrations were measured at baseline and in response to the stressful challenge. There were no differences in stress-induced myocardial ischaemia or plasma cortisol response to stress between CHD patients with and without depression. Depressed CHD patients with a history of psychological trauma (n = 5) had an increase in stress-induced ischaemia scores [7; standard deviation (SD) = 5] compared with CHD patients with depression without a history of psychological trauma (2 SD = 2) and CHD patients without depression or psychological trauma (1; SD = 2) (F = 8.51; degree of freedom = 2,23; p = 0.007). Eighty per cent of CHD/depression trauma-exposed subjects had stress-induced ischaemia as opposed to 38 per cent of CHD/depression subjects without trauma exposure and 23 per cent of subjects with CHD without depression or trauma. Self-reported nervousness during the cognitive stressor was correlated with stress-induced ischaemia. These preliminary findings suggest that depression with a history of prior exposure to traumatic stress is associated with increased risk for stress-induced cardiovascular ischaemia.

Lithium, arginine vasopressin and the dex/CRH test in mood disordered patients

The impact of lithium on arginine vasopressin (AVP) release has implications for our understanding of the pathophysiology and treatment of mood disorders and for the interpretation of neuroendocrine studies. In this secondary analysis of neuroendocrine, data from 23 patients with chronic major depressive disorder, 41 patients with bipolar disorder and 18 healthy controls, we examine the relationship between lithium therapy, AVP levels and the cortisol response to the dexamethasone/corticotropin-releasing hormone (dex/CRH) test. These data demonstrate that patients taking lithium have elevated post-dexamethasone AVP levels compared to both healthy controls and patients not on lithium.

The dex/CRH test--is it better than the DST?

The dexamethasone suppression test (DST), frequently abnormal in mood disorder patients, is considered to measure glucocorticoid receptor-mediated negative feedback. We examined the hypothesis that the, apparently more sensitive, dexamethasone/corticotrophin-releasing-hormone (dex/CRH) test unveils subtle hypothalamic-pituitary-adrenal axis disturbance not detected by the DST in 82 patients with mood disorders and 28 controls. There was a close correlation between the cortisol responses on the two tests (r(s)=0.73, p<0.0005). However, ROC analysis revealed that the dex/CRH test had better diagnostic performance than the DST (p=0.031). The sensitivity of delta cortisol (from the dex/CRH) was 61.9% and the specificity 71.4%. The sensitivity of 1500 h cortisol (the DST) was 66.6% and the specificity was 47.6%. This suggests that the two tests measure common pathology but that the dex/CRH test has better diagnostic utility.

Neuropsychological impairment in bipolar disorder: the relationship with glucocorticoid receptor function

OBJECTIVE

Basal levels of glucocorticoids, such as cortisol, are generally unaltered in bipolar disorder. However, neuroendocrine tests of glucocorticoid receptor (GR) function such as the dexamethasone suppression test (DST) are frequently abnormal. Neuropsychological impairment is well documented in healthy volunteers after administration of glucocorticoids and in patients with bipolar affective disorder. This suggests a potential link between neuropsychological and hypothalamic-pituitary-adrenal axis function. We examined the hypothesis that neuropsychological impairment in bipolar disorder is associated with abnormal GR function.

METHODS

Seventeen euthymic bipolar patients and 16 controls completed tests of verbal declarative and working memory (WM) tests and the DST. The correlation between neuroendocrine and neuropsychological function was examined.

RESULTS

Bipolar patients made significantly more errors of omission and commission on the WM paradigm and demonstrated impaired verbal recognition memory. Patients' post-dexamethasone cortisol correlated with WM commission errors (r(s) = 0.64, p = 0.0006). No such relationship was evident in controls.

CONCLUSION

Deficits in declarative memory and WM are evident in patients with bipolar disorder. The deficit in retrieval accuracy from WM appears to be correlated with abnormal GR function.

Hypothalamic-pituitary-adrenal axis function in patients with bipolar disorder

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA) axis function, as variously measured by the responses to the combined dexamethasone/corticotrophin-releasing hormone (dex/CRH) test, the dexamethasone suppression test (DST) and basal cortisol levels, has been reported to be abnormal in bipolar disorder.

AIMS

To test the hypothesis that HPA axis dysfunction persists in patients in remission from bipolar disorder.

METHOD

Salivary cortisol levels and the plasma cortisol response to the DST and dex/CRH test were examined in 53 patients with bipolar disorder, 27 of whom fulfilled stringent criteria for remission, and in 28 healthy controls. Serum dexamethasone levels were measured.

RESULTS

Patients with bipolar disorder demonstrated an enhanced cortisol response to the dex/CRH test compared with controls (P=0.001). This response did not differ significantly between remitted and non-remitted patients. These findings were present after the potentially confounding effects of dexamethasone levels were accounted for.

CONCLUSIONS

The dex/CRH test is abnormal in both remitted and non-remitted patients with bipolar disorder. This measure of HPA axis dysfunction is a potential trait marker in bipolar disorder and thus possibly indicative of the core pathophysiological process in this illness.

Effects of glucocorticoids on declarative memory function in major depression

BACKGROUND

Major depression has been associated with hypercortisolemia in a subset of patients with depression. Administration of exogenous cortisol and other glucocorticoids to healthy human subjects has been observed to result in a transient impairment in verbal declarative memory function. The purpose of this study was to assess the effects of the glucocorticoid, dexamethasone, on verbal declarative memory function in patients with untreated unipolar major depressive disorder (MDD).

METHODS

Fifty two men and women with (n = 28) and without (n = 24) MDD received placebo or dexamethasone (1 mg and 2 mg on 2 successive days) in a double-blind, randomized fashion. Declarative memory was assessed with paragraph recall at baseline (day 1) and day 3.

RESULTS

There was a significant interaction between diagnosis and drug (dexamethasone vs. placebo) on paragraph recall. In the healthy subjects, memory improved from baseline to day 3 with placebo and was unchanged with dexamethasone, whereas in MDD patients memory function showed a pattern of decreasing with placebo and improving with dexamethasone from baseline to day 3.

CONCLUSIONS

These findings are consistent with an altered sensitivity of declarative memory function in MDD to regulation by glucocorticoids. Possible explanations of the findings include alterations in glucocorticoid receptors in the hippocampus or other brain regions mediating declarative memory, or differential sensitivity to dexamethasone-induced reductions in cortisol, in patients with MDD.

Lack of a Fluoxetine Effect on Prednisolone Disposition and Cortisol Suppression

STUDY OBJECTIVE

To evaluate the potential effect of fluoxetine, a cytochrome P450 isoenzyme inhibitor, on prednisolone disposition and cortisol suppression.

DESIGN

Sequential, two-phase, crossover, open-label pharmacokinetic study.

SETTING

General clinical research center.

SUBJECTS

Fourteen healthy volunteers.

INTERVENTION

A single intravenous dose of prednisolone 40 mg before and after 14 days of treatment with fluoxetine 20 mg/day for 5 days followed by 60 mg/day for 9 days to achieve steady-state concentrations.

MEASUREMENTS AND MAIN RESULTS

Pharmacokinetic parameters of the prednisolone and resulting pharmacodynamic effects on the time course of plasma cortisol suppression before and after fluoxetine administration were evaluated. No significant differences were observed for the mean +/- SD area under the prednisolone concentration-time curve (3739 +/- 992 vs 3498 +/- 797 microg x hr/L, respectively), clearance (8.58 +/- 2.62 vs 8.92 +/- 2.05 L/hr, respectively), volume of distribution (39.5 +/- 12.4 vs 38.2 +/- 9.9 L, respectively), elimination half-life (3.32 +/- 0.83 vs 3.05 +/- 0.80 hrs, respectively), or duration of plasma cortisol suppression (23.5 +/- 3.1 vs 22.0 +/- 4.2 hrs, respectively).

CONCLUSION

Fluoxetine administration did not significantly affect prednisolone disposition or prolong cortisol suppression. This finding suggests that coadministration of these agents is unlikely to result in clinically important pharmacokinetic or pharmacodynamic drug interactions. Prednisolone may be a useful alternative for patients who require both glucocorticoid and fluoxetine therapy.

Dexamethasone metabolism in dexamethasone suppression test suppressors and nonsuppressors

BACKGROUND

Variable dexamethasone kinetics is a possible confound in the dexamethasone suppression test. Modifications to include dexamethasone plasma levels and specific dexamethasone "windows" have been proposed. Our study aims to validate our proposed dexamethasone windows in an independent sample of 121 subjects.

METHODS

We performed dexamethasone suppression tests in 162 subjects with mixed psychiatric diagnoses. Dexamethasone levels and beta-phase half-life of dexamethasone were computed for suppressors and nonsuppressors.

RESULTS

Dexamethasone levels were lower in nonsuppressors than in suppressors. Dexamethasone levels correlated inversely with cortisol levels in the total sample, but were nonsignificant or weakly associated in those samples restricted to the windows. The beta-phase half-life of dexamethasone was shorter in nonsuppressors. The dexamethasone windows were validated at 3:00 PM and 10:00 PM. We propose 4.0 ng/mL as a revised upper limit of the 8:00 AM dexamethasone window.

CONCLUSIONS

The plasma dexamethasone level is confirmed as a confound in the dexamethasone suppression test through more rapid dexamethasone clearance in nonsuppressors. Application of dexamethasone windows will reduce this source of test variance.

The lower limits of dexamethasone window in Chinese depressives

BACKGROUND

Previous studies have shown wide variation in plasma dexamethasone (DEX) concentrations following a standard 1-mg dexamethasone suppression test (DST), and significantly lower DEX concentrations in DST nonsuppressors compared with suppressors, suggesting that DEX pharmacokinetics/bioavailability is an important variable associated with DST nonsuppression.

METHODS

To determine the effect of plasma DEX levels on the DST in Chinese depressives, we measured plasma DEX and post-DEX cortisol levels at 4:00 PM in a group of 50 depressed outpatients, 28 anxiety outpatients, and 33 normal subjects during the course of 1-mg oral overnight DST.

RESULTS

We found a significant difference in the plasma DEX levels between DST nonsuppressors and suppressors in the depression group and overall subject population, and a significant negative correlation between the plasma DEX and cortisol levels in the depression, anxiety, and total groups. Within a DEX "window", the DST performance was enhanced, whereas the relationships between plasma DEX and post-DEX cortisol levels remained equally strong.

CONCLUSIONS

Our findings support a relationship between plasma DEX and post-DEX cortisol levels, a relationship that might be superimposed on the hypothalamic-pituitary-adrenal axis. Comparing our "window" range with those of previous studies, we suggest that Chinese depressives may have lower limits of plasma DEX window, and that ethnicity may be an intervening variable in both DST response and pharmacokinetics of DEX.

Psychoneuroendocrinology of depression. Hypothalamic-pituitary-adrenal axis

Among the more consistent observations in patients with major depression is dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis presenting as elevation of basal cortisol, dexamethasone-mediated negative feedback resistance, increased cerebrospinal fluid levels of corticotropin-releasing factor (CRF), and a blunted adrenocorticotropic hormone (ACTH) response to challenge with exogenous CRF. These features appear to be state, rather than trait markers, and are normalized upon successful treatment. These pathophysiologic adaptations may arise from defects in central drive to the neuroendocrine hypothalamus, disruption of normal adrenocortical hormone receptor function or a modification of HPA axis function at any level. Functional assessment of the HPA axis is thought to provide a window into central nervous system operation that may be of diagnostic value in this and other affective disorders regardless of whether CRF and glucocorticoids are directly involved in the origin of major depression or merely exacerbate the consequences of other primary defects.

Plasma dexamethasone concentration and cortisol response during manic episodes

BACKGROUND

Despite the widespread study of the dexamethasone suppression test (DST) in patients diagnosed with major depression, it has been less well studied during manic and mixed states of bipolar disorder.

METHODS

Cortisol response to the administration of 1 mg of dexamethasone was studied in 44 patients diagnosed bipolar disorder, manic (n = 37) or mixed (n = 7). Dexamethasone levels and cortisol responses were compared between these groups. Four patients initially meeting criteria for bipolar disorder, mixed, and 7 patients initially meeting criteria for bipolar disorder, manic, all of whom were characterized as DST nonsuppressors, were retested after remission.

RESULTS

Dexamethasone levels were lower and cortisol levels higher in those patients diagnosed bipolar disorder, mixed. An inverse correlation was found between log-transformed dexamethasone levels and log-transformed cortisol levels at 3 PM (r = -.619, p < or = .001) and 10 PM (r = -.501, p < or = .001). In those subjects retested after remission, dexamethasone levels were higher and cortisol levels lower than during the manic and mixed states.

CONCLUSIONS

Disturbances in the hypothalamic-pituitary-adrenal axis are observed frequently during mixed states of bipolar disorder, but are also not uncommon in purely manic episodes. These changes appear to be state dependent and revert with treatment.

Recurrence pattern of serum creatine phosphokinase levels in repeated acute psychosis

BACKGROUND

Elevated serum creatine phosphokinase (CPK)MM level is frequently found in acute psychosis. Theories relate this CPKemia to psychomotor agitation and medication. We hypothesized that psychosis-related CPKemia observed in individual patients is relatively consistent.

METHODS

Ninety psychotic patients were studied; 83% were schizophrenics (Brief Psychiatric Rating Scale scores > or = 40) whose serum CPKMM levels were recorded during two or more different acute psychoses. The serum CPKMM levels used were the maximal levels monitored during the beginning of each hospitalization. The last CPK measurement in a circumscribed period was defined as the index serum CPK level (IndCPK). The mean of all other individual maximal CPK measurements during other psychotic episodes was defined as the average CPK (AvgCPK).

RESULTS

Multiple linear regression analysis showed a significant correlation of natural logarithm (Ln) of (IndCPK with Ln(AvgCPK), as well as with gender (coefficient = .65 and .63, p < .0001 and p < .01, respectively). There were significantly higher IndCPK levels among male patients than among female patients (p < or = .001). A relatively consistent individual pattern of serum CPKMM levels during repeated acute psychotic episodes was observed.

CONCLUSIONS

Serum CPKMM levels and gender were found to be good predictors of maximal serum CPKMM levels during every repeated acute psychotic episode. High IndCPK levels are probably risk factors for neuroleptic malignant syndrome.

The dexamethasone suppression test and treatment outcome in elderly depressed patients participating in a placebo-controlled multicenter trial involving moclobemide and nortriptyline

The dexamethasone suppression test (DST) was conducted in 95 elderly DSM-III-R depressed patients randomized for treatment with moclobemide (MOC; 400 mg daily), nortriptyline (NT; 75 mg daily), or placebo (PBO) in a 7-week double-blind multicenter study. Patients were assessed weekly using various clinical scales, including the 17-item Hamilton Depression Rating Scale. The DST was administered at baseline and at the end of treatment. At baseline, no relationship was found between DST status and the various clinical scales used. At the end of treatment, suppressors (DST-) had significantly improved clinical ratings compared to nonsuppressors (DST+), and were mostly found among those treated with NT (71%) as compared to MOC (41%) or PBO (33%) (p < .03). On the other hand, baseline DST measures influenced treatment outcome; DST+ patients had a greater number of treatment responders to NT (48%) than MOC (19%) or PBO (20%) (p < .07). For DST- patients, the situation was reversed: NT, 7%; MOC, 31%. Postdexamethasone cortisol levels were lower in MOC responders (p < .07). An interaction was found between DST and drug-specific response. The DST may be a useful adjunct for predicting and evaluating the outcome of antidepressant therapy.

Pharmacokinetics of dexamethasone and its relationship to dexamethasone suppression test outcome in depressed patients and healthy control subjects

The pharmacokinetics of dexamethasone (DEX) were studied in 9 drug-free melancholically depressed patients and 10 healthy control subjects matched by sex and age. Each subject received 1 mg of DEX administered orally and by the (i.v.) route at 11:00 PM and serial blood samples were collected over the next 17 hours until 4:00 PM. There were no significant differences between the diagnostic groups and DEX bioavailability, peak plasma level, time to maximum concentration, or in elimination half-life after oral administration. Bioavailability estimates indicated that DEX absorption was incomplete and variable mean = 61%, SD = 14) in controls as well as depressed patients. In both groups there was a wide interindividual variability in plasma DEX levels following both oral and i.v. routes of administration. This variability could not be reliably predicted by differences in age, sex, or weight between subjects. The factors that accounted for most the variability in 4:00 PM plasma DEX levels after oral administration were clearance, bioavailability, and time to reach maximum concentration. Plasma DEX levels were lower in 3 depressed nonsuppressors compared to 3 matched controls who suppressed. No single pharmacokinetic factor was shown to be responsible for the lower DEX levels in the depressed nonsuppressors. These results indicate that plasma DEX levels need to be measured in each individual during the DST procedure so that this information may be taken into consideration when interpreting DST results.

Depressive psychomotor disturbance, cortisol, and dexamethasone

We examine the dexamethasone suppression test as a biological correlate of melancholia as defined by the CORE system, a scale for rating objective signs of psychomotor disturbance. Postdexamethasone cortisol concentrations and rates of nonsuppression were higher in CORE, Newcastle, and DSM-III-R defined melancholic groups. These differences, however, were no longer significant after partialling out the combined effects of age, dexamethasone, and basal cortisol concentrations. There was a significant correlation between the CORE (but not the Newcastle) scale and 8:00 AM postdexamethasone cortisol levels, which persisted after partialling out those same three covariates. Dexamethasone concentrations themselves were lower in CORE- and Newcastle-defined melancholics, though these were no longer significant after covarying for cortisol concentrations. Dexamethasone levels were also significantly inversely correlated with CORE and Newcastle scales. A significant correlation between CORE (but not Newcastle) scores and dexamethasone levels at 4:00 PM persisted after partialling out the effects of age and cortisol. These findings indicate an intriguing relationship between the CORE system as a dimensional construct for rating psychomotor disturbance, and both postdexamethasone cortisol and dexamethasone concentrations.

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.

Hypercortisolemia and hippocampal changes in depression

Hypercortisolemia is a frequently observed abnormality in patients with major depression. It has been hypothesized that the hippocampus, as a major feedback site for glucocorticoids, is involved in the pathophysiology of hypercortisolemia. Some have in fact posited that the hippocampus is marked by diminished size in depressed patients with hypercortisolemia. We tested this hypothesis by examining the relationship between hippocampal volume, assessed with magnetic resonance imaging, and hypercortisolemia using the dexamethasone suppression test (DST) in a group of 19 depressed patients. No differences in hippocampal volume were observed between patients and control subjects (n = 30). Within the patient group, DST suppressors did not differ from DST nonsuppressors in hippocampal volume. However, a relationship between hippocampal volume and 11 p.m. cortisol concentration was observed after covariance adjustment for age and sex. Furthermore, significant negative correlations were observed between hippocampal volume and both age of depressive onset and number of hospitalizations. The results of this study therefore provide limited support for the hypothesis regarding an essential role of the hippocampus in the neuroendocrine elevation of glucocorticoids in depression.

Dose response relationship between plasma ACTH and cortisol after the infusion of ACTH1-24

The authors examined the dose response relationship between plasma ACTH and cortisol concentrations after the administration of various doses of ACTH1-24 (0.025 micrograms, 0.125 micrograms, 0.25 micrograms, 1 microgram, 250 micrograms) in dexamethasone-suppressed normal volunteers. A logarithmic dose-response relationship between the dose of ACTH administered and plasma cortisol concentration was found. Although there was considerable variability in plasma ACTH concentrations, there was, however, a definite correlation between area under the curve for ACTH and area under the curve for cortisol after the various doses of ACTH.

Relationship of object loss during development to hypothalamic-pituitary-adrenal axis function during major affective illness later in life

Although many studies have attempted to determine whether early object loss influences the risk of developing major affective illness in adulthood, there are few empirical data relating early loss to subsequent hypothalamic-pituitary-adrenal (HPA) axis dysfunction in adulthood. Forty-five psychiatric inpatients admitted for an active major affective illness, all of whom had a previous history of a significant permanent object loss (by death only), were studied retrospectively in this preliminary investigation to examine whether the type and timing of object loss experienced earlier in life would discriminate affectively ill patients who exhibit HPA dysfunction. Several loss variables were found to be statistically significant predictors of cortisol responses following glucocorticoid challenge. A median split of the distribution was used to classify patients into early loss (< or = 19 years) and late loss (> or = 20 years) groups. Analyses for all subjects, early and late loss combined, showed that late loss was associated with higher 11 p.m. cortisol levels. Within the early loss group, however, age of first loss was the most significant predictor of 4 p.m. cortisol levels after dexamethasone challenge. Consistent with the hypothesis that childhood object loss may be associated with long-term alterations in HPA axis function, younger age of loss correlated significantly with higher 4 p.m. cortisol responses. These preliminary data suggest that future prospective investigation of the neurobiological as well as psychosocial consequences of various types of early loss warrant further study.

Preliminary studies of 6 beta-hydroxydexamethasone and its importance in the DST

The role of the metabolites of dexamethasone (DEX) in the dexamethasone suppression test (DST) has never been fully elucidated. We report here our preliminary studies of 6 beta-hydroxydexamethasone (6 OH-Dex), a known metabolite of DEX, on the hypothalamic-pituitary-adrenal (HPA) axis of the rat; its activity in the most commonly used radioimmunoassay for plasma DEX; and its plasma concentrations in a normal human subject during the standard 1.0 mg DST. Six OH-Dex administered subcutaneously to rats at a dose of 1 mg/kg was able to completely suppress corticosterone production for at least 3 hr. In the IgG Corp. radioimmunoassay for plasma DEX, 6 OH-Dex was moderately cross-reactive yielding a 50% cross-reactivity of 10%. Gas chromatographic coupled mass spectroscopic analysis of human plasma samples, obtained 12 to 20 hr after the oral ingestion of 1.0 mg DEX, demonstrated similar plasma concentrations for both the parent compound and the 6-hydroxyl metabolite. The relevance of these findings, particularly to pharmacokinetic studies of the DST, is discussed.

In vivo assessment of pituitary volume with magnetic resonance imaging and systematic stereology: relationship to dexamethasone suppression test results in patients

The relationship between dexamethasone suppression test (DST) results and in vivo pituitary volume was studied in 24 psychiatric inpatients. The principles of systematic stereology were used to measure pituitary volume from 3-mm contiguous sagittal spin-echo magnetic resonance (MR) images of the brain. There was no correlation between pituitary volume and 3 p.m. or 10 p.m. postdexamethasone (post-DEX) plasma cortisol concentrations. However, when multiple regression analysis was performed to relate pituitary volume to gender, age, and post-DEX plasma cortisol concentrations, there was a significant relationship between pituitary volume and age, gender, and 10 p.m. post-DEX cortisol plasma concentration. This is the first study to demonstrate a method that directly measures, rather than estimates, in vivo pituitary volume. Furthermore, it suggests that activation of the hypothalamic-pituitary-adrenal axis in psychiatric patients, as manifested by elevated post-DEX cortisol concentrations, may influence pituitary volume.

Symptomatology and cognitive impairment associate independently with post-dexamethasone cortisol concentrations in unmedicated schizophrenic patients

Serum cortisol concentrations were measured after dexamethasone administration (1 mg) in 21 neuroleptic-free schizophrenic inpatients. Patients were assessed using the Brief Psychiatric Rating Scale and a battery of cognitive tests. A significant correlation was found between negative symptoms and both 8:00 AM and 4:00 PM post-dexamethasone cortisol concentration (PDC). Cognitive impairment on several measures was also correlated with 8 AM PDC, but in an independent manner. Although positive and negative symptoms were unrelated, exploratory analysis revealed a significant inverse correlation between a positive symptom grouping and both 8:00 AM and 4:00 PM PDC.

Effect of high plasma dexamethasone levels on DST sensitivity: dose-response study in depressed patients and controls

The aim of this study was to examine cortisol dynamics over a range of plasma dexamethasone (DEX) levels using a two-dose dexamethasone suppression test (DST). Two doses of DEX (0.5 and 1.5 mg) were administered in a randomized crossover design to 29 inpatients with major depression and 26 controls to identify the upper range of plasma DEX levels that would allow reliable interpretation of DST results. It was hypothesized that due to inappropriately high plasma DEX levels following 1.5 mg, several depressed patients would switch from suppressors after the 1.5 mg dose to nonsuppressors after 0.5 mg. In contrast, the nondepressed controls with high DEX levels following 1.5 mg would remain suppressors after the lower dose. Fourteen patients were identified as having high 4 p.m. DEX levels (greater than 4 nmol/l) after the 1.5 mg DST. Cortisol was suppressed in all of the subjects with high DEX levels. After 0.5 mg, five of the eight depressed patients with high DEX levels switched to nonsuppressors. In contrast, all six controls with high DEX levels remained suppressors. These results indicate that patients with high DEX levels after a 1 mg DST should be retested with a lower dose. This strategy enhances the sensitivity of the DST without loss of specificity.