Dexamethasone bioavailability: implications for DST research

The effect of oral dexamethasone administration on testosterone levels in combat veterans with or without a history of suicide attempt

Combat exposure has been linked to increased risk of suicidal ideation, suicide attempts, and death by suicide, and suicidality has been linked with altered testosterone levels. In this study, we examined morning baseline free and total testosterone levels and the effect of dexamethasone administration on testosterone levels in male combat veterans with or without a history of suicide attempt. Demographic and clinical parameters of the study participants were assessed and recorded. Blood samples were collected between 8:00 and 8:30 a.m. on the day prior to and following dexamethasone (0.5 mg) ingestion. Suicide attempters had higher schedule for suicidal ideation (SSI) scores in comparison to non-attempters. Baseline free and total testosterone levels were lower in suicide attempters compared to non-attempters. In the whole sample, both baseline free and total testosterone levels negatively correlated with SSI scores. Free testosterone levels decreased after dexamethasone administration among non-attempters but not among attempters. Free testosterone post-dexamethasone levels positively correlated with aggression scores among non-attempters but not among suicide attempters. Our findings indicate that there are substantial differences in the testosterone regulation between combat veterans with or without a history of suicide attempt. Studies of the relation between the testosterone function and suicidal behavior among combat veterans may lead to improvement in detection of suicidality and finding new pharmacological targets for prevention of suicide among veterans.

Alterations in Systemic and Cognitive Glucocorticoid Sensitivity in Depression

BACKGROUND

Decades of research point to cortisol insensitivity as a biomarker of depression. Despite a vast literature on cortisol's effects on memory, the role of cortisol insensitivity in core psychological features of depression, such as emotional memory biases, is unknown.

METHODS

Sixty-five premenopausal women with varying levels of depression completed this study involving an at-home low-dose dexamethasone suppression test and four experimental sessions (i.e., two visits for memory encoding of emotionally arousing pictures, each of which was followed 48 hours later by a recall test). Participants received 20 mg of oral cortisol (CORT) or placebo prior to encoding. We tested whether systemic cortisol insensitivity measured with the dexamethasone suppression test predicted cognitive sensitivity to CORT, which was operationalized as the change in negatively biased memory formation for pictures encoded following CORT versus placebo administration.

RESULTS

Cortisol insensitivity was associated with more severe depression and flatter diurnal cortisol levels. Cortisol insensitivity predicted negative memory bias for pictures encoded during the placebo session and reduction in negative memory bias for pictures encoded during the CORT (compared with placebo) session, even after accounting for psychiatric symptomatology.

CONCLUSIONS

Our findings replicate research showing that cortisol insensitivity predicts depression severity and flatter diurnal cortisol levels. The results further suggest that systemic cortisol insensitivity is related to negative memory bias and its alleviation by cortisol administration. These novel cognitive findings tie together knowledge regarding endocrine and psychological dysfunction in depression and suggest that boosting cortisol signal may cognitively benefit individuals with cortisol insensitivity.

Evidence for an association between an enhanced reactivity of interleukin-6 levels and reduced glucocorticoid sensitivity in patients with fibromyalgia

Pain and fatigue have been identified as core symptoms of fibromyalgia syndrome (FMS). Since both symptoms are also characteristic of hypocortisolemic disorders, reduced cortisol levels have been thought to promote an exacerbation of these FMS core symptoms by an enhanced reactivity of interleukin-6 (IL-6) levels. The aim of the current study was to investigate the pathophysiologic relevance of reduced cortisol levels for manifestation of FMS core symptoms. Twelve female FMS patients with 15 female controls were compared regarding the function of hypothalamus-pituitary-adrenal (HPA) axis and behavioral, endocrine and IL-6 responses after measuring the pressure pain thresholds (PPTs) at tender points. Function of HPA axis was assessed by determining the cortisol awakening response, daytime profile of cortisol secretion, low dose overnight dexamethasone suppression test (DST) and glucocorticoid sensitivity (GC) of inflammatory cytokine production. While endocrine and IL-6 responses were determined by collecting blood and saliva samples behavioral responses were assessed by pain and fatigue recordings of participants before and after PPT measurement using visual analogue scale (VAS). Whereas FMS patients were found not to differ from controls in cortisol awakening response, daytime profile of cortisol secretion and cortisol suppression after overnight DST, they did exhibit a reduced GC sensitivity of inflammatory cytokine production. PPT measurement did induce three times higher cortisol and four times higher IL-6 levels in FMS patients, but no change in their ACTH levels. The enhanced IL-6 reactivity after PPT measurement was accompanied by an increase in the severity of FMS patients' pain and fatigue ratings. The findings of the present study provide evidence for the pathophysiologic relevance of a disturbed glucocorticoid receptor (GR) function, rather than reduced cortisol levels for the maintenance of FMS core symptoms.

Comparison of the dexamethasone-suppressed corticotropin-releasing hormone test and low-dose dexamethasone suppression test in the diagnosis of Cushing's syndrome

CONTEXT

The low-dose dexamethasone suppression test (LDDST) is widely used in confirming a diagnosis of Cushing's syndrome. CRH administration at the end of an LDDST has been reported to improve the diagnostic accuracy of this test.

OBJECTIVE

Our objective was to assess whether CRH administration after a standard LDDST (LDDST-CRH test) improves diagnostic accuracy in Cushing's syndrome.

DESIGN, SETTING, AND PARTICIPANTS

Thirty-six individuals with a clinical suspicion of Cushing's syndrome each completed a standard LDDST and an LDDST-CRH test at Hammersmith Hospitals NHS Trust, London. The LDDST involved administration of 0.5 mg oral dexamethasone given 6-hourly for 48 h. Serum cortisol was measured 6 h after the last dose of dexamethasone, with a value of 50 nmol/liter or below excluding Cushing's syndrome. Immediately after this, the LDDST-CRH test commenced with administration of a ninth dose of 0.5 mg dexamethasone. Exactly 2 h later, 100 mug human-sequence CRH was administered. Serum cortisol was measured 15 min after the CRH injection, with a value of less than 38 nmol/liter also excluding Cushing's syndrome.

MAIN OUTCOME MEASURE

Diagnosis or exclusion of Cushing's syndrome was the main outcome measure.

RESULTS

Twelve subjects were diagnosed with Cushing's syndrome (eight Cushing's disease and four primary adrenal). The sensitivity of the LDDST in diagnosing Cushing's syndrome was 100%, with a specificity of 88%. In contrast, although the sensitivity of the LDDST-CRH test was also 100%, specificity was reduced at 67%. These results give a positive predictive value of 80% for the LDDST and 60% for the LDDST-CRH test.

CONCLUSION

This small study suggests that the addition of CRH to the LDDST does not improve the diagnostic accuracy of the standard LDDST in Cushing's syndrome.

Enhanced cortisol suppression following dexamethasone administration in domestic violence survivors

OBJECTIVE

The authors compared responses of female domestic violence survivors and a matched group of nontraumatized participants to a low-dose (0.5 mg) dexamethasone suppression test (DST).

METHOD

Seventy female domestic violence survivors and 14 nontraumatized women matched for age and race were recruited. Participants were assessed for trauma severity, severity of PTSD and depressive symptoms, and DST cortisol response. Of the domestic violence survivors who were DST-compliant, comparisons were made among those with PTSD (N=15), those with PTSD plus depression (N=27), and those with no PTSD or depression diagnosis (N=8) along with the nontraumatized comparison subjects (N=14).

RESULTS

Domestic violence survivors with PTSD, regardless of whether or not they had comorbid depression, had significantly lower baseline cortisol levels at 9:00 a.m. than the healthy subjects and trauma survivors with no diagnosis. Survivors with a sole diagnosis of PTSD showed significantly greater cortisol suppression to dexamethasone than did healthy subjects or the group diagnosed with PTSD plus depression.

CONCLUSIONS

These findings agree with previous studies showing hypothalamic-pituitary-adrenal (HPA) axis abnormalities in PTSD. The findings suggest that the chronic nature of domestic violence leads to a severe dysregulation of the HPA axis.

Neuroendocrine response to intravenous citalopram in healthy control subjects: pharmacokinetic influences

RATIONALE

The neuroendocrine response to intravenous citalopram may provide an acute, functional, in vivo measure of the neural serotonin (5-HT) system.

OBJECTIVE

To refine the quantification of acute neuroendocrine responses following intravenous citalopram in studies of 5-HT function.

METHODS

In 75 adult healthy subjects taking part in four similar protocols, we measured plasma prolactin and cortisol, as well as serial citalopram concentrations following intravenous citalopram (10 mg, 20 mg, 40 mg, 0.33 mg/kg) and placebo. The relationship between the AUC for intravenous citalopram during the first 150 min (AUC(150)) and the magnitude of the neuroendocrine response was determined. The role of pharmacokinetic (PK) parameters, as well as sensitivity to placebo injections, in influencing the neuroendocrine response to citalopram was then evaluated.

RESULTS

Citalopram produced a dose-dependent increase in cortisol and prolactin. The maximal increase from baseline correlated significantly but modestly with citalopram's AUC(150) (prolactin r(2)=0.23, P<0.0001; cortisol r(2)=0.3, P<0.0001). Additionally, citalopram's AUC(150) was affected by between-subject differences in both the peripheral and central volume of distribution. However, the neuroendocrine responses to citalopram did not correlate with the responses to placebo.

CONCLUSIONS

The parenteral citalopram challenge test is characterized by a modest concentration-response relationship, with concentration influenced by variable PK factors. Accounting for individual differences in drug distribution may improve the power of the citalopram challenge test, when used as an in vivo measure of central 5-HT function.

Predicting the failure of disc surgery by a hypofunctional HPA axis: evidence from a prospective study on patients undergoing disc surgery

Patients with postoperative ongoing sciatic pain have been shown to exhibit reduced cortisol levels along with enhanced IL-6 levels. The aim of the present study was to clarify the relationship between a reduced cortisol secretion and enhanced cytokine levels by performing a prospective study on patients with disc herniation. Twenty-two patients were examined before and after their disc surgery. Twelve healthy, pain-free subjects matched for age, education and gender constituted the control group. The preoperative examinations included the assessment of the diurnal pattern of cortisol secretion and the feedback sensitivity of the hypothalamus-pituitary-adrenal (HPA) axis. Patients' subjective stress levels also were assessed during the preoperative examination. The diurnal pattern of cortisol secretion was again assessed during the postoperative examination. Furthermore, blood samples were collected to measure catecholamine, adrenocorticotropic hormone (ACTH)- and interleukin-6 (IL-6) levels before and after measuring the pressure pain thresholds (PPTs). An assessment of the sensitivity of circulating monocytes to the immunosuppressive effects of glucocorticoids was further included in the postoperative examinations. Failed back syndrome (FBS) patients (n=12) showed a reduced cortisol secretion in the morning hours and enhanced feedback sensitivity of the HPA axis. Furthermore, FBS patients displayed an increased in-vitro production of proinflammatory cytokines and a relative glucocorticoid resistance of pro-inflammatory cytokine producing monocytes as compared to non-FBS patients (n=10) and controls. After PPT measurement FBS patients exhibited an increased norepinephrine but decreased epinephrine response, together with lower ACTH levels and a four times higher plasma IL-6 response. These findings suggest that chronically stressed patients are at a higher risk for a poor surgical outcome as their reduced cortisol secretion promotes the postoperative ongoing synthesis of proinflammatory cytokines.

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 trauma exposure on the cortisol response to dexamethasone administration in PTSD and major depressive disorder

OBJECTIVE

To evaluate cortisol suppression following 0.5 mg of dexamethasone (DEX) in trauma survivors (N=52) with posttraumatic stress disorder (PTSD), major depressive disorder (MDD), both, or neither disorder, and in subjects never exposed to trauma (N=10), in order to examine interactions between diagnosis and trauma history on cortisol negative feedback inhibition.

METHOD

Lifetime trauma exposure and psychiatric diagnoses were assessed and blood samples were obtained at 8:00 a.m. for the determination of baseline cortisol. Participants ingested 0.5 mg of DEX at 11:00 p.m. and blood samples for determination of cortisol and DEX were obtained at 8:00 a.m. the following day.

RESULTS

PTSD was associated with enhanced cortisol suppression in response to DEX. Among trauma survivors, the presence of a traumatic event prior to the "focal" trauma had a substantial impact on cortisol suppression in subjects with MDD. Such subjects were more likely to show cortisol alterations similar to those associated with PTSD, whereas subjects with MDD with no prior trauma were more likely to show alterations in the opposite direction, i.e. relative non-suppression.

CONCLUSIONS

Cortisol hypersuppression in PTSD appears not to be dependent on the presence of traumatic events prior to the focal trauma. However, prior trauma exposure may affect cortisol suppression in MDD. This finding may have implications for understanding why only some depressed patients show non-suppression on the DST.

The cortisol and glucocorticoid receptor response to low dose dexamethasone administration in aging combat veterans and holocaust survivors with and without posttraumatic stress disorder

BACKGROUND

Because alterations in cortisol negative feedback inhibition associated with aging are generally opposite of those observed in posttraumatic stress disorder (PTSD), we examined the cortisol and glucocorticoid receptor (GR) response to dexamethasone (DEX) in older trauma survivors.

METHODS

Twenty-three Holocaust survivors (9 men, 14 women), 27 combat veterans (all male), and 10 comparison subjects (7 men, 3 women) provided samples for plasma or salivary cortisol and glucocorticoid receptor determination in mononuclear leukocytes at 8:00 AM on the day of, and following, 0.5 mg of DEX at 11:00 PM.

RESULTS

Greater percent suppression of cortisol and lymphocyte GR was observed in older trauma survivors with PTSD compared to survivors without PTSD and comparison subjects. There was a significant main effect of depression in the direction of reduced suppression following DEX, consistent with the effects of DEX in major depressive disorder patients. Responses to DEX were uncorrelated with PTSD symptom severity, but cortisol suppression was associated with years elapsed since the most recent, but not focal, traumatic event.

CONCLUSIONS

The response to DEX is generally similar in older and younger trauma survivors, but the findings suggest that age, symptom severity, and lifetime trauma exposure characteristics may influence this response.

Vasoconstrictor response to topical beclomethasone in major depression

Overactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been frequently described in depression. Due to the closed-loop nature of the HPA axis, one possible cause of this overactivity may be a defect in negative feedback regulation, in particular an abnormality of the glucocorticoid receptor (GR). In the present study, the vasoconstrictor response to the topical glucocorticoid, beclomethasone, was used to examine GR function in depression. Topical beclomethasone was applied in four concentrations (10 microl each of 3, 10, 30 and 100 microg/ml) to the forearms of 22 subjects with major depression and their age- and sex-matched controls. Skin blanching responses were compared between the depressed and control groups and, within the depressed group, on the basis of the modified dexamethasone suppression test (DST), between cortisol suppressors and non-suppressors. Depressed subjects demonstrated a significantly reduced vasoconstrictor response compared to controls (P=0.0001). No difference was detected between cortisol suppressors and non-suppressors in their skin blanching responses. These findings suggest that peripheral GR function is abnormal in depression but that the reduced vasoconstrictor response to beclomethasone is not necessarily a secondary effect of hypercortisolaemia or HPA axis overactivity.

Low-dose dexamethasone suppression test in chronic fatigue syndrome and health

OBJECTIVE

Subtle dysregulations of the hypothalamus-pituitary-adrenal axis in chronic fatigue syndrome have been described. The aim of this study was to examine the negative feedback regulations of the hypothalamus-pituitary-adrenal axis in chronic fatigue syndrome.

METHODS

In 21 patients with chronic fatigue syndrome and 21 healthy control subjects, awakening and circadian salivary free cortisol profiles were assessed over 2 consecutive days and compared with awakening and circadian salivary free cortisol profiles after administration of 0.5 mg of dexamethasone at 11:00 PM the previous day.

RESULTS

Patients with chronic fatigue syndrome had normal salivary free cortisol profiles but showed enhanced and prolonged suppression of salivary free cortisol after the administration of 0.5 mg of dexamethasone in comparison to the control subjects.

CONCLUSIONS

Enhanced negative feedback of the hypothalamus-pituitary-adrenal axis could be a plausible explanation for the previously described alterations in hypothalamus-pituitary-adrenal axis functioning in chronic fatigue syndrome. Because similar changes have been described in stress-related disorders, a putative role of stress in the pathogenesis of the enhanced feedback is possible.

Effect of phenobarbitone on the low-dose dexamethasone suppression test and the urinary corticoid: creatinine ratio in dogs

OBJECTIVES

To investigate potential effects of phenobarbitone on the low-dose dexamethasone suppression (LDDS) test and urinary corticoid to creatinine ratio in dogs in a controlled prospective study and in a clinical setting.

ANIMALS

Ten crossbreed experimental dogs and 10 client-owned dogs of mixed breeds treated chronically with phenobarbitone to control seizures.

PROCEDURES

Experimental dogs were allocated to treatment (6 mg/kg oral phenobarbitone, n = 6) and control (n = 4) groups. LDDS tests (dexamethasone 0.01 mg/kg intravenously, cortisol concentration determined at 0, 2, 4, 6 and 8 h) were conducted repeatedly over a 3-month period. Urinary corticoid to creatinine ratios were measured before LDDS tests. A single LDDS test was performed on 10 epileptic dogs.

RESULTS

LDDS and urinary corticoid to creatinine ratios in dogs were not affected by treatment with phenobarbitone.

CONCLUSIONS

Phenobarbitone does not interfere with LDDS testing regardless of dosage or treatment time. Urinary corticoid to creatinine ratios are also unaffected.

Abuse-related posttraumatic stress disorder and alterations of the hypothalamic-pituitary-adrenal axis in women with chronic pelvic pain

OBJECTIVE

Although numerous organic conditions may cause chronic pelvic pain (CPP), diagnostic laparoscopy reveals a normal pelvis in many patients with CPP. However, psychological studies yield a high frequency of psychopathology and increased prevalences of chronic stress and traumatic life events, ie, sexual and physical abuse, in women with CPP, suggesting a relationship between posttraumatic stress disorder (PTSD) and CPP. As chronic stress and PTSD have been associated with specific alterations of the hypothalamic-pituitary-adrenal (HPA) axis, we explored stress history, psychopathology and HPA axis alterations in women with CPP.

METHOD

We recruited 16 patients with CPP and 14 painfree, infertile controls from a general hospital where diagnostic laparoscopy was performed. Psychological assessment included standardized interviews on clinical symptoms, abuse experiences and major life events as well as psychometric testing for PTSD-like symptoms and depression. Endocrinological evaluation involved determinations of diurnal salivary cortisol levels and hormonal responses to a corticotropin-releasing factor (CRF) stimulation test (100 microg human CRF) and a low-dose dexamethasone suppression test (0.5 mg).

RESULTS

We observed increased prevalences of abuse experiences and PTSD in women with CPP as well as a higher total number of major life events, whereas the mean extent of depression was within the normal range. With respect to endocrine measures, women with CPP demonstrated normal to low diurnal salivary cortisol levels, normal plasma-adrenocorticotropin (ACTH), but reduced salivary cortisol levels in the CRF stimulation test, and an enhanced suppression of salivary cortisol by dexamethasone.

CONCLUSION

Women with CPP demonstrate HPA axis alterations, that partly parallel and partly contrast neuroendocrine correlates of PTSD, but show marked similarity to findings in patients with other stress-related bodily disorders. These findings suggest that a lack of protective properties of cortisol may be of relevance for the development of bodily disorders in chronically stressed or traumatized individuals.

The dexamethasone suppression test and sleep electroencephalogram in nonbipolar major depressed inpatients: a multivariate analysis

BACKGROUND

The present study further examined relationships between postdexamethasone cortisol plasma values and sleep electroencephalogram (EEG) parameters.

METHODS

The dexamethasone suppression test (DST) and polysomnographic recordings were performed in a sample of 300 inpatients with primary major depressive disorder (MDD) (102 men and 198 women, mean age 44 +/- 12 years, range 20-74 years) consecutively admitted to Erasme Hospital (Brussels, Belgium) between 1981 and 1992.

RESULTS

The DST was abnormal in 40% of the sample. Postdexamethasone cortisol plasma values at 4:00 PM were significantly influenced by age, but not by gender. They were also significantly and positively correlated with weight loss, total scores on the Hamilton Depression Rating Scale, total scores on the Newcastle Scale, percentage of awakenings during sleep, and percent of stage 1. They were significantly and negatively correlated with percent of stage 2, slow-wave sleep, and REM sleep. Multiple regression analyses were conducted in two successive steps. First among clinical variables, only age and depressive symptom severity remained correlated with postdexamethasone plasma cortisol values. In the second step, with age and severity held constant, postdexamethasone plasma cortisol values were positively associated with amount of wake time and stage 1, and negatively with amount of slow-wave sleep.

CONCLUSIONS

These findings provide further indirect support for an overarousal state in MDD with sympathoadrenal system hyperactivity and impaired sleep continuity. They also underline the importance of taking into account various clinical confounding factors in the interpretation of both DST and sleep EEG results.

Glucocorticoid interactions with memory function in schizophrenia

Glucocorticoid (GC) exposure can affect brain function, including potential adverse effects on hippocampal physiology and on specific elements of cognitive performance. In a prior study of healthy adult humans, decreased verbal memory performance was detected during four days of double-blind, placebo-controlled dexamethasone (DEX) treatment. Using an identical experimental design and sample size (n = 19), the cognitive effect of DEX treatment was studied in 11 subjects with schizophrenia, compared with 8 receiving placebo. In contrast to the effect in healthy adults, GC treatment with DEX at this dose (cumulative 3.5 mg) and duration did not decrease verbal memory performance or other measures of cognitive function in the patients with schizophrenia. When data from this experiment was compared with data from the previous study of healthy adults, covarying differences in baseline memory performance, a significant 3-way interaction was detected between subject group, treatment condition, and the repeated measurements of verbal memory performance across baseline, treatment and washout (F[3,87] = 4.84, p = .0066), suggesting differential cognitive effects of DEX in the patients versus the previously studied healthy subjects. Baseline plasma cortisol concentrations (0800 h) prior to DEX treatment were inversely correlated with baseline delayed (rs = -0.536, p = .03) verbal recall performance, supporting a previous report. The current results await replication using a larger sample size but provide preliminary evidence for an altered behavioral response to acute GC exposure in schizophrenic versus healthy subjects, and further evidence for a relationship between chronic changes in circulating cortisol and the memory impairments found in this disorder.

Hypothalamic-pituitary-adrenal axis function and platelet serotonin concentrations in depressed patients

Plasma cortisol and platelet serotonin (5-hydroxytryptamine, 5-HT) concentrations were determined in 39 male psychotic and 39 male non-psychotic depressed inpatients, and in 69 male healthy control subjects. Psychotic or non-psychotic depressed patients had higher predexamethasone plasma cortisol levels than found in the control group. After the dexamethasone suppression test (DST), psychotic and non-psychotic depressed patients were subdivided into suppressors and non-suppressors. Psychotic and non-psychotic patients had significantly different platelet 5-HT concentrations among themselves and compared with the control group. However, there was no significant correlation between plasma cortisol levels and platelet 5-HT concentrations. Dexamethasone administration did not affect platelet 5-HT concentrations within subtypes of depressed patients. Abnormal cortisol suppression after the DST occurred more frequently in psychotic than in non-psychotic patients. Platelet 5-HT and plasma cortisol concentrations were decreased in patients with pronounced suicidal behaviour. Our results suggest that plasma cortisol and platelet 5-HT concentrations might serve as independent biological markers for different subtypes of depression.

Neuroendocrine challenge studies of suicidal behavior

This article reviews the research data regarding human neuroendocrine systems and suicidal behavior. Special emphasis is placed on pharmacochallenge studies. Such studies uniquely allow for functional assessment of neuroendocrine parameters in living subjects. Serotonergic mechanisms have been the most fruitful areas of research. While discussing the major areas of controversy, theoretical approaches to integration are offered.

Stress-restress: effects on ACTH and fast feedback

Glucocorticoid secretion is tightly regulated by negative feedback. Glucocorticoid feedback has been found to be altered in depression and post-traumatic stress disorder (PTSD). While hyposensitive glucocorticoid feedback has been found in depression, hypersensitive or enhanced negative feedback was described in PTSD. Enhanced negative feedback, can be seen as a sensitization of the inhibitory elements of HPA axis, and stress-restress or time dependent sensitization (TDS) model, has been suggested as an animal model for PTSD. We have studied the effects of this model on the HPA axis to determine whether it will produce increased sensitivity to negative feedback as found in PTSD patients. Adult Sprague-Dawley male rats were exposed to a single session of prolonged stress (restraint followed by a forced swim and exposure to ether vapors) and briefly restressed 7 days later. The effects of single prolonged stress on plasma ACTH and corticosterone responses (0, 5, and 30 min) and on glucocorticoid fast feedback (cortisol vs. saline pretreatment) were assessed in two studies. Animals exposed to single prolonged stress showed enhanced negative feedback in comparison to naive animals (F = 4.6371, df = 3, p = .0107), but there was no difference in ACTH or corticosterone responses during the restress. Pretreatment with cortisol, in the first stress session, did not prevent the development of the enhanced fast feedback when restressed. This can be seen as a sensitization of the inhibitory elements of HPA axis, suggesting that stress-restress paradigm might serve as a good animal model for HPA abnormalities found in PTSD patients.

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.

Prolactin response to low-dose dexamethasone challenge in combat-exposed veterans with and without posttraumatic stress disorder and normal controls

The prolactin and cortisol responses to dexamethasone (0.5 mg) were studied in combat veterans with (n = 18) and without (n = 12) posttraumatic stress disorder (PTSD) and normal controls (n = 18). Both veteran groups demonstrated greater prolactin suppression than the normals. In contrast, only veterans with PTSD showed an enhanced cortisol suppression in response to dexamethasone. These findings suggest that the prolactin response to dexamethasone may reflect a feature of combat exposure rather than PTSD per se.

A subtle disturbance in the feedback regulation of the hypothalamic-pituitary-adrenal axis in the early phase of Alzheimer's disease

In an attempt to find if a disturbance in the function of the feedback regulation of the hypothalamic-pituitary-adrenal axis is an early feature in Alzheimer's disease (AD), 35 outpatients (mean age 76.8 years) with a mild to moderate AD were compared to 20 controls (mean age 73.8 years) in their response to different doses of dexamethasone. After 0.5 mg dexamethasone, serum cortisol levels were significantly less suppressed in patients with early AD (p = .03) and these patients were significantly more often dexamethasone nonsuppressors (serum cortisol > or = 138 nmol/l) than controls (14/35 vs. 2/20; p = .03). Nonsuppression to 1 mg dexamethasone did not differ between groups (2/35 vs. 0/20). Plasma adrenocorticotropin levels were significantly lower in patients with Alzheimer's disease (n = 16) after 0.5 mg as well as after 1.0 mg dexamethasone (p = .01 and p < .001, respectively). The relationship between cortisol resistance to dexamethasone suppression and pathophysiology of AD is discussed.

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.

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.

Hypothalamic-pituitary-adrenal dysfunction in posttraumatic stress disorder

Neuroendocrine studies examining the hypothalamic-pituitary-adrenal (HPA) axis under baseline conditions and in response to neuroendocrine challenges have supported the hypothesis of altered HPA functioning in posttraumatic stress disorder (PTSD). However, to date, there is much debate concerning the nature of HPA changes in PTSD. Furthermore, in studies showing parallel findings in PTSD and major depressive disorder there is controversy regarding whether the HPA alterations suggest a specific pathophysiology of PTSD, or, rather, reflect comorbid major depressive disorder. This review summarizes findings of HPA axis dysfunction in both PTSD and major depressive disorder, and shows distinct patterns of HPA changes, which are probably due to different mechanisms of action for cortisol and its regulatory factors.

Incidence of hypercortisolism and dexamethasone resistance increases with age among wild baboons

While many features of the adrenocortical axis are unchanged with age in humans, there is a pattern of senescent hypercortisolism. This occurs basally, following threshold doses of dexamethasone, and in synergy with depression or Alzheimer's disease. An understanding of neuroendocrine aging is important, for both its gerontological implications, and determination of normative values for comparison with neuropsychiatric states. We have investigated whether aging is associated with hypercortisolism in a population of wild primates. The subjects were 108 yellow baboons (Papio cynocephalus) that have been under long-term study of Amboseli National Park in Kenya. Animals were anesthetized by blowgun under similar circumstances that allow for determination of basal cortisol concentrations. Sixty minutes later, 5.0 mg dexamethasone was administered to each animal, and cortisol determinations were made on serum collected immediately before administration and 6 hr later. Basal cortisol concentrations rose with age (p less than 0.028; r = 0.23). This occurred in a nonprogressive manner, in that there were no differences in concentrations among the youngest three quartiles of animals, whereas animals in the oldest quartile (older than approximately 16 years) had significantly higher values. In addition, there was a significant increase in postdexamethasone cortical concentrations with age (p less than 0.01; r = 0.31). This feature emerged progressively with age in both sexes. A number of possible artifactual causes of this senescent pattern could be eliminated, including medication confound, coincident disease, and body weight. These findings suggest that hypercortisolism and glucocorticoid feedback resistance might be general features of primate aging.

Disturbed glucocorticoid receptor autoregulation and corticotropin response to dexamethasone in depressives pretreated with metyrapone

We studied glucocorticoid receptor autoregulation and corticotropin response to dexamethasone in depressed patients and controls, attempting to control for the confounding effect of endogenous glucocorticoids. After depletion of endogenous cortisol, depressed patients showed an attenuated suppressibility of corticotropin by dexamethasone in the face of unchanged dexamethasone plasma levels. Beta-endorphin levels were strongly correlated with adrenocorticotropic hormone (ACTH) concentrations. Although metyrapone administration resulted in a marked rise of glucocorticoid receptor sites per cell in controls, this effect was not present in depressives. These data support the hypothesis of a decreased glucocorticoid receptor plasticity and a partial steroid resistance in depression.

Do serum dexamethasone levels improve the DST?

Some investigators have reported that dexamethasone suppression test (DST) accuracy might be improved by incorporating dexamethasone concentrations ([dex]) into test results. Using receiver operating characteristic methods, we evaluated data from four studies in which cortisol and dexamethasone levels were measured simultaneously at one or more times after drug ingestion. We compared DST accuracy using cortisol alone with various diagnostic indices incorporating [dex]. In none of the 21 comparisons did the [dex] factor enhance diagnostic performance.

A robust assay for dexamethasone in plasma using a heterologous 125I radioligand and a magnetizable solid-phase antiserum

An assay using an antiserum raised against a dexamethasone 21-hemisuccinate conjugate and the heterologous radioligand dexamethasone 21-(carboxymethyl) ether was developed, validated, and used to study the pharmacokinetics of this steroid for 12 h following administration to patients with congenital adrenal hyperplasia. Coupling the antiserum to magnetizable cellulose allowed rapid separation of bound/free steroid. A C-21 rather than a C-3 antiserum was used to minimize interference with a main metabolite, 6 beta-hydroxydexamethasone. Close correspondence of assay (0.35 nmol/L) and curve (0.25 nmol/L) sensitivities suggests that interference by matrix effects is minimal. This was confirmed by good agreement in data from the in-house assay and that of a reference procedure. Good precision was demonstrated by the precision profile and Shewhart chart quality control data. The latter also demonstrated the assay was robust and reliable in routine practice.

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.

Determination of plasma dexamethasone by chemical oxidation and electron capture negative ionization mass spectrometry

A quantitative assay for dexamethasone in human plasma is described as based on methodology employing electron capture negative ionization mass spectrometry (ECNI/MS). The unique feature of this assay is the sample preparation involving chemical oxidation which transforms dexamethasone to a highly electrophilic species while not significantly affecting the electrophilic character of the biochemical matrix, thereby permitting selective and sensitive detection of the analyte. Optimized chemical procedures and instrumental parameters are described for the detection of oxidized dexamethasone. Finally, the newly developed methodology, based on gas chromatography/mass spectrometry (GC/MS) with ECNI, is evaluated by comparison with a conventional GC/MS assay using electron impact of an 11,17,21-tris-trimethylsilyl ether 20-enol-trimethylsilyl ether derivative of dexamethasone and with a radioimmunoassay in the analysis of pooled samples of human plasma containing widely varying concentrations of the drug as obtained from patients at different stages of the dexamethasone suppression test.

Hypercortisolism and its possible neural bases

As is clear from the pages of this journal, biological psychiatrists remain fascinated by the phenomenon of dexamethasone (DEX) resistance and the hypercortisolism of various neuropsychiatric disorders. The mere existence of the endocrine abnormalities attests to the biological reality of these disorders. Furthermore, progress continues in using the occurrence of these endocrine defects as both diagnostic and prognostic markers of disease subtypes. Progress has also been made in understanding the mechanisms underlying the endocrine defects. The adrenocortical axis is vastly complex, involving multiple hypothalamic-releasing factors under CNS control, shifting pituitary and adrenal sensitivies to hormonal signals, and feedback regulation at all three levels. What defects within this system produce DEX resistance and hypercortisolism? In this paper, we review data suggesting that the endocrine problems is, at least in part, neural in nature. Drawing upon a rodent literature, we will also suggest some models by which this can occur. The hypercortisolism found in cases of affective disorders, anorexia nervosa, Alzheimer's disease, among the very aged or the chronically stressed, is not a uniform phenomenon. Basal cortisol concentrations can be elevated in all or part of the circadian cycle. Resistance to glucocorticoid (GC) feedback inhibition (as typically demonstrated by DEX resistance) can occur; the resistance can be complete, or occur as early escape from DEX suppression. Finally, elevated basal cortisol concentrations and DEX resistance can occur independently of each other. Until the end of this review, we will conveniently refer to these variants of adrenocortical hyperactivity as "hypercortisolism." In addition, rather than using the term "hypercortisolism" for the rat, we will use "hyperadrenocorticism" (as they secrete corticosterone, rather than cortisol).

Plasma dexamethasone levels in children given the dexamethasone suppression test

To determine whether children who demonstrate dexamethasone suppression test (DST) nonsuppression have lower plasma dexamethasone levels than DST suppressors, we administered the DST to 73 patients ranging in age from 5-14 years. Plasma dexamethasone levels and postdexamethasone cortisol levels were measured at 4:00 PM on day 2. We found: (1) DST nonsuppressors had significantly lower plasma dexamethasone levels (p less than 0.03) than suppressors; similar trends were observed when the population was divided into depressed and nondepressed patients; (2) mg/m2 dose of dexamethasone was directly correlated with plasma dexamethasone (p less than 0.003) and inversely correlated with postdexamethasone plasma cortisol levels (p less than 0.04); and (3) a statistically significant inverse correlation between plasma dexamethasone levels and postdexamethasone cortisol levels (p less than 0.04). Our findings show that plasma dexamethasone levels are important in evaluating DST results in psychiatrically disturbed children and suggest that dexamethasone dosage for use in the DST in children might be better calculated in terms of body surface area.

CSF 5-HIAA, serum cortisol, and age differentially predict vegetative and cognitive symptoms in depression

Prior studies have shown that both cerebrospinal fluid (CSF) concentrations of 5-hydroxyindolacetic acid (5-HIAA) and serum cortisol levels are related to overall symptom severity in depression. In the present study, 30 unmedicated inpatients meeting Research Diagnostic Criteria (RDC) criteria for depression participated in serum cortisol collection and a lumbar puncture for CSF. A multiple regression evaluated the ability of CSF 5-HIAA, serum cortisol, and age to predict cognitive and vegetative symptom clusters of the Hamilton Rating Scale for Depression. The multiple regression to predict the vegetative symptom cluster was highly significant overall (p = 0.002) and found that age and cortisol but not 5-HIAA predicted vegetative symptoms. The regression to predict the cognitive cluster narrowly missed overall significance (p = 0.06). Both CSF 5-HIAA and serum cortisol predicted cognitive symptoms and 5-HIAA predicted the cognitive cluster more strongly than cortisol. Age did not predict cognitive symptoms. The results suggest a dissociation between serum cortisol levels and CSF 5-HIAA in predicting vegetative and cognitive symptom clusters in depression.

Neuroendocrine aspects of primary endogenous depression: IX. Receiver operating characteristic analysis of the dexamethasone suppression index vs. the dexamethasone suppression test in patients and controls

The dexamethasone suppression index (DSI), which is the product of the postdexamethasone (DEX) serum DEX concentration and the post-DEX serum cortisol concentration, has been suggested to be a more sensitive discriminative test for depression than the standard DEX suppression test (DST). We used receiver operating characteristic (ROC) analysis to examine the DSI, calculated in several ways, versus the standard DST in a sample of 40 endogenous major depressives and 40 matched normal control subjects. The ROC analysis indicated that the DSI offers no advantage over the standard DST, regardless of which criterion values are used to define cortisol nonsuppression. Serum DEX determinations appear to have value primarily as an indicator of the minimum DEX concentration necessary for an accurate DST.

Direct radioimmunoassay procedure for plasma dexamethasone with a sensitivity at the picogram level

A simple radioimmunoassay (RIA) for the direct quantitation of plasma dexamethasone (DEX) at the picogram level has been developed. An antiserum with high specificity and avidity was obtained by the immunization of a carefully synthesized dexamethasone-21-succinyl-thyroglobulin with a high incorporation ratio. As little as 1 pg of DEX in 50 microL of plasma sample can be detected directly by this RIA without extraction and other purification procedures. Intra- and interassay coefficients of variation were 2.1 and 3.3% for plasma levels at 2.93 ng/mL or 2.3 and 7.2% for plasma levels at 0.88 ng/mL. Blank values for plasma of normal or pre-DEX patients were always under the detection limit (20 pg/mL). Excellent linearity (r = 0.9991-0.9999) was demonstrated between the serial dilutions of six plasma samples and their corresponding DEX concentrations. In single-dose DEX (0.25-1 mg) pharmacokinetic studies, plasma DEX was consistently detectable up to 24 h post dose. Compared with existing methods, this direct RIA demonstrates superior performance with regard to simplicity, sensitivity, specificity, and reproducibility. It also enables high sample throughput and has proven robust in our hands. This assay should be readily transferable to other laboratories for clinical or research purposes.

Liver function, plasma dexamethasone, and DST results in detoxified alcoholics

Alcohol abuse, alcohol withdrawal, and deterioration of hepatic function have been associated with abnormal dexamethasone suppression test (DST) results. Chronic alcohol abuse may also directly alter the pharmacokinetic disposition of dexamethasone. Plasma dexamethasone concentrations following a DST were determined in 53 detoxified alcoholics. Those with abnormal liver function had higher 4 p.m. plasma dexamethasone concentrations and lower DST cortisol concentrations. Those with normal liver function had lower plasma dexamethasone and higher DST cortisol concentrations consistent with induction of hepatic metabolic enzymes from chronic use of alcohol. The data indicate that liver function is one of the variables influencing dexamethasone disposition and DST cortisol suppression.

Persistent cortisol non-suppression after clinical recovery predicts symptomatic relapse in unipolar depression

We assessed the length and the quality of remission of 13 unipolar endogenous depressed patients, DST non-suppressors before treatment, in a 2-year prospective study. During this period, we recorded stressful life events. Persistent dexamethasone non-suppression, after treatment and complete clinical recovery, correlated highly with early clinical relapse. All six non-normalizers but only one normalizer were rehospitalized within the following 2 years for a major depressive relapse. Persistent DST non-suppression was unrelated to any impact of drug discontinuation, the occurrence of stressful life events or the length of illness-free intervals in the patient's prior course of illness. Persistent DST non-suppression appears to have significant prognostic value.

Psychoneuroendocrine research in depression. I. Hormone levels of different neuroendocrine axes and the dexamethasone suppression test

Psychoneuroendocrinology is of major importance in the biological research of depression. Most studies have focussed on the regulation of the hypothalamic-pituitary-adrenal (HPA) axis but other endocrine systems such as the hypothalamic-pituitary-thyroid (HPT), hypothalamic-pituitary-somatotropic (HPS), and the hypothalamic-pituitary-gonadal (HPG) axis have also been shown to be involved in the psychobiology of depression. There are close interrelations between various endocrine axes which possibly are affected during depressive illness. A variety of neuroendocrine abnormalities has been detected in depressive disorder but the pathophysiology of these derangements remains still unclear. Although the currently used neuroendocrine tests are not of diagnostic validity they may help to clarify the pathophysiological significance of the complex regulatory mechanisms of different neuroendocrine axes in affective disorders. Neuroendocrine regulation is determined both by peripheral and central mechanisms which both have to be adequately considered as well as potent interactions between various endocrine systems in further neuroendocrine depression research.

The influences of dexamethasone levels on the predictive value of the DST for unipolar major depression and the relationships between post-dexamethasone cortisol and ACTH levels

To investigate the relationships between dexamethasone (DEX) and post-DEX cortisol and adrenocorticotropic hormone (ACTH) levels, the authors measured DEX at 8.00 a.m. and post-DEX cortisol and ACTH levels at 8.00 a.m. and 4.00 p.m. in 72 depressed patients categorized according to DSM-III. Cortisol non-suppressors exhibited significantly (P = 0.0006) decreased levels of DEX compared to suppressors. DEX levels at 8.00 a.m. explained 21.1% of the variance in the post-DEX cortisol values at 8.00 a.m. and 34.5% of those at 4.00 p.m. DEX levels were not significantly different among minor depressives (300.40, 309.00), major depressives without melancholia (296.X2) or with melancholia and/or psychotic features (296.X3, 296.X4). In the latter the post-DEX cortisol was significantly increased compared to all other depressives and these differences remained significant even after adjusting for the variations in DEX (by means of regression analysis). Also the diagnostic performance of the post-DEX cortisol values for major depression with associated features versus minor depression was not substantially affected when the DEX levels were accounted for. ACTH levels after DEX were shown to correlate significantly (P less than 0.05) and negatively with DEX. Although post-DEX ACTH levels did not differ among the DSM-III diagnostic categories, cortisol non-suppressors averaged significantly (P = 0.0004) higher ACTH levels than suppressors.

The effect of age on cortisol and plasma dexamethasone concentrations in depressed patients and controls

The aim of this study was to identify any relationships between various patient factors such as age, gender and concurrent medication that may affect plasma cortisol or dexamethasone (DEX) concentrations. Multiple regression analysis was used to formulate an equation to predict plasma DEX levels to identify factors that may influence DEX bioavailability. Pre- and post-DST cortisol levels did not increase with age, but DEX levels were higher in elderly depressed patients. Neither gender nor psychotropic medication affected plasma cortisol or DEX levels. There was no indication that pre-DST cortisol levels influenced plasma DEX levels to account for the lower DEX values in non-suppressors. Age was the only significant factor found in this study to influence DEX levels and it could be argued that the dose of DEX should be lowered when administering the DST to elderly patients to reduce plasma DEX variability.

The plasma dexamethasone window: evidence supporting its usefulness to validate dexamethasone suppression test results

Two doses of dexamethasone (DEX) (0.5 and 1.0 mg) were administered in a randomized crossover design to 31 patients with major depression, 9 healthy controls, and 14 nondepressed psychiatric patients. Using this modified Dexamethasone Suppression Test (DST), minimum DEX levels of 6 nmol/liter at 8:00 AM and 2.0 nmol/liter at 4:00 PM were required to achieve reliable suppression of cortisol in healthy controls and nondepressed psychiatric patients. Failure to achieve these minimum plasma DEX levels was associated with similar rates of nonsuppression in both depressed and nondepressed patients, thereby reducing the specificity of the DST. Conversely, high DEX levels greater than 13 nmol/liter at 8:00 AM or 4.0 nmol/liter at 4:00 PM were associated with abnormal "suppressibility" in depressed patients, thereby reducing the sensitivity of the test. Controlling for plasma DEX concentrations by selecting a test result that fell within a plasma DEX window at 8:00 AM and 4:00 PM increased the sensitivity and specificity of the DST. Significant differences in plasma DEX between suppressors and nonsuppressors were no longer evident when comparing patients with adequate DEX levels, thus ensuring that cortisol escape reflected HPA axis changes associated with depression and not peripheral mechanisms responsible for the availability of DEX. These results suggest that the clinical utility of the DST would be significantly enhanced by extending the standard 1.0-mg DST and retesting those patients with levels outside the DEX window with a higher or lower dose. The data also indicate that the measurement of plasma DEX is essential to validly interpret DST status and highlight the need to standardize DEX assays to compare DST results between research centers.

Hypothalamo-pituitary-adrenal activity in endogenously depressed post-traumatic stress disorder patients

We studied the hypothalamo-pituitary-adrenal (HPA) system in Vietnam veterans with post-traumatic stress disorder (PTSD) who also met Research Diagnostic Criteria for endogenous depression (MDD-ED). Over half also abused alcohol, and many complained of pain-confounding factors usually associated with increased HPA activity. Nonetheless, not even one patient had elevated basal plasma cortisol concentrations or an abnormal dexamethasone suppression test (DST); the subjects' post-dexamethasone cortisol values and plasma cortisol per ng plasma dexamethasone were in the low-normal range. These results highlight the biological heterogeneity of endogenous depression and its possible influence by past psychological trauma, and they raise questions about the use of current typological criteria for research purposes.

The pharmacokinetics of low-dose dexamethasone in congenital adrenal hyperplasia

The pharmacokinetics of dexamethasone, given at low dose, were studied in 13 patients with congenital adrenal hyperplasia (CAH) to ascertain whether kinetics differed in this inherited disorder of cortisol metabolism from those seen in healthy individuals. Changes in plasma dexamethasone concentration after intravenous bolus, measured using a simple novel radioimmunoassay, were well described by a two-compartment open model with first-order kinetics. Values for lambda 2: 0.206 h-1, t1/2: 3.53 h, Vc: 24.41 and f: 0.64 were similar to those previously reported for normal subjects. There were considerable interindividual differences in parameter values and Cmaxp.o. (range 22-67 nmol/l). As suppression of the hypothalamo-pituitary-adrenal axis correlates with plasma dexamethasone levels, this variability may partly explain the differing dose and dose schedule requirements necessary to achieve adequate therapeutic control in the clinical management of CAH.

Comparison of in vivo and in vitro glucocorticoid sensitivity in depression: relationship to the dexamethasone suppression test

The effect of in vivo (1 mg) and in vitro (10(-7)-10(-10) M) dexamethasone administration on mitogen-induced lymphocyte proliferation was examined in drug-free depressed patients, nondepressed psychiatric patients, as well as normal controls, and was related to the results of a standard overnight Dexamethasone Suppression Test (DST). The effect of oral dexamethasone administration was also examined for its effect on lymphocyte cytosolic glucocorticoid receptor content. Oral dexamethasone administration significantly decreased both phytohemagglutinin (PHA) and concanavalin A (Con-A) induced lymphocyte proliferation, as well as glucocorticoid receptor number in suppressors, whereas dexamethasone failed to decrease these responses in nonsuppressors. Nonsuppressors had significantly lower serum dexamethasone levels compared to suppressors at both 8:00 AM and 4:00 PM. However, when differences in serum dexamethasone levels were covaried out, there were still significant differences between suppressors and nonsuppressors on the dexamethasone-induced mitogen changes, but the changes in glucocorticoid receptor content were no longer significant. In vitro incubation of lymphocytes with dexamethasone produced a dose-related decrease in mitogenesis, which was not different between the depressed and nondepressed groups. However, at physiologically relevant concentrations of dexamethasone (10(-9)-10(-10) M), nonsuppressors as compared to suppressors were more resistant to the immunosuppressive effects of in vitro dexamethasone on the Con-A response. The inhibitory effect of in vitro dexamethasone on Con-A-stimulated lymphocytes was positively correlated with basal 4:00 PM cortisol values. In conclusion, in vitro techniques are useful probes to assess glucocorticoid sensitivity in depression. The present results also further support the hypothesis that glucocorticoid insensitivity is associated with DST nonsuppression.

Judgement of the hypothalamic-pituitary-adrenocortical function in psychiatric patients by betamethasone-induced cortisol suppressibility

Betamethasone induced cortisol suppressibility was examined in 62 drug free consecutively admitted psychiatric inpatients. Betamethasone was choosen instead of the commonly used dexamethasone, because its double half-life compared to dexamethasone and its higher tissue availability. After a base-line evaluation with blood samples drawn at 8 a.m., 4 p.m., and 11 p.m., 0.5 mg or 1.0 mg betamethasone was given orally at 11 p.m. Postbetamethasone cortisol as well as betamethasone blood levels were then measured at the same time points as on the baseline day. In the groups receiving 1.0 mg betamethasone non-depressed patients had significantly (p less than 0.05) lower postbetamethasone cortisol levels than depressed patients for each time point measured whereas 0.5 mg betamethasone did not differentiate depressed from non-depressed patients. Patients with other depressions like schizoaffective psychosis-depressive subtype- or organic brain syndrome with depressive symptomatology demonstrated similar postbetamethasone cortisol profiles as the group of patients with major depression. Betamethasone plasma concentrations differed significantly (p less than 0.001) with respect to the oral dosage with higher values for the 1.0 mg betamethasone groups.