Hypothalamic--pituitary function in depressive illness: insensitivity to hylycaemia

Hypothalamic-pituitary-adrenocortical axis: neuropsychiatric aspects

Evidence of aberrant hypothalamic-pituitary-adrenocortical (HPA) activity in many psychiatric disorders, although not universal, has sparked long-standing interest in HPA hormones as biomarkers of disease or treatment response. HPA activity may be chronically elevated in melancholic depression, panic disorder, obsessive-compulsive disorder, and schizophrenia. The HPA axis may be more reactive to stress in social anxiety disorder and autism spectrum disorders. In contrast, HPA activity is more likely to be low in PTSD and atypical depression. Antidepressants are widely considered to inhibit HPA activity, although inhibition is not unanimously reported in the literature. There is evidence, also uneven, that the mood stabilizers lithium and carbamazepine have the potential to augment HPA measures, while benzodiazepines, atypical antipsychotics, and to some extent, typical antipsychotics have the potential to inhibit HPA activity. Currently, the most reliable use of HPA measures in most disorders is to predict the likelihood of relapse, although changes in HPA activity have also been proposed to play a role in the clinical benefits of psychiatric treatments. Greater attention to patient heterogeneity and more consistent approaches to assessing treatment effects on HPA function may solidify the value of HPA measures in predicting treatment response or developing novel strategies to manage psychiatric disease.

Evaluation of pituitary function in the fatigued patient: a review of 59 cases

OBJECTIVE

The aim of this study was to review the results of dynamic pituitary testing in patients presenting with fatigue.

METHODS

We reviewed clinical histories and insulin tolerance test (ITT) results of 59 patients who presented with fatigue and other symptoms of glucocorticoid insufficiency over a 4-year period. All patients referred for ITT had an early-morning cortisol level of <400 nM and a low or normal ACTH level.

RESULTS

Peak cortisol and GH responses following insulin-induced hypoglycaemia were normal in only seven patients (12%). Median age of the remaining 52 patients was 47 years (range, 17-67 years); all but five were female. Common presenting symptoms were neuroglycopaenia (n = 47), depression (n = 37), arthralgia and myalgia (n = 28), weight gain (n = 25), weight loss (n = 9), postural dizziness (n = 15) and headaches (n = 13). Other medical history included autoimmune disease (n = 20; particularly Hashimoto's thyroiditis, Graves' disease and coeliac disease), postpartum (n = 8) and gastrointestinal (n = 2) haemorrhage and hyperprolactinaemia (n = 13). 31 subjects had peak cortisol levels of <500 nM (suggestive of ACTH deficiency; 18 of whom had levels < 400 nM) and a further six had indeterminate results (500-550 nM). The remaining 15 subjects had normal cortisol responses (median 654 nM; range, 553-1062 nM) but had low GH levels following hypoglycaemic stimulation (5.9 mU/l; 3-11.6 mU/l).

CONCLUSION

Our results suggest that patients presenting with fatigue and symptoms suggestive of hypocortisolism should be considered for screening for secondary adrenal insufficiency, particularly in the presence of autoimmune disease or a history of postpartum or gastrointestinal haemorrhage. Whether physiological glucocorticoid replacement improves symptoms in this patient group is yet to be established.

Insulin resistance: a metabolic link between depressive disorder and atherosclerotic vascular diseases

The association of depression with insulin resistance (IR) and athersclerotic vascular diseases has been well documented. This review examines the relevance of IR as a link between depressive disorder and atherosclerotic vascular diseases. Relevant articles collected from Medline database over the period of 1966-2001 were reviewed. Studies have shown that IR is a state-dependent abnormality in depression and depression increases the risk of vascular morbidity and mortality. Given that IR is a central component of cardiovascular risk factors, depression-related IR might play a role in the development and progression of coronary and cerebral atherosclerosis in chronic-resistant depression. Further, IR may contribute to the pathophysiology of depressive disorder. In conclusion IR could account for the linkage between depression and atherosclerotic vascular diseases. More studies are needed to examine the importance of improving insulin sensitivity in the treatment of chronic-resistant depression and prevention of depression-related vascular morbidity and mortality.

Use of the dexamethasone suppression test on a combined medicine-psychiatry inpatient unit

The dexamethasone suppression test (DST) appears to be a sensitive and specific biological marker for endogenous depression that can have important diagnostic and treatment implications. The authors present three case studies of patients treated on a combined medicine-psychiatric inpatient unit, and who presented with complex psychobiological illnesses. They discuss the usefulness of the DST in the hospital management of these patients from a diagnostic and treatment perspective.

Homicidal poisoning with glibenclamide

Homicidal poisoning is rare in Sri Lanka although suicidal poisoning, especially with pesticides, is a grave health problem. Clinical and medicolegal findings and the subsequent court proceedings of two cases of homicide due to induced hypoglycaemia with an anti-diabetic drug are presented. The drug used was glibenclamide. Findings emphasize the importance of toxicological analysis and extensive police investigations when the clinical diagnosis and the cause of death are in doubt.

Corticosterone influences forced swim-induced immobility

The effect of corticosterone (CS) synthesis inhibition with metyrapone-a blocker of the 11 beta-hydroxylase (150 mg/kg IP)-on immobility time during the forced swim test was recorded. Immobility time was measured during a 15-min forced swim (test). Twenty-four hours later rats were subjected to an additional 5 min forced swim (retest). In one experiment, metyrapone or vehicle was administered 3 h before the initial test, while CS (0, 5, 10, or 20 mg/kg SC) was administered 1 h prior to the initial test. Metyrapone significantly reduced immobility time during both test and retest. This effect was reverted in a dose-dependent fashion by CS. In a second experiment, animals exposed to the initial test 24 h before were injected with metyrapone or vehicle 3 h before the retest, while CS (0, 10, or 20 mg/kg SC) was administered 1 h prior the retest. Metyrapone, administered before the retest, reduced immobility time and CS partially reverted metyrapone effect. In another group of animals, serum CS concentrations were evaluated before and after test and retest. In vehicle groups, the high immobility time during test and retest was associated with high CS serum concentrations poststress. In animals receiving metyrapone prior to the initial test, the reduced immobility time was related to low levels of CS after the test and an attenuated secretion following the retest. Moreover, CS (20 mg/kg) and metyrapone+CS groups had high CS levels before the test, which remained high 2 h after the test, although after the retest, both groups showed a pattern of CS secretion similar to that observed in vehicle animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Blunted ACTH response to hypoglycemic stress in depressed patients but not in patients with schizophrenia

In this study, 7 hospitalized patients with major depression (MD), 5 hospitalized patients with schizophrenia (S), and 13 control subjects (C) were administered 0.15 units/kg of regular insulin at 1600 h by intravenous bolus infusion. ACTH, cortisol, and glucose levels were measured intermittently for 2h following infusion. Baseline ACTH, cortisol and glucose levels were similar in Cs, MDs, and Ss. The mean glucose nadir was equivalent for Cs, patients with MD, and patients with S. Patients with MD had a blunted ACTH response (F = 3.28; df = 12,126; p = .0004) and cortisol response (F = 4.20; df = 12,132; p = .0001) to hypoglycemia when compared to Cs and patients with S. Carroll Depression Rating Scale scores in patients with S (23 +/- 10) were similar to patients with MD (30 +/- 8) and significantly higher than in controls (1 +/- 2) (F = 55.2; df = 2.22; p = .0001). These findings suggest that patients with MD show different ACTH and cortisol responses to hypoglycemic stress which are not explained by negative feedback of baseline ACTH or cortisol, glucose nadir, or the number of depressive symptoms per se.

Imipramine effect on hypothalamic-pituitary-adrenal axis response to hypoglycemia

Six control subjects underwent an insulin tolerance test before and after the administration of therapeutic doses of imipramine hydrochloride for 10 days to investigate effects of tricyclic antidepressants on hypothalamic-pituitary-adrenal axis response to hypoglycemia. The mean steady-state tricyclic blood level was 141 (SD = 66) ng/ml. Baseline levels of glucose, cortisol, and adrenocorticotropic hormone (ACTH) were not affected by the administration of imipramine. After administration of imipramine for 10 days, subjects uniformly had a significantly lower glucose nadir than before its administration (before imipramine: mean = 32 mg/dl; SD = 5; after imipramine: mean = 24 mg/dl; SD = 6). There was no difference in ACTH or cortisol response before and after the administration of imipramine. These findings suggest that imipramine hydrochloride increases sensitivity to the hypoglycemic effects of insulin, but does not alter the counterregulatory response of ACTH and cortisol.

Type 2 diabetes and depressive symptoms in older adults: a population-based study

The prevalence of depressive symptoms and its association with Type 2 (non-insulin-dependent) diabetes was examined in a population-based study of 1586 men and women aged 50 years or older. Men and women with previously diagnosed diabetes had significantly higher mean Beck Depression Inventory total, somatic subscale, and affective subscale scores than normal men and women and individuals with newly diagnosed diabetes. The age- and sex-adjusted rates of Inventory scores of 13 or greater among individuals with previously diagnosed diabetes was 3.7 times greater than the rates among individuals with newly diagnosed diabetes (p less than 0.05). Medication use and fasting plasma glucose were unrelated to symptom score. The number of other chronic conditions and age were significant independent predictors of depressive symptoms in all diabetic men and women. Results suggest that depressive symptoms in individuals with Type 2 diabetes may be related to awareness of diabetic condition in addition to poor health.

Steroids and depression

Patients with endogenous depression (major affective disorder) frequently have high cortisol levels, but the diurnal rhythm is usually maintained and they do not develop the physical signs of Cushing's syndrome. On the other hand, depression is a frequent feature of Cushing's syndrome regardless of etiology, and it is often relieved when the cortisol levels are reduced, by whatever means. The mechanisms of the hypercortisolemia and resistance to dexamethasone suppression commonly found in endogenous depression are poorly understood; contrary to expectations, ACTH levels are not clearly elevated. There is a striking difference in the psychiatric features seen in endogenous hypercorticism compared to those seen after exogenous administration of glucocorticoids or ACTH. This suggests that either there are other stimulating or modifying factors besides ACTH or that the steroids stimulated by ACTH or other peptides differ from those in control subjects, i.e. there may be an alteration in the metabolism of steroids in depression. Little is known about the metabolic changes or the many steroids besides glucocorticoids produced by the hyperactive steroid-producing tissue. Preliminary studies suggest that major depression may be improved by steroid suppression. It is hypothesized that steroids themselves may be important in causing and perpetuating depression.

Serotonergic function in diabetic rats: psychotherapeutic implications

Extracellular serotonin in striatum was studied in untreated streptozotocin-induced diabetic rats and in untreated nondiabetic rats that served as age-, food-, and sex-matched controls. Extracellular serotonin was studied under anesthesia in vivo and dynamically with voltammetry. The results showed that an early and significant increase in extracellular serotonin occurred in striatum in the untreated acutely (3 days) diabetic rat. In untreated long-term (3-7 weeks) diabetic rats, however, the increase in serotonin in extracellular fluid in striatum decreased and returned to normal. The findings show a change in serotonergic function in acutely diabetic rats. The serotonergic alteration may have psychotherapeutic implications.

Growth hormone response to clonidine after recovery in patients with endogenous depression

The growth hormone response to clonidine was measured in ten drug-free recovered patients, seven of whom had previously been tested when endogenously depressed, and compared with the response in ten individually matched controls. In eight of the patients there was an impairment of the growth hormone response, despite clinical recovery, although the hypotensive effect of clonidine in these patients was normal. This is suggestive of a persisting abnormal alpha2-adrenoceptor function in forebrain regions after recovery from an episode of endogenous depression, and may represent a trait marker for this condition.

The HPA axis response to insulin hypoglycemia in depression

Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, demonstrated by failure to suppress cortisol secretion after dexamethasone, is found in approximately 50% of patients with major depression (MD). In this study, we examined the response of adrenocorticotrophic hormone (ACTH) and cortisol to insulin-induced hypoglycemia in 20 healthy controls and 18 inpatients with MD [12 dexamethasone suppressors (S) and 5 dexamethasone nonsuppressors (NS)]. After the administration of 0.15 U/kg of regular insulin, both controls and patients with MD showed an increase in plasma ACTH and cortisol levels. Controls had a significantly higher ACTH peak (p less than 0.01) and ACTH increment (p less than 0.01) than MD patients. There were no statistically significant differences between patients who were S and NS. Although baseline plasma cortisol levels were significantly higher in MD patients, there were no significant differences in the peak cortisol or increment in plasma cortisol after hypoglycemia between patients with MD and controls or between patients who were S and those who were NS. These findings suggest that a defect exists in the regulation of the HPA axis at the pituitary level in MD and that this defect is not necessarily reflected in the dexamethasone suppression status of the patient.

[Causal analytic studies on demonstration of neuroendocrine parameters in combined hypoglycemia test in depressive subgroups]

With the help of an analytical path structure model (causal analysis) the aim of the study was to elucidate further, in female patients with various depressive disorders, some correlations of causal interdependencies between changes both in basal secretion of anterior pituitary hormones and in their responses to the (combined) insulin tolerance test (ITT) with extraneous factors--such as age, deviation from ideal body weight (in percentage), severity of depression and score in the Newcastle Scale (NCS)--that may influence these abnormalities. In various depressive subgroups the strength of influence and the different importance of deviation from ideal body weight and basal growth hormone (GH) concentration (as exclusion criteria) for their neuroendocrine reactivity in the combined ITT was shown. The hypothesis that cortisol hypersecretion may be the primary disturbance and the other possible neuroendocrine changes such as blunted GH, cortisol and TSH responses to stimuli in some depressive patients all may be secondary to the (elevated) cortisol level could not be corroborated. The endogenous mono- and bipolar subtypes of major depressive disorders showed intimate connections between the various neuroendocrine functional systems and the above mentioned extraneous factors resulting in a narrowed variability and a stronger coupling in the reactivity of these hormonal functional systems, a condition which can be seen as analogous to experimental results at the psychophysiological level in these nuclear groups of depressed patients, whose psychopathological state is also characterized by similar limitations in their "degree of freedom" (Heimann).

The dexamethasone suppression test in depression

The Dexamethasone Suppression Test (DST) was performed in 91 patients (depressive, manic and schizophrenic) and 11 healthy control persons. It was found that more endogenously depressed patients than non-endogenously depressed patients showed abnormal test results. The results were markedly influenced by the time of blood sampling, the diagnostic criteria and the plasma cortisol concentration threshold.

Evidence for physiological effects of hypercortisolemia in psychiatric patients

Although some psychiatric patients may have a disorder of hypothalamic-pituitary-adrenal (HPA) function equal in character and severity to that noted in milder cases of Cushing's disease, it is generally accepted that such patients do not show Cushingoid stigmata. This conclusion, however, appears to be based more on clinical observation than on the results of formal scientific investigation. Since some depressed patients appear to overlap with Cushing's disease patients in incidence of such signs and symptoms as amenorrhea, hypertension, sleep disturbance, and insulin resistance, we were interested in examining whether a group of psychiatric patients showing evidence of marked nonsuppression might not also show physiological changes consonant with the effect of glucocorticoid excess. Nonsuppressors selected on this basis differed slightly from a matched suppressor control group on percentage of polyneutrophils and lymphocytes in blood. A discriminant function constructed from blood sample measurements of 12 factors and systolic/diastolic blood pressure successfully predicted suppressor or nonsuppressor status in the original and in an independent group of psychiatric patients. A comparison group of Cushing's disease patients was also successfully reclassified on the basis of the discriminant function. These data are interpreted as evidence for a subtle physiological effect of HPA dysregulation and suggest that behavioral symptom complexes may be similarly shaped by changes in this neuroendocrine system. The long-term functional significance of such changes is at present speculative.

Dexamethasone suppression, protirelin stimulation, and insulin infusion in subtypes of recovered depressive patients

Twenty-eight patients (10 bipolar, 13 depressive spectrum disease, and 5 familial pure depressive), recovered from depression for an average of 1 year, underwent a series of basal and provocative endocrine tests. No significant differences were found among depressive subtypes in thyrotropin, cortisol, or growth hormone measurements either before or after provocative testing with the exception of growth hormone response to insulin-induced hypoglycemia. Patients with depressive spectrum disease showed a significantly different growth hormone response to insulin-induced hypoglycemia than patients with bipolar disorder, a finding which suggests differences in alpha-adrenergic receptor sensitivity between these groups.

Relative insulin insensitivity and cortisol secretion in depressed patients

Relative insulin insensitivity occurs in a substantial portion of patients with major endogenous depressions, and about half such cases also hypersecrete cortisol in the afternoon and evening. This study assessed the relation between these two abnormalities in 16 patients with major endogenous depression. Over several days, insulin tolerance tests (ITTs) were performed in the morning and evening, and measures of cortisol secretion taken: plasma cortisol at 0800, 1600, and 2300 hours, both before and after dexamethasone; baseline cortisol before ITTs; and mean 24-hour plasma cortisol concentrations (in 10 cases). After clinical recovery, some of these patients had repeat ITTs (n = 10) and repeat predexamethasone and postdexamethasone cortisol assessments (n = 9). Additionally two control groups of 15 normal subjects and of 12 schizophrenic patients received morning ITTs. None of the control subjects manifested insulin insensitivity. However, during illness, 8 of the 16 depressed patients manifested relative insulin insensitivity (glucose drop less than 50%, glucose nadir greater than 50 mg/dl); compared to the insulin responsive depressed group, the insensitive group had insignificantly greater afternoon and evening cortisol secretion by nearly all indices. After clinical recovery, hypoglycemic response for the entire group was significantly greater than during illness; this improvement was accounted for by the increased insulin responsivity of the previously insulin resistant subgroup. There was also substantial plasma cortisol reduction in the previously insulin resistant group after clinical recovery, but not in the insulin sensitive group.

Neuroendocrine tests of monoamine function in man: a review of basic theory and its application to the study of depressive illness

Neuroendocrine tests are now available for studying monoamine function in the brains of patients with mental illness. Great care is required in the selection of drugs which act upon specific monoamine receptors to produce specific hormonal responses. Equal care is required in the control of biological variables which may influence hormonal release. Recently reported neuroendocrine studies of depressive illness are assessed in these terms. The results of these studies support the hypothesis that there is defective noradrenergic function in the brains of some patients with depressive illness.

The effects of opioid drugs and of lithium on steroidogenesis in rat adrenal cell suspensions

1. The effects of opioid drugs and of Na+ replacement on steroidogenesis in rat adrenal cell suspensions were investigated. 2. In medium containing normal Na+ (156 mM), opioid antagonists but not opioid agonists reduced the steroidogenic response to adrenocorticotrophic hormone1-24 (ACTH1-24) but not to dibutyryl adenosine 3',5' cyclic monophosphate (db cyclic AMP). 3. Replacement of 50% Na+ in the medium by choline had no effect on steroidogenesis, but further reductions in Na+ content reduced the steroidogenic activity of both ACTH1-24 and db cyclic AMP. 4. In 50% Na+ medium both opioid agonists and antagonists inhibited ACTH1-24 induced steroidogenesis. 5. Addition of therapeutic concentrations of lithium to otherwise normal medium inhibited the steroidogenic response to ACTH1--24 but not to db cyclic AMP. 6. The selective inhibition of ACTH1--24-induced steroidogenesis by opioid drugs suggests some similarity between the opioid and ACTH receptors. 7. The relevance of the potent inhibitory effect of lithium to its therapeutic actions is discussed.

The Hamilton Rating Scale for depression: a factor analysis

A factor analysis was carried out of ratings on the Hamilton Scale on a group of 134 male and 213 female depressed patients. The original data covered a wide range of severity of illness and the distribution of severity scores was not biased from normal. Hamilton's general factor was confirmed but his bipolarity between agitated and retarded depression did not emerge. Sex differences in factor patterns were found and a preliminary experiment showed that factor scores could isolate anxiety features and personality factors.

Clinical associations of 11-hydroxycorticosteroid suppression and non-suppression in severe depressive illnesses

Fifty patients with severe depression were separated into two groups by the responses of their plasma 11-hydroxycorticosteriod levels to a midnight dose of 2 mg. of dexamethasone. Clinical and questionary comparisons were made between the two groups of patients, who were similar as regards age, sex, and length of symptoms before admission to hospital. No differences were found between the groups of severely ill patients as regards the severity of their depression and anxiety assessed by questionary. Nevertheless, agitation was significantly greater in the patients whose corticosteroid levels were not suppressed by dexamethasone and adverse childhood experiences in those whose levels were suppressed.