The assessment of abnormalities in hormonal responsiveness at multiple levels of the hypothalamic-pituitary-adrenocortical axis in depressive illness

Differentiating melancholic and non-melancholic depression via biological markers: A review

OBJECTIVES

Melancholia is a severe form of depression that is typified by greater genetic and biological influence, distinct symptomatology, and preferential response to physical treatment. This paper sought to broadly overview potential biomarkers of melancholia to benefit differential diagnosis, clinical responses and treatment outcomes. Given nuances in distinguishing melancholia as its own condition from other depressive disorder, we emphasised studies directly comparing melancholic to non-melancholic depression.

METHODS

A comprehensive literature search was conducted. Key studies were identified and summarised qualitatively.

RESULTS

105 studies in total were identified. These studies covered a wide variety of biomarkers, and largely fell into three domains: endocrinological (especially cortisol levels, particularly in response to the dexamethasone suppression test), neurological, and immunological (particularly inflammatory markers). Less extensive evidence also exists for metabolic, genetic, and cardiovascular markers.

CONCLUSIONS

Definitive conclusions were predominantly limited due to substantial heterogeneity in how included studies defined melancholia. Furthermore, this heterogeneity could be responsible for the between- and within-group variability observed in the candidate biomarkers that were examined. Therefore, clarifying these definitional parameters may help identify underlying patterns in biomarker expression to improve diagnostic and therapeutic precision for the depressive disorders.

Atypical depression and non-atypical depression: Is HPA axis function a biomarker? A systematic review

BACKGROUND

The link between the abnormalities of the Hypothalamic-pituitary-adrenal (HPA) axis and depression has been one of the most consistently reported findings in psychiatry. At the same time, multiple studies have demonstrated a stronger association between the increased activation of HPA-axis and melancholic, or endogenous depression subtype. This association has not been confirmed for the atypical subtype, and some researchers have suggested that as an antinomic depressive subtype, it may be associated with the opposite type, i.e. hypo-function, of the HPA-axis, similarly to PTSD. The purpose of this systematic review is to summarise existing studies addressing the abnormalities of the HPA-axis in melancholic and/or atypical depression.

METHOD

We conducted a systematic review in the literature by searching MEDLINE, PsycINFO, OvidSP and Embase databases until June 2017. The following search items were used: "hypothalamic-pituitary-adrenal" OR "HPA" OR "cortisol" OR "corticotropin releasing hormone" OR "corticotropin releasing factor" OR "glucocorticoid*" OR "adrenocorticotropic hormone" OR "ACTH" AND "atypical depression" OR "non-atypical depression" OR "melancholic depression" OR "non-melancholic depression" OR "endogenous depression" OR "endogenomorphic depression" OR "non-endogenous depression". Search limits were set to include papers in English or German language published in peer-reviewed journals at any period. All studies were scrutinized to determine the main methodological characteristics, and particularly possible sources of bias influencing the results reported.

RESULTS

We selected 48 relevant studies. Detailed analysis of the methodologies used in the studies revealed significant variability especially regarding the samples' definition comparing the HPA axis activity of melancholic patients to atypical depression, including healthy controls. The results were subdivided into 4 sections: (1) 27 studies which compared melancholic OR endogenous depression vs. non-melancholic or non-endogenous depression or controls; (2) 9 studies which compared atypical depression or atypical traits vs. non-atypical depression or controls; (3) 7 studies which compared melancholic or endogenous and atypical depression subtypes and (4) 5 studies which used a longitudinal design, comparing the measures of HPA-axis across two or more time points. While the majority of studies did confirm the association between melancholic depression and increased post-challenge cortisol levels, the association with increases in basal cortisol and basal ACTH were less consistent. Some studies, particularly those focusing on reversed vegetative symptoms, demonstrated a decrease in the activity of the HPA axis in atypical depression compared to controls, but the majority did not distinguish it from healthy controls.

CONCLUSIONS

In conclusion, our findings indicate that there is a difference in the activity of the HPA-axis between melancholic and atypical depressive subtypes. However, these are more likely explained by hypercortisolism in melancholia; and most often normal than decreased function in atypical depression. Further research should seek to distinguish a particular subtype of depression linked to HPA-axis abnormalities, based on symptom profile, with a focus on vegetative symptoms, neuroendocrine probes, and the history of adverse childhood events. New insights into the dichotomy addressed in this review might be obtained from genetic and epigenetic studies of HPA-axis related genes in both subtypes, with an emphasis on the presence of vegetative symptoms.

Neural control of chronic stress adaptation

Stress initiates adaptive processes that allow the organism to physiologically cope with prolonged or intermittent exposure to real or perceived threats. A major component of this response is repeated activation of glucocorticoid secretion by the hypothalamo-pituitary-adrenocortical (HPA) axis, which promotes redistribution of energy in a wide range of organ systems, including the brain. Prolonged or cumulative increases in glucocorticoid secretion can reduce benefits afforded by enhanced stress reactivity and eventually become maladaptive. The long-term impact of stress is kept in check by the process of habituation, which reduces HPA axis responses upon repeated exposure to homotypic stressors and likely limits deleterious actions of prolonged glucocorticoid secretion. Habituation is regulated by limbic stress-regulatory sites, and is at least in part glucocorticoid feedback-dependent. Chronic stress also sensitizes reactivity to new stimuli. While sensitization may be important in maintaining response flexibility in response to new threats, it may also add to the cumulative impact of glucocorticoids on the brain and body. Finally, unpredictable or severe stress exposure may cause long-term and lasting dysregulation of the HPA axis, likely due to altered limbic control of stress effector pathways. Stress-related disorders, such as depression and PTSD, are accompanied by glucocorticoid imbalances and structural/ functional alterations in limbic circuits that resemble those seen following chronic stress, suggesting that inappropriate processing of stressful information may be part of the pathological process.

Pituitary volume in first-episode schizophrenia

Pituitary volumes were measured in 55 first-episode schizophrenia patients at a baseline timepoint with 38 receiving a followup scan after antipsychotic treatment. Fifty-nine healthy volunteers had baseline scans with 34 receiving a followup scan. There were no baseline group differences in pituitary volumes or changes in volume following antipsychotic treatment.

Psychobiology of depression/distress in congestive heart failure

Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed.

Is there a role for the endocannabinoid system in the etiology and treatment of melancholic depression?

With advances in basic and clinical neuroscience, many gaps have appeared in the traditional monoamine theory of depression that have led to reformulation of the hypotheses concerning the neurobiology of depression. The more recent hypotheses suggest that melancholic depression is characterized by central glucocorticoid resistance that results in hypercortisolemia, which in turn leads to down-regulation of neurotrophins and subsequent neurodegeneration. Examining the neurobiology of depression from this perspective suggests that the endocannabinoid system may play a role in the etiology of melancholic depression. Specifically, pharmacological and genetic blockade of the cannabinoid CB1 receptor induces a phenotypic state that is analogous to melancholic depression, including symptoms such as reduced food intake, heightened anxiety, increased arousal and wakefulness, deficits in extinction of aversive memories and supersensitivity to stress. These similarities between melancholic depression and an endocannabinoid deficiency become more interesting in light of recent findings that endocannabinoid activity is down-regulated by chronic stress and possibly increased by some antidepressant regimens. We propose that an endocannabinoid deficiency may underlie some of the symptoms of melancholic depression, and that enhancement of this system may ultimately be a novel form of pharmacotherapy for treatment-resistant depression.

Bone mineral density in premenopausal women with major depression

AIM

To investigate the relationship between the major depression and bone mineral density (BMD) in premenopausal women.

MATERIAL AND METHODS

We compared BMD, plasma cortisol level, osteocalcin and C-telopeptide levels of 35 premenopausal women with major depression with those of 30 healthy women who were matched for age and body mass index. Major depression was diagnosed according to Diagnostic and Statistical Manual of Mental Disorders (fourth edition) criteria. Nineteen patients had mild and 16 patients had moderate severity of major depression as measured by Hamilton rating scale for depression.

RESULTS

Women with any risk factor for osteoporosis were excluded from the study. All women underwent BMD measurement by DEXA at lumbar (L2-4) and femoral neck region. After an overnight fasting, plasma cortisol levels were measured at 08:00 h by using competitive immunoassay method. Osteocalcin and C-telopeptide were used for the evaluation of bone turnover. There were no significant differences in BMD, plasma cortisol level, osteocalcin and C-telopeptide levels between the patients and the control groups. There was also no correlation between the plasma cortisol level, the duration and the severity of disease, antidepressant drug use and BMD.

CONCLUSION

Major depression had no significant effect on BMD and bone turnover markers in our patient group of mild to moderate severity of the disorder.

Depression and bone mineral density in a community sample of perimenopausal women: Geelong Osteoporosis Study

OBJECTIVE

Reduced bone mineral density (BMD) in women with a history of depressive disorders has been shown in some, but not all studies. This study investigated the association between self-reported depression and BMD in an age-stratified community sample of perimenopausal women residing in the South-Eastern region of Australia.

DESIGN

Symptoms of depression in the year between July 2000 and July 2001 were ascertained by a self-report questionnaire based on Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria. Women in the perimenopausal group who had undergone a BMD total hip and spine assessment within the 12-month period after the depression assessment were included in the analysis, resulting in a sample of 78 women aged 45 to 60 years.

RESULTS

In this sample, 14 women were identified as depressed. There was no difference in age, hormone therapy (HT) use, or unadjusted BMD at the total hip or spine between the depressed and nondepressed women (P = 0.14, 0.89, 0.57, and 0.70, respectively), but the depressed women tended to be heavier [depressed (median weight, interquartile range = 80 kg, 66-94) vs nondepressed (72 kg, 61-80) P = 0.06]. Whereas there was no significant difference in age-, HT-, and weight-adjusted BMD at the spine [depressed (mean +/- SE = 1.21 +/- 0.05) vs nondepressed (1.28 +/- 0.03 g/cm(2)) P = 0.18], adjusted BMD at the total hip for the depressed women was 7.8% lower than for the nondepressed [depressed (mean +/- SE = 0.957 +/- 0.038) vs nondepressed (1.038 +/- 0.023 g/cm(2)) P = 0.04].

CONCLUSIONS

These results suggest that in perimenopausal women, self-reported depression is associated with lower BMD at the hip.

Anxious and depressive disorders and their comorbidity: effect on central nervous system noradrenergic function

BACKGROUND

Although comorbidity of anxiety with depression is common, investigations of physiologic abnormalities related specifically to comorbidity are rare. This study examined relationships of DSM-IV-defined depression, anxiety, and their comorbidity to noradrenergic function measured by blunting of the growth hormone (GH) response to the alpha2 adrenoreceptor agonist (and imidazoline receptor agent) clonidine and by blood pressure and symptom responses.

METHODS

Fifteen subjects with pure social anxiety or panic disorder, 15 with pure major depression, and 18 with both depression and anxiety were compared with healthy control subjects matched for age and gender. Other factors known to affect GH (weight, menstrual status, prior antidepressant, or other drug exposure) were controlled.

RESULTS

Anxiety produced GH blunting, but depression was associated with normal GH responses. The comorbid state did not affect results beyond the impact of anxiety. Preclonidine stress-related GH elevations were observed, to the greatest degree in anxious subjects. Relevant symptom, but not blood pressure, changes were significantly associated with blunting.

CONCLUSIONS

With use of pure depression and anxiety groups and careful control of other factors known to affect GH, these results demonstrate central nervous system noradrenergic dysfunction in anxiety disorders. In contrast to less rigorously controlled studies, noradrenergic function in depression was normal.

Inescapable shock induces resistance to the effects of dexamethasone

Administration of bacterial endotoxin (lipopolysachharide; LPS) elevates proinflammatory cytokines, such as interleukin-1beta (IL-1beta) and IL-6, and activates the hypothalamic-pituitary-adrenal (HPA) axis. Corticosterone (CORT), the glucocorticoid (GC) effector hormone of the HPA axis in rats, inhibits both proinflammatory cytokine production/release and activity of the HPA axis itself. Exposure to chronic or repeated stressors often induces resistance to the effects of GCs. The following experiments were conducted to test the hypothesis that an acute stressor, inescapable tailshock (IS), alters responsivity of the HPA axis and proinflammatory cytokine system to dexamethasone (DEX), a synthetic GC. First, we examined the ability of various doses of DEX to suppress proinflammatory cytokine and HPA activity in response to LPS challenge 24 h after either home cage (HCC) or IS treatment. Upon finding resistance to DEX in IS animals, we examined the duration of the altered response to DEX by testing animals 1, 4 and 21 days after IS. To test whether IS animals were selectively resistant to the suppressive effects of DEX on the response to LPS, the ability of DEX to suppress HPA activity in response to a non-inflammatory stressor, exposure to an elevated "pedestal", was assessed. Again, DEX resistance was observed in IS animals. Finally, we examined whether changes in the responsivity to DEX were dependent upon the controllability of the stressor. The induction of DEX resistance was independent of the degree of behavioral control that the animal had over the stressor. Thus, a single session of IS induces DEX resistance of both HPA axis and cytokine responses measured in vivo.

Neuroendocrine aspects of hypercortisolism in major depression

A consistent finding in biological psychiatry is that hypothalamic-pituitary-adrenal (HPA) axis physiology is altered in humans with major depression. These findings include hypersecretion of cortisol at baseline and on the dexamethasone suppression test. In this review, we present a process-oriented model for HPA axis regulation in major depression. Specifically, we suggest that acute depressions are characterized by hypersecretion of hypothalamic corticotropin-releasing factor, pituitary adrenocorticotropic hormone (ACTH), and adrenal cortisol. In chronic depressions, however, enhanced adrenal responsiveness to ACTH and glucocorticoid negative feedback work in complementary fashion so that cortisol levels remain elevated while ACTH levels are reduced. In considering the evidence for hypercortisolism in humans, studies of nonhuman primates are presented and their utility and limitations as comparative models of human depression are discussed.

Self-esteem, cortisol reactivity, and depressed mood mediated by perceptions of control

This study investigated cortisol reactivity (CR) as a moderator and perceptions of control as a mediator between low self-esteem (SE) and depressed mood. Fifty-four participants completed SE and mood inventories before an uncontrollable laboratory stressor. Salivary cortisol was determined before and after the stressor. Analyses indicated significance for SE (beta=-0.30), CR (beta=-0.92) and their interaction (beta=-0.90) in predicting depressed mood (P=0.03 for all). Low SE and decreased CR predicted the highest levels of depressed mood. The interaction indicated that depressed mood was predicted by increases in cortisol in individuals with higher SE, but by decreases in cortisol in individuals with lower SE. These relationships were statistically explained by low perceptions of control at baseline. Findings support biopsychological explanations for depression, with SE, CR, and uncontrollability as putative markers of depressed mood that may be even more pronounced in depressive disorders.

Psychological distress as a risk factor for coronary heart disease in the Whitehall II Study

BACKGROUND

Psychiatric disorder and psychological distress are increasingly recognized as risk factors for coronary heart disease (CHD). Elucidation of the mechanisms of these associations has implications for prevention. This study aims to confirm the association between psychological distress and CHD and examine if it could be explained by other factors such as health behaviours, social isolation and low control at work.

METHODS

A prospective occupational cohort study of London-based civil service employees (Whitehall II Study) with baseline data collected from 1985-1988 with a 5-year follow-up. The participants were male and female middle-aged civil servants working in 20 Government Departments; 73% of eligible employees attended baseline screening. Psychological distress measured by the General Health Questionnaire (GHQ) at baseline was used to predict incidence of self-reported CHD and possible and probable electrocardiographic (ECG) abnormalities during follow-up.

RESULTS

In men, baseline psychological distress was associated with an increased incidence of overall self-reported CHD (odds ratios [OR] = 1.83, 95% CI : 1.5-2.3) and ECG abnormalities (OR = 1.51, 95% CI : 1.1-2.1), after adjustment for age, employment grade and length of follow-up. In women, baseline psychological distress was also associated with an increased incidence of CHD (OR = 1.60, 95% CI : 1.2-2.1), but not with ECG abnormalities. Adjustment for health behaviours, marital status, social networks and work characteristics reduced the risks for incident CHD by 12% in men and by 10% in women; for ECG abnormalities these adjustments increased the risk in men by 16% and had little effect in women.

CONCLUSIONS

The experience of psychological distress confers increased risk of CHD in men that is not explained by health behaviours, social isolation or work characteristics. The increased risk of CHD associated with psychological distress is not consistently demonstrated in women.

Cushing’s disease and melancholia

Striking similarities exist in the endocrinology of Cushing's disease and melancholic depression.Laboratory abnormalities, which have been found in both, include raised urinary,plasma and salivary cortisol, non-suppression of cortisol in the dexamethasone suppression test and adrenocorticotrophin (ACTH) hypersecretion. The hypercortisolism can be so severe in melancholic depression that it is difficult to distinguish from Cushing's disease and has been described as a "pseudo-Cushing's" state. Cerebrospinal fluid corticotrophin-releasing hormone (CRH) levels have been found to be lower in patients with Cushing's disease than in depressed subjects. Dynamic endocrine tests may help to distinguish between the two disorders.An exaggerated response to synacthen has been found in both but a reduced ACTH response to CRH occurs in depression, unlike those with Cushing's disease who show ACTH hyper-responsiveness. Other tests, which may help to distinguish between the two disorders,include the dexamethasone-CRH test, the naloxone test, the insulin-induced hypoglycemia test and the desmopressin stimulation test. Similarities in psychiatric symptoms have been recognised for many years. More recently, the physical complications of melancholic depression have been noted. These include osteoporosis, an increased risk of death from cardiovascular disease, hypertension, a redistribution of fat to intra abdominal sites and insulin resistance. Cushing's disease shares these physical complications and we propose that the common underlying factor is excessive plasma glucocorticoids. The increasing recognition of the physical complications and the increased morbidity and mortality in those who suffer from depression underscores the necessity for early detection and treatment of this illness and screening for undetected physical complications.

Treatment of depression with antiglucocorticoid drugs

OBJECTIVE

The theoretical and empirical rationales for the potential therapeutic use of antiglucocorticoid agents in the treatment of depression are reviewed.

METHOD

Individual case reports, case series, open-label, and double-blind, controlled trials of the usage of cortisol-lowering treatments in Cushing's syndrome and major depression are evaluated and critiqued.

RESULTS

In each of the 28 reports of antiglucocorticoid treatment of Cushing's syndrome, antidepressant effects were noted in some patients; the largest two series document a response rate of 70% to 73%. Full response, however, was at times erratic and delayed. Across the 11 studies of antiglucocorticoid treatment of major depression, some degree of antidepressant response was noted in 67% to 77% of patients. Antidepressant or antiobsessional effects of antiglucocorticoid augmentation of other psychotropic medications have also been noted in small studies of patients with treatment-resistant depression, obsessive-compulsive disorder, and schizoaffective disorder or schizophrenia.

CONCLUSIONS

These promising results with antiglucocorticoid treatment must be interpreted cautiously because of the small sample sizes and heterogeneity of the studies reviewed, the bias favoring publication of positive results, and the open-label nature of most of the studies. Although definitive controlled trials remain to be conducted, there is a consistent body of evidence indicating that cortisol-lowering treatments may be of clinical benefit in select individuals with major depression and other hypercortisolemic conditions.

Selective serotonin reuptake inhibitor efficacy in severe and melancholic depression

Depression with melancholic features appears to be a discrete affective syndrome characterised by profound psychomotor, cognitive and mood disturbances that are qualitatively different from other forms of depression. Some investigators have hypothesised that melancholia may have a neurological basis with psychomotor disturbances associated with selective alterations in dopamine neurotransmission and disturbances in basal ganglia function. A number of studies have examined the role of selective serotonin reuptake inhibitors (SSRIs) in the treatment of melancholia. Although relatively few prospective trials have focused on melancholic depression, several retrospective meta-analyses and trials in populations that are likely to include a high proportion of melancholic patients have provided a wealth of data. While some early studies suggested that SSRIs might be less effective in the treatment of melancholia, the results of these may have been biased and confounded by several side-effects of tricyclic antidepressants (TCAs), which might contribute to their apparent efficacy. It appears, however, that the SSRIs may vary among themselves in their apparent efficacy in melancholia. In this regard, sertraline may be more efficacious than other SSRIs and similar to TCAs in the treatment of patients with melancholia. Several studies have suggested that the presence of melancholic features may predict a good response to sertraline, and it has been hypothesised that this may be the result of the relatively potent dopaminergic activity of sertraline, compared with other SSRIs.

Adrenal responsivity in normal aging and mild to moderate Alzheimer's disease

BACKGROUND

Enhanced levels of cortisol have been found in moderate to severe Alzheimer's disease (AD) and in major depression, while recent studies have suggested decreased levels of serum dehydroepiandrosterone sulfate (DHAS) in patients with dementia. In this study the responsivity of the adrenal cortex to stimulation with a new low dose adrenocorticotropin (ACTH) test was investigated in patients with AD and in normal aging.

METHODS

Thirteen patients with mild to moderate AD, 12 healthy old controls, and 15 young controls (78.0 +/- 8.4, 76.7 +/- 7.0, and 28.3 +/- 4.1 years old, mean: +/- SD, respectively) received an intravenous bolus injection of 1 microgram ACTH. Serum cortisol and androgen levels were analyzed before and 5, 10, 20, 25, 30, 35, 40, 60, 90, 120, 180, and 240 minutes after injection.

RESULTS

The cortisol responsivity did not differ between the three groups. An enhanced release of androgens was present in patients with AD. AD per se had an independent influence on androstenedione levels after ACTH stimulation after adjustments for age and gender in a general linear regression model.

CONCLUSIONS

In contrast to major depression, increased cortisol release to ACTH stimulation does not seem to be a feature of AD. Abnormal androgen levels after ACTH stimulation are characteristic features of mild to moderate Alzheimer's disease.

Bone density measurement in major depression

1. Disturbances in cortisol secretory patterns and excessive secretion of cortisol after a variety of neuroendocrine stimulation tests indicate excessive activity of the hypothalamic-pituitary-adrenocortical axis in depression. 2. Peripheral indicators of hypercortisolemia have also been observed (e.g. enlarged adrenal glands, glucocorticoid insensitivity and insulin intolerance). 3. Excessive cortisol production may also result in altered bone metabolism and bone architecture, and a recent study by Michelson et al. (1996) found slightly lower bone density in depressed women with hypercortisoluria versus healthy controls. 4. In this study, the authors examined bone mineral density (BMD) using dual energy radiographic absorptometry (DEXA) technique in 6 depressed patients (3 with and 3 without hypercortisoluria) with a mean (+/- SD) age of 41 +/- 13 years, and in 5 healthy, controls with mean age 38 +/- 4 years). 5. DEXA images of the lumbar vertebrae (L1 to L4) for BMD were acquired over a 5-minute interval. 6. Overall, the authors observed no difference in mean BMD values between patients and controls, nor were differences observed between patients with and without hypercortisoluria.

Cortisol and affective responses to exercise

It has been reported that physically active individuals demonstrate attenuated cortisol responses to acute exercise compared to inactive individuals. Furthermore, a number of studies have demonstrated that increased cortisol levels are associated with negative affective states. Conversely, low cortisol levels have been demonstrated to be related to positive psychological constructs such as self-efficacy. However, the roles of activity history and adrenocortical activity in affective responses to acute exercise have not been examined. We therefore compared salivary cortisol, perceived exertion and affective responses to acute exercise in 13 male cross-country runners and 13 non-runners. The experimental trial consisted of a 30 min treadmill run at 60% VO2 max. Cortisol and affective responses were assessed before, during and after exercise; ratings of perceived exertion (RPEs) were recorded during exercise. Analyses of variance indicated no significant group differences in cortisol responses. However, there was a main effect for time (P< 0.05), with cortisol increasing from baseline to the 29th minute of exercise and then decreasing to 30 min post-exercise. Non-runners possessed greater perceptions of effort and negative affect during exercise compared to cross-country runners. Furthermore, the RPEs were positively related to post-exercise cortisol levels (P< 0.05), and affect and cortisol responses were inversely related 30 min post-exercise (P< 0.05). These results provide partial support for the hypothesis that cortisol levels are related to exercise-induced affective states.

Novel strategies for treatment-resistant depression

This article describes a highly selective constellation of the more unique strategies for managing the treatment-resistant patient. In light of the often-devastating toll that treatment-resistant depression takes on an individual's life, it behooves us to continue the search for more effective strategies for those patients that fail more traditional interventions. As each successive move down the treatment algorithm flowchart becomes necessary, the risk/benefit ratio may shift toward less well-substantiated, but still biologically informed, strategies. Although some of the more unusual treatments described in this article represent minimally charted territories, the more promising techniques are deserving of further careful exploration.

Enhanced adrenal sensitivity to adrenocorticotrophic hormone (ACTH) is evidence of HPA axis hyperactivity in Alzheimer's disease

Adrenal sensitivity was assessed in 16 non-depressed patients with NINCDS/ADRDA Alzheimer's disease (AD) and 18 control subjects by measuring cortisol response to low dose (0.05 microgram/kg i.v.) exogenous adrenocorticotrophic hormone (ACTH). Controlling for sex and medication, both peak cortisol level (peak-baseline) and area under cortisol response curve (AUC above baseline) were significantly greater in AD subjects. This shows that HPA axis hyperactivity, as demonstrated by enhanced adrenal sensitivity to ACTH, occurs in AD. Similar findings have been reported to occur in depression. Among AD subjects, AUC cortisol response correlated with current age (r = 0.70, P = 0.001) and age at onset of dementia (r = 0.73, P = 0.001) and an inverse correlation was seen between cortisol AUC and cognitive test (CAMCOG) score (r = -0.51, P = 0.044). Our findings suggest that HPA axis hyperactivity in AD is associated with advancing age and cognitive dysfunction. Such changes may be cause, or consequence, of neuronal loss.

Gonadotropin (LH and FSH) response after submaximal GnRH stimulation in depressed premenopausal women and healthy controls

Although hormonal response abnormalities in depression have been demonstrated in several hypothalamic-pituitary-target organ axes after a variety of neuroendocrine challenge tests, studies of hypothalamic-pituitary-gonadal (HPG) axis function have been inconsistent in their findings. The use of maximal or supramaximal doses of gonadotropin-releasing hormone (GnRH) in early studies (150-600 micrograms) may have masked the presence of more subtle disturbances in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responsiveness in depression. We hypothesized that submaximal doses of GnRH might reveal a more subtle dysregulation in gonadotropin responsiveness in depression, and therefore measured LH and FSH responses after GnRH 10 micrograms and 90 micrograms doses in nine premenopausal depressed women and six healthy controls. There were no statistically significant differences between subject groups for mean basal LH, FSH, and estradiol concentrations, nor for any of the LH and FSH response values after either GnRH stimulation dose. The present observations of an intact HPG axis in depression contrast with findings of disturbances in most other hypothalamic-pituitary axes, and suggest that neuroendocrine dysregulation in depression might not represent a generalized limbic system-hypothalamic-pituitary abnormality, but rather a more restricted lesion sparing the medial preoptic and/or arcuate region of the hypothalamus which regulates gonadotropin secretion.

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.

Abnormalities in adrenal androgens, but not of glucocorticoids, in early Alzheimer's disease

In an attempt to evaluate possible adrenal abnormalities in Alzheimer's disease (AD), prestimulus levels and ACTH-stimulated serum levels of steroid hormones, corticosteroid-binding globulin (CBG), and insulin-like growth factor I (IGF-I) were measured in 18 patients with early AD (8 men, 10 women; 74.6 +/- 6.5 years, mean +/- SD) and 19 healthy controls (10 men, 9 women; 74.2 +/- 7.6 years, mean +/- SD). Steroid hormone levels were measured before and after an intravenous bolus injection of 250 micrograms ACTH. AD per se had an independent influence on hormone levels when evaluated in MANOVA models. AD patients had significantly higher prestimulus levels of dehydroepiandrosterone and androstenedione (p = .04 and p = .003, respectively) with accentuated differences after ACTH (p = .02 and p < .001 for peak responses, respectively). Serum levels of cortisol, CBG, free cortisol, 17 alpha-hydroxyprogesterone (17 alpha-OHP), and IGF-I did not differ between groups. These abnormalities may have implications for neuronal degeneration as well as for behavioural symptoms in AD.

The function of the hypothalamic-pituitary-adrenal axis in Alzheimer's disease. Response to insulin hypoglycaemia

BACKGROUND

To investigate an association between HPA axis dysfunction, depression and cognitive impairment, we assessed subjects with mild Alzheimer's disease (AD).

METHOD

Sixteen non-depressed subjects with AD according to NINCDS/ADRDA criteria and 18 normal controls underwent the insulin hypoglycaemia (IH) test and the dexamethasone suppression test (DST).

RESULTS

The AD subjects showed a blunted response of adrenocorticotrophic hormone (ACTH) to IH compared with controls (P = 0.019). ACTH response (area under curve) correlated with a score for cognitive ability (CAMCOG) (r = 0.64, P < 0.01). AD subjects had a shorter time to peak cortisol level than controls (P = 0.004), although total cortisol response was normal.

CONCLUSIONS

The AD subjects show evidence of adrenal hyper-responsiveness and normal immediate (rate-sensitive) glucocorticoid feedback. An association between HPA axis dysfunction and organic brain pathology in AD subjects may be mediated by cell loss in the hippocampus.

Stimulation of the pituitary-adrenal axis with a low dose [Arg8]-vasopressin in depressed patients and healthy subjects

Graded doses arginine-vasopressin (AVP) were administered to depressed patients and control subjects to compare the sensitivity of the pituitary-adrenal system of these subjects for this compound. The plasma levels of cortisol, adrenocorticotropic hormone (ACTH) and beta-endorphin were measured before and after intravenous AVP injection. The hormonal output was taken as a measure of pituitary-adrenal function. In control subjects 3 doses AVP and placebo were used, whereas in patients two doses AVP, a low and a high dose, and placebo were tested. All tests were carried out in the afternoon when the pituitary-adrenal system is stable and more susceptible for stimulation. Patients were subdivided into dexamethasone suppressors and nonsuppressors based on their DST status before testing to look for differences among these groups. Control subjects showed no response of the hormones to the lowest dose AVP and a moderate response to the higher doses. Interestingly, depressed patients as compared to controls responded more to the lowest dose AVP in particular with respect to ACTH. DST status did not influence the results. These findings suggest an enhanced sensitivity of the pituitary to low doses AVP in depressed patients. Thus, AVP might play a role in HPA dysfunction in depression.

Cerebrospinal fluid neuropeptides in mood disorder and dementia

Cerebrospinal fluid (CSF) concentrations of immunoreactive corticotropin-releasing hormone (CRH) and somatostatin (SRIF) were measured in female psychiatric inpatients with DSM-III-R diagnoses of major depression, mania, generalized anxiety and somatization disorder. In addition, elderly patients with dementia disorders, with or without concomitant major depression, were also investigated. CSF SRIF was not significantly different among these groups; on the other hand, mean CSF CRH concentrations were significantly higher in major depression and in dementia with depression as compared with neurological controls with no psychiatric disorders. CSF CRH levels in mania, simple dementia, or anxiety or somatization disorder were not significantly different from the controls. Background physical or clinical variables did not account for the differences in CRH concentrations. It is concluded that CSF CRH elevation may be present in some patients with major depression independent of age and an underlying dementia disorder.

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.

Clinical and biochemical aspects of depressive disorders: II. Transmitter/receptor theories

The present document is the second of three parts in a review that focuses on recent data from clinical and animal research concerning the biochemical bases of depressive disorders, diagnosis, and treatment. Various receptor/transmitter theories of depressive disorders are discussed in this section. Specifically, data supporting noradrenergic, serotonergic, cholinergic, dopaminergic, GABAergic, and peptidergic theories, as well as interactions between noradrenergic and serotonergic, or cholinergic and catecholaminergic systems are presented. Problems with the data and future directions for research are also discussed. A previous publication, Part I of this review, dealt with the classification of depressive disorders and research techniques for studying the biochemical mechanisms of these disorders. A future publication, Part III of this review, discusses treatments for depression and some of the controversies in this field.

The limbic-hypothalamic-pituitary-adrenal axis in Huntington's disease

The functional integrity of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis was studied in 10 patients with Huntington's disease (HD) and 10 age- and weight-matched control subjects by measuring basal ACTH and cortisol secretion, analyzing the subjects' ACTH and cortisol responses to corticotropin-releasing hormone (CRH) challenge, and by means of the dexamethasone-suppression test (DST). Basal cortisol and ACTH levels were significantly higher in patients with HD compared with controls. Following CRH administration, ACTH responses tended to be blunted in concert with normal cortisol levels. Two patients with HD and one control subject were DST nonsuppressors. Post-DST plasma dexamethasone levels were 57% lower among patients compared with the control group. Only in the HD group age was there an important variable in influencing spontaneous cortisol secretion as well as plasma dexamethasone levels during DST. These results suggest that patients with HD have an endogenous CRH overdrive, possibly due to a loss of (GABA) gamma-aminobutyric acid-containing neurons, and that age might have an effect on the outcome of LHPA axis function tests in patients only.

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.