Do panic disorder and posttraumatic stress disorder share a common psychoneuroendocrinology?

Pharmacotherapeutics in clinical ethology: treatment efficacy, clinical pathology and outcome

The use of psychopharmaceutical agents is a core aspect of treatment in veterinary behavioural medicine. Psychotropic medication use has shifted the focus of treatment from purely behavioural and environmental interventions to a multi-modal approach. Objective measures of efficacy are required for the licensing of medication. Pharmacotherapeutics have come to encompass supplements and diets, in addition to prescription medications. The first part of this paper examines the efficacy of medications, supplements and diets used in behavioural medicine. Foci include the role of evolution in the types of behavioural concerns reported, the importance of defining abnormal or pathological behaviour, use of terminology that supports stratified mechanistic diagnoses aid in understanding presentation and response clusters, and rational use of medication to relieve emotional, mental and behavioural suffering, given these diagnoses and clusters. The second part of this paper examines the extent to which variation in patient response to medication can enlighten us about mechanisms and outcomes of distress using a series of 3 patient populations who are the focus of studies on separation anxiety and noise reactivity. This response surface approach can be useful for understanding differences in populations in susceptibility to behavioural pathology and in medication response, and may suggest new avenues for drug development and application.

The Emerging Role of Atrial Natriuretic Peptide in Psychiatry

INTRODUCTION

Atrial natriuretic peptide (ANP), composed by 28 amino-acids, is well known to modulate fluid and electrolyte homeostasis, the hypothalamic-pituitary-adrenal (HPA) axis activity and the immune system. Since ANP is produced in both heart and in the central nervous system (CNS), in the last years, increasing attention has been devoted to its possible role in neuropsychiatric disorders. Indeed, scattered data would indicate its possible role in anxiety, major depression, addictive behaviors, post-traumatic stress disorder and other stress-related disorders. Further, ANP has been hypothesized to represent one of the factors linking depression to cardiovascular health and the immune system.

AIMS

Given the paucity of available information, the aim of this paper was to review the current literature on the role of ANP in the CNS and in the pathophysiology of different neuropsychiatric and stress-related conditions.

DISCUSSION

Supporting data on ANP in psychiatric disorders are still limited to animal studies, or to a few "real" findings in patients gathered some decades ago that should be replicated in larger clinical samples.

CONCLUSION

Further studies are necessary to understand the possible implications of ANP in neuropsychiatry, because potentially it might represent a new way for innovative psychopharmacological treatments in different conditions, all underlaid by hyperactive HPA axis.

Cortisol stress response in post-traumatic stress disorder, panic disorder, and major depressive disorder patients

BACKGROUND

Previous research has focussed extensively on the distinction of HPA-axis functioning between patient groups and healthy volunteers, with relatively little emphasis on a direct comparison of patient groups. The current study's aim was to analyse differences in the cortisol stress response as a function of primary diagnosis of panic disorder (PD), post-traumatic stress disorder (PTSD), and major depressive disorder (MDD).

METHODS

A total of n=30 PD (mean age±SD: 36.07±12.56), n=23 PTSD (41.22±10.17), n=18 MDD patients (39.00±14.93) and n=47 healthy control (HC) individuals (35.51±13.15) participated in this study. All the study participants were female. The Trier Social Stress Test (TSST) was used for reliable laboratory stress induction. Blood sampling accompanied the TSST for cortisol and ACTH assessment. Panic-related, PTSD-specific questionnaires and the Beck Depression Inventory II were handed out for the characterisation of the study groups. Repeated measure ANCOVAs were conducted to test for main effects of time or group and for interaction effects. Regression analyses were conducted to take comorbid depression into account.

RESULTS

26.7% of the PD patients, 43.5% of the PTSD patients, 72.2% of the MDD patients and 80.6% of the HC participants showed a cortisol stress response upon the TSST. ANCOVA revealed a cortisol hypo-responsiveness both in PD and PTSD patients, while no significant group differences were seen in the ACTH concentrations. Additional analyses showed no impact of comorbid depressiveness on the cortisol stress response. MDD patients did not differ in the hormonal stress response neither compared to the HC participants nor to the PD and PTSD patients.

CONCLUSION

Our main findings provide evidence of a dissociation between the cortisol and ACTH concentrations in response to the TSST in PTSD and in PD patients, independent of comorbid depression. Our results further support overall research findings of a cortisol hypo-responsiveness in PD patients. A hypo-response pattern was also seen in the PTSD patients agreeing with previous finding on the cortisol stress reactivity following TSST stress induction in these patients. Patients with a primary MDD diagnosis showed descriptively higher cortisol concentrations compared to the anxiety patients, and lower cortisol concentrations as the healthy individuals. The limitations of the study and implications for future studies will be discussed.

Preclinical perspectives on posttraumatic stress disorder criteria in DSM-5

Posttraumatic stress disorder (PTSD) now sits within the newly created "Trauma- and Stressor-Related Disorders" section of the Diagnostic and Statistical Manual of Mental Disorders (fifth edition; DSM-5). Through the refinement and expansion of diagnostic criteria, the DSM-5 version better clarifies the broad and pervasive effects of trauma on functioning, as well as the impact of development on trauma reactions. Aggressive and dissociative symptoms are more thoroughly characterized, reflecting increasing evidence that reactions to trauma often reach beyond the domains of fear and anxiety (these latter domains were emphasized in DSM-IV). These revised criteria are supported by decades of preclinical and clinical research quantifying traumatic stress-induced changes in neurobiological and behavioral function. Several features of the DSM-5 PTSD criteria are similarly and consistently represented in preclinical animal models and humans following exposure to extreme stress. In rodent models, for example, increases in anxiety-like, helplessness, or aggressive behavior, along with disruptions in circadian/neurovegetative function, are typically induced by severe, inescapable, and uncontrollable stress. These abnormalities are prominent features of PTSD and can help us in understanding the pathophysiology of this and other stress-associated psychiatric disorders. In this article we examine some of the changes to the diagnostic criteria of PTSD in the context of trauma-related neurobiological dysfunction, and discuss implications for how preclinical data can be useful in current and future clinical conceptualizations of trauma and trauma-related psychiatric disorders.

Effects of chronic posttraumatic stress disorder on metabolic risk, quality of life, and stress hormones in aging former refugee children

It is still unclear whether the association between traumatic stress and physical disease is mediated by posttraumatic stress disorder (PTSD). Therefore, we examined the long-term consequences of PTSD on cardiovascular risk, stress hormones, and quality of life in a sample of former refugee children who were severely traumatized more than six decades ago. In 25 subjects with chronic PTSD and 25 trauma-controlled subjects, we measured the variables of metabolic syndrome supplemented by the ankle-brachial index and highly sensitive C-reactive protein. Quality of life was assessed using the 36-item Short-Form Health Survey. Cortisol, adrenocorticotropin-releasing hormone (ACTH), and dehydroepiandrosterone (DHEA) were measured using the low-dose-dexamethasone suppression test. In addition, salivary cortisol was assessed at 8:00 a.m., 12:00 p.m., 4:00 p.m., and 8:00 p.m. We found a significant group effect between participants with and without PTSD regarding quality of life but not in any metabolic parameter including the ankle-brachial index or cortisol, ACTH, and DHEA in plasma before and after dexamethasone or salivary cortisol. The postulated association between traumatic stress and physical illness does not appear to be mediated by PTSD in this population. Nevertheless, the search for subgroups of PTSD patients with childhood traumatization leading to different metabolic and endocrine long-term consequences in aging PTSD patients is needed.

Increased DHEA and DHEA-S plasma levels in patients with post-traumatic stress disorder and a history of childhood abuse

Current findings about dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEA-S) in patients with post-traumatic stress disorder (PTSD) have been inconsistent. We investigated whether a history of severe childhood traumatisation affects these steroids in PTSD patients. Patients of 33 with chronic PTSD (15 with and 18 without sexual and/or severe physical abuse before age 12) were studied in a combined low dose dexamethasone/corticotropin-releasing hormone (CRH) test. Mean pre-CRH levels of both plasma DHEA and DHEA-S were significantly increased in the subgroup with childhood abuse, the respective ratios with plasma cortisol were significantly lower. In the entire population of PTSD patients significant amounts of the variation of these parameters could be explained by childhood trauma history. Further studies are needed to clarify the potential role of DHEA and DHEA-S as biomarkers for severe early adverse events in patients suffering from PTSD and in other stress-related disorders.

Susceptibility to stress in transgenic mice overexpressing TrkC, a model of panic disorder

Stressful life events increase the susceptibility for subsequent onset of psychiatric disorders in humans. Previous research has implicated neurotrophins in the onset of some stress-related diseases, such as major depression disorder, post-traumatic stress disorder or panic disorder. We have tested the hypothesis that the neurotrophin-3 (NT-3)/TrkC system is a genetic interface mediating the deleterious effects of stress on the initiation of panic disorder and other pathologies. To this aim, we have analyzed the functionality of HPA axis and the behavioral consequences of different types of stressful conditions in a mouse model of panic disorder, which overexpresses TrkC, the high affinity-receptor for NT-3 (TgNTRK3). Our results reveal that TgNTRK3 mice exhibit an altered circadian corticosterone rhythm that is reversed by clonidine treatment, but normal expression of genes involved in the control of the hypothalamus-pituitary-adrenal (HPA) axis (CRH, GR) and normal corticosterone response to acute and chronic stressors. In contrast, they exhibit an altered pattern of activation of stress-related brain areas and showed enhanced anxiety-related behavior and more passive strategies than wild types under some chronic stress conditions. We conclude that TgNTRK3 mice present differences in their response to stress characterized by subtle changes in the HPA axis, marked changes in acute stress-induced brain activation and altered coping strategies, suggesting a key role of TrkC receptor in the stress neural circuitry and in the behavioral consequences of chronic stress.

Behavioral correlates of anxiety

The tripartite model of anxiety includes three response domains: cognitive (most often identified by self report), behavioral, and physiological. Each is suggested to bring a separate element of response characteristics and, in some cases, potentially independent underlying mechanisms to the construct of anxiety. In this chapter, commonly used behavioral correlates of anxiety in human research, including startle reflex, attentional bias, and avoidance tasks, as well as future tasks using virtual reality technology will be discussed. The focus will be in evaluating their translational utility supported by (1) convergent validity with other measures of anxiety traits or anxiety disorders, (2) their use in identifying neural and genetic mechanisms of anxiety, and (3) ability to predict treatment efficacy.

Specificity of autonomic arousal to DSM-IV panic disorder and posttraumatic stress disorder

Although research on the hierarchical model of anxiety and depression has confirmed that autonomic arousability (AA) is more germane to panic disorder with or without agoraphobia (PD/A) than other DSM-IV anxiety and mood disorders, studies have not evaluated the differential relevance of AA to posttraumatic stress disorder (PTSD). This issue was addressed in multivariate analytic models using 295 outpatients with anxiety and mood disorders. Consistent with prediction, the presence of current DSM-IV PTSD and PD/A was significantly predictive of AA, even when other forms of anxiety disorder comorbidity were held constant. Moreover, latent structural analyses indicated that PTSD and PD/A were the only DSM-IV anxiety disorder constructs to have significant direct effects on AA (in accord with previous findings, the DSM-IV constructs of generalized anxiety disorder, social phobia, and obsessive-compulsive disorder did not have significant structural relationships with AA). The current findings, which attest to the specificity of AA to PTSD and PD/A, are discussed in context of other clinically salient shared features of these disorders and their relevance to treatment and diagnostic classification.

Test of the role of nicotine dependence in the relation between posttraumatic stress disorder and panic spectrum problems

Posttraumatic stress disorder (PTSD) frequently co-occurs with panic spectrum problems. Relatively little empirical work has tested possible mechanisms accounting for this association. Nicotine dependence often ensues subsequent to PTSD onset and research suggests smoking high numbers of cigarettes daily may lead to panic problems. The current study tested the hypotheses that nicotine dependence partially mediates the relations between PTSD and both panic attacks and panic disorder within a nationally representative sample of 5,692 (3,020 women; M(Age) = 45, SD = 18) adults from the National Comorbidity Survey-Replication. Results were consistent with hypotheses. These findings support the theory suggesting smoking among people with PTSD may be involved in the development of panic problems.

Endogenous cortisol suppression with metyrapone enhances acoustic startle in healthy subjects

Previous human studies have shown that excess cortisol sufficient to fully occupy central nervous system (CNS) corticosteroid receptors may reduce startle eye blink. The present study tested whether cortisol depletion and the resulting reduction in activity of CNS corticosteroid receptors has the opposite effect. In a single-blind, placebo-controlled, randomized study, eye blink EMG responses to 105 dB acoustic startle stimuli were assessed in 25 healthy subjects who received oral metyrapone (1500 mg) to suppress endogenous cortisol production, while 24 controls received oral placebo. As expected, metyrapone significantly reduced salivary cortisol, indicating effective endogenous cortisol suppression. Startle eye blink responses were significantly increased in the metyrapone group. Short-term habituation of the startle reflex was not different between groups. Our results suggest that startle is enhanced during depletion of cortisol. This effect may be mediated by CNS mechanisms controlling cortisol feedback.

Melatonin, consciousness, and traumatic stress

Descartes intuitively anticipated the so-called 'binding problem' of consciousness and thought that the pineal gland enables spatio-temporal integration in cognitive processing. Recent findings indicate that a major role in the process of temporal integration and binding involve neurons in suprachiasmatic nuclei, specifically targeting the pineal gland and other structures, and control the neuroendocrine rhythms. Melatonin is an endocrine output signal of the clock and provides circadian information as an endogenous synchronizer which stabilizes and reinforces circadian rhythms. This integrative process occurs at the different levels of the circadian network via gene expression in some brain regions and peripheral structures that enables integration of circadian, hormonal, and metabolic information and creating temporal order of bodily and mental experience. This specific temporal order is reflected in associative sequentiality that is necessary for cognition, behavior and all processes of memory consolidation that must preserve all information in the temporal causal order and synchrony. In this context, recent findings suggest that melatonin could be a potential regulator in the processes that contribute to memory formation, long-term potentiation, and synaptic plasticity in the hippocampus and other brain regions. There is evidence that stress disrupts normal activity and memory consolidation in the hippocampus and prefrontal cortex, and this process leads to memories that are stored without a contextual or spatiotemporal frame. These findings emphasize a specific role of melatonin in mechanisms of consciousness, memory and stress and are also consistent with reported studies that indicate melatonin alterations under stressful conditions and in mental disorders.

[Overlap between atypical depression, seasonal affective disorder and chronic fatigue syndrome]

OBJECTIVE

We reviewed previous studies that have described an association between abnormal functioning of the hypothalamic-pituitary-adrenal axis and depression. In addition to melancholic depression, a spectrum of conditions may be associated with increased and prolonged activation of the hypothalamic-pituitary-adrenal axis. In contrast another group of states is characterized by hypoactivation of the stress system, rather than sustained activation, in which chronically reduced secretion of corticotropin releasing factor may result in pathological hypoarousal and an enhanced hypothalamic-pituitary-adrenal negative feedback. Patients with atypical depression, seasonal affective disorder and chronic fatigue syndrome fall in this category.

METHOD

The literature data on the overlap between the key-words were reviewed, summarized and discussed.

RESULTS

Many studies suggest that these conditions themselves overlap biologically, showing hypofunction of central corticotropin releasing factor neuronal systems.

CONCLUSIONS

Therefore, in the real world of clinical practice, patients often present in a grey area between classical idiopathic fatigue and early chronic atypical depression and/or seasonal depression. This underscores the potential common biological links underpinning common symptom clusters not only between depression (atypical and seasonal) and chronic fatigue syndrome, but also other conditions characterized by the hypothalamic-pituitary-adrenal axis mainly diminished the corticotropin realising factor activity.

Role of dopamine D1 and D2 receptors in CRF-induced disruption of sensorimotor gating

Corticotropin-releasing factor (CRF), a neuropeptide released during stress, has been reported to modulate startle behavior, including reducing the threshold for acoustic startle responding and reducing prepulse inhibition (PPI). The central mechanisms mediating CRF system regulation of startle and PPI are still unclear. Some antipsychotic drugs attenuate CRF-induced deficits in PPI in rats and mice. Here we tested the hypothesis that indirect activation of DA(1)-receptors (D(1)) and DA(2)-receptors (D(2)) contributes to the effects of CRF on PPI. We compared the effect of central administration of h/r-CRF (0.2-0.6 nmol) on PPI in mice with either a D(1) or D(2) receptor null mutation (knockout, KO) or in mice pretreated with D(1) or D(2) receptor antagonists SCH23390 (1 mg/kg) or haloperidol (1 mg/kg). D(1) and D(2) KO mice exhibited no significant differences in their sensitivity to CRF-induced disruptions of PPI. Similarly, neither SCH23390 nor haloperidol pretreatment altered the CRF-induced disruption in PPI, although both increased PPI at baseline. CRF-induced increases in startle also remained unchanged by any of the DA receptor manipulations. These results indicate that neither D(1)- nor D(2)-receptor activation is necessary for CRF to exert its effects on acoustic startle and PPI in mice.

The effects of sertraline on severe tinnitus suffering--a randomized, double-blind, placebo-controlled study

OBJECTIVE

The relationship between tinnitus and anxiety and depressive disorders has been frequently alluded to, but there are few studies on antidepressants in the treatment of tinnitus, and the efficacy of sertraline on severe refractory tinnitus has not been reported.

METHOD

Consecutive tinnitus patients (n = 76) considered to be at high risk for severe and disabling tinnitus according to a recently developed screening procedure were randomly assigned to 16 weeks of double-blind treatment with placebo (n = 38) or sertraline (n = 38) at a fixed dose (25 mg/d on the first week and 50 mg/d on the following 15 weeks). Between-group comparisons of Tinnitus Severity Questionnaire scores over 16 weeks were made as the primary outcome measure. Secondary outcomes of tinnitus loudness and tinnitus annoyance were also measured using a visual analogue scale. Severity of depressive and anxiety symptoms was evaluated using the Hamilton rating scales (Hamilton Depression Rating Scale and Hamilton Anxiety Rating Scale, interview-based ratings) and the Comprehensive Psychopathological Rating Scale (self-ratings).

RESULTS

The intention-to-treat analysis showed sertraline to be more effective than placebo (P = 0.024) in decreasing reported tinnitus severity according to the Tinnitus Severity Questionnaire at 16 weeks' follow-up. There was also more improvement (P = 0.014) in perceived tinnitus loudness. There were significant correlations between reduction of tinnitus according to the Tinnitus Severity Questionnaire over 16 weeks and improvements in depressive (r = 0.42-0.46) and anxiety symptoms (r = 0.34-0.42). Sertraline was well tolerated after a somewhat high (17%) dropout rate within the first 2 weeks.

CONCLUSIONS

Sertraline is more effective than placebo in the treatment of severe refractory tinnitus.

Hormone Responses to Social Stress in Abstinent Alcohol-Dependent Subjects and Social Drinkers with No History of Alcohol Dependence

BACKGROUND

Previous studies have described blunted stress hormone responses after pharmacological activation of the hypothalamic-pituitary-adrenal (HPA) axis in sober alcoholics. The aim of the present study was to compare ACTH, cortisol, and prolactin responses to a psychological stressor in abstinent alcohol-dependent subjects matched to healthy control subjects.

METHODS

Individuals who met DSM-IV diagnostic criteria for a history of alcohol dependence but not for other axis I disorders were included in the study (n = 18; mean duration of abstinence +/- SEM, 3.5 +/- 5.7 years). Social drinkers (n = 23) served as control subjects. The sober alcohol-dependent and control subjects were matched for demographic measures including levels of stress symptoms. All subjects underwent the Trier Social Stress Test (TSST), a laboratory-based psychological stressor. Prestress and poststress plasma ACTH, cortisol, and prolactin levels, as well as a self-report measure of anxiety (State-Trait Anxiety Inventory), were obtained.

RESULTS

Nondepressed, abstinent alcoholics and control subjects did not differ with regard to age, racial composition, or baseline or poststress ratings of anxiety. Whereas ACTH and cortisol levels increased in response to the TSST, prolactin levels did not. Stress hormone response curves for the three hormones did not differ between the alcoholics and control subjects.

CONCLUSIONS

When matched for levels of stress, a laboratory-based psychological stress test did not induce differential hormone response curves for abstinent alcoholics and control subjects.

Metyrapone tests in patients with panic disorder

BACKGROUND

Studies of hypothalamic secretion of corticotropin-releasing hormone (CRH) in patients with panic disorder in the nonpanic state (using CRH tests) are contradictory. No data about the hypothalamic-pituitary response to metyrapone are available.

METHODS

Study participants included 14 patients with panic disorder (DSM-IV criteria) and 14 healthy control subjects who underwent a standard overnight metyrapone test and a combined metyrapone/low-dose dexamethasone test.

RESULTS

Significant treatment effects of metyrapone and combined metyrapone/dexamethasone were found on plasma corticotropin, cortisol, and 11-deoxycortisol, but no differences between patients and control subjects emerged. Considering visual analogue scale ratings of anxiety, tension, restlessness, and Beck Depression Inventory scores as covariates, no group effects were detected.

CONCLUSIONS

Standard overnight metyrapone tests do not support a hypersecretion of hypothalamic CRH in panic disorder. Furthermore, no evidence for increased glucocorticoid negative feedback in panic was found. Hypothalamic CRH secretion in the nonpanic state needs further research.

[The hypothalamic pituitary adrenal axis, glucocorticoid receptor function and relevance to depression]

OBJECTIVES

Changes in the hypothalamic-pituitary-adrenocortical (HPA) system are characteristic of depression. Because the effects of glucocorticoids are mediated by intracellular receptors including, most notably, the glucocorticoid receptor (GR), several studies have examined the number and/or function of GRs in depressed patients.

METHODS

Review scientific evidences have consistently demonstrated that GR function is impaired in major depression, resulting in reduced GR-mediated negative feedback on the HPA axis and increased production and secretion of CRF in various brain regions postulated to be involved in the causality of depression.

RESULTS

This article summarizes the literature on GR in depression and on the impact of antidepressants on the GR in clinical and preclinical studies, and supports the concept that impaired GR signalling is a key mechanism in the pathogenesis of depression, in the absence of clear evidence of decreased GR expression. The data also indicate that antidepressants have direct effects on the GR, leading to enhanced GR function and increased GR expression. Although the effects of antidepressants on glucocorticoid hormones and their receptors are relevant for the therapeutic action of these drugs, the molecular mechanisms underlying these effects are unclear. We propose that antidepressants in humans could inhibit steroid transporters localised on the blood-brain barrier and in neurones, like the multidrug resistance p-glycoprotein, and thus increase the access of cortisol to the brain and the glucocorticoid-mediated negative feedback on the HPA axis.

CONCLUSION

Enhanced cortisol action in the brain might prove to be a successful approach to maximise therapeutic antidepressant effects. Hypotheses regarding the mechanism of these receptor changes involve non-steroid compounds that regulate GR function via second messenger pathways. Research in this field will lead to new insights into the pathophysiology and treatment of affective disorders.

Sleep in post-traumatic stress disorder and panic: convergence and divergence

Disturbed sleep is a common clinical problem in anxiety disorders, particularly in patients with post-traumatic stress disorder (PTSD) and panic disorder (PD). Several studies have attempted to validate the subjective sleep complaints of these disorders using laboratory polysomnography. These attempts, typically focusing on PTSD or PD independently, have demonstrated inconsistent results. To our knowledge, no such studies have attempted to directly compare and contrast sleep disturbances in PTSD and PD together. Our review of the studies of subjective sleep disturbances, sleep architecture, and sleep-related biologic phenomena suggests that a comparative characterization of sleep disturbances in these two disorders is timely. Such an inference is based on our identification of several areas of convergence and divergence between PTSD and PD found in the published literature, as well as our own preliminary investigations. Specifically, PTSD and PD seem to converge on several sleep-related parameters, namely, sleep quality, presence of episodic parasomnias, and movement time. They also appear to diverge in other important sleep-related areas such as respiratory disturbances and the particular phenomenological nature of episodic parasomnias, namely nightmares or nocturnal panic attacks. Investigations focusing on such overlapping phenomena may provide groundwork for further elucidation of central fear systems underlying these two disorders. Additionally, such sleep studies have the potential to provide important insights into ongoing efforts to develop a cohesive conceptual framework into the patho-physiologies of these disorders.

Olfactory-triggered panic attacks among Khmer refugees: a contextual approach

One hundred Khmer refugees attending a psychiatric clinic were surveyed to determine the prevalence of olfactory-triggered panic attacks as well as certain characteristics of the episodes, including trigger (i.e. type of odor), frequency, length, somatic symptoms, and the rate of associated flashbacks and catastrophic cognitions. Forty-five of the 100 patients had experienced an olfactory-triggered panic attack in the last month. Trauma associations and catastrophic cognitions (e.g. fears of a 'wind attack', 'weakness', and 'weak heart') were common during events of olfactory panic. Several case examples are presented. A multifactorial model of the generation of olfactory panic is adduced. The therapeutic implications of this model for the treatment of olfactory panic are discussed.

Molecular mechanisms of glucocorticoid receptor sensitivity and relevance to affective disorders

Changes in the hypothalamic-pituitary-adrenocortical (HPA) system are characteristic of depression, and in the majority of these patients these result in HPA axis hyperactivity. This is further supported by the reduced sensitivity to the inhibitory effects of the glucocorticoid, dexamethasone (DEX), on the production of adrenocorticotropic hormone (ACTH) and cortisol, during the DEX suppression test and the DEX-corticotropin-releasing hormone (DEX/CRH) test. Because the effects of glucocorticoids are mediated by intracellular receptors including, most notably, the glucocorticoid receptor (GR), several studies have examined the number and/or function of GRs in depressed patients. These studies have consistently demonstrated that GR function is impaired in major depression, resulting in reduced GR-mediated negative feedback on the HPA axis and increased production and secretion of CRH in various brain regions postulated to be involved in the causality of depression. This article summarizes the literature on GR in depression and on the impact of antidepressants on the GR in clinical and preclinical studies, and supports the concept that impaired GR signaling is a key mechanism in the pathogenesis of depression, in the absence of clear evidence of decreased GR expression. The data also indicate that antidepressants have direct effects on the GR, leading to enhanced GR function and increased GR expression. Hypotheses regarding the mechanism of these receptor changes involve non-steroid compounds that regulate GR function via second messenger pathways, such as cytokines and neurotransmitters. Moreover, we present recent evidence suggesting that membrane steroid transporters such as the multidrug resistance (MDR) p-glycoprotein, which regulate access of glucocorticoids to the brain, could be a fundamental target of antidepressant treatment. Research in this field will lead to new insights into the pathophysiology and treatment of affective disorders.

Low cortisol levels and the balance between punishment sensitivity and reward dependency

The neuro-endocrinological basis of psychopathy, a disorder characterized by lack of fear, is relatively unknown. However, low levels of cortisol may result in fearlessness and have been observed in individuals with psychopathic tendencies. Low fear models state that psychopaths are not motivated to avoid punishment, especially when reward is pending. In agreement, disadvantageous decision making on the IOWA gambling task in psychopaths and psychopathic analogous, indicates low punishment sensitivity and high reward dependency. Here, it was investigated whether low basal cortisol levels predicted the balance between punishment sensitivity and reward dependency in the same manner. As hypothesized, the most disadvantageous pattern of decision making was found in the subjects with the lowest cortisol levels. These findings suggest that low levels of cortisol may set the balance between the sensitivity for punishment and reward dependency towards a pre-disposition for psychopathy.

The mineralocorticoid receptor agonist, fludrocortisone, inhibits pituitary-adrenal activity in humans after pre-treatment with metyrapone

Whereas animal studies have shown a clear inhibitory effect of hippocampal mineralocorticoid receptors (MR) on hypothalamic-pituitary-adrenal (HPA) axis activity, investigations in humans revealed equivocal results. To further clarify the influence of MR in HPA activity we studied 10 healthy men during the circadian nadir of HPA activity (14:00 to 21:00) after pre-treatment with 3 g metyrapone to minimize the impact of basal endogenous cortisol secretion. On three separate occasions, in a placebo-controlled design, subjects received in a randomized order either 0.5 mg fludrocortisone p.o. or 0.2 mg aldosterone i.v. or placebo. Fludrocortisone exerted a significant inhibition of ACTH, cortisol and 11-desoxycortisol (p < 0.05), whereas no such effect was observed after aldosterone or placebo. These preliminary data suggest that MR are involved in the inhibition of the HPA axis during the circadian nadir of glucocorticoid concentrations in humans.

The Khmer 'Weak Heart' Syndrome: Fear of Death from Palpitations

According to the Khmer conception, a person suffering 'weak heart' (khsaoy beh daung) has episodes of palpitations on slight provocation (e.g. triggered by orthostasis, anger, a noise, worry, an odor or exercise) and runs the risk of dying of heart arrest during these periods of palpitations; too, the sufferer typically has other symptoms attributed to the purported cardiac dysfunction: fatigue, shortness of breath, and orthostatic dizziness. Many Khmer refugees suffer this cultural syndrome, an anxious-dysphoria ontology, most probably of French colonial provenance. The syndrome demonstrates considerable overlap with those Western illness categories that feature panic attacks, in particular post-traumatic stress disorder (PTSD) and panic disorder. In a psychiatric clinic survey, 60 percent (60/100) of those assessed believed themselves to currently suffer 'weak heart'; 90 percent (54/60) of those considering themselves to suffer from 'weak heart' thought that palpitations (e.g., those resulting from a loud noise or orthostasis) might result in death. The article illustrates the profoundly culturally constructed nature of 'cardiac sensations,' located in a specific historical trajectory and episteme; too, the article suggests that trauma may result more in panic disorder than 'PTSD' when autonomic arousal symptoms (in the present case, palpitations) are considered potentially life-threatening.

A pilot study of noradrenergic and HPA axis functioning in PTSD vs. panic disorder

The biological literature in the anxiety disorders has focused on comparisons between patient groups and normal volunteers, with relatively little comparative study of the anxiety disorders. We therefore conducted this pilot study to compare a group of patients with post-traumatic stress disorder (PTSD) (n = 7) to a contiguously studied panic disorder group (n = 17) and healthy control subjects (n = 16) on baseline levels of cortisol and 3-methoxy-4-hydroxyphenylglycol (MHPG), and response to clonidine challenge. Despite the small sample size, highly significant differences were found on the following measures: PTSD patients had lower cortisol, lower MHPG, reduced MHPG volatility to clonidine challenge, and marginally reduced cortisol volatility compared to patients with panic disorder. These biological findings support existing clinical, epidemiologic, family study, and clinical trial findings that distinguish these two disorders as distinct syndromes.

A novel prednisolone suppression test for the hypothalamic-pituitary-adrenal axis

We have developed a suppressive test for the hypothalamic-pituitary-adrenal (HPA) axis using prednisolone, which is similar to endogenous glucocorticoids. We used a single-blind, repeated-measure design in healthy volunteers. In the first phase of the study, we compared placebo or prednisolone 2.5 mg, 5 mg, or 10 mg; in the second phase of the study, we compared placebo or prednisolone 5 mg or dexamethasone.5 mg. On the following day, we collected plasma and salivary cortisol levels from 9 AM to 5 PM. Maximal average prednisolone plasma levels (at 9 AM after the 10-mg dose) were 30 to 35 ng/mL. At all doses, prednisolone caused a larger suppression of salivary cortisol (approximately 20% after 2.5 mg, 30% to 35% after 5 mg, and 70% to 75% after 10 mg) than of plasma cortisol (approximately 5% after 2.5 mg, 10% after 5 mg, and 35% after 10 mg). Dexamethasone.5 mg gave 80% suppression of plasma cortisol and 90% suppression of salivary cortisol. Plasma and salivary cortisol levels were more consistently correlated in each subject after prednisolone than after dexamethasone. We propose that prednisolone at the 5-mg dosage (which gave partial HPA suppression), together with the assessment of salivary cortisol, can be used to investigate both impaired and enhanced glucocorticoid-mediated negative feedback in large samples of patients with psychiatric disorders.

Mice with targeted mutations of glucocorticoid and mineralocorticoid receptors: models for depression and anxiety?

Impaired corticosteroid receptor signaling is a key mechanism in the pathogenesis of stress-related psychiatric disorders such as depression and anxiety. Since in vivo expression and functional studies of corticosteroid receptors are not feasible in the human central nervous system, such analyses have to be done in animal models. Transgenic mice with mutations of corticosteroid receptors are promising tools, which allow us to investigate the role of these proteins in the pathogenesis of symptoms characteristic for depression and anxiety. This review summarizes the neuroendocrinological and behavioral findings that have been obtained in six different mouse strains with specific mutations that influence the expression or the function of the glucocorticoid or the mineralocorticoid receptor (MR). The analyses of these mice helped to define molecular concepts of how corticosteroid receptors regulate the activity of the hypothalamic-pituitary-adrenal (HPA) system. Furthermore, some of these mutant mice exhibited characteristic alterations in behavioral tests for anxiety and despair. However, so far, none of the mouse strains described here can be viewed as an animal model of a specific psychiatric disease defined by common diagnostic criteria. Using high throughput technologies for the identification of genes regulated by glucocorticoid receptor (GR) and MR in brain areas responsible for specific symptoms of stress-related disorders will yield potential new drug targets for the treatment of depression and anxiety.

Panic disorder among Vietnamese refugees attending a psychiatric clinic: prevalence and subtypes

This study surveys Vietnamese refugees attending two psychiatric clinics to determine both the prevalence of panic disorder (PD) as well as panic attack subtypes in those suffering PD. A culturally valid adaptation of the SCID-panic module (the Vietnamese Panic Disorder Survey or VPDS) was administered to 100 Vietnamese refugees attending two psychiatric clinics. Utilizing culturally sensitive panic probes, the VPDS provides information regarding both the presence of PD and panic attack subtypes during the month prior to interview. Of 100 patients surveyed, 50 (50%) currently suffered PD. Among the 50 patients suffering PD, the most common panic attack subtypes during the previous month were the following: "orthostatic dizziness" (74% of the 50 panic disorder patients [PDPs]), headache (50% of PDPs), wind-induced/temperature-shift-induced (24% of PDPs), effort-induced (18% of PDPs), gastro-intestinal (16% of PDPs), micturition-induced (8% of PDPs), out-of-the-blue palpitations (24% of PDPs), and out-of-the-blue shortness of breath (16% of PDPs). Five mechanisms are adduced to account for this high PD prevalence as well as the specific profile of subtypes: 1) a trauma-caused panic attack diathesis; 2) trauma-event cues; 3) ethnic differences in physiology; 4) catastrophic cognitions generated by cultural syndromes; and 5) a modification of Clark's spiral of panic.

Panic disorder among Cambodian refugees attending a psychiatric clinic. Prevalence and subtypes

This study surveys Khmer refugees attending two psychiatric clinics to determine both the prevalence of panic disorder as well as panic attack subtypes in those suffering panic disorder. A culturally valid adaptation of the SCID-panic module, the Cambodian Panic Disorder Survey (CPDS), was administered to 89 consecutive Cambodian refugees attending these psychiatric clinics. Utilizing culturally sensitive panic probes, the CPDS provides information regarding both the presence of panic disorder and panic-attack subtypes during the month prior to interview. Of 89 patients surveyed at two psychiatric clinics, 53 (60%) currently suffered panic disorder. Among the 53 patients suffering panic disorder, the most common panic attack subtypes during the previous month were the following: "sore neck" [51% of the 53 panic disorder patients (PDPs)], orthostatic dizziness (49% of PDPs), gastrointestinal distress (26% of PDPs), effort induced (21% of PDPs), olfactory induced (21% of PDPs), and "while-sitting dizziness" (16% of PDPs).

Natural animal models of human psychiatric conditions: assessment of mechanism and validity

1. The classic animal models for human psychiatric conditions involves rodents. As prey species, their normal behaviors of avoidance would be considered pathological in humans and dogs. Hence, such models may not be homologous for similar behaviors found in psychiatric pathology in humans. 2. Dogs exhibit pathological behavioral conditions that may be equivalent to certain human psychiatric conditions. These canine conditions appear spontaneously or endogenously in the absence of genetic or neurochemcial manipulation, and as such, may be homologous to the human condition. 3. If canine conditions approach homology with human conditions they should have excellent face, predictive, and construct validity. 4. The canine conditions of separation anxiety, obsessive-compulsive disorder, cognitive dysfunction, dominance aggression, and panic disorder have good to excellent validity at all explored levels for human generalized anxiety disorder, obsessive-compulsive disorder, Alzheimer's disease, impulse control disorders, and panic disorder. 5. Natural canine models can aid our understanding of human psychiatric conditions.