The incidence of abnormal dexamethasone suppression in schizophrenia: a review and a meta-analytic comparison with the incidence in normal controls

Diurnal neurobiological alterations after exposure to clozapine in first-episode schizophrenia patients

BACKGROUND

Irregular circadian rhythm and some of its most characteristic symptoms are frequently observed in patients with schizophrenia. However, changes in the expression of clock genes or neuropeptides that are related to the regulation of circadian rhythm may influence the susceptibility to recurrence after antipsychotic treatment in schizophrenia, but this possibility has not been investigated.

METHODS

Blood samples were collected from 15 healthy male controls and 13 male schizophrenia patients at 4h intervals for 24h before and after treatment with clozapine for 8 weeks. The outcome measures included the relative expression of clock gene mRNA PERIOD1 (PER1), PERIOD2 (PER2), PERIOD3 (PER3) and the levels of plasma cortisol, orexin, and insulin.

RESULTS

Compared with healthy controls, schizophrenia patients presented disruptions in diurnal rhythms of the expression of PER1, PER3, and NPAS2 and the release of orexin, accompanied by a delayed phase in the expression of PER2, decreases in PER3 and NPAS2 expression, and an increase in cortisol levels at baseline. Several of these disruptions (i.e., in PER1 and PER3 expression) persisted after 8 weeks of clozapine treatment, similar to the decreases in the 24-h expression of PER3 and NPAS2. Clozapine treatment for 8 weeks significantly decreased the 24-h levels of PER2 and increased the 24-h levels of insulin.

CONCLUSION

These persistent neurobiological changes that occur after 8 weeks of clozapine treatment may contribute to the vulnerability to recurrence and efficacy of long-term maintenance treatment in schizophrenia.

Hypothalamic-pituitary-adrenal axis and clinical symptoms in first-episode psychosis

BACKGROUND

Abnormalities in hypothalamic-pituitary-adrenal (HPA) axis activity have been reported in patients with psychosis, but it is still unclear how these are related to the clinical symptomatology. Inconsistent findings have emerged from previous studies on the association between cortisol levels and clinical symptoms. Methodological and/or clinical factors, such as patients' diagnosis or illness phase, might partially account for these inconsistencies. The aim of this study was to investigate the association between HPA axis activity and clinical symptoms in first-episode psychosis, taking into account diagnosis and illness phase.

METHOD

Saliva samples were collected in 55 subjects with first-episode psychosis to assess the Cortisol Awakening Response (CAR) and diurnal cortisol levels (AUC-DAY). Severity of symptoms was assessed with the Positive and Negative Syndrome Scale (PANSS). Scores for subscales and symptom dimensions were used as predictors in multivariate analyses in different diagnostic subgroups and in clinically remitted patients. In addition, a systematic review of the literature on this topic was conducted.

RESULTS

In subjects with schizophrenia (n=36), the CAR was predicted by the severity of positive symptoms (beta=0.47, p=0.04); in subjects with depressive psychoses (n=8) the CAR was predicted by excitement (beta=0.58, p=0.005), disorganization (beta=0.39, p=0.007) and depressive symptoms (beta=0.32, p=0.005). In patients with bipolar psychoses (n=11) AUC-DAY was predicted negatively by disorganization (beta=-2.82, p=0.009) and positively by excitement (beta=2.06, p=0.009) and positive symptoms (beta=1.28, p=0.02). In the sample in clinical remission (n=9), the CAR was associated with the severity of positive symptoms (beta=1.34, p=0.009) and, negatively, with excitement (beta=-1.05, p=0.04). The systematic review (on a total of 28 papers, including n=1022 patients), found that in patients with psychosis cortisol levels have been associated with the severity of multiple symptom dimensions.

CONCLUSIONS

HPA axis activity is associated with the severity of multiple types of symptoms in first-episode psychosis. Patients' diagnosis and clinical phase partially influence these associations.

Inflammatory processes in schizophrenia: a promising neuroimmunological target for the treatment of negative/cognitive symptoms and beyond

Emerging evidence indicates that schizophrenia is associated with activated peripheral and central inflammatory responses. Such inflammatory processes seem to be influenced by a number of environmental and genetic predisposition factors, and they may critically depend on and contribute to the progressive nature of schizophrenic disease. There is also appreciable evidence to suggest that activated inflammatory responses can undermine disease-relevant affective, emotional, social, and cognitive functions, so that inflammatory processes may be particularly relevant for the precipitation of negative and cognitive symptoms of schizophrenia. Recent clinical trials of anti-inflammatory pharmacotherapy in this disorder provide promising results by showing superior beneficial treatment effects when standard antipsychotic drugs are co-administered with anti-inflammatory compounds, as compared with treatment outcomes using antipsychotic drugs alone. Given the limited efficacy of currently available antipsychotic drugs to ameliorate negative and cognitive symptoms, the further exploration of inflammatory mechanisms and anti-inflammatory strategies may open fruitful new avenues for improved treatment of symptoms undermining affective, emotional, social and cognitive functions pertinent to schizophrenic disease.

A randomised controlled study of risperidone and olanzapine for schizophrenic patients with neuroleptic-induced acute dystonia or parkinsonism

The objective of this study was to compare the effects of risperidone and olanzapine in schizophrenic patients with intolerant extrapyramidal side effects (EPS) on first generation antipsychotics. We conducted an 8-week, rater-blinded, flexible dose study. Seventy patients with schizophrenia, who met the DSM-IV research criteria of having neuroleptic-induced acute dystonia or parkinsonism, were randomly assigned to risperidone or olanzapine group. The primary outcome was a comparison of the incidence of concomitant anticholinergic drugs usage between the groups to manage their acute dystonia and parkinsonism. The average doses of risperidone and olanzapine from baseline to study end point were 1.8-3.5 mg/day and 7.7-11.7 mg/day, respectively. There were no significant differences in demographic data, severity of EPS or psychotic symptoms between the groups at baseline assessment. Patients taking risperidone had significantly higher incidence of using anticholinergic drugs to manage acute dystonia or parkinsonism overall during the study (OR = 5.17, 95%CI = 1.49-17.88, P = 0.013). There was no significant between-group difference in the changing of rating scales of EPS and psychotic symptoms. The results of our study favour olanzapine as a better choice in schizophrenic patients with intolerant EPS. Double-blinded, fixed dose and different ethnical study for EPS-intolerant schizophrenic patients is needed to confirm the results of our study.

A systematic review of hypothalamic-pituitary-adrenal axis function in schizophrenia: implications for mortality

There is convincing evidence that environmental stress plays a significant role in modifying both mental and physical health. The biological mechanisms linking stress to ill health are not fully understood, but significant evidence points to a central role of the stress axes; the hypothalamic- pituitary-adrenal (HPA) axis and the sympathetic nervous system. Together these two systems link the brain and the body and are crucial in maintaining homeostasis as well as improving an organism's survival chances in the face of environmental challenge. There is evidence of altered HPA axis function in people with a range of mental disorders, and this may in part explain the poor physical health of people with psychotic, mood and anxiety disorders. This paper systematically reviews HPA axis function in people with schizophrenia and relates this to the pattern of physical health seen in this disease. In summary, the evidence suggests people with schizophrenia can experience both hyper- and hypo-function of the HPA axis. It is likely that this contributes to the pattern of poor physical health and premature mortality suffered by people with schizophrenia, in particular the high rates of cardiovascular and metabolic disturbance.

Hyperactivity of the hypothalamus-pituitary-adrenal axis in lipopolysaccharide-induced neurodevelopmental model of schizophrenia in rats: effects of antipsychotic drugs

Recent data indicate that a significant number of schizophrenic patients are hypercortisolemic and that glucocorticoids are involved in the pathogenesis of schizophrenia. The aim of the present study was to evaluate whether behavioural schizophrenia-like changes in the lipopolysaccharide (LPS)-induced neurodevelopmental model of this brain disorder are associated with alterations in the level of plasma corticosterone, the concentration of glucocorticoid receptors and the amount of the immunophilin FKBP51, the glucocorticoid receptor co-chaperone, in the hippocampus and frontal cortex. We found that the adult offspring of prenatally LPS-treated rats showed a deficit in prepulse inhibition (PPI), an enhancement of amphetamine-induced locomotor activity, an elevated plasma level of corticosterone and a decrease in both the glucocorticoid receptor level in the hippocampus and the FKBP51 concentration in the frontal cortex. Most of these changes were reversed by the atypical antipsychotic drug clozapine, whereas chlorpromazine had no effect on PPI but attenuated the amphetamine-induced hyperactivity and normalised the hippocampal level of glucocorticoid receptors. The changes in the level of plasma corticosterone and cortical FKBP51 were attenuated by chlorpromazine in female offspring only. This study supports the hypothesis of hypothalamic-pituitary-adrenal (HPA) axis hyperactivity in schizophrenia and suggests that this hyperactivity results from a decrease in the hippocampal glucocorticoid receptor level and a decrease in FKBP51 in the frontal cortex.

Review: The biological basis of antipsychotic response in schizophrenia

Schizophrenia is a severe mental illness affecting approximately 1% of the population worldwide. Antipsychotic drugs are effective in symptom control in up to two-thirds of patients, but in at least one-third of patients the response is poor. The reason for this is not clear, but one possibility is that good and poor responders have different neurochemical pathologies, and may therefore benefit from different treatment approaches. In this selective review we summarise research findings investigating the biological differences between patients with schizophrenia who show a good or a poor response to treatment with antipsychotic drugs.

Revisiting the Dexamethasone Suppression Test in unipolar major depression: an exploratory study

BACKGROUND

Important methodological questions still exist concerning the Dexamethasone Suppression Test (DST), including the possibility of a better way of interpreting it. The aim of the present study was to explore the feasibility of an alternative way of interpreting DST results.

METHODS

A total of 50 patients with major depression aged 41.0 +/- 11.4 years old participated in the study. Past and present suicide attempts were recorded. Psychometric assessment included the Hamilton Depression Rating Scale (HDRS), the Hamilton Anxiety Scale (HAS), the Newcastle Depression Diagnostic Scale (NDDS), the Diagnostic Melancholia Scale (DMS) and the General Assessment of Functioning (GAF) scale. The 1 mg DST protocol was used. Analysis methods included the chi square test and analysis of covariance (ANCOVA) with Fisher least significant difference (LSD) as post hoc tests.

RESULTS

In all, 34 patients (68%) were suppressors, 16 (32%) were non-suppressors and 14 patients had cortisol values above 5 microg/dl at baseline. Baseline cortisol level did not influence the classical DST interpretation. A total of 18 patients (36%) showed an increase of their cortisol levels after dexamethasone administration and 32 patients (64%) showed a decrease. Reducers had less melancholic features, similar levels of depression, better sleep and less suicidal thoughts in comparison to increasers. No relationship of DST to suicidality was found.

DISCUSSION

The present study explored the pattern of cortisol response to dexamethasone suppression and suggested an alternative way of coding and interpreting the DST on the basis of whether the cortisol levels remain stable or increase vs decrease after the administration of cortisol. The results put forward a complex way of understanding the relationship of the DST results with clinical symptoms.

The biochemical womb of schizophrenia: A review

The conclusive identification of specific etiological factors or pathogenic processes in the illness of schizophrenia has remained elusive despite great technological progress. The convergence of state-of-art scientific studies in molecular genetics, molecular neuropathophysiology, in vivo brain imaging and psychopharmacology, however, indicates that we may be coming much closer to understanding the genesis of schizophrenia. In near future, the diagnosis and assessment of schizophrenia using biochemical markers may become a "dream come true" for the medical community as well as for the general population. An understanding of the biochemistry/ visa vis pathophysiology of schizophrenia is essential to the discovery of preventive measures and therapeutic intervention.

Stress and HPA-axis functioning in young people at ultra high risk for psychosis

It is thought that hypothalamic-pituitary-adrenal (HPA) axis functioning mediates between the experience of stress and development of psychotic symptoms. This study aimed to evaluate this model in a cohort of young people at ultra high risk (UHR) of psychosis. Information about the experience of psychological symptoms and recent stressful experiences was obtained from 23 young people who met UHR criteria. Plasma samples were taken to assess cortisol and glucocorticoid receptor numbers, and an MRI scan was also performed. Plasma cortisol levels were significantly and positively correlated with the experience of 'hassles' but not with the experience of stressful life events. Significant positive associations were also found between plasma cortisol levels and level of depression and anxiety. No significant relationships were found between plasma cortisol level and global psychopathology, psychotic symptomatology, functioning or pituitary and hippocampal volumes. These results suggest that the number of hassles experienced by young people at UHR of psychosis could be an important factor in raising their cortisol levels, which might, in turn, affect the severity of depressive and anxiety symptoms. No other relationships were found between plasma cortisol levels and the experience of psychotic symptoms, functioning or hippocampal and pituitary volumes. These results indicate possible impairment in HPA-axis functioning in the early stages of psychotic illness, but further investigation of the relationships between these parameters is required.

HPA axis functioning associated with transition to psychosis: combined DEX/CRH test

We investigated functioning of the hypothalamic-pituitary-adrenal (HPA) axis in 12 young people at ultra high risk for developing psychosis, using the combined dexamethasone corticotrophin releasing hormone (DEX/CRH) test. Over a two year period, three of the 12 participants developed an acute psychosis. Descriptive analysis of the data indicated that contrary to expectations, participants who did not make the transition to psychosis had on average higher cortisol levels at the latter stages of the test, as well as a greater severity of depression and anxiety symptoms, than participants who subsequently developed psychosis. These preliminary results suggest that dysregulated HPA-axis functioning in individuals at high risk for psychosis may be associated more with comorbid depression symptoms than factors specifically related to the process of emerging psychosis illness.

Involvement of neuropeptide systems in schizophrenia: human studies

Neuropeptides are heterogeneously distributed throughout the digestive, circulatory, and nervous systems and serve as neurotransmitters, neuromodulators, and hormones. Neuropeptides are phylogenetically conserved and have been demonstrated to regulate numerous behaviors. They have been hypothesized to be pathologically involved in several psychiatric disorders, including schizophrenia. On the basis of preclinical data, numerous studies have sought to examine the role of neuropeptide systems in schizophrenia. This chapter reviews the clinical data, linking alterations in neuropeptide systems to the etiology, pathophysiology, and treatment of schizophrenia. Data for the following neuropeptide systems are included: arginine-vasopressin, cholecystokinin (CCK), corticotropin-releasing factor (CRF), interleukins, neuregulin 1 (NRG1), neurotensin (NT), neuropeptide Y (NPY), opioids, secretin, somatostatin, tachykinins, thyrotropin-releasing hormone (TRH), and vasoactive intestinal peptide (VIP). Data from cerebrospinal fluid (CSF), postmortem and genetic studies, as well as clinical trials are described. Despite the inherent difficulties associated with human studies (including small sample size, variable duration of illness, medication status, the presence of comorbid psychiatric disorders, and diagnostic heterogeneity), several findings are noteworthy. Postmortem studies support disease-related alterations in several neuropeptide systems in the frontal and temporal cortices. The strongest genetic evidence supporting a role for neuropeptides in schizophrenia are those studies linking polymorphisms in NRG1 and the CCKA receptor with schizophrenia. Finally, the only compounds that act directly on neuropeptide systems that have demonstrated therapeutic efficacy in schizophrenia are neurokinin receptor antagonists. Clearly, additional investigation into the role of neuropeptide systems in the etiology, pathophysiology, and treatment of schizophrenia is warranted.

Stress, the hippocampus and the hypothalamic-pituitary-adrenal axis: implications for the development of psychotic disorders

OBJECTIVE

The experience of stress is commonly implicated in models of the onset of psychotic disorders. However, prospective studies investigating associations between biological markers of stress and the emergence of psychotic disorders are limited and inconclusive. One biological system proposed as the link between the psychological experience of stress and the development of psychosis is the Hypothalamic-Pituitary-Adrenal (HPA) axis. This paper summarizes and discusses evidence supporting a role for HPA-axis dysfunction in the early phase of schizophrenia and related disorders.

METHOD

A selective review of psychiatric and psychological research on stress, coping, HPA-axis, the hippocampus and psychotic disorders was performed, with a particular focus on the relationship between HPA-axis dysfunction and the onset of psychotic disorders.

RESULTS

Individual strands of past research have suggested that the HPA-axis is dysfunctional in at least some individuals with established psychotic disorders; that the hippocampus is an area of the brain that appears to be implicated in the onset and maintenance of psychotic disorders; and that an increase in the experience of stress precedes the onset of a psychotic episode in some individuals. Models of the onset and maintenance of psychotic disorders that link these individual strands of research and strategies for examining these models are proposed in this paper.

CONCLUSIONS

The current literature provides some evidence that the onset of psychotic disorders may be associated with a higher rate of stress and changes to the hippocampus. It is suggested that future research should investigate whether a relationship exists between psychological stress, HPA-axis functioning and the hippocampus in the onset of these disorders. Longitudinal assessment of these factors in young people at 'ultra' high risk of psychosis and first-episode psychosis cohorts may enhance understanding of the possible interaction between them in the early phases of illness.

Some biological correlates of drug resistance in schizophrenia: a multidimensional approach

Drug resistance in schizophrenic disorders treated with an antipsychotic medication is highly problematic, lacking sound criteria to define it, and to discriminate between drug response and clinical remission. This article reviews some neurochemical, psychoimmunological, pharmacogenetic and neuromorphological patterns which can affect drug response and determine drug-resistance phenomena in schizophrenia. Several neurochemical abnormalities have been reported to be relevant for the pathogenesis of schizophrenic disorders and have been related to clinical symptoms as well as to the quality of response to antipsychotics: most of the findings come from studies on DA and 5HT brain metabolism, but more recently other non-dopaminergic pathways have been implicated (e.g., glutamatergic ones). Literature data suggest that schizophrenia may be associated with significant alterations of T-cell functions, showing the activation of the inflammatory response system (IRS), particularly in treatment-resistant schizophrenia, and differential effects on IRS have been reported for conventional and atypical antipsychotics. Furthermore molecular genetic approaches provide a novel method of dissecting the heterogeneity of psychotropic drug response, providing the means of determining the molecular substrates of drug efficacy and drug-induced adverse events. On the other hand, functional neuroimaging techniques, including single photon emission computed tomography (SPECT), positron emission tomography (PET) and functional magnetic resonance imaging (FMRI), providing an in vivo assessment of the expression and function of neuroreceptors, transporters and enzymes, seem to be particularly promising for a better understanding of 'real' drug resistance. Finally, a multidimensional approach taking into account all these variables in the future would likely be the more valuable strategy to optimise response, reducing relapses or resistant clinical situations.

Cortisol and cytokines in chronic and treatment-resistant patients with schizophrenia: association with psychopathology and response to antipsychotics

The bilateral communication between the immune and neuroendocrine systems plays an essential role in modulating the adequate response of the hypothalamic-pituitary-adrenal (HPA) axis to the stimulatory influence of cytokines and stress-related mediators. Growing evidence suggests that neuro-immune-endocrine crosstalk may be impaired in schizophrenia. We determined the relationship between cortisol, cytokines interleukin-2 (IL-2) and interleukin-6 (IL-6), and symptoms in schizophrenia during treatment with typical and atypical antipsychotic drugs. Subjects included 30 healthy controls (HC) and 78 schizophrenic (SCH) in-patients. SCH were randomly assigned to 12-week treatment with 6 mg/day of risperidone or 20 mg/day of haloperidol using a double-blind design. Clinical efficacy was determined using the Positive and Negative Syndrome Scale (PANSS). Serum cortisol and IL-2 levels were assayed by radioimmunometric assay, and serum IL-6 levels by quantitative enzyme-linked immunosorbent assay. Following a 2-week washout period, serum levels of cortisol, IL-2, and IL-6 were increased in patients with schizophrenia compared to HC. Elevations in cortisol were associated with increase in both IL-2 and IL-6 in SCH. Moreover, elevations in cortisol were associated with negative symptoms and IL-2 with positive symptoms. In all, 12 weeks of risperidone treatment significantly decreased elevated cortisol and improved negative symptoms, but produced similar effects on IL-2 and IL-6 as well as on positive symptoms compared to haloperidol. The improvement of negative symptoms was related to the change in cortisol. Our results suggest that the imbalance in the HPA axis and cytokine system in patients with SCH is implicated in clinical symptoms, and is improved with atypical antipsychotic treatment.

Prenatal exposure to a repeated variable stress paradigm elicits behavioral and neuroendocrinological changes in the adult offspring: potential relevance to schizophrenia

Exposure to stress during gestation induces marked changes in the behavior of the affected offspring. Examining the consequences of prenatal stress may prove useful in understanding more about the origins of schizophrenia because a number of clinical investigations have suggested that developmental insults are associated with an increased incidence of schizophrenia. The purpose of these studies is to investigate the effects of stress during gestation on the behaviors of the adult male rat offspring with an emphasis on developing a heuristic animal model of schizophrenia. Pregnant female Sprague-Dawley rats were exposed to a novel variable stress paradigm during either the second or third week of gestation. Behavioral and neuroendocrinological consequences of prenatal stress exposure were evaluated in the male offspring on postnatal day 35 or 56. Prenatal stress exposure during the third week of pregnancy caused adult male rats to exhibit prolonged elevation in plasma glucocorticoid levels following acute exposure to restraint stress indicative of diminished glucocorticoid negative feedback. Similarly, exposure to stress during the third week of pregnancy elicited an enhanced locomotor response to the psychomotor stimulant amphetamine on postnatal day 56 but not on postnatal day 35. In addition, prepulse inhibition of the acoustic startle response was diminished across a range of prepulse stimulus intensities in prenatally stressed adult male rats. Similarly, prenatally stressed rats showed evidence of a disruption in auditory sensory gating as measured by the N40 response. Taken together, these findings suggest that prenatal stress exposure significantly changed many facets of adult rat behavior. Interestingly, the behaviors that are altered have been used to validate animal models of schizophrenia and therefore, suggest that this preparation may be useful to learn more about some aspects of the pathophysiology of schizophrenia.

Different neuroendocrine profiles of remitted and nonremitted schizophrenic patients

BACKGROUND

Thyrotropin-releasing hormone (TRH) test and Dexamethasone Suppression Test (DST) are two neuroendocrine tests that have been extensively used in an attempt to predict treatment response and outcome in schizophrenia. The objectives of this study were to investigate (1) the relationship between TRH test and DST and various psychiatric symptoms and (2) the potential value of these tests in prediction of short-term outcome in schizophrenic patients.

METHODS

TRH test and DST were administered to 58 patients with schizophrenia. All patients were evaluated with a battery of rating scales before neuroendocrine test procedures and at regular intervals for 1 year. Patients were divided into two groups as remitted (RP; n = 30) and nonremitted patients (NRP; n = 28). Baseline results of these two groups were compared with each other and 30 healthy controls.

RESULTS

Basal levels of total T3 (T3T) and free T3 (T3F) were higher in RP group than controls. Basal prolactin (PRL) level was higher in RP group, but not in NRP, compared to controls. Basal growth hormone (GH) and thyroid-stimulating hormone (TSH) levels of NRP were significantly higher than those of RP. DST nonsuppression was observed at a significantly higher rate in RP than NRP and control group. Blunted TSH response rate in RP group was higher significantly compared to other two groups.

CONCLUSIONS

The data implicate that higher basal TSH and GH levels may be associated with a poorer treatment response, whereas higher total and free T3 levels, a blunted TSH response to TRH and nonsuppression on the DST may indicate a better response in schizophrenics.

Are cognitive symptoms of schizophrenia mediated by abnormalities in emotional arousal?

We tested 28 individuals with schizophrenia (SZ) and 16 healthy individuals on a test of logical reasoning and "cognitive gating," defined as the ability to discriminate between relevant and irrelevant information in confirming or disconfirming a given belief. The Logical Reasoning and Cognitive Gating Task tests both processes under neutral and affect-laden conditions. This is done by presenting formally identical constructs using benign and emotionally arousing language. When separated by symptom profiles, we found statistically significant differences for performance and arousal response between patients with delusions, patients with formal thought disorder, and patients with neither delusions nor formal thought disorder, as well as between patients and healthy controls. When analyzed by error type, we found that nearly all errors by delusional patients were caused by overly restrictive information choice, a pattern that may be related to a delusional patient's tendency to "jump to conclusions" on Bayesian probabilistic tasks. This is in contrast to patients with formal thought disorder, whose low performance resulted also from overly extensive information choice. The tendencies towards restriction were exacerbated by arousal, which is consistent with studies on cognition and arousal in healthy individuals. After briefly examining research on emotional arousal and SZ, and the interaction between emotional arousal and restriction of perceptual cues in healthy individuals, we conclude by suggesting a model which accounts for the distinctive cognitive characteristics of delusional patients by their possessing distinct vulnerabilities to emotional arousal. Specifically, these results suggest the possibility that delusional patients process information in a manner that is essentially intact. However, delusional patients may possess an acute vulnerability to emotional arousal that might cause delusional individuals to behave cognitively as if they were healthy individuals under significantly more severe forms of stress.

Could stress cause psychosis in individuals vulnerable to schizophrenia?

It has long been considered that psychosocial stress plays a role in the expression of symptoms in schizophrenia (SZ), as it interacts with latent neural vulnerability that stems from genetic liability and early environmental insult. Advances in the understanding of the neurobiology of the stress cascade in both animal and human studies lead to a plausible model by which this interaction may occur: through neurotoxic effects on the hippocampus that may involve synaptic remodeling. Of late, the neurodevelopmental model of SZ etiology has been favored. But an elaboration of this schema that credits the impact of postnatal events and considers a role for neurodegenerative changes may be more plausible, given the evidence for gene-environment interaction in SZ expression and progressive structural changes observed with magnetic resonance imaging. Furthermore, new insights into nongliotic neurotoxic effects such as apoptosis, failure of neurogenesis, and changes in circuitry lead to an expansion of the time frame in which environmental effects may mediate expression of SZ symptoms.

5-HT(1A) receptor dysfunction in female patients with schizophrenia

BACKGROUND

Serotonin (5-HT)(1A) receptors are of interest in the pathophysiology of schizophrenia (SCH) and the mechanism of action of atypical antipsychotic drugs. To test the hypothesis that 5-HT(1A) receptor responsivity is significantly different in patients with SCH compared to normal control subjects, the neuroendocrine study was performed using ipsapirone (IPS), a 5-HT(1A) partial agonist, as a probe.

METHODS

Ipsapirone 0.5 mg/kg, p.o. or placebo were administered, in random order, to patients with SCH (n = 43; 32 male) and normal controls (n = 33; 21 male). Blood samples for plasma cortisol and body temperature were obtained from 30 min before to 180 min after administration of IPS or placebo.

RESULTS

Female normal control subjects had markedly greater increases in plasma cortisol following IPS than did male control subjects. The placebo response-corrected plasma cortisol response to IPS was significantly blunted in female SCH compared to female normal control subjects (p =.0001). The IPS-stimulated plasma cortisol response in male SCH did not differ from that of male normal control subjects or female SCH. There were no significant differences in the IPS-induced hypothermia in men and women or between patients with SCH and normal control subjects. Behavioral responses to IPS, including nausea, dizziness, irritability, and feeling less well, did not differ between groups.

CONCLUSIONS

These results suggest that the post-synaptic 5-HT(1A) receptor mediated endocrine response is diminished in female SCH compared to female normal control subjects, possibly secondary to an abnormality in intracellular signal transduction mechanism.

The neurobiology of the stress cascade and its potential relevance for schizophrenia

This review explores the neurobiology of stress and its possible role in the etiology of schizophrenia. Major life events may play a role in onset and relapse in schizophrenia. Other data suggest that early stress exposure increases schizophrenia risk, especially in individuals with latent vulnerability. Animal research has led to an elucidation of the mechanisms by which stress and cortisol are toxic to the hippocampus and impair cognition. Associations among these factors have been found in a variety of human conditions, including psychiatric illness and normal aging. These mechanisms are plausible in schizophrenia, which is characterized by a degree of cortisol dysregulation, hippocampal abnormality, and cognitive impairment. Characterization of the role of the stress cascade in schizophrenia has implications for novel pharmacologic and other treatment, especially for cognitive symptoms, which are debilitating and largely refractory to treatment.

HPA axis and cytokines dysregulation in schizophrenia: potential implications for the antipsychotic treatment

The authors discuss literature evidence on the possible dysfunctioning of HPA axis and the inflammatory response system (IRS) in schizophrenia in relation to a more comprehensive bio-pathogenetic hypothesis of the disorder and to the development of specific clinical patterns or 'core' schizophrenic symptoms, like those included in the so called negative/depressive dimension. The dysfunctions of HPA axis and IRS could be linked to some neurodevelopmental damage in relevant brain areas like hippocampus and it could involve mainly the glutamatergic pathways (e.g. NMDA receptors). Moreover, these changes could have some predictive value for response to typical antipsychotics (specifically for negative symptoms and drug resistance) in schizophrenia. Finally, the differential activity of typical versus atypical antipsychotic compounds on the basic HPA axis and IRS dysregulations in schizophrenia could account, at least partly, for the better clinical stabilization achieved in patients treated with the latter drugs compared to those receiving conventional neuroleptics.

Biological predictors of 1-year outcome in schizophrenia in males and females

This paper describes a prospective study designed to ascertain the predictive value of biological factors associated with schizophrenia in males and females. In a sample of 59 medication-free schizophrenic inpatients (41 males; 18 females), we assessed the correlation of four factors--rapid eye movement (REM) sleep latency, delta (slow-wave) sleep, dexamethasone suppression test (DST) cortisol levels, and ventricle-brain ratio (VBR)--with several dimensions of outcome at 1-year post-discharge. In the total sample, shorter REM latency was associated with poor outcome on all dimensions measured: rehospitalization, employment, social activity, symptomatology, and global functioning. However, none of the other biological factors were associated with any measure of outcome. The predictive value of REM latency appeared to be gender-specific; in general, the relationships between reduced REM latency and poor outcome were consistently noted in females, but were not significant in males. These results suggest that a common, possibly gender-related, pathophysiological mechanism might underlie both abnormal REM latency and poor outcome. The findings underscore the importance of considering gender differences in studies of schizophrenia.

Negative symptoms of schizophrenia and the dexamethasone suppression test

The dexamethasone suppression test (DST) was administered to 30 inpatients who met the DSM-III-R criteria for chronic schizophrenia and shared similar environments. Four of them (13%) were DST nonsuppressors. The mean and maximum postdexamethasone cortisol levels were correlated with the patient's score on the scale for the Schedule for the Assessment of Negative Symptoms and with the score on the anergia subscale of the Brief Psychiatric Rating Scale. None of the correlations were statistically significant. Furthermore, the scores on the above scales were not significantly correlated with clinical variables such as duration of illness, number of admissions or length of hospitalization, nor were any significant correlations found between the postdexamethasone cortisol levels and the score on the Beck Depression Inventory. In addition, depressed and nondepressed schizophrenics did not differ regarding the rate of nonsuppression and the postdexamethasone cortisol levels. This study found that: 1) dexamethasone nonsuppression in schizophrenia was not related to the presence of negative symptoms; 2) there was no relationship between negative symptoms and illness variables; and 3) the depressed schizophrenics did not display increased nonsuppression compared with nondepressed schizophrenics.

Regional neuropathology in schizophrenia: where are we? Where are we going?

This paper presents a neurologic formulation for the clinical features of the schizophrenic syndrome, and tests it against a systematic, region by region review of available postmortem neuroanatomical and neuropharmacological data. Based on this review a model is proposed that postulates a developmental lesion affecting the midline neurotransmitter-specific ascending projection systems. Due to the facilitatory role these systems play in the development of the brain regions to which they project, such a lesion is one parsimonious, and testable, explanation for virtually all the clinical, laboratory, and pathological findings reported to date in schizophrenia research. A case is made for establishing a global antemortem-postmortem collaboration using a Latin square design; the alternative may be that, as has happened in the past, the best efforts of dilligent researchers around the world may lead to little improvement in our understanding of schizophrenia.

Post-dexamethasone cortisol levels and computerized tomographic findings in manic patients

The relations of post-dexamethasone cortisol levels to computerized tomography (CT) scan findings of lateral and third ventricle size and cortical sulcal prominence rated separately for frontal and parieto-occipital distributions were examined in 15 manic patients. Failure to suppress endogenous cortisol after a dexamethasone challenge was associated with larger third ventricles, but not to any of the other CT scan measures.

Dexamethasone target sites in the central nervous system and their potential relevance to mental illness

1. The topical distribution of tritiated dexamethasone (DEX), a potent synthetic glucocorticoid of widespread use in the diagnosis and assessment of mental illness, was studied in rat CNS by autoradiography to obtain information on potential target sites for feedback and other centrally mediated effects of glucocorticoids. 2. The cells of the arcuate nucleus of the hypothalamus and the lateral thalamic nuclei displayed the most concentrated nuclear accumulation of silver grains. 3. Significant accumulation, exceeding that found in the hippocampal formation, also occurred in the cells of the ventromedial, periventricular, and paraventricular nuclei of the hypothalamus, the locus ceruleus, the nucleus tractus solitarii, and the area postrema, none of which are targeted by corticosterone, the native glucocorticoid of the rat. 4. Nuclear accumulation of silver grains was prominent in neural and glial cells of the cerebral cortex, the olfactory nucleus, the dorsolateral septum, the amygdala, the subfornical organ, the lateral parabrachial, medial trapezoid, and dorsal reticular nuclei, the nucleus centralis of the raphe, the cerebellum, and vascular tissues. 5. The localization of DEX in hypothalamic and brain-stem nuclei coincided with that of the glucocorticoid receptor, possibly implicating these sites in direct or modulating effects of glucocorticoids in various forms of mental disturbance, including depression, anxiety, panic disorders, and alcohol withdrawal. 6. The extent to which various CNS regions targeted by DEX feature in negative feedback control of adrenocortical secretion remains to be defined, as does the site of impaired feedback disclosed by the dexamethasone suppression test in psychiatric patients.

Seasonal variations of the dexamethasone suppression test in depression compared with schizophrenia: a gender effect

The circannual results of the dexamethasone suppression test (DST) were compared in depressed and schizophrenic patients for the periods November-February and March-October. During the winter months, female depressive and schizophrenic patients had lower rates of DST nonsuppression as well as lower concentrations of post-dexamethasone plasma cortisol, compared to the March-October period, despite similar pre-dexamethasone cortisol levels. Male depressed patients had lower pre-dexamethasone cortisol levels during the winter months while male schizophrenics had higher pre- and post-dexamethasone cortisol levels and higher rates of DST nonsuppression. This may suggest less disturbance of HPA axis function in winter months in depressed patients, mostly females, and confirms findings from some previous studies. A gender effect of DST seasonality was also demonstrated, with male schizophrenic patients presenting a reverse DST nonsuppression pattern compared with female depressive and female schizophrenic patients.

Dexamethasone suppression test in schizophrenia: relationship to symptomatology, ventricular enlargement, and outcome

To relieve confusion about the clinical correlates and prognostic implications of the dexamethasone suppression test (DST) in schizophrenia, we conducted a DST in 44 schizophrenic inpatients at drug-free baseline and approximately 4 weeks after neuroleptic treatment. Patients were rated on positive, negative, and depressive symptoms at both times. A head computed tomography (CT) scan was performed and measures of ventricle-brain ratio (VBR) obtained. Clinical improvement was monitored at four weeks, and longer-term outcome assessed at 1 year. Seventeen of the 44 patients were DST nonsuppressors at baseline, and five of these remained nonsuppressors at 4 weeks posttreatment. Postdexamethasone plasma cortisol levels were correlated with negative symptoms at baseline (r = 0.45; p less than 0.01), but not after 4 weeks of neuroleptic treatment. Postdexamethasone plasma cortisols were not related to global severity, positive, or depressive symptoms at either timepoint or to VBR. Persistent nonsuppression was associated with poor outcome, but baseline postdexamethasone cortisol levels were unrelated to outcome at 4 weeks and 1 year. The literature on DST in schizophrenia is reviewed and attempts are made to reconcile discrepant findings and to discuss pathophysiological implications.