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

Taurine prevents MK-801-induced shoal dispersion and altered cortisol responses in zebrafish

Schizophrenia is a chronic neuropsychiatric disorder characterized by a shortened lifespan and significant impaired social and vocational functioning. Schizophrenic patients can present hypothalamic-pituitary-adrenal (HPA) axis dysfunctions and cortisol dysregulation, which play an important role on the etiology onset, exacerbation, and relapsing of symptoms. Based on its intrinsic neuroprotective properties, taurine is considered a promising substance with beneficial role on various brain disorders, including schizophrenia. Here, we evaluated the effects of taurine on shoaling behavior and whole-body cortisol levels in zebrafish treated with dizocilpine (MK-801), which elicits schizophrenia-like phenotypes in animal models. Briefly, zebrafish shoals (4 fish per shoal) were exposed to dechlorinated water or taurine (42, 150, or 400 mg/L) for 60 min. Then, saline (PBS, pH 7.4 or 2.0 mg/kg MK-801) were intraperitoneally injected and zebrafish behavior was recorded 15 min later. In general, MK-801 disrupted shoaling behavior and reduced whole-body cortisol levels in zebrafish. All taurine pretreatments prevented MK-801-induced increase in shoal area, while 400 mg/L taurine prevented the MK-801-induced alterations in neuroendocrine responses. Moreover, all taurine-pretreated groups showed increased geotaxis, supporting a modulatory role in the overall dispersion pattern of the shoal. Collectively, our novel findings show a potential protective effect of taurine on MK-801-induced shoal dispersion and altered neuroendocrine responses, fostering the use of zebrafish models to assess schizophrenia-like phenotypes.

Emerging therapeutic targets for schizophrenia: a framework for novel treatment strategies for psychosis

Introduction: Antipsychotic drugs are central to the treatment of schizophrenia, but their limitations necessitate improved treatment strategies. Multiple lines of research have implicated glutamatergic dysfunction in the hippocampus as an early source of pathophysiology in schizophrenia. Novel compounds have been designed to treat glutamatergic dysfunction, but they have produced inconsistent results in clinical trials. Areas covered: This review discusses how the hippocampus is thought to drive psychotic symptoms through its influence on the dopamine system. It offers the reader an evaluation of proposed treatment strategies including direct modulation of GABA or glutamate neurotransmission or reducing the deleterious impact of stress on circuit development. Finally, we offer a perspective on aspects of future research that will advance our knowledge and may create new therapeutic opportunities. PubMed was searched for relevant literature between 2010 and 2020 and related studies. Expert opinion: Targeting aberrant excitatory-inhibitory neurotransmission in the hippocampus and its related circuits has the potential to alleviate symptoms and reduce the risk of transition to psychosis if implemented as an early intervention. Longitudinal multimodal brain imaging combined with mechanistic theories generated from animal models can be used to better understand the progression of hippocampal-dopamine circuit dysfunction and heterogeneity in treatment response.

Immediate Early Genes Anchor a Biological Pathway of Proteins Required for Memory Formation, Long-Term Depression and Risk for Schizophrenia

While the causes of myriad medical and infectious illnesses have been identified, the etiologies of neuropsychiatric illnesses remain elusive. This is due to two major obstacles. First, the risk for neuropsychiatric disorders, such as schizophrenia, is determined by both genetic and environmental factors. Second, numerous genes influence susceptibility for these illnesses. Genome-wide association studies have identified at least 108 genomic loci for schizophrenia, and more are expected to be published shortly. In addition, numerous biological processes contribute to the neuropathology underlying schizophrenia. These include immune dysfunction, synaptic and myelination deficits, vascular abnormalities, growth factor disruption, and N-methyl-D-aspartate receptor (NMDAR) hypofunction. However, the field of psychiatric genetics lacks a unifying model to explain how environment may interact with numerous genes to influence these various biological processes and cause schizophrenia. Here we describe a biological cascade of proteins that are activated in response to environmental stimuli such as stress, a schizophrenia risk factor. The central proteins in this pathway are critical mediators of memory formation and a particular form of hippocampal synaptic plasticity, long-term depression (LTD). Each of these proteins is also implicated in schizophrenia risk. In fact, the pathway includes four genes that map to the 108 loci associated with schizophrenia: GRIN2A, nuclear factor of activated T-cells (NFATc3), early growth response 1 (EGR1) and NGFI-A Binding Protein 2 (NAB2); each of which contains the "Index single nucleotide polymorphism (SNP)" (most SNP) at its respective locus. Environmental stimuli activate this biological pathway in neurons, resulting in induction of EGR immediate early genes: EGR1, EGR3 and NAB2. We hypothesize that dysfunction in any of the genes in this pathway disrupts the normal activation of Egrs in response to stress. This may result in insufficient electrophysiologic, immunologic, and neuroprotective, processes that these genes normally mediate. Continued adverse environmental experiences, over time, may thereby result in neuropathology that gives rise to the symptoms of schizophrenia. By combining multiple genes associated with schizophrenia susceptibility, in a functional cascade triggered by neuronal activity, the proposed biological pathway provides an explanation for both the polygenic and environmental influences that determine the complex etiology of this mental illness.

Perceived stress and hair cortisol: Differences in bipolar disorder and schizophrenia

INTRODUCTION

Bipolar disorder (BD) and schizophrenia (SCZ) are psychiatric disorders with shared and distinct clinical and genetic features. In both disorders, stress increases the risk for onset or relapse and dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis has been reported. The latter is frequently investigated by measuring changes in the hormonal end product of the HPA axis, i.e., the glucocorticoid cortisol, whose concentration exhibits diurnal variation. The analysis of hair cortisol concentration (HCC) is a new method, which allows assessment of cumulative cortisol secretion over the preceding three months.

AIMS

To explore whether perceived stress and HCC: (i) differ between BD patients, SCZ patients, and controls; (ii) change over disease course; and iii) are associated with an increased genetic risk for BD or SCZ.

METHODS

159 SCZ patients, 61 BD patients and 82 controls were included. Assessment included psychopathology, perceived stress, and HCC. Inpatients with an acute episode (38 BD and 77 SCZ) were assessed shortly after admission to hospital and at 3 and 6 months follow-up. Outpatients in remission and controls were assessed at one time point only. Polygenic risk scores for BD and SCZ were calculated based on results of the Psychiatric Genomic Consortium.

RESULTS

(i) Perceived stress was higher in BD and SCZ patients compared to controls (p<0.02), and was lower in outpatients in remission compared to inpatients on admission. HCC was higher in BD patients compared to SCZ patients and controls (p<0.02), and higher in inpatients on admission than in outpatients in remission (p=0.0012). In BD patients (r=0.29; p=0.033) and SCZ patients (r=0.20; p=0.024) manic symptoms were correlated with HCC. (ii) In both BD and SCZ inpatients, perceived stress decreased over the 6 month study period (p=0.048), while HCC did not change significantly over the 6 month study period. (iii) In controls, but not in the patient groups, the genetic risk score for BD was associated with HCC (r=0.28, p=0.023).

CONCLUSIONS

While our results are consistent with previous reports of increased perceived stress in BD and SCZ, they suggest differential involvement of the HPA axis in the two disorders. The genetic study supports this latter finding, and suggests that this effect is present below the threshold of manifest disorder.

Association of SNPs in EGR3 and ARC with Schizophrenia Supports a Biological Pathway for Schizophrenia Risk

We have previously hypothesized a biological pathway of activity-dependent synaptic plasticity proteins that addresses the dual genetic and environmental contributions to schizophrenia. Accordingly, variations in the immediate early gene EGR3, and its target ARC, should influence schizophrenia susceptibility. We used a pooled Next-Generation Sequencing approach to identify variants across these genes in U.S. populations of European (EU) and African (AA) descent. Three EGR3 and one ARC SNP were selected and genotyped for validation, and three SNPs were tested for association in a replication cohort. In the EU group of 386 schizophrenia cases and 150 controls EGR3 SNP rs1877670 and ARC SNP rs35900184 showed significant associations (p = 0.0078 and p = 0.0275, respectively). In the AA group of 185 cases and 50 controls, only the ARC SNP revealed significant association (p = 0.0448). The ARC SNP did not show association in the Han Chinese (CH) population. However, combining the EU, AA, and CH groups revealed a highly significant association of ARC SNP rs35900184 (p = 2.353 x 10⁻⁷; OR [95% CI] = 1.54 [1.310–1.820]). These findings support previously reported associations between EGR3 and schizophrenia. Moreover, this is the first report associating an ARC SNP with schizophrenia and supports recent large-scale GWAS findings implicating the ARC complex in schizophrenia risk. These results support the need for further investigation of the proposed pathway of environmentally responsive, synaptic plasticity-related, schizophrenia genes.

Htr2a Expression Responds Rapidly to Environmental Stimuli in an Egr3-Dependent Manner

Pharmacologic and genetic findings have implicated the serotonin 2A receptor (5-HT2AR) in the etiology of schizophrenia. Recent studies have shown reduced 5-HT2AR levels in schizophrenia patients, yet the cause of this difference is unknown. Environmental factors, such as stress, also influence schizophrenia risk, yet little is known about how environment may affect this receptor. To determine if acute stress alters 5-HT2AR expression, we examined the effect of sleep deprivation on cortical Htr2a mRNA in mice. We found that 6 h of sleep deprivation induces a twofold increase in Htr2a mRNA, a more rapid effect than has been previously reported. This effect requires the immediate early gene early growth response 3 (Egr3), as sleep deprivation failed to induce Htr2a expression in Egr3-/- mice. These findings provide a functional link between two schizophrenia candidate genes and an explanation of how environment may influence a genetic predisposition for schizophrenia.

The neurobiology of relapse in schizophrenia

Dopamine's proposed role in psychosis proved a starting point in our understanding of the neurobiology of relapse, fitting given the central role positive symptoms play. This link is reflected in early work examining neurotransmitter metabolite and drug (e.g. amphetamine, methylphenidate) challenge studies as a means of better understanding relapse and predictors. Since, lines of investigation have expanded (e.g. electrophysiological, immunological, hormonal, stress), an important step forward if relapse per se is the question. Arguably, perturbations in dopamine represent the final common pathway in psychosis but it is evident that, like schizophrenia, relapse is heterogeneous and multidimensional. In understanding the neurobiology of relapse, greater gains are likely to be made if these distinctions are acknowledged; for example, efforts to identify trait markers might better be served by distinguishing primary (i.e. idiopathic) and secondary (e.g. substance abuse, medication nonadherence) forms of relapse. Similarly, it has been suggested that relapse is 'neurotoxic', yet individuals do very well on clozapine after multiple relapses and the designation of treatment resistance. An alternative explanation holds that schizophrenia is characterized by different trajectories, at least to some extent biologically and/or structurally distinguishable from the outset, with differential patterns of response and relapse. Just as with schizophrenia, it seems naïve to conceptualize the neurobiology of relapse as a singular process. We propose that it is shaped by the form of illness and in place from the outset, modified by constitutional factors like resilience, as well as treatment, and confounded by secondary forms of relapse.

Schizophrenia: from epidemiology to rehabilitation

Purpose/Objective:

We discuss recent evidences about schizophrenia (frequency, onset, course, risk factors and genetics) and their influences to some epidemiological myths about schizophrenia diffuse between psychiatric and psychopathology clinicians. The scope is to evaluate if the new acquisitions may change the rehabilitation approaches to schizophrenia modifying the balance about the neurodevelopmental hypothesis of schizophrenia accepting that the cognitive deficits are produced by errors during the normal development of the brain (neurodevelopmental hypothesis) that remains stable in the course of illness and the neurodegenerative hypothesis according of which they derived from a degenerative process that goes on inexorably.

Research Method/Design:

A review of the literature about epidemiology of schizophrenia has been performed and the contributions of some of these evidence to neurodevelopmental hypothesis and to rehabilitation has been described.

Results:

It cannot be definitively concluded for or against the neurodevelopmental or degenerative hypothesis, but efforts in understanding basis of schizophrenia must go on. Until now, rehabilitation programs are based on the vulnerability-stress model: supposing an early deficit that go on stable during the life under favorable circumstances. So, rehabilitation approaches (as neuro-cognitive approaches, social skill training, cognitive-emotional training) are focused on the individual and micro-group coping skills, aiming to help people with schizophrenia to cope with environmental stress factors.

Conclusions/Implications:

Coping of cognitive deficits in schizophrenia may represents the starting-point for further research on schizophrenia, cohort studies and randomized trials are necessary to defined the range of effectiveness and the outcome of the treatments.

Sex-specific cortisol levels in bipolar disorder and schizophrenia during mental challenge--relationship to clinical characteristics and medication

OBJECTIVE

Our objective was to examine the cortisol release during a mental challenge in severe mental disorders versus healthy controls (HC), analyzing effects of sex, clinical characteristics and medication, and comparing Bipolar Disorder (BD) to Schizophrenia (SCZ).

METHODS

Patients with BD and SCZ (n=151) were recruited from a catchment area. HC (n=98) were randomly selected from the same area. Salivary samples were collected before and after a mental challenge and cortisol levels determined.

RESULTS

During the challenge there was an interaction between group and sex (P = 0.015) with male patients having a blunted cortisol release compared to male HC (P = 0.037). Cortisol change did not differ significantly between BD and SCZ. In all patients, the cortisol change correlated with number of psychotic episodes (r = -0.23, P = 0.025), and in females patients, with number of depressive episodes (r = -0.33, P = 0.015). Patients using antidepressants had a greater cortisol release during challenge than those not using antidepressants (P = 0.043).

CONCLUSIONS

Male patients with severe mental disorders seem to have a uniform abnormal cortisol release during mental challenges which associates with clinical course, and with beneficial effects of antidepressants.

Posttraumatic stress disorder and negative symptoms of schizophrenia

Posttraumatic stress disorder (PTSD) is highly comorbid with schizophrenia and may be associated with higher levels or lower levels of negative symptoms. In the current study, we attempted to clarify the relationship between PTSD and negative symptoms by examining the proportion of patients meeting various negative symptom criteria in a sample of patients diagnosed with schizophrenia alone or schizophrenia and comorbid PTSD. Results indicated that the presence of PTSD in schizophrenia was associated with increased secondary negative symptoms, with the deficit syndrome (DS) and primary negative symptoms associated with lower rates of current and lifetime diagnoses of PTSD. Furthermore, the deficit/nondeficit classification provided greater differentiation of PTSD symptoms than did negative symptoms defined more broadly using the Scale for the Assessment of Negative Symptoms or primary vs secondary distinctions. These findings suggest that DS patients are at a uniquely low risk for PTSD.

Multiple 'hits' during postnatal and early adulthood periods disrupt the normal development of sensorimotor gating ability in rats

In the present study, we evaluated a multiple-hit animal model of schizophrenia in an attempt to capture the complex interactions among various adverse developmental factors in schizophrenia. Sprague-Dawley rats were assigned to receive either repeated daily 3-h maternal separation for eight days (first 'hit') on postnatal days (PND) 3 to 10, and/or avoidance conditioning for six days (second 'hit') on PND 49-56, and/or repeated phencyclidine treatment (third 'hit', 3.0 mg/kg, sc) immediately after each daily avoidance conditioning. Prepulse inhibition (PPI) of acoustic startle reflex was assessed at late adolescence (PND 41-43) and early adulthood (PND 62-63). The change in %PPI from the adolescence phase to adulthood phase was used to index the maturation-related improvement of sensorimotor gating ability. Maternal separation, avoidance conditioning and PCP treatment had a complex three-way interaction on the functional improvement of sensorimotor gating. Maternal separation impaired PPI improvement preferentially in the saline rats that were not subjected to avoidance conditioning. Avoidance conditioning had no effect on PPI improvement in the non-maternally separated rats, but restored the maternal separation-induced disruption. However, this restoration effect was abolished by PCP treatment. The present study also identified a number of behavioral, emotional and learning abnormalities caused by these three developmental insults which may precede their interactive disruption of normal development of sensorimotor gating ability.

The dreaming brain/mind, consciousness and psychosis

Several independent lines of research in neurobiology seem to support the phenomenologically-grounded view of the dreaming brain/mind as a useful model for psychosis. Hallucinatory phenomena and thought disorders found in psychosis share several peculiarities with dreaming, where internally generated, vivid sensorimotor imagery along with often heightened and incongruous emotion are paired with a decrease in ego functions which ultimately leads to a severe impairment in reality testing. Contemporary conceptualizations of severe mental disorders view psychosis as one psychopathological dimension that may be found across several diagnostic categories. Some experimental data have shown cognitive bizarreness to be equally elevated in dreams and in the waking cognition of acutely psychotic subjects and in patients treated with pro-dopaminergic drugs, independent of the underlying disorder. Further studies into the neurofunctional underpinnings of both conditions will help to clarify the use and validity of this model.

Cortisol response to a psychosocial stressor in schizophrenia: blunted, delayed, or normal?

BACKGROUND

Patients with schizophrenia may differ from healthy controls by having dysregulated physiological responses to stress. Our objective was to determine the extent to which cortisol reaction can discriminate between controls and schizophrenia patients while controlling for symptom severity, personality, body mass index (BMI) and smoking.

METHOD

30 chronic schizophrenia patients and 30 matched controls underwent a modified version of the Trier Social Stress Test (TSST), consisting of public speaking and mental arithmetic. Heart rate, blood pressure, and salivary cortisol were measured repeatedly throughout the TSST. In addition, participants completed the NEO Personality Inventory (NEO-FFI), and were interviewed with the Brief Psychiatric Rating Scale (BPRS).

RESULTS

Both groups had a significant increase in heart rate and mean arterial pressure following the TSST. Results of a logistic regression suggests that patients can be discriminated from controls with a smaller change in cortisol between baseline and 15 min post-TSST, controlling for BMI and severity of positive symptoms. There was a trend for lower overall cortisol secretion in patients.

CONCLUSIONS

Despite demonstrable effects of the stressor on cardiac measures, schizophrenia patients tend to have smaller acute cortisol reaction to psychosocial stress. The significance of this conclusion for vulnerability-stress models of schizophrenia is discussed.

Stress and health

The impact of stress on physical functioning (endocrine, gastrointestinal, immune, and cardiovascular systems) is reviewed. The effect of stress on psychiatric functioning and health behaviors also is discussed. The importance of stress screening in primary care is emphasized, and several methods of stress reduction (including exercise, cognitive-behavioral therapy, and mindfulness-based stress reduction) appropriate to primary care settings are described.

Does reactivity to stress cosegregate with subclinical psychosis? A general population twin study

OBJECTIVE

This study assessed the relationship between stress reactivity (trait 1) and psychosis (trait 2) across genetically related persons (cross-twin, cross-trait design) to examine whether stress reactivity is an uncontaminated and unconfounded familial marker of psychosis risk.

METHOD

Reactivity to stress and subclinical psychotic experiences were assessed in 289 female, general population twin-pairs. Cross-trait, within-twin associations investigating the association between stress reactivity and subclinical psychotic experiences in each person, were calculated. In addition, cross-trait, cross-twin associations were calculated to assess whether stress reactivity in one twin was moderated by subclinical psychotic experiences in the co-twin.

RESULTS

Cross-trait, within-twin analyses showed significant associations between stress reactivity and subclinical psychotic experiences in each person. In addition, the cross-trait cross-twin analyses showed that stress reactivity in twin 1 was significantly moderated by subclinical experiences in the co-twin.

CONCLUSION

The results suggest that the psychosis phenotype cosegregates with increased emotional reactivity to stress in daily life.

Patterns of stress in schizophrenia

Although it is widely recognized that stress plays a key role in the pathophysiology of schizophrenia, little is known regarding the particular types of stress patients experience. Less is known about the interplay among stressful events, personality mediators, and emotional responses. In this study, we investigated 10 stress dimensions in 29 patients with schizophrenia and 36 healthy volunteers using the Derogatis Stress Profile (DSP), and the relationship between these dimensions and symptoms in patients. Overall, patients had an approximate 0.75 standard deviation increase in stress compared with healthy volunteers. Significant increases in stress among patients compared with healthy volunteers were observed specifically in areas related to domestic environment, driven behavior, and depression, but not in health, attitude posture, time pressure, relaxation potential, role definition, hostility, or anxiety. More DSP-rated depression among patients correlated significantly with greater negative symptom severity. Patients with a shorter duration of antipsychotic drug exposure had significantly greater hostility than did patients with a longer duration of exposure, but did not differ in any other dimension. Continued investigation of domestic environmental stressors, driven behavior, and depression may be useful in identifying high-risk groups, and understanding symptom exacerbation and precipitants of relapse in patients already diagnosed with schizophrenia.

Repeated stress alters dendritic spine morphology in the rat medial prefrontal cortex

Anatomical alterations in the medial prefrontal cortex (mPFC) are associated with hypothalamopituitary adrenal (HPA) axis dysregulation, altered stress hormone levels, and psychiatric symptoms of stress-related mental illnesses. Functional imaging studies reveal impairment and shrinkage of the mPFC in such conditions, and these findings are paralleled by experimental studies showing dendritic retraction and spine loss following repeated stress in rodents. Here we extend this characterization to how repeated stress affects dendritic spine morphology in mPFC through the utilization of an automated approach that rapidly digitizes, reconstructs three dimensionally, and calculates geometric features of neurons. Rats were perfused after being subjected to 3 weeks of daily restraint stress (6 hours/day), and intracellular injections of Lucifer Yellow were made in layer II/III pyramidal neurons in the dorsal mPFC. To reveal spines in all angles of orientation, deconvolved high-resolution confocal laser scanning microscopy image stacks of dendritic segments were reconstructed and analyzed for spine volume, surface area, and length using a Rayburst-based automated approach (8,091 and 8,987 spines for control and stress, respectively). We found that repeated stress results in an overall decrease in mean dendritic spine volume and surface area, which was most pronounced in the distal portion of apical dendritic fields. Moreover, we observed an overall shift in the population of spines, manifested by a reduction in large spines and an increase in small spines. These results suggest a failure of spines to mature and stabilize following repeated stress and are likely to have major repercussions on function, receptor expression, and synaptic efficacy.

Marital status and variability in cortisol excretion in postmenopausal women

Based on the premise that acute and chronic stresses stimulate and suppress cortisol secretion, respectively, and the hypothesis that marriage provides a buffer to stress, we tested whether extreme values of serum cortisol concentrations would be less likely in married women than in unmarried women. Three hundred women were recruited from two central Connecticut communities. Cortisol was measured in overnight urine samples using liquid chromatography-tandem mass spectrometry. Information on each subject's demographic characteristics, such as income and education level was collected. Mean log urinary cortisol was virtually identical in married and unmarried women, however, as predicted, the variance was significantly larger in the unmarried group (p=0.01). After adjustment for potential confounders, multivariate logistic regression still revealed that absolute deviation of log(10) cortisol from the mean was smaller for married versus unmarried women (p<0.01); deviation from the mean cortisol was also higher for non-working than working women. These results support the idea that marriage and employment reduce the extreme levels of cortisol secretion, and by extension, this may reflect differences in levels of stress in married and in working women compared to unmarried and non-working women.

Adaptogenic potential of a polyherbal natural health product: report on a longitudinal clinical trial

Stress is a risk factor for a number of diseases and is an important predictor of health in general. Herbal medicines have been used as adaptogens to regulate and improve the stress response and there is evidence to support the use of herbal medicines for this purpose. We conducted an open-label longitudinal study on the natural health product, OCTA(c), a compound mixture of eight herbs, to determine its effects on perceptions of stress. Eighteen participants were enrolled in the study and were followed over a period of 3 months. Primary endpoints included scores from four validated questionnaires (SF-36v2, PSS, STAI and BDI-II), serum DHEA, ALT, AST and creatinine all measured at 12 weeks. Seventeen patients completed the study. Except for the physical summary score of the SF36 questionnaire, all the subjective scores indicated a highly significant (P < 0.0001) improvement in the participants' ability to cope with stress. No adverse effects were reported and there was no evidence of damage to the liver or kidney based on serum markers. Initial evidence for this polyherbal compound supports its potential as an effective 'adaptogenic' aid in dealing with stress. Further research using a randomized controlled design is necessary to confirm the findings from this pilot study.

Neurocognitive deterioration in elderly chronic schizophrenia patients with and without PTSD

Neurocognitive deficits are associated with chronic schizophrenia and aging. We investigated whether elderly chronic schizophrenia inpatients who also suffer from posttraumatic stress disorder (PTSD) have more severe cognitive impairment than elderly schizophrenia inpatients that do not. Fourteen schizophrenia inpatients that are Holocaust survivors and suffer from PTSD (survivor group) were compared with schizophrenia inpatients not exposed to the holocaust and without PTSD (comparison group) using neurocognitive assessments and psychiatric evaluation instruments. The survivors performed significantly worse on measures of processing speed and visual scanning, recognition memory, and general mental status, than the comparison group. Though nonsignificantly, the comparison group revealed better performance on tests that measured visuospatial perception, visuospatial planning and strategies, organizational and constructional skills. The survivor group displayed a greater severity of antipsychotic-induced side effects that were not associated with differences in cognitive performance. Comorbid PTSD may contribute to the severity of neurocognitive impairment in elderly chronic schizophrenia patients.

Cholinergic circuits and signaling in the pathophysiology of schizophrenia

Central cholinergic signaling has long been associated with aspects of memory, motivation, and mood, each affected functions in neuropsychiatric disorders such as schizophrenia. In this chapter, we review evidence related to the core hypothesis that dysregulation of central cholinergic signaling contributes to the pathophysiology of schizophrenia. Although central cholinergic circuits are resistant to simplification-particularly when one tries to parse the contributions of various classes of cholinergic receptors to disease related phenomena--the potential role of ACh signaling in Schizophrenia pathophysiology deserves careful consideration for prospective therapeutics. The established role of cholinergic circuits in attentional tuning is considered along with recent work on how the patterning of cholinergic activity may modulate corticostriatal circuits affected in schizophrenia.

Immunological stress at the maternal-foetal interface: a link between neurodevelopment and adult psychopathology

Maternal infection during pregnancy is associated with a higher incidence of mental disorders, including schizophrenia, in the offspring in later life. Our recent attempt to study this link between prenatal immunological challenge and subsequent psychopathology has led to the establishment of a mouse model demonstrating the emergence of multiple psychotic-like phenotypes following immunological challenge on gestation day (GD) 9. However, little is known about the impact of similar in utero challenge at different times of pregnancy. Here, we compare the efficacy of identical maternal immune stimulation induced by the exposure to polyriboinosinic-polyribocytidilic acid (Poly(I:C)) at a dose of 5mg/kg (i.v.) on distinct days of gestation (GD 6, 9, 13 or 17). The offspring derived were then compared to those collected from vehicle- and non-treated dams in two paradigms of selective associative learning: latent inhibition (LI) and the US-pre-exposure effect (USPEE). LI deficiency was observed in animals born to dams treated with Poly(I:C) on GD 6, 9 or 13, but not in those on GD17. In contrast, a loss of the USPEE was equivalently seen in all Poly(I:C) treatment groups, regardless of treatment times. Evaluation of the acute cytokine response in a separate cohort of pregnant dams receiving Poly(I:C) challenge on either GD9 or GD17 revealed that the ratio of interleukin-10/tumor necrosis factor-alpha was elevated in the GD17 relative to the GD9 group. The present report thus provides evidence that the acute cytokine reaction as well as the long-term pattern of behavioural sequelae of maternal immune challenge can be affected by its precise timing during pregnancy. The present study provides further support to the use of the prenatal Poly(I:C) model in the elucidation of mechanisms involved in the aetiology and disease process of immuno-precipitated neurodevelopmental mental diseases, including but not limited to, schizophrenia.

Identifying vulnerability markers in prodromal patients: a step in the right direction for schizophrenia prevention

Research has shown that many of the long-term deficits that are observable in schizophrenia populations are present prior to the emergence of psychotic symptoms. Recent research suggests schizophrenia has a "prodromal" period, whereby significant changes from premorbid functioning can be observed. Accurate classification of this period could have far-reaching implications for schizophrenia prevention. This article aims to provide an indepth evaluation of the perceived benefits of vulnerability marker research in this unique phase. It is hoped that identification of such markers may improve the predictive potency of prodromal criteria, and perhaps pave the way for future screening and primary prevention strategies.

Prediction and prevention of transition to psychosis in young people at incipient risk for schizophrenia

The treatment of psychotic disorders, particularly schizophrenia, had been viewed with pessimism until a recent shift in focus from established or chronic illness to earlier phases of illness around the onset highlighted opportunities for enhanced recovery. Associated with this change in focus of research and clinical efforts has been the recognition that the biological and social changes underpinning the development of psychotic disorders may already be active in the pre-psychotic or prodromal phase. It has therefore been suggested that efforts toward the prevention of psychotic disorders should focus on the emerging illness. This article provides a review of work that has been conducted at the PACE Clinic in Melbourne, Australia since 1994. This clinical research program was established to develop strategies for the identification of young people at high risk of developing a psychotic disorder within a short period of time- primarily by virtue of recent mental state changes. Additionally, biological and psychological processes that have been proposed to underlie the development of illness have been investigated and potential preventive interventions have been evaluated.

The PACE Clinic: identification and management of young people at "ultra" high risk of psychosis

Over the past decade, both clinical and research interest in the early stages of psychotic disorders has grown. This has been associated with research suggesting that early intervention in these disorders may limit their impact on the life of the affected individual and his or her family. It has also been recognized that the biological and psychological changes underpinning the development of psychotic disorders may already be active in the prepsychotic or prodromal phase. It has been suggested that efforts to prevent psychotic disorders should be focused on this phase of emerging illness. In this article, the authors review work conducted at the PACE Clinic in Melbourne, Australia since 1994. This clinical research program was established to develop strategies for identifying young people at high risk for developing a psychotic disorder within a short period. The program has also investigated biological and psychological processes thought to underlie the development of psychosis and evaluated potential preventive interventions.

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.