Psychosocial stress and psychosis. A review of the neurobiological mechanisms and the evidence for gene-stress interaction

Disruption of the neuregulin 1 gene in the rat alters HPA axis activity and behavioral responses to environmental stimuli

Exposure to stress can result in an increased risk for psychiatric disorders, especially among genetically predisposed individuals. Neuregulin 1 (NRG1) is a susceptibility gene for schizophrenia and is also associated with psychotic bipolar disorder. In the rat, the neurons of the hypothalamic paraventricular nucleus show strong expression of Nrg1 mRNA. In patients with schizophrenia, a single nucleotide polymorphism in the 5' region of NRG1 interacts with psychosocial stress to affect reactivity to expressed emotion. However, there is virtually no information on the role of NRG1 in hypothalamic-pituitary-adrenal axis function, and whether the protein is expressed in the paraventricular nucleus is unknown. The present studies utilize a unique line of Nrg1 hypomorphic rats (Nrg1(Tn)) generated by gene trapping with the Sleeping Beauty transposon. We first established that the Nrg1(Tn) rats displayed reduced expression of both the mRNA and protein corresponding to the Type II NRG1 isoform. After confirming, using wild type animals, that Type II NRG1 is expressed in the neurocircuitry involved in regulating hypothalamic-pituitary-adrenal axis responses to environmental stimuli, the Nrg1(Tn) rats were then used to test the hypothesis that altered expression of Type II NRG1 disrupts stress regulation and reactivity. In support of this hypothesis, Nrg1(Tn) rats have disrupted basal and acute stress recovery corticosterone secretion, differential changes in expression of glucocorticoid receptors in the pituitary, paraventricular nucleus and hippocampus, and a failure to habituate to an open field. Together, these findings point to NRG1 as a potential novel regulator of neuroendocrine responses to stress as well as behavioral reactivity.

Investigation of shared genetic effects for psychotic and obsessive symptoms in young adult twins

Genetic and environmental architecture of psychotic and obsessive symptoms are not completely elucidated. This study estimated for these symptoms (i) the genetic and environmental components, (ii) the within-individual association, and (iii) the extent to which this association originates from common genetic and environmental factors. Young adult twins (N=701) from the population-based Italian Twin Register were assessed for psychotic and obsessive-compulsive symptoms by using the Symptom Check List (SCL-90). Multivariate Cholesky models were fitted by the Mx statistical program. No previous study used this design to examine the same dimensions. The best-fitting model included additive genetic and nonshared environmental components, each accounting for about half of total variance in the symptoms. Genetic influences on the different symptoms overlapped considerably (r(g)=0.81 to 0.99). Phenotypic correlations of psychotic symptoms and of psychotic with obsessive symptoms were high (r=0.61 to 0.76), with 53% to 69% explained by shared genetic effects. This study shows substantial genetic influence on psychotic and obsessive symptoms, and indicates that their co-occurrence may be due to genetic factors to a greater extent than to environmental effects. These results encourage the search for genetic and environmental factors underlying the covariance between different psychotic traits as well as between psychotic and obsessive traits.

Childhood abuse, the BDNF-Val66Met polymorphism and adult psychotic-like experiences

BACKGROUND

The well-established relationship between childhood adversity and psychosis is likely to involve other factors such as genetic variants that can help us to understand why not everyone exposed to adverse events develops psychotic symptoms later in life.

AIMS

We investigated the influence of childhood abuse and neglect on positive and negative psychotic-like experiences in adulthood and the potential moderating effect of the BDNF-Val66Met polymorphism.

METHOD

Psychotic-like experiences and childhood adversity were assessed in 533 individuals from the general population.

RESULTS

Childhood abuse showed a strong independent effect on the positive dimension of psychotic-like experiences (β = 0.16, s.e. = 0.05, P = 0.002). Furthermore, this association was moderated by the BDNF-Val66Met polymorphism (β = 0.27, s.e. = 0.10, P = 0.004).

CONCLUSIONS

Individuals exposed to childhood abuse are more likely to report positive psychotic-like experiences. Met carriers reported more positive psychotic-like experiences when exposed to childhood abuse than did individuals carrying the Val/Val genotype. Therefore, the observed gene-environment interaction effect may be partially responsible for individual variation in response to childhood abuse.

A twin study of genetic and environmental determinants of abnormal persistence of psychotic experiences in young adulthood

Evidence suggests that subclinical psychotic experiences are more likely to cause transition to psychotic disorder if their expression becomes persistent. The study of longitudinal patterns of subclinical psychotic experiences may help to distinguish subgroups with transient and persistent psychotic symptoms, who may differ in risk of later psychosis. The current study investigated patterns of developmental course of subclinical psychotic experiences in a general population sample of 566 female twins, aged 18-45 years. The positive symptoms subscale of the Community Assessment of Psychic Experiences (CAPE), completed three times in 2 years, was analyzed with growth modeling. Using Latent Class Analysis, two developmental courses were distinguished: a Persistent and a Low (expression of subclinical psychotic experiences) group. The Persistent group reported significantly higher levels of depressive and negative symptoms and worse functioning in daily life. Childhood trauma (OR: 3.26, P < 0.0001) and stressful life events over the study period (OR: 3.15, P = 0.031) predicted membership of the Persistent group. Of the monozygotic (MZ) twins with their co-twin in the Persistent group, 49% also were in the Persistent group themselves (OR: 9.32, P < 0.0001), compared to only 14% in the dizygotic (DZ) co-twins (OR: 1.56, P = 0.42) (χ(2)(2) = 22.97; P < 0.001). The findings suggest that persistence of subclinical psychosis is influenced by both genetic and environmental factors, providing the possibility to study the (possibly modifiable) etiology underlying the longitudinal process of persistence of the early expression of psychosis liability.

Aripiprazole inhibits superoxide generation from phorbol-myristate-acetate (PMA)-stimulated microglia in vitro: implication for antioxidative psychotropic actions via microglia

Altered antioxidant status has been implicated in schizophrenia. Microglia, major sources of free radicals such as superoxide (•O(2)(-)), play crucial roles in various brain pathologies. Recent postmortem and imaging studies have indicated microglial activation in the brain of schizophrenic patients. We previously demonstrated that atypical antipsychotics including aripiprazole significantly inhibited the release of nitric oxide and proinflammatory cytokines from interferon-γ-stimulated microglia in vitro. Antioxidative effects of antipsychotics via modulating microglial superoxide generation have never been reported. Therefore, we herein investigated the effects of antipsychotics on the •O(2)(-) generation from phorbol-myristate-acetate (PMA)-stimulated rodent microglia by the electron spin resonance (ESR) spectroscopy and also examined the intracellular mechanism by intracellular Ca(2+) imaging and immunostaining. Neuronal damage induced by microglial activation was also investigated by the co-culture experiment. Among various antipsychotics, only aripiprazole inhibited the •O(2)(-) generation from PMA-stimulated microglia. Aripiprazole proved to inhibit the •O(2)(-) generation through the cascade of protein kinase C (PKC) activation, intracellular Ca(2+) regulation and NADPH oxidase activation via cytosolic p47(phox) translocation to the plasma/phagosomal membranes. Formation of neuritic beading, induced by PMA-stimulated microglia, was attenuated by pretreatment of aripiprazole. D2R antagonism has long been considered as the primary therapeutic action for schizophrenia. Aripiprazole with D2R partial agonism is effective like other antipsychotics with fewer side effects, while aripiprazole's therapeutic mechanism itself remains unclear. Our results imply that aripiprazole may have psychotropic effects by reducing the microglial oxidative reactions and following neuronal reactions, which puts forward a novel therapeutic hypothesis in schizophrenia research.

Mouse models of genetic effects on cognition: relevance to schizophrenia

Cognitive dysfunction is a core feature of schizophrenia. Growing evidence indicates that a wide variety of genetic mutations and polymorphisms impact cognition and may thus be implicated in various aspects of this mental disorder. Despite differences between human and rodent brain structure and function, genetic mouse models have contributed critical information about brain mechanisms involved in cognitive processes. Here, we summarize discoveries of genetic modifications in mice that impact cognition. Based on functional hypotheses, gene modifications within five model systems are described: 1) dopamine (D1, D2, D3, D4, D5, DAT, COMT, MAO); 2) glutamate (GluR-A, NR1, NR2A, NR2B, GRM2, GRM3, GLAST); 3) GABA (α(5), γ(2), α(4), δGABA(A), GABA(B(1)), GAT1); 4) acetylcholine (nAChRβ2, α7, CHRM1); and 5) calcium (CaMKII-α, neurogranin, CaMKKβ, CaMKIV). We also consider other risk-associated genes for schizophrenia such as dysbindin (DTNBP1), neuregulin (NRG1), disrupted-in-schizophrenia1 (DISC1), reelin and proline dehydrogenase (PRODH). Because of the presumed importance of environmental factors, we further consider genetic modifications within the stress-sensitive systems of corticotropin-releasing factor (CRF), brain-derived neurotrophic factor (BDNF) and the endocannabinoid systems. We highlight the missing information and limitations of cognitive assays in genetically modified mice models relevant to schizophrenia pathology.

Synergistic pathways to delusions: enduring vulnerabilities, proximal life stressors and maladaptive psychological coping

AIM

We sought to extend findings on the vulnerability to psychosis by investigating multifactorial pathways to delusions. Risk factors assessed spanned across early acquired vulnerabilities (heredity, childhood trauma, early cannabis use), proximal life stressors (life hassles, methamphetamine use) and psychological coping (experiential avoidance).

METHODS

Participants were recruited to a non-clinical sample (n = 133) or a clinical sample of psychosis patients (n = 100).

RESULTS

Path analyses indicated three distinct pathways predicting vulnerability to delusions in the non-clinical sample: (i) childhood emotional trauma combined with subsequent experiences of life hassles; (ii) heredity in combination with experiential avoidance; and (iii) early cannabis use combined with proximal methamphetamine use. The first pathway was partially mediated by experiential avoidance. The model was largely replicated in the clinical sample, with childhood sexual trauma replacing emotional trauma in the model.

CONCLUSION

The study demonstrated that vulnerability to delusions can be usefully predicted by a synergistic model incorporating early-acquired vulnerability factors, proximal day-to-day factors and cognitive styles.

Serotonin transporter gene variants and prediction of stress-induced risk for psychological distress

The response to psychosocial stress is influenced by both psychosocial factors and genetic vulnerability. The most investigated gene in gene × environment studies in abnormal response to environmental stressors is the one coding for the serotonin transporter (SLC6A4). Variability within this gene has been associated with functional brain differences, personality dimensions, reactivity to stress and risk for various psychopathological conditions. In the present study, we set out to investigate the association of common genetic variants within SLC6A4 with state psychopathology in a community sample homogeneously exposed to stress, thus inquiring about potential genetic differences in stress sensitivity. One thousand eight hundred seventy-five young conscripts were evaluated for psychopathological distress with the 90-item Symptoms Checklist Revised in their first 2 weeks of admission to obligatory military service. Of these, 1594 were genotyped for the biallelic ins/del polymorphism (5-HTTLPR S/L) within the promoter region of SLC6A4, as well as the variation within the 'long' 5-HTTLPR allele (rs25531A/G). Homozygous for the 5-HTTLPR S allele reported significantly higher scores for paranoid ideation as compared with L-allele carriers. Slight effects on other subscales were observed, but were not significant after correction for multiple testing. Despite limitations linked to the evaluation of psychopathology by a single general scale and multiple comparisons, the present study support a role of SLC6A4 in modulating abnormal responses to environmental stress. In particular, variation within this gene may confer risk for paranoid/defensive reactions under conditions of environmental stress associated with military induction.

Psychotic symptoms in young adults exposed to childhood trauma--a 20 year follow-up study

Childhood adversity has been shown to increase the risk of psychotic symptoms in adult life. However, there are no previous studies looking at the association between experiencing a natural disaster during childhood and the development of psychotic symptoms in young adulthood. Eight hundred and six bushfire-exposed children and 725 control children were evaluated following the 1983 South Australian bushfires. Five hundred and twenty nine (65.6%) of the bushfire group and 464 (64%) controls participated in a follow up study 20 years later. Childhood data on emotional and behavioural disorders and dysfunctional parenting was available. The adult assessment included the Australian National Health and Well-Being psychosis screen and detailed information about trauma, childhood adversity and alcohol and cannabis abuse. 5.6% of subjects responded positively to the psychosis screen and 2.6% responded positively to a further probe question. Psychotic symptoms were more common in subjects exposed to a greater number of traumas, and were associated with higher rates of childhood adversity, emotional and behavioural disturbance, dysfunctional parenting, and alcohol and cannabis abuse. Subjects exposed to bushfires as children did not have a greater risk of psychosis. Our results indicate that exposure to multiple traumas, rather than a single major trauma, increases the risk of later psychosis.

Effects of progressive muscle relaxation on state anxiety and subjective well-being in people with schizophrenia: a randomized controlled trial

Objective: To examine the efficacy of a single progressive muscle relaxation session compared with a control condition on state anxiety, psychological stress, fatigue and subjective well-being in patients with schizophrenia.

Design: Randomized controlled trial.

Setting: An acute inpatient care unit of an University Psychiatric Centre.

Subjects: Sixty-four out of 88 eligible patients with schizophrenia.

Interventions: Patients were randomly assigned to either a single progressive muscle relaxation session during 25 minutes or a resting control condition with the opportunity to read for an equal amount of time.

Main outcome measures: Before and after the single interventions the State anxiety inventory and the Subjective exercise experiences scale were completed. Effect sizes were calculated.

Results: Only within progressive muscle relaxation, participants (n=27) showed decreased state anxiety, psychological stress and fatigue and increased subjective well-being. Between-group differences in post scores were found for state anxiety, subjective well-being and psychological stress, but not for fatigue. The effect size favouring progressive muscle relaxation was 1.26 for subjective well-being and −1.25 and −1.02 for respectively state anxiety and psychological stress.

Conclusions: Progressive muscle relaxation is highly effective in reducing acute feelings of stress and anxiety in patients with schizophrenia. A reduction in stress and state anxiety is associated with an increase in subjective well-being.

Emotional reactivity in chronic schizophrenia: structural and functional brain correlates and the influence of adverse childhood experiences

BACKGROUND

Despite behavioural signs of flattened affect, patients affected by schizophrenia show enhanced sensitivity to negative stimuli. The current literature concerning neural circuitry for emotions supports dysregulations of cortico-limbic networks, but gives contrasting results. Adverse childhood experiences (ACEs) could persistently influence emotional regulation and neural correlates of response to emotional stimuli in healthy humans. This study evaluated the effect of ACEs and chronic undifferentiated schizophrenia on neural responses to emotional stimuli (negative facial expression).

METHOD

Brain blood-oxygen-level-dependent functional magnetic resonance imaging neural responses to a face-matching paradigm, and regional grey matter (GM) volumes were studied at 3.0 T in the amygdala, hippocampus, anterior cingulated cortex (ACC) and prefrontal cortex (PFC). The severity of ACEs was assessed. Participants included 20 consecutively admitted in-patients affected by chronic undifferentiated schizophrenia, and 20 unrelated healthy volunteers from the general population.

RESULTS

Patients reported higher ACEs than controls. Worse ACEs proportionally led to decreasing responses in the amygdala and hippocampus, and to increasing responses in the PFC and ACC in all participants. Patients showed higher activations in the amygdala and hippocampus, and lower activations in the PFC and ACC. Higher ACEs were associated with higher GM volumes in the PFC and ACC, and schizophrenia was associated with GM reduction in all studied regions.

CONCLUSIONS

Structural and functional brain correlates of emotional reactivity are influenced by both current chronic undifferentiated schizophrenia and the severity of past ACEs.

Adolescent development of psychosis as an outcome of hearing impairment: a 10-year longitudinal study

BACKGROUND

It has long been acknowledged that hearing impairment may increase the risk for psychotic experiences. Recent work suggests that young people in particular may be at risk, indicating a possible developmental mechanism.

METHOD

The hypothesis that individuals exposed to hearing impairment in early adolescence would display the highest risk for psychotic symptoms was examined in a prospective cohort study of a population sample of originally 3021 adolescents and young adults aged 14-24 years at baseline, in Munich, Germany (Early Developmental Stages of Psychopathology Study). The expression of psychosis was assessed at multiple time points over a period of up to 10 years, using a diagnostic interview (Munich Composite International Diagnostic Interview; CIDI) administered by clinical psychologists.

RESULTS

Hearing impairment was associated with CIDI psychotic symptoms [odds ratio (OR) 2.04, 95% confidence interval (CI) 1.10-3.81], particularly more severe psychotic symptoms (OR 5.66, 95% CI 1.64-19.49). The association between hearing impairment and CIDI psychotic symptoms was much stronger in the youngest group aged 14-17 years at baseline (OR 3.28, 95% CI 1.54-7.01) than in the older group aged 18-24 years at baseline (OR 0.82, 95% CI 0.24-2.84).

CONCLUSIONS

The finding of an age-specific association between hearing impairment and psychotic experiences suggests that disruption of development at a critical adolescent phase, in interaction with other personal and social vulnerabilities, may increase the risk for psychotic symptoms.

Influence of the serotonin transporter gene polymorphism, cannabis and childhood sexual abuse on phenotype of bipolar disorder: a preliminary study

OBJECTIVE

The gene coding for the 5-HT transporter (5-HTT) is considered as a candidate gene for bipolar disorder, either as a "vulnerability" or as a "modifying the phenotype" gene. Psychotic symptoms occur at least once in one bipolar patient out of two, the relevant risk factors being insufficiently understood. The gene × environment interaction approach offers the opportunity to disentangle the latter, including childhood sexual abuse and cannabis abuse.

METHODS

We investigated the 5-HTTLPR of the 5-HTT gene (G) and the presence of childhood sexual abuse and cannabis comorbidity (E) in 137 bipolar patients with (versus without) lifetime psychotic symptoms.

RESULTS

The short allele and cannabis abuse were significantly more frequent among patients with psychotic symptoms than in those without (p=0.01 and p=0.004, respectively), while childhood sexual abuse was not. Complex interactions were found between presence of the short allele, cannabis abuse or dependence and childhood sexual abuse.

CONCLUSIONS

The short allele of the 5-HTTLPR polymorphism of the 5-HTT gene was a risk factor for psychotic symptoms in bipolar disorder in the present sample, directly but also indirectly, through the presence of cannabis abuse or dependence, as an exacerbating factor heightening psychotic symptoms.

Isolated delusional syndrome in Parkinson's Disease

Psychotic features in patients with Parkinson's Disease usually present as visual hallucinations against a background of cognitive deterioration and dopaminomimetic therapy. Isolated delusions are rare. We report here 4 patients with Parkinson's Disease who developed a delusional syndrome resembling schizophreniform psychosis in the absence of changes in alertness, visual hallucinations or dementia. We suggest that this syndrome may be more common than previously recognized, and that it may be related to the use of dopaminergic medications and environmental triggers on a background of a susceptible individual. This syndrome suggests interesting parallels with the pathophysiology of amphetamine-induced psychosis and schizophrenia.

Childhood trauma and increased stress sensitivity in psychosis

OBJECTIVE

The notion that traumatic experiences in childhood may predict later psychotic outcomes would be strengthened if a plausible mechanism could be demonstrated. Because increased stress sensitivity is part of the behavioural expression of psychosis liability, the possible mediating role of childhood trauma was investigated.

METHOD

Fifty patients with psychosis were studied with the experience sampling method to assess stress reactivity in daily life, defined as emotional and psychotic reactivity to stress. Traumatic experiences in childhood were assessed with the Childhood Trauma Questionnaire.

RESULTS

A significant interaction was found between stress and CT on both negative affect (event stress: β = 0.04, P < 0.04; activity stress: β = 0.12, P < 0.001) and psychotic intensity (event stress: β = 0.06, P < 0.001; activity stress: β = 0.11, P < 0.001), showing that a history of CT is associated with increased sensitivity to stress.

CONCLUSION

A history of childhood trauma in patients with psychosis is associated with increased stress reactivity later in life, suggestive for an underlying process of behavioural sensitization.

Cognitive control deficits in schizophrenia: mechanisms and meaning

Although schizophrenia is an illness that has been historically characterized by the presence of positive symptomatology, decades of research highlight the importance of cognitive deficits in this disorder. This review proposes that the theoretical model of cognitive control, which is based on contemporary cognitive neuroscience, provides a unifying theory for the cognitive and neural abnormalities underlying higher cognitive dysfunction in schizophrenia. To support this model, we outline converging evidence from multiple modalities (eg, structural and functional neuroimaging, pharmacological data, and animal models) and samples (eg, clinical high risk, genetic high risk, first episode, and chronic subjects) to emphasize how dysfunction in cognitive control mechanisms supported by the prefrontal cortex contribute to the pathophysiology of higher cognitive deficits in schizophrenia. Our model provides a theoretical link between cellular abnormalities (eg, reductions in dentritic spines, interneuronal dysfunction), functional disturbances in local circuit function (eg, gamma abnormalities), altered inter-regional cortical connectivity, a range of higher cognitive deficits, and symptom presentation (eg, disorganization) in the disorder. Finally, we discuss recent advances in the neuropharmacology of cognition and how they can inform a targeted approach to the development of effective therapies for this disabling aspect of schizophrenia.

Developmental trajectories of psychotic-like experiences across adolescence: impact of victimization and substance use

BACKGROUND

Research suggests that psychotic-like experiences (PLEs) in the general population are common, but can reflect either transitory or persistent developmental phenomena. Using a general adolescent population it was examined whether different developmental subtypes of PLEs exist and whether different trajectories of PLEs are associated with certain environmental risk factors, such as victimization and substance use.

METHOD

Self-reported PLEs were collected from 409 adolescents (mean age 14 years 7 months) at four time points, each 6 months apart. General growth mixture modelling was utilized to identify classes of adolescents who followed distinct trajectories of PLEs across this period. Predictors of class membership included demographics, personality, victimization, depression, anxiety and substance use.

RESULTS

We identified the following three developmental subgroups of PLEs: (1) persistent; (2) increasing; (3) low. Adolescents on the persistent trajectory reported frequent victimization and consistent elevated scores in depression and anxiety. Adolescents on the increasing trajectory were engaging in cigarette use prior to any increases in PLEs and were engaging in cocaine, cannabis and other drug use as PLEs increased at later time points.

CONCLUSIONS

The findings suggest that different developmental subgroups of PLEs exist in adolescence and are differentially related to victimization and substance use.

Schizophrenia: current therapy and review

Schizophrenia is a disorder that affects a significant portion of the population. This case report and review article discusses potential causes and pathophysiology. The treatment of schizophrenia is outlined in detail, followed by a discussion of the perioperative management of schizophrenic patients, highlighting important information to keep in mind when treating this patient population.

Perceived discrimination and health outcomes a gender comparison among Asian-Americans nationwide

OBJECTIVES

We examined whether similarities and differences exist in the association between perceived discrimination and poor mental and physical health among Asian-American adult women and men. We also tested whether Asian-American women would have a lower perceived discrimination threshold for developing negative health outcomes than Asian-American men.

METHODS

Data were derived from the National Latino and Asian-American Study (2002-2003). A nationally representative sample of Asian-American adults (1,075 women and 972 men) was examined.

RESULTS

There were more gender similarities than differences in the strong association between discrimination and health. More prominent gender differences were found for the specific level of discrimination and its potential health effects. Specifically, for both Asian women and men, a high level of perceived discrimination showed stronger associations with mental health than with physical health outcomes. And yet, compared with men, the threshold of discrimination was lower for women in affecting mental and physical health status.

CONCLUSION

The findings underscore that a high level of discrimination was associated with negative mental and physical health outcomes for both women and men. However, women had more negative mental and physical health outcomes when exposed to a lower threshold of discrimination than men. These findings suggest that failing to examine women and men separately in discrimination research may no longer be appropriate among the Asian-American population. Future research should focus attention on the biological, social, and political mechanisms that mitigate the adverse health effects of discrimination in order to develop a more comprehensive approach to eliminate disparities in health.

Evidence that the impact of hearing impairment on psychosis risk is moderated by the level of complexity of the social environment

BACKGROUND

It has been suggested that part of the increased vulnerability for psychosis in individuals with hearing impairment (HI) is the consequence of a decreased ability to form correct representations of the social world and attributions of intention of others. It was therefore hypothesized that associations between HI and psychosis risk would be sensitive to contextual variables representing higher level of social complexity, conceptualized as the population density of the social environment ('urbanicity').

METHODS

Urbanicity and objective HI were assessed in the Maastricht Aging Study (MAAS), a longitudinal study of 1,823 participants from the general population in Maastricht, the Netherlands. Participants were tested at baseline (T0) and at 6-year (T2) and 12-year follow-up (T4). The degree to which the association between HI (T0-T2) and psychotic experiences at T4 was moderated by T0 urbanicity was examined.

RESULTS

The association between HI and psychosis was conditional on level of urbanicity (interaction chi2=7.51, p=.006), with low effect size in non-urbanized areas (b=-0.81, 95% CI:-2.98, 1.36) and high effect size in the most urbanized areas (b=2.56, 95% CI: 0.47, 4.65). Although social isolation (b=1.74, p=.022) and loneliness (b=0.61, pb.001) were both associated with psychosis, they could not explain the observed interaction.

CONCLUSION

The findings suggest that level of complexity of the social world, in interaction with the individual's ability to correctly process this information, may impact on risk for psychotic experiences.

Systematic reviews of categorical versus continuum models in psychosis: evidence for discontinuous subpopulations underlying a psychometric continuum. Implications for DSM-V, DSM-VI, and DSM-VII

Diagnostic systems, phenotype models, and theories of etiology incorporate propositions on the underlying nature of psychosis and schizophrenia phenotypes. These propositions, whether implicit or explicit, are that the distributions of the phenotypes, or the phenotype experiences themselves, are dimensional or categorical. On one hand, evidence on the epidemiology of schizophrenia phenotypes suggests symptom phenotypes may not be bound by conventional diagnostic thresholds but instead may blend imperceptibly with subclinical, statistically frequent experience, supporting continuum viewpoints. On the other hand, evidence on the population structure suggests a latent categorical structure; the population may be composed of two types of people. However, both sets of evidence are beset by methodological limitations that point unequivocally to the need to move beyond current diagnostic conceptualizations, observation, and anamnesis of psychosis, and toward responsive and scientifically refutable formulations of schizophrenia.

REVIEW: Genome-wide findings in schizophrenia and the role of gene-environment interplay

The recent advent of genome-wide mass-marker technology has resulted in renewed optimism to unravel the genetic architecture of psychotic disorders. Genome-wide association studies have identified a number of common polymorphisms robustly associated with schizophrenia, in ZNF804A, transcription factor 4, major histocompatibility complex, and neurogranin. In addition, copy number variants (CNVs) in 1q21.1, 2p16.3, 15q11.2, 15q13.3, 16p11.2, and 22q11.2 were convincingly implicated in schizophrenia risk. Furthermore, these studies have suggested considerable genetic overlap with bipolar disorder (particularly for common polymorphisms) and neurodevelopmental disorders such as autism (particularly for CNVs). The influence of these risk variants on relevant intermediate phenotypes needs further study. In addition, there is a need for etiological models of psychosis integrating genetic risk with environmental factors associated with the disorder, focusing specifically on environmental impact on gene expression (epigenetics) and convergence of genes and environment on common biological pathways bringing about larger effects than those of genes or environment in isolation (gene-environment interaction). Collaborative efforts that bring together expertise in statistics, genetics, epidemiology, experimental psychiatry, brain imaging, and clinical psychiatry will be required to succeed in this challenging task.

Borderline personality disorder and psychosis: a review

Early views of borderline personality disorder (BPD) were based on the idea that patients with this pathology were "on the border" of psychosis. However, more recent studies have not supported this view, although they have found evidence of a malevolent interpersonal evaluation and a significant proportion of BPD patients showing psychotic symptoms. For example, in one study, 24% of BPD patients reported severe psychotic symptoms and about 75% had dissociative experiences and paranoid ideation. Thus, we start with an overview regarding the prevalence of psychotic symptoms in BPD patients. Furthermore, we report findings of studies investigating the role of comorbidity (eg, post-traumatic stress disorder) in the severity and frequency of psychotic symptoms in BPD patients. We then present results of genetic and neurobiological studies comparing BPD patients with patients with schizophrenia or nonschizophrenic psychotic disorders. In conclusion, this review reveals that psychotic symptoms in BPD patients may not predict the development of a psychotic disorder but are often permanent and severe and need careful consideration by clinicians. Therefore, adequate diagnosis and treatment of psychotic symptoms in BPD patients is emphasized.

Considering a frame of reference for physical activity research related to the cardiometabolic risk profile in schizophrenia

This article reviews evidence that researchers and mental health service providers need to take into account four modifiable factors that affect the prevalence of the metabolic syndrome in people with schizophrenia: (a) physical activity as part of a health-related lifestyle, (b) physical fitness, (c) mental health status and (d) antipsychotic medication. The implementation of physical activity in order to prevent and treat cardiometabolic risk factors in people with schizophrenia is discussed. English language articles published until July 2009 were identified by PubMed, CINAHL, PsychINFO, and Cochrane Central Register of Controlled Trials. The search terms schizophrenia and metabolic syndrome, physical activity, health, fitness, and lifestyle were used. Physical activity interventions result in positive effects on metabolic outcomes, physical fitness, health-related behavior and mental health. Considering present knowledge, physical therapists should take into account the emotional (negative symptoms, self-esteem, self-efficacy, and stress) and physiological (cardiometabolic parameters) components of mental illness when offering physical activity interventions. The physical activity stimulus should be adapted to the individual's physical fitness level and the side effects of the antipsychotic medications. More research is needed to assist in the practical development of effective evidence-based preventive and curative strategies in psychiatric services for metabolic syndrome in persons with schizophrenia.

A unifying hypothesis of schizophrenia: abnormal immune system development may help explain roles of prenatal hazards, post-pubertal onset, stress, genes, climate, infections, and brain dysfunction

We propose a unifying hypothesis of schizophrenia to help reconcile findings from many different disciplines. This hypothesis proposes that schizophrenia often involves pre- or perinatal exposure to adverse factors that produce a latent immune vulnerability. When this vulnerability is manifested, beginning around puberty with changes in immune function and involution of the thymus, individuals become more susceptible to infections and immune dysfunctions that contribute to schizophrenia. Our hypothesis suggests theoretical bridges between different lines of evidence on schizophrenia and offers explanations for many puzzling findings about schizophrenia. For example, the hypothesis helps account for why schizophrenia patients tend to have had increased exposure to neurotropic infections, but most individuals with such exposure do not develop schizophrenia, and why prenatal hardships increase risk for schizophrenia, but the onset of symptoms typically does not occur until after puberty. The hypothesis also explains another paradox: lower socioeconomic status and poor prenatal care increase risk for schizophrenia at the same geographic site, but international comparisons indicate that countries with higher per capita incomes and better prenatal care actually tend to have higher schizophrenia prevalences. As the hypothesis predicts, (1) prenatal adversity, which increases risk for schizophrenia, also impairs post-pubertal immune competence, (2) schizophrenia patients experience elevated morbidity from infectious and auto-immune diseases, (3) genetic and environmental risk factors for schizophrenia increase vulnerability to these diseases, (4) factors that exacerbate schizophrenic symptoms also tend to impair immune function, (5) many anti-psychotic medications combat infection, (6) effects of early infections may not appear until after puberty, when they can produce neurologic and psychiatric symptoms, and (7) immune dysfunctions, such as imbalances of pro- and anti-inflammatory cytokines, may contribute to the onset of psychotic symptoms and the progressive loss of brain tissue in schizophrenia. The disruptive effects of prenatal adversity on the development of the immune system may often combine with adverse effects on prenatal brain development to produce schizophrenia. This paper focuses on the adverse immune system effects, because effects on the brain have been extensively discussed in neurodevelopmental theories of schizophrenia. We propose new tests of scientific predictions. We also point out potential clinical implications of the hypothesis; for example, individuals with schizophrenia may often have underlying infections or immune dysfunctions, such as imbalances in inflammatory cytokines, that contribute to the illness. This possibility could be tested experimentally--e.g., by clinical trials in which patients' exposure to infection is reduced or immune function is normalized.

Psychotherapy and recovery from schizophrenia: A review of potential applications and need for future study

Recovery from schizophrenia has been conceptualized to involve not only symptom remission of symptoms and achievement of psychosocial milestones but also subjective changes in how persons appraise their lives and the extent to which they experience themselves as meaningful agents in the world. In this paper we review the potential of individual psychotherapy to address these more subjective aspects of recovery. Literature on the effectiveness of psychotherapy for persons with schizophrenia is discussed and two different paths by which psychotherapy might modify self-experience are described. First we detail how psychotherapy could be conceptualized and tailored to help persons with schizophrenia to construct richer and fuller narrative accounts of their lives including their strengths, challenges, losses and hopes. Second we explore how psychotherapy could target the capacity for metacognition or thinking about thinking, assisting persons with psychosis to become able to think about themselves and others in a generally more complex and flexible manner. The needs for future research are discussed along with a commentary on how current evidence- and skill-based treatments may contain key elements which could be considered psychotherapeutic.

Epigenetics and biomarkers in the staging of neuropsychiatric disorders

Epigenetics, or alterations in the phenotype or gene expression due to mechanisms other than changes in the underlying DNA sequence, reflects the sensitivity and responsiveness of human and animal brains in constantly varying circumstances regulating gene expression profiles that define the biomarkers and present the ultimate phenotypical outcomes, such as cognition and emotion. Epigenetics is associated with functionally relevant alterations to the genome in such a fashion that under the particular conditions of early, adolescent, and adult life, environmental signals may activate intracellular pathways that remodel the "epigenome," triggering changes in gene expression and neural function. Thus, genetic influences in neuropsychiatric disorders that are subject to clinical staging, epigenetics in schizophrenia, epigenetic considerations in the expression of sensorimotor gating resulting from disease conditions, biomarkers of drug use and addiction, current notions on the role of dopamine in schizophrenia spectrum disorders, and the discrete interactions of biomarkers in persistent memory were to greater or lesser extents reflected upon. The relative contributions of endophenotypes and epistasis for mediating epigenetic phenomena and the outcomes as observed in the analysis of biomarkers appear to offer a multitude of interactive combinations to further complicate the labyrinthine machinations of diagnosis, intervention, and prognosis.

The interplay between mitochondrial complex I, dopamine and Sp1 in schizophrenia

Schizophrenia is currently believed to result from variations in multiple genes, each contributing a subtle effect, which combines with each other and with environmental stimuli to impact both early and late brain development. At present, schizophrenia clinical heterogeneity as well as the difficulties in relating cognitive, emotional and behavioral functions to brain substrates hinders the identification of a disease-specific anatomical, physiological, molecular or genetic abnormality. Mitochondria play a pivotal role in many essential processes, such as energy production, intracellular calcium buffering, transmission of neurotransmitters, apoptosis and ROS production, all either leading to cell death or playing a role in synaptic plasticity. These processes have been well established as underlying altered neuronal activity and thereby abnormal neuronal circuitry and plasticity, ultimately affecting behavioral outcomes. The present article reviews evidence supporting a dysfunction of mitochondria in schizophrenia, including mitochondrial hypoplasia, impairments in the oxidative phosphorylation system (OXPHOS) as well as altered mitochondrial-related gene expression. Abnormalities in mitochondrial complex I, which plays a major role in controlling OXPHOS activity, are discussed. Among them are schizophrenia specific as well as disease-state-specific alterations in complex I activity in the peripheral tissue, which can be modulated by DA. In addition, CNS and peripheral abnormalities in the expression of three of complex I subunits, associated with parallel alterations in their transcription factor, specificity protein 1 (Sp1) are reviewed. Finally, this review discusses the question of disease specificity of mitochondrial pathologies and suggests that mitochondria dysfunction could cause or arise from anomalities in processes involved in brain connectivity.

Sensitization, epileptic-like symptoms and local synchronization in patients with paranoid schizophrenia

Recent findings indicate that changes in synchronization of neural activities underlying sensitization and kindling could be more comprehensively understood using nonlinear methods. With this aim we have examined local synchronization using novel measure of coarse-grained information rate (CIR) in 8 EEG signals recorded at different cortical areas in 44 patients with paranoid schizophrenia. The values of local synchronization that could reflect sensitization related changes in EEG activities of cortical sites were then related to psychometric measures of epileptic-like symptoms and positive and negative schizophrenia symptoms (PANSS). While no significant correlations between CIR and positive and negative symptoms have been found, statistically significant relationships described by Spearman correlation coefficients between CIR indices and results of LSCL-33 have been observed in 7 (of 8) EEG channels (r in the range from 0.307 to 0.374, p<0.05). Results of this study provide first supportive evidence for the relationship between local synchronization measured by CIR and epileptic-like symptoms in schizophrenia.

Progress Toward a Resurgence and Remodeling of Psychotherapy for Schizophrenia: Editors’ Introduction to Special Issue of Clinical Case Studies

This special issue of Clinical Case Studies focuses on recent developments in the psychotherapy of schizophrenia. Approaches such as these are needed to address the multiple rate-limiting factors for psychotherapy outcome in this population, such as poor insight, comorbid disorders, low motivation, cognitive impairments, and self and interpersonal disturbances. In this introductory article, each of the case studies is briefly reviewed, with the goals of: (a) noting how each therapeutic approach fills a gap in current practice, and (b) placing the focus of treatment within a larger context of relevant research on schizophrenia. Concluding comments note the implications of these multiple therapeutic developments for future psychological treatment of schizophrenia.

Involvement of NOX2 in the development of behavioral and pathologic alterations in isolated rats

BACKGROUND

Social stress leads to oxidative stress in the central nervous system, contributing to the development of mental disorders. Loss of parvalbumin in interneurons is an important feature of these diseases. We studied the role of the superoxide-producing nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) in rats exposed to social isolation.

METHODS

Male rats were kept for 7 weeks in group or in social isolation (n = 6-10 per group). Behavioral tests, immunohistochemistry, and analysis of NOX2 expression were performed at the end of social isolation. Apocynin was given in the drinking water (5 mg/kg/day).

RESULTS

NOX2 was below detection level in the brains of control animals, whereas it was highly expressed in isolated rats, particularly in nucleus accumbens and prefrontal cortex. Indirect markers of oxidative stress (oxidized nucleic acid 8-hydroxy-2'-deoxyguanosine, redox-sensitive transcription factor c-fos, and hypoxia-inducible factor-1alpha) were increased after social isolation in brain areas with high NOX2 expression. An increase in immunoreactive microglia suggested that oxidative stress could be in part due to NOX2 activation in microglia. In response to social isolation, rats showed increased locomotor activity, decreased discrimination, signs of oxidative stress in neurons, and loss of parvalbumin-immunoreactivity. Treatment of isolated rats with the antioxidant/NOX inhibitor apocynin prevented the behavioral and histopathological alterations induced by social isolation.

CONCLUSIONS

Our data suggest that NOX2-derived oxidative stress is involved in loss of parvalbumin immunoreactivity and development of behavioral alterations after social isolation. These results provide a molecular mechanism for the coupling between social stress and brain oxidative stress, as well as potential new therapeutic avenues.

The dopamine hypothesis of schizophrenia: version III--the final common pathway

The dopamine hypothesis of schizophrenia has been one of the most enduring ideas in psychiatry. Initially, the emphasis was on a role of hyperdopaminergia in the etiology of schizophrenia (version I), but it was subsequently reconceptualized to specify subcortical hyperdopaminergia with prefrontal hypodopaminergia (version II). However, these hypotheses focused too narrowly on dopamine itself, conflated psychosis and schizophrenia, and predated advances in the genetics, molecular biology, and imaging research in schizophrenia. Since version II, there have been over 6700 articles about dopamine and schizophrenia. We selectively review these data to provide an overview of the 5 critical streams of new evidence: neurochemical imaging studies, genetic evidence, findings on environmental risk factors, research into the extended phenotype, and animal studies. We synthesize this evidence into a new dopamine hypothesis of schizophrenia-version III: the final common pathway. This hypothesis seeks to be comprehensive in providing a framework that links risk factors, including pregnancy and obstetric complications, stress and trauma, drug use, and genes, to increased presynaptic striatal dopaminergic function. It explains how a complex array of pathological, positron emission tomography, magnetic resonance imaging, and other findings, such as frontotemporal structural and functional abnormalities and cognitive impairments, may converge neurochemically to cause psychosis through aberrant salience and lead to a diagnosis of schizophrenia. The hypothesis has one major implication for treatment approaches. Current treatments are acting downstream of the critical neurotransmitter abnormality. Future drug development and research into etiopathogenesis should focus on identifying and manipulating the upstream factors that converge on the dopaminergic funnel point.

Stigmatization as an environmental risk in schizophrenia: a user perspective

Stigmatization represents a chronic negative interaction with the environment that most people with a diagnosis of schizophrenia face on a regular basis. Different types of stigma-public stigma, self--stigma, and label avoidance--may each have detrimental effects. In the present article, the possible consequences of stigma on onset, course, and outcome of schizophrenia are reviewed. Stigmatization may be conceptualized as a modifiable environmental risk factor that exerts its influence along a variety of different pathways, not only after the illness has been formally diagnosed but also before, on the basis of subtle behavioral expressions of schizophrenia liability. Integrating stigma-coping strategies in treatment may represent a cost-effective way to reduce the risk of relapse and poor outcome occasioned by chronic exposure to stigma. In addition, significant gains in quality of life may result if all patients with schizophrenia routinely receive information about stigma and are taught to use simple strategies to increase resilience vis-à-vis adverse, stigmatizing environments.

Cannabis and Psychosis: What Can Daily Diaries Tell Us About Who is Vulnerable?

The association between cannabis use and the initial development of psychotic symptoms has attracted increased interest over the past decade. In particular, researchers have attempted to elucidate whether cannabis use increases the risk of psychosis among vulnerable individuals or may just represent attempts to self-medicate distressing symptoms. While a growing literature suggests that cannabis use may contribute to the development of psychotic symptoms, these findings are based primarily on retrospective assessments that have limited ability to clarify the temporal link between cannabis use and psychotic symptoms. The authors review the literature regarding the link between cannabis use and psychotic symptoms; point out the limitations associated with retrospective assessments; and discuss advantages of incorporating daily diary methods, such as Experience Sampling Method (ESM), to study cannabis use and symptoms during daily functioning in "real world" environments. The authors also discuss potential future applications of ESM in research and clinical practice that may inform the identification of individuals vulnerable to develop psychotic symptoms, as well as the development of treatments that target this population.