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

COMT Val158Met-stress interaction in psychosis: role of background psychosis risk

BACKGROUND

The interplay between the catechol-O-methyltransferase (COMT) Val158Met polymorphism and environmental stress may have etiological relevance for psychosis, but differential effects have been reported in healthy control and patient groups, suggesting that COMT Val158Met interactions with stress may be conditional on background genetic risk for psychotic disorder.

METHODS

Patients with a nonaffective psychotic disorder (n = 86) and control participants (n = 109) were studied with the experience sampling method (a structured diary technique) in order to assess stress, negative affect and momentary psychotic symptoms in the flow of daily life.

RESULTS

Multilevel analyses revealed significant three-way interactions between group status (patient or control), COMT genotype and stress in the model of negative affect (χ(2)(2) = 13.26, P < 0.01) as well as in the model of momentary psychotic symptoms (χ(2)(2) = 6.92, P < 0.05). Exploration of the three-way interaction revealed that in patients, COMT genotype moderated the association between stress and negative affect (χ(2)(4) = 11.50, P < 0.005), as well as the association between stress and momentary psychosis (χ(2)(4) = 12.79, P < 0.005). Met/Met genotype patients showed significantly increased psychotic and affective reactivity to stress in comparison to the Val/Met and Val/Val genotypes. In contrast, healthy controls did not display large or significant COMT Val158Met X stress interactions.

CONCLUSIONS

Important differences exist in the effect of COMT Val158Met on stress reactivity, which may depend on background risk for psychotic disorder. Differential sensitivity to environmental stress occasioned by COMT Val158Met may be contingent on higher order interactions with genetic variation underlying psychotic disorder.

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.

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.

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.

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.

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.