Development, disease and degeneration in schizophrenia: a unitary pathophysiological model

Volumes of hippocampal subfields suggest a continuum between schizophrenia, major depressive disorder and bipolar disorder

Objective

There is considerable debate as to whether the continuum of major psychiatric disorders exists and to what extent the boundaries extend. Converging evidence suggests that alterations in hippocampal volume are a common sign in psychiatric disorders; however, there is still no consensus on the nature and extent of hippocampal atrophy in schizophrenia (SZ), major depressive disorder (MDD) and bipolar disorder (BD). The aim of this study was to verify the continuum of SZ - BD - MDD at the level of hippocampal subfield volume and to compare the volume differences in hippocampal subfields in the continuum.

Methods

A total of 412 participants (204 SZ, 98 MDD, and 110 BD) underwent 3 T MRI scans, structured clinical interviews, and clinical scales. We segmented the hippocampal subfields with FreeSurfer 7.1.1 and compared subfields volumes across the three diagnostic groups by controlling for age, gender, education, and intracranial volumes.

Results

The results showed a gradual increase in hippocampal subfield volumes from SZ to MDD to BD. Significant volume differences in the total hippocampus and 13 of 26 hippocampal subfields, including CA1, CA3, CA4, GC-ML-DG, molecular layer and the whole hippocampus, bilaterally, and parasubiculum in the right hemisphere, were observed among diagnostic groups. Medication treatment had the most effect on subfields of MDD compared to SZ and BD. Subfield volumes were negatively correlated with illness duration of MDD. Positive correlations were found between subfield volumes and drug dose in SZ and MDD. There was no significant difference in laterality between diagnostic groups.

Conclusion

The pattern of hippocampal volume reduction in SZ, MDD and BD suggests that there may be a continuum of the three disorders at the hippocampal level. The hippocampus represents a phenotype that is distinct from traditional diagnostic strategies. Combined with illness duration and drug intervention, it may better reflect shared pathophysiology and mechanisms across psychiatric disorders.

Viral Infections and Schizophrenia: A Comprehensive Review

Schizophrenia is a complex mental disorder with multiple genetic and environmental factors contributing to its pathogenesis. Viral infections have been suggested to be one of the environmental factors associated with the development of this disorder. We comprehensively review all relevant published literature focusing on the relationship between schizophrenia and various viral infections, such as influenza virus, herpes virus 1 and 2 (HSV-1 and HSV-2), cytomegalovirus (CMV), Epstein-Barr virus (EBV), retrovirus, coronavirus, and Borna virus. These viruses may interfere with the normal maturation of the brain directly or through immune-induced mediators, such as cytokines, leading to the onset of schizophrenia. Changes in the expression of critical genes and elevated levels of inflammatory cytokines have been linked to virally-induced infections and relevant immune activities in schizophrenia. Future research is necessary to understand this relationship better and provide insight into the molecular mechanisms underlying the pathophysiology of schizophrenia.

Characterization of childhood trauma, hippocampal mediation and Cannabis use in a large dataset of psychosis and non-psychosis individuals

BACKGROUND

Cannabis use (CA) and childhood trauma (CT) independently increase the risk of earlier psychosis onset; but their interaction in relation to psychosis risk and association with endocannabinoid-receptor rich brain regions, i.e. the hippocampus (HP), remains unclear. The objective was to determine whether lower age of psychosis onset (AgePsyOnset) is associated with CA and CT through mediation by the HP volumes, and genetic risk, as measured by schizophrenia polygene scores (SZ-PGRS).

METHODS

Cross-sectional, case-control, multicenter sample from 5 metropolitan US regions. Participants (n = 1185) included 397 controls not affected by psychosis (HC); 209 participants with bipolar disorder type-1; 279 with schizoaffective disorder; and 300 with schizophrenia (DSM IV-TR). CT was assessed using the Childhood Trauma Questionnaire (CTQ); CA was assessed by self-reports and trained clinical interviewers. Assessment included neuroimaging, symptomatology, cognition and calculation of the SZ polygenic risk score (SZ-PGRS).

RESULTS

In survival analysis, CT and CA exposure interact to be associated with lower AgePsyOnset. At high CT or CA, CT or CA are individually sufficient to affect AgePsyOnset. CT relation with AgePsyOnset is mediated in part by the HP in CA users before AgePsyOnset. CA before AgePsyOnset is associated with higher SZ-PGRS and correlated with younger age at CA usage.

DISCUSSION

CA and CT interact to increase risk when moderate; while severe CT and/or CA abuse/dependence are each sufficient to affect AgePsyOnset, indicating a ceiling effect. Probands with/out CA before AgePsyOnset differ on biological variables, suggesting divergent pathways to psychosis.

FUNDING

MH077945; MH096942; MH096913; MH077862; MH103368; MH096900; MH122759.

Brain ageing and neurodegeneration in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a psychiatric condition characterized by alternating episodes of mania and depression frequently associated with cognitive impairments. BD is associated with brain alterations in fronto-temporal and limbic networks. Recent conceptualizations view BD as a neurodegenerative disorder characterized by progressive deterioration of grey and white matter (GM, WM) volumes and accelerated brain ageing. Therefore, we conducted a review gathering neuroimaging evidence about neurodegenerative processes in BD.

METHODS

A literature search was conducted on the PubMed, Scopus and Web of Science databases in September 2021. After title and abstract screening of the retrieved records, 19 studies that met our inclusion criteria were included in the review.

RESULTS

The available evidence suggests the presence of a progressive reduction of GM volumes at the whole-brain level and in the amygdala, prefrontal regions and the anterior cingulate cortex. Conversely, WM lesions and alterations seem to emerge only in the early phases of the condition masking the effects of normal ageing. Lastly, machine learning models indicate that the gap between predicted and chronological brain age differs considerably between healthy controls and BD patients, as the latter are characterized by larger gaps.

LIMITATIONS

The included studies had cross-sectional study design, small sample sizes and heterogeneous methodology, and lack of control for pharmacological treatment.

CONCLUSIONS

BD seems to be associated with generalized age-related structural GM volumes reductions and functional brain alterations thus suggesting the presence of neurodegenerative processes. Future systematic reviews and meta-analyses should be conducted to quantify the magnitude of brain ageing-related effects in BD.

Biological hypotheses, risk factors, and biomarkers of schizophrenia

Both the discovery of biomarkers of schizophrenia and the verification of biological hypotheses of schizophrenia are an essential part of the process of understanding the etiology of this mental disorder. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function and the establishment of a new homeostatic setpoint characterized by biomarkers. Different risk factors and biomarkers can converge to the same symptoms of schizophrenia, suggesting that the primary cause of the disease can be highly individual. Schizophrenia-related biomarkers include measurable biochemical changes induced by stress (elevated allostatic load), mitochondrial dysfunction, neuroinflammation, oxidative and nitrosative stress, and circadian rhythm disturbances. Here is a summary of selected valid biological hypotheses of schizophrenia formulated based on risk factors and biomarkers, neurodevelopment, neuroplasticity, brain chemistry, and antipsychotic medication. The integrative neurodevelopmental-vulnerability-neurochemical model is based on current knowledge of the neurobiology of the onset and progression of the disease and the effects of antipsychotics and psychotomimetics and reflects the complex and multifactorial nature of schizophrenia.

Infections and schizophrenia

This paper provides a critical review of the literature, demonstrating a certain pathogenetic role of various infections, primarily viruses from the herpes and chlamydia groups, in the development and progression of schizophrenia, including published results of the authors’ own long-term studies.

Development of Thalamocortical Structural Connectivity in Typically Developing and Psychosis Spectrum Youths

BACKGROUND

Thalamocortical white matter connectivity is disrupted in psychosis and is hypothesized to play a role in its etiology and associated cognitive impairment. Attenuated cognitive symptoms often begin in adolescence, during a critical phase of white matter and cognitive development. However, little is known about the development of thalamocortical white matter connectivity and its association with cognition.

METHODS

This study characterized effects of age, sex, psychosis symptomatology, and cognition in thalamocortical networks in a large sample of youths (N = 1144, ages 8-22 years, 46% male) from the Philadelphia Neurodevelopmental Cohort, which included 316 typically developing youths, 330 youths on the psychosis spectrum, and 498 youths with other psychopathology. Probabilistic tractography was used to quantify percent total connectivity between the thalamus and six cortical regions and assess microstructural properties (i.e., fractional anisotropy) of thalamocortical white matter tracts.

RESULTS

Overall, percent total connectivity of the thalamus was weakly associated with age and was not associated with psychopathology or cognition. In contrast, fractional anisotropy of all thalamocortical tracts increased significantly with age, was generally higher in males than females, and was lowest in youths on the psychosis spectrum. Fractional anisotropy of tracts linking the thalamus to prefrontal and posterior parietal cortices was related to better cognitive function across subjects.

CONCLUSIONS

By characterizing the pattern of typical development and alterations in those at risk for psychotic disorders, this study provides a foundation for further conceptualization of thalamocortical white matter microstructure as a marker of neurodevelopment supporting cognition and an important risk marker for psychosis.

Differential effects of chronic adolescent glucocorticoid or methamphetamine on drug-induced locomotor hyperactivity and disruption of prepulse inhibition in adulthood in mice

Sensitization of dopaminergic activity has been suggested as an underlying mechanism in the psychotic symptoms of schizophrenia. Adolescent stress and chronic abuse of methamphetamine (Meth) are well-known risk factors for psychosis and schizophrenia; however it remains unknown how these factors compare in terms of dopaminergic behavioural sensitization in adulthood. In addition, while Brain-Derived Neurotrophic Factor (BDNF) has been implicated in dopaminergic activity and schizophrenia, its role in behavioural sensitization remains unclear. In this study we therefore compared the effect of chronic adolescent treatment with the stress hormone, corticosterone (Cort), or with Meth, on drug-induced locomotor hyperactivity and disruption of prepulse inhibition in adulthood in BDNF heterozygous mice and their wild-type controls, as well as on dopamine receptor gene expression. Between 6 and 9 weeks of age, the animals either received Cort in the drinking water or were treated with an escalating Meth dose protocol. In adulthood, Cort-pretreated mice showed significantly reduced Meth-induced locomotor hyperactivity compared to vehicle-pretreated mice. In contrast, Meth hyperlocomotion was significantly enhanced in animals pretreated with the drug in adolescence. There were no effects of either pretreatment on prepulse inhibition. BDNF Het mice showed greater Meth-induced hyperlocomotion and lower prepulse inhibition than WT mice. There were no effects of either pretreatment on D1 or D2 gene expression in either the dorsal or ventral striatum, while D3 mRNA was shown to be reduced in male mice only irrespective of genotype. These results suggest that in adolescence, chronically elevated glucocorticoid levels, a component of chronic stress, do not cause dopaminergic sensitization adulthood, in contrast to the effect of chronic Meth treatment in the same age period. BDNF does not appear to be involved in the effects of chronic Cort or chronic Meth.

Virus-Induced Maternal Immune Activation as an Environmental Factor in the Etiology of Autism and Schizophrenia

Maternal immune activation (MIA) is mediated by activation of inflammatory pathways resulting in increased levels of cytokines and chemokines that cross the placental and blood-brain barriers altering fetal neural development. Maternal viral infection is one of the most well-known causes for immune activation in pregnant women. MIA and immune abnormalities are key players in the etiology of developmental conditions such as autism, schizophrenia, ADHD, and depression. Experimental evidence implicating MIA in with different effects in the offspring is complex. For decades, scientists have relied on either MIA models or human epidemiological data or a combination of both. MIA models are generated using infection/pathogenic agents to induce an immunological reaction in rodents and monitor the effects. Human epidemiological studies investigate a link between maternal infection and/or high levels of cytokines in pregnant mothers and the likelihood of developing conditions. In this review, we discuss the importance of understanding the relationship between virus-mediated MIA and neurodevelopmental conditions, focusing on autism and schizophrenia. We further discuss the different methods of studying MIA and their limitations and focus on the different factors contributing to MIA heterogeneity.

Maternal Inflammation Exaggerates Offspring Susceptibility to Cerebral Ischemia–Reperfusion Injury via the COX-2/PGD2/DP2 Pathway Activation

The pathogenesis of cerebral ischemia–reperfusion (I/R) injury is complex and does not exhibit an effective strategy. Maternal inflammation represents one of the most important factors involved in the etiology of brain injury in newborns. We aimed to investigate the effect of maternal inflammation on offspring susceptibility to cerebral I/R injury and the mechanisms by which it exerts its effects. Pregnant SD rats were intraperitoneally injected with LPS (300 μg/kg/day) at gestational days 11, 14, and 18. Pups were subjected to MCAO/R on postnatal day 60. Primary neurons were obtained from postnatal day 0 SD rats and subjected to OGD/R. Neurological deficits, brain injury, neuronal viability, neuronal damage, and neuronal apoptosis were assessed. Oxidative stress and inflammation were evaluated, and the expression levels of COX-2/PGD2/DP pathway-related proteins and apoptotic proteins were detected. Maternal LPS exposure significantly increased the levels of oxidative stress and inflammation, significantly activated the COX-2/PGD2/DP₂ pathway, and increased proapoptotic protein expression. However, maternal LPS exposure significantly decreased the antiapoptotic protein expression, which subsequently increased neurological deficits and cerebral I/R injury in offspring rats. The corresponding results were observed in primary neurons. Moreover, these effects of maternal LPS exposure were reversed by a COX-2 inhibitor and DP₁ agonist but exacerbated by a DP₂ agonist. In conclusion, maternal inflammatory exposure may increase offspring susceptibility to cerebral I/R injury. Moreover, the underlying mechanism might be related to the activation of the COX-2/PGD2/DP₂ pathway. These findings provide a theoretical foundation for the development of therapeutic drugs for cerebral I/R injury.

Biopsychosocial Exposure to the Covid-19 Pandemic and the Relative Risk of Schizophrenia: Interrupted Time-Series Analysis of a Nationally Representative Sample

Background

Studies of COVID-19 pandemic biopsychosocial exposure and schizophrenia risk showed contradictory results, were undertaken early in the pandemic, and did not consider lockdowns or COVID-19 infection. Hence, we examined the association between COVID-19 biopsychosocial exposure and incident schizophrenia.

Methods

An interrupted time-series study design was implemented based on Israeli electronic health records from 2013 to 2021 with national coverage. The period coinciding with the COVID-19 pandemic biopsychosocial exposures from March 2020 to February 2021 was classified as exposed, otherwise unexposed. The effect of the COVID-19 pandemic on incident schizophrenia was quantified by fitting a Poisson regression and modeling the relative risk (RR) and corresponding 95% confidence intervals (CI). Three scenarios were projected from the third lockdown to 10 months to forecast incident schizophrenia rates and their associated 95% prediction intervals (PI).

Results

The total population (N = 736,356) yielded 4,310 cases of incident schizophrenia over time. The primary analysis showed that the period exposed to the COVID-19 pandemic was associated with a reduced RR (RR = 0.81, 95% CI = 0.73, 0.91, p < 0.001). This conclusion was supported in 12 sensitivity analyses, including scrutinizing lockdowns and COVID-19 infection status. Two of three forecast scenarios projected an incident increase (6.74, 95% PI = 5.80, 7.84; 7.40, 95% PI = 6.36, 8.60).

Conclusions

The reduced risk of schizophrenia during the pandemic suggests no immediate triggering of new onsets either by the virus or the pandemic-induced psychosocial adversities. Once restrictions are lifted, the increased projected presentations have implications for clinicians and healthcare policy.

Detection of Morphological Abnormalities in Schizophrenia: An Important Step to Identify Associated Genetic Disorders or Etiologic Subtypes

Current research suggests that alterations in neurodevelopmental processes, involving gene X environment interactions during key stages of brain development (prenatal period and adolescence), are a major risk for schizophrenia. First, epidemiological studies supporting a genetic contribution to schizophrenia are presented in this article, including family, twin, and adoption studies. Then, an extensive literature review on genetic disorders associated with schizophrenia is reviewed. These epidemiological findings and clinical observations led researchers to conduct studies on genetic associations in schizophrenia, and more specifically on genomics (CNV: copy-number variant, and SNP: single nucleotide polymorphism). The main structural (CNV) and sequence (SNP) variants found in individuals with schizophrenia are reported here. Evidence of genetic contributions to schizophrenia and current knowledge on genetic syndromes associated with this psychiatric disorder highlight the importance of a clinical genetic examination to detect minor physical anomalies in individuals with ultra-high risk of schizophrenia. Several dysmorphic features have been described in schizophrenia, especially in early onset schizophrenia, and can be viewed as neurodevelopmental markers of vulnerability. Early detection of individuals with neurodevelopmental abnormalities is a fundamental issue to develop prevention and diagnostic strategies, therapeutic intervention and follow-up, and to ascertain better the underlying mechanisms involved in the pathophysiology of schizophrenia.

Novel approaches in schizophrenia-from risk factors and hypotheses to novel drug targets

Schizophrenia is a severe psychiatric disorder characterized by emotional, behavioral and cognitive disturbances, and the treatment of schizophrenia is often complicated by noncompliance and pharmacoresistance. The search for the pathophysiological mechanisms underlying schizophrenia has resulted in the proposal of several hypotheses to explain the impacts of environmental, genetic, neurodevelopmental, immune and inflammatory factors on disease onset and progression. This review discusses the newest insights into the pathophysiology of and risk factors for schizophrenia and notes novel approaches in antipsychotic treatment and potential diagnostic and theranostic biomarkers. The current hypotheses focusing on neuromediators (dopamine, glutamate, and serotonin), neuroinflammation, the cannabinoid hypothesis, the gut-brain axis model, and oxidative stress are summarized. Key genetic features, including small nucleotide polymorphisms, copy number variations, microdeletions, mutations and epigenetic changes, are highlighted. Current pharmacotherapy of schizophrenia relies mostly on dopaminergic and serotonergic antagonists/partial agonists, but new findings in the pathophysiology of schizophrenia have allowed the expansion of novel approaches in pharmacotherapy and the establishment of more reliable biomarkers. Substances with promising results in preclinical and clinical studies include lumateperone, pimavanserin, xanomeline, roluperidone, agonists of trace amine-associated receptor 1, inhibitors of glycine transporters, AMPA allosteric modulators, mGLUR_2-3 agonists, D-amino acid oxidase inhibitors and cannabidiol. The use of anti-inflammatory agents as an add-on therapy is mentioned.

Neurobiology and the Hierarchical Taxonomy of Psychopathology: progress toward ontogenetically informed and clinically useful nosology

The Hierarchical Taxonomy of Psychopathology (HiTOP) is an empirical structural model of psychological symptoms formulated to improve the reliability and validity of clinical assessment. Neurobiology can inform assessments of early risk and intervention strategies, and the HiTOP model has greater potential to interface with neurobiological measures than traditional categorical diagnoses given its enhanced reliability. However, one complication is that observed biological correlates of clinical symptoms can reflect various factors, ranging from dispositional risk to consequences of psychopathology. In this paper, we argue that the HiTOP model provides an optimized framework for conducting research on the biological correlates of psychopathology from an ontogenetic perspective that distinguishes among indicators of liability, current symptoms, and consequences of illness. Through this approach, neurobiological research can contribute more effectively to identifying individuals at high dispositional risk, indexing treatment-related gains, and monitoring the consequences of mental illness, consistent with the aims of the HiTOP framework.


Association between retinal vascular caliber and brain structure in schizophrenia

OBJECTIVE

Several lines of research in the last decade have indicated the potential utility of retina as a window to the brain. Emerging evidence suggests abnormalities in retinal vascular caliber in schizophrenia. However, the relationship between retinal vascular measures and brain structure has not been examined in schizophrenia to date. Hence, we examined the relationship between retinal vasculature measured using fundus photography and brain structure measured using magnetic resonance imaging.

METHOD

We recruited 17 healthy volunteers and 20 patients with schizophrenia. Using a non-mydriatic camera, we captured the images for left and right eyes separately and retinal vascular calibers were calculated using a semi-automated software package. Whole-brain anatomical T1 MPRAGE images were acquired using a 3-Tesla MRI scanner. Whole-brain and regional volume and cortical thickness were calculated using the Freesurfer software package. We used FreeSurfer's QDEC interface to compute vertex-by-vertex for analysis of the volume and cortical thickness. The relation between brain volume, cortical thickness, and retinal vascular caliber was examined using partial correlation and regression analysis.

RESULTS

There was a significant negative correlation between average CRVE and global cortical mean thickness in schizophrenia but not in healthy. In schizophrenia patients, there was a significant negative correlation between average CRVE and cortical thickness in frontal regions - left rostral middle frontal, left superior frontal, and right caudal middle frontal gyri and posterior brain regions - left lateral occipital gyrus and left posterior cingulate cortex.

DISCUSSION

The findings of the study suggest potential utility of retinal venular diameter as a proxy marker to abnormal neurodevelopment in schizophrenia.

Glutamate and microglia activation as a driver of dendritic apoptosis: a core pathophysiological mechanism to understand schizophrenia

Schizophrenia disorder remains an unsolved puzzle. However, the integration of recent findings from genetics, molecular biology, neuroimaging, animal models and translational clinical research offers evidence that the synaptic overpruning hypothesis of schizophrenia needs to be reassessed. During a critical period of neurodevelopment and owing to an imbalance of excitatory glutamatergic pyramidal neurons and inhibitory GABAergic interneurons, a regionally-located glutamate storm might occur, triggering excessive dendritic pruning with the activation of local dendritic apoptosis machinery. The apoptotic loss of dendritic spines would be aggravated by microglia activation through a recently described signaling system from complement abnormalities and proteins of the MHC, thus implicating the immune system in schizophrenia. Overpruning of dendritic spines coupled with aberrant synaptic plasticity, an essential function for learning and memory, would lead to brain misconnections and synaptic inefficiency underlying the primary negative symptoms and cognitive deficits of schizophrenia. This driving hypothesis has relevant therapeutic implications, including the importance of pharmacological interventions during the prodromal phase or the transition to psychosis, targeting apoptosis, microglia cells or the glutamate storm. Future research on apoptosis and brain integrity should combine brain imaging, CSF biomarkers, animal models and cell biology.

Updating and characterizing neuroanatomical markers in high-risk subjects, recently diagnosed and chronic patients with schizophrenia: A revised coordinate-based meta-analysis

Characterizing neuroanatomical markers of different stages of schizophrenia (SZ) to assess pathophysiological models of how the disorder develops is an important target for the clinical practice. We performed a meta-analysis of voxel-based morphometry studies of genetic and clinical high-risk subjects (g-/c-HR), recently diagnosed (RDSZ) and chronic SZ patients (ChSZ). We quantified gray matter (GM) changes associated with these four conditions and compared them with contrast and conjunctional data. We performed the behavioral analysis and networks decomposition of alterations to obtain their functional characterization. Results reveal a cortical-subcortical, left-to-right homotopic progression of GM loss. The right anterior cingulate is the only altered region found altered among c-HR, RDSZ and ChSZ. Contrast analyses show left-lateralized insular, amygdalar and parahippocampal GM reduction in RDSZ, which appears bilateral in ChSZ. Functional decomposition shows involvement of the salience network, with an enlargement of the sensorimotor network in RDSZ and the thalamus-basal nuclei network in ChSZ. These findings support the current neuroprogressive models of SZ and integrate this deterioration with the clinical evolution of the disease.

White matter abnormalities across the lifespan of schizophrenia: a harmonized multi-site diffusion MRI study

Several prominent theories of schizophrenia suggest that structural white matter pathologies may follow a developmental, maturational, and/or degenerative process. However, a lack of lifespan studies has precluded verification of these theories. Here, we analyze the largest sample of carefully harmonized diffusion MRI data to comprehensively characterize age-related white matter trajectories, as measured by fractional anisotropy (FA), across the course of schizophrenia. Our analysis comprises diffusion scans of 600 schizophrenia patients and 492 healthy controls at different illness stages and ages (14-65 years), which were gathered from 13 sites. We determined the pattern of age-related FA changes by cross-sectionally assessing the timing of the structural neuropathology associated with schizophrenia. Quadratic curves were used to model between-group FA differences across whole-brain white matter and fiber tracts at each age; fiber tracts were then clustered according to both the effect-sizes and pattern of lifespan white matter FA differences. In whole-brain white matter, FA was significantly lower across the lifespan (up to 7%; p < 0.0033) and reached peak maturation younger in patients (27 years) compared to controls (33 years). Additionally, three distinct patterns of neuropathology emerged when investigating white matter fiber tracts in patients: (1) developmental abnormalities in limbic fibers, (2) accelerated aging and abnormal maturation in long-range association fibers, (3) severe developmental abnormalities and accelerated aging in callosal fibers. Our findings strongly suggest that white matter in schizophrenia is affected across entire stages of the disease. Perhaps most strikingly, we show that white matter changes in schizophrenia involve dynamic interactions between neuropathological processes in a tract-specific manner.

Prenatal and perinatal risk and protective factors for psychosis: a systematic review and meta-analysis

BACKGROUND

Prenatal and perinatal insults are implicated in the aetiopathogenesis of psychotic disorders but the consistency and magnitude of their associations with psychosis have not been updated for nearly two decades. The aim of this systematic review and meta-analysis was to provide a comprehensive and up-to-date synthesis of the evidence on the association between prenatal or perinatal risk and protective factors and psychotic disorders.

METHODS

In this systematic review and meta-analysis, we searched the Web of Science database for articles published up to July 20, 2019. We identified cohort and case-control studies examining the association (odds ratio [OR]) between prenatal and perinatal factors and any International Classification of Diseases (ICD) or Diagnostic and Statistical Manual of Mental Disorders (DSM) non-organic psychotic disorder with a healthy comparison group. Other inclusion criteria were enough data available to do the analyses, and non-overlapping datasets. We excluded reviews, meta-analyses, abstracts or conference proceedings, and articles with overlapping datasets. Data were extracted according to EQUATOR and PRISMA guidelines. Extracted variables included first author, publication year, study type, sample size, type of psychotic diagnosis (non-affective psychoses or schizophrenia-spectrum disorders, affective psychoses) and diagnostic instrument (DSM or ICD and version), the risk or protective factor, and measure of association (primary outcome). We did random-effects pairwise meta-analyses, Q statistics, I² index, sensitivity analyses, meta-regressions, and assessed study quality and publication bias. The study protocol was registered at PROSPERO, CRD42017079261.

FINDINGS

152 studies relating to 98 risk or protective factors were eligible for analysis. Significant risk factors were: maternal age younger than 20 years (OR 1·17) and 30-34 years (OR 1·05); paternal age younger than 20 years (OR 1·31) and older than 35 years (OR 1·28); any maternal (OR 4·60) or paternal (OR 2·73) psychopathology; maternal psychosis (OR 7·61) and affective disorder (OR 2·26); three or more pregnancies (OR 1·30); herpes simplex 2 (OR 1·35); maternal infections not otherwise specified (NOS; OR 1·27); suboptimal number of antenatal visits (OR 1·83); winter (OR 1·05) and winter to spring (OR 1·05) season of birth in the northern hemisphere; maternal stress NOS (OR 2·40); famine (OR 1·61); any famine or nutritional deficits in pregnancy (OR 1·40); maternal hypertension (OR 1·40); hypoxia (OR 1·63); ruptured (OR 1·86) and premature rupture (OR 2·29) of membranes; polyhydramnios (OR 3·05); definite obstetric complications NOS (OR 1·83); birthweights of less than 2000 g (OR 1·84), less than 2500 g (OR 1·53), or 2500-2999 g (OR 1·23); birth length less than 49 cm (OR 1·17); small for gestational age (OR 1·40); premature birth (OR 1·35), and congenital malformations (OR 2·35). Significant protective factors were maternal ages 20-24 years (OR 0·93) and 25-29 years (OR 0·92), nulliparity (OR 0·91), and birthweights 3500-3999 g (OR 0·90) or more than 4000 g (OR 0·86). The results were corrected for publication biases; sensitivity and meta-regression analyses confirmed the robustness of these findings for most factors.

INTERPRETATION

Several prenatal and perinatal factors are associated with the later onset of psychosis. The updated knowledge emerging from this study could refine understanding of psychosis pathogenesis, enhance multivariable risk prediction, and inform preventive strategies.

FUNDING

None.

Right care, first time: a highly personalised and measurement-based care model to manage youth mental health

Mood and psychotic syndromes most often emerge during adolescence and young adulthood, a period characterised by major physical and social change. Consequently, the effects of adolescent-onset mood and psychotic syndromes can have long term consequences. A key clinical challenge for youth mental health is to develop and test new systems that align with current evidence for comorbid presentations and underlying neurobiology, and are useful for predicting outcomes and guiding decisions regarding the provision of appropriate and effective care. Our highly personalised and measurement-based care model includes three core concepts: ▶ A multidimensional assessment and outcomes framework that includes: social and occupational function; self-harm, suicidal thoughts and behaviour; alcohol or other substance misuse; physical health; and illness trajectory. ▶ Clinical stage. ▶ Three common illness subtypes (psychosis, anxious depression, bipolar spectrum) based on proposed pathophysiological mechanisms (neurodevelopmental, hyperarousal, circadian). The model explicitly aims to prevent progression to more complex and severe forms of illness and is better aligned to contemporary models of the patterns of emergence of psychopathology. Inherent within this highly personalised approach is the incorporation of other evidence-based processes, including real-time measurement-based care as well as utilisation of multidisciplinary teams of health professionals. Data-driven local system modelling and personalised health information technologies provide crucial infrastructure support to these processes for better access to, and higher quality, mental health care for young people. CHAPTER 1: MULTIDIMENSIONAL OUTCOMES IN YOUTH MENTAL HEALTH CARE: WHAT MATTERS AND WHY?: Mood and psychotic syndromes present one of the most serious public health challenges that we face in the 21st century. Factors including prevalence, age of onset, and chronicity contribute to substantial burden and secondary risks such as alcohol or other substance misuse. Mood and psychotic syndromes most often emerge during adolescence and young adulthood, a period characterised by major physical and social change; thus, effects can have long term consequences. We propose five key domains which make up a multidimensional outcomes framework that aims to address the specific needs of young people presenting to health services with emerging mental illness. These include social and occupational function; self-harm, suicidal thoughts and behaviours; alcohol or other substance misuse; physical health; and illness type, stage and trajectory. Impairment and concurrent morbidity are well established in young people by the time they present for mental health care. Despite this, services and health professionals tend to focus on only one aspect of the presentation - illness type, stage and trajectory - and are often at odds with the preferences of young people and their families. There is a need to address the disconnect between mental health, physical health and social services and interventions, to ensure that youth mental health care focuses on the outcomes that matter to young people. CHAPTER 2: COMBINING CLINICAL STAGE AND PATHOPHYSIOLOGICAL MECHANISMS TO UNDERSTAND ILLNESS TRAJECTORIES IN YOUNG PEOPLE WITH EMERGING MOOD AND PSYCHOTIC SYNDROMES: Traditional diagnostic classification systems for mental disorders map poorly onto the early stages of illness experienced by young people, and purport categorical distinctions that are not readily supported by research into genetic, environmental and neurobiological risk factors. Consequently, a key clinical challenge in youth mental health is to develop and test new classification systems that align with current evidence on comorbid presentations, are consistent with current understanding of underlying neurobiology, and provide utility for predicting outcomes and guiding decisions regarding the provision of appropriate and effective care. This chapter outlines a transdiagnostic framework for classifying common adolescent-onset mood and psychotic syndromes, combining two independent but complementary dimensions: clinical staging, and three proposed pathophysiological mechanisms. Clinical staging reflects the progression of mental disorders and is in line with the concept used in general medicine, where more advanced stages are associated with a poorer prognosis and a need for more intensive interventions with a higher risk-to-benefit ratio. The three proposed pathophysiological mechanisms are neurodevelopmental abnormalities, hyperarousal and circadian dysfunction, which, over time, have illness trajectories (or pathways) to psychosis, anxious depression and bipolar spectrum disorders, respectively. The transdiagnostic framework has been evaluated in young people presenting to youth mental health clinics of the University of Sydney's Brain and Mind Centre, alongside a range of clinical and objective measures. Our research to date provides support for this framework, and we are now exploring its application to the development of more personalised models of care. CHAPTER 3: A COMPREHENSIVE ASSESSMENT FRAMEWORK FOR YOUTH MENTAL HEALTH: GUIDING HIGHLY PERSONALISED AND MEASUREMENT-BASED CARE USING MULTIDIMENSIONAL AND OBJECTIVE MEASURES: There is an urgent need for improved care for young people with mental health problems, in particular those with subthreshold mental disorders that are not sufficiently severe to meet traditional diagnostic criteria. New comprehensive assessment frameworks are needed to capture the biopsychosocial profile of a young person to drive highly personalised and measurement-based mental health care. We present a range of multidimensional measures involving five key domains: social and occupational function; self-harm, suicidal thoughts and behaviours; alcohol or other substance misuse; physical health; and illness type, stage and trajectory. Objective measures include: neuropsychological function; sleep-wake behaviours and circadian rhythms; metabolic and immune markers; and brain structure and function. The recommended multidimensional measures facilitate the development of a comprehensive clinical picture. The objective measures help to further develop informative and novel insights into underlying pathophysiological mechanisms and illness trajectories to guide personalised care plans. A panel of specific multidimensional and objective measures are recommended as standard clinical practice, while others are recommended secondarily to provide deeper insights with the aim of revealing alternative clinical paths for targeted interventions and treatments matched to the clinical stage and proposed pathophysiological mechanisms of the young person. CHAPTER 4: PERSONALISING CARE OPTIONS IN YOUTH MENTAL HEALTH: USING MULTIDIMENSIONAL ASSESSMENT, CLINICAL STAGE, PATHOPHYSIOLOGICAL MECHANISMS, AND INDIVIDUAL ILLNESS TRAJECTORIES TO GUIDE TREATMENT SELECTION: New models of mental health care for young people require that interventions be matched to illness type, clinical stage, underlying pathophysiological mechanisms and individual illness trajectories. Narrow syndrome-focused classifications often direct clinical attention away from other key factors such as functional impairment, self-harm and suicidality, alcohol or other substance misuse, and poor physical health. By contrast, we outline a treatment selection guide for early intervention for adolescent-onset mood and psychotic syndromes (ie, active treatments and indicated and more specific secondary prevention strategies). This guide is based on experiences with the Brain and Mind Centre's highly personalised and measurement-based care model to manage youth mental health. The model incorporates three complementary core concepts: ▶A multidimensional assessment and outcomes framework including: social and occupational function; self-harm, suicidal thoughts and behaviours; alcohol or other substance misuse; physical health; and illness trajectory. ▶Clinical stage. ▶Three common illness subtypes (psychosis, anxious depression, bipolar spectrum) based on three underlying pathophysiological mechanisms (neurodevelopmental, hyperarousal, circadian). These core concepts are not mutually exclusive and together may facilitate improved outcomes through a clinical stage-appropriate and transdiagnostic framework that helps guide decisions regarding the provision of appropriate and effective care options. Given its emphasis on adolescent-onset mood and psychotic syndromes, the Brain and Mind Centre's model of care also respects a fundamental developmental perspective - categorising childhood problems (eg, anxiety and neurodevelopmental difficulties) as risk factors and respecting the fact that young people are in a period of major biological and social transition. Based on these factors, a range of social, psychological and pharmacological interventions are recommended, with an emphasis on balancing the personal benefit-to-cost ratio. CHAPTER 5: A SERVICE DELIVERY MODEL TO SUPPORT HIGHLY PERSONALISED AND MEASUREMENT-BASED CARE IN YOUTH MENTAL HEALTH: Over the past decade, we have seen a growing focus on creating mental health service delivery models that better meet the unique needs of young Australians. Recent policy directives from the Australian Government recommend the adoption of stepped-care services to improve the appropriateness of care, determined by severity of need. Here, we propose that a highly personalised approach enhances stepped-care models by incorporating clinical staging and a young person's current and multidimensional needs. It explicitly aims to prevent progression to more complex and severe forms of illness and is better aligned to contemporary models of the patterns of emergence of psychopathology. Inherent within a highly personalised approach is the incorporation of other evidence-based processes, including real-time measurement-based care and use of multidisciplinary teams of health professionals. Data-driven local system modelling and personalised health information technologies provide crucial infrastructure support to these processes for better access to, and higher quality of, mental health care for young people.

Schizophrenia and Influenza at the Centenary of the 1918-1919 Spanish Influenza Pandemic: Mechanisms of Psychosis Risk

Associations between influenza infection and psychosis have been reported since the eighteenth century, with acute "psychoses of influenza" documented during multiple pandemics. In the late 20th century, reports of a season-of-birth effect in schizophrenia were supported by large-scale ecological and sero-epidemiological studies suggesting that maternal influenza infection increases the risk of psychosis in offspring. We examine the evidence for the association between influenza infection and schizophrenia risk, before reviewing possible mechanisms via which this risk may be conferred. Maternal immune activation models implicate placental dysfunction, disruption of cytokine networks, and subsequent microglial activation as potentially important pathogenic processes. More recent neuroimmunological advances focusing on neuronal autoimmunity following infection provide the basis for a model of infection-induced psychosis, potentially implicating autoimmunity to schizophrenia-relevant protein targets including the N-methyl-D-aspartate receptor. Finally, we outline areas for future research and relevant experimental approaches and consider whether the current evidence provides a basis for the rational development of strategies to prevent schizophrenia.

Clozapine response trajectories and predictors of non-response in treatment-resistant schizophrenia: a chart review study

Although clozapine is the main antipsychotic medication for treatment-resistant schizophrenia, 40-70% of patients on clozapine have persistent psychotic symptoms (i.e. ultra-treatment-resistant schizophrenia, UTRS). We aimed to examine clozapine response/non-response patterns in patients with treatment-resistant schizophrenia, as well as determine patient clinico-demographic factors associated with long-term clozapine non-response. Clinico-demographic characteristics of 241 patients on clozapine were collected through a retrospective chart review. The median (interquartile range, IQR) follow-up from illness onset was 25.0 (IQR = 24.0) years. Clozapine response was assessed at median 10.8 (IQR = 14.0) months (Time 1, T1) and 7.2 (IQR = 13.5) years (Time 2, T2) after its initiation. It was evaluated by chart reviewers based on the information provided in clinical notes. Binomial logistic regression was used to determine clinico-demographic factors associated with clozapine non-response at both T1 and T2 (i.e. stable UTRS, S-UTRS) compared to clozapine response at both times (i.e. stable clozapine responders, S-ClozResp). Among clozapine responders (n = 122) at T1, 83.6% remained clozapine responsive and 16.4% became non-responsive at T2. In the UTRS group (n = 119) at T1, 87.4% remained clozapine non-responsive and 12.6% became responsive at T2. Duration of delay in clozapine initiation (OR = 0.94, Wald χ² = 5.33, p = 0.021) and number of pre-clozapine hospitalizations (OR = 0.95, Wald χ² = 5.20, p = 0.023) were associated with S-UTRS. Most UTRS patients were non-responsive to clozapine from the start of treatment. Preventing delay in initiating clozapine and relapses could help promote long-term clozapine response in patients with treatment-resistant schizophrenia. Future longitudinal studies are required to explore the neuropathological correlates of relapses and delay in clozapine initiation.

The connection between microbiome and schizophrenia

There has been an accumulation of knowledge about the human microbiome, some detailed investigations of the gastrointestinal microbiota and its functions, and the highlighting of complex interactions between the gut, the gut microbiota, and the central nervous system. That assumes the involvement of the microbiome in the pathogenesis of various CNS diseases, including schizophrenia. Given this information and the fact, that the gut microbiota is sensitive to internal and environmental influences, we have speculated that among the factors that influence the formation and composition of gut microbiota during life, possible key elements in the schizophrenia development chain are hidden where gut microbiota is a linking component. This article aims to describe and understand the developmental relationships between intestinal microbiota and the risk of developing schizophrenia.

A multimodal attempt to follow-up linkage regions using RNA expression, SNPs and CpG methylation in schizophrenia and bipolar disorder kindreds

The complexity of schizophrenia (SZ) and bipolar disorder (BD) has slowed down progress in understanding their genetic roots. Alternative genomic approaches are needed to bypass these difficulties. We attempted a multimodal approach to follow-up on reported linkage findings in SZ and BD from the Eastern Quebec kindreds in chromosomes 3q21, 4p34, 6p22, 8p21, 8p11, 13q11-q14, 15q13, 16p12, and 18q21. First, in 498 subjects, we measured RNA expression (47 K Illumina chips) in SZ and BD patients that we compared with their non-affected relatives (NARs) to identify, for each chromosomal region, genes showing the most significant differences in expression. Second, we performed SNP genotyping (700 K Illumina chips) and cis-eQTN analysis. Third, we measured DNA methylation on genes with RNA expression differences or eQTNs. We found a significant overexpression of the gene ITGB5 at 3q25 in SZ and BD after multiple testing p value adjustment. SPCS3 gene at 4q34, and FZD3 gene at 8p21, contained significant eQTNs after multiple testing corrections, while ITGB5 provided suggestive results. Methylation in associated genes did not explain the expression differences between patients and NARs. Our multimodal approach involving RNA expression, dense SNP genotyping and eQTN analyses, restricted to chromosomal regions having shown linkage, lowered the multiple testing burden and allowed for a deeper examination of candidate genes in SZ or BD.

Inefficient neural system stabilization: a theory of spontaneous resolutions and recurrent relapses in psychosis

A striking feature of psychosis is its heterogeneity. Presentations of psychosis vary from transient symptoms with no functional consequence in the general population to a tenacious illness at the other extreme, with a wide range of variable trajectories in between. Even among patients with schizophrenia, who are diagnosed on the basis of persistent deterioration, marked variation is seen in response to treatment, frequency of relapses and degree of eventual recovery. Existing theoretical accounts of psychosis focus almost exclusively on how symptoms are initially formed, with much less emphasis on explaining their variable course. In this review, I present an account that links several existing notions of the biology of psychosis with the variant clinical trajectories. My aim is to incorporate perspectives of systems neuroscience in a staging framework to explain the individual variations in illness course that follow the onset of psychosis.

Peripheral Biomarkers for First-Episode Psychosis-Opportunities from the Neuroinflammatory Hypothesis of Schizophrenia

OBJECTIVE

Schizophrenia is a disabling disorder of unknown aetiology, lacking definite diagnostic method and cure. A reliable biological marker of schizophrenia is highly demanded, for which traceable immune mediators in blood could be promising candidates. We aimed to gather the best findings of neuroinflammatory markers for first-episode psychosis (FEP).

METHODS

We performed an extensive narrative review of online literature on inflammation-related markers found in human FEP patients only.

RESULTS

Changes to cytokine levels have been increasingly reported in schizophrenia. The peripheral levels of IL-1 (or its receptor antagonist), soluble IL-2 receptor, IL-4, IL-6, IL-8, and TNF-α have been frequently reported as increased in FEP, in a suggestive continuum from high-risk stages for psychosis. Microglia and astrocytes establish the link between this immune signalling and the synthesis of noxious tryptophan catabolism products, that cause structural damage and directly hamper normal neurotransmission. Amongst these, only 3-hydroxykynurenine has been consistently described in the blood of FEP patients.

CONCLUSION

Peripheral molecules stemming from brain inflammation might provide insightful biomarkers of schizophrenia, as early as FEP or even prodromal phases, although more time- and clinically-adjusted studies are essential for their validation.

Age-Related Reduction in Cortical Thickness in First-Episode Treatment-Naïve Patients with Schizophrenia

Substantial evidence supports the neurodevelopmental hypothesis of schizophrenia. Meanwhile, progressive neurodegenerative processes have also been reported, leading to the hypothesis that neurodegeneration is a characteristic component in the neuropathology of schizophrenia. However, a major challenge for the neurodegenerative hypothesis is that antipsychotic drugs used by patients have profound impact on brain structures. To clarify this potential confounding factor, we measured the cortical thickness across the whole brain using high-resolution T1-weighted magnetic resonance imaging in 145 first-episode and treatment-naïve patients with schizophrenia and 147 healthy controls. The results showed that, in the patient group, the frontal, temporal, parietal, and cingulate gyri displayed a significant age-related reduction of cortical thickness. In the control group, age-related cortical thickness reduction was mostly located in the frontal, temporal, and cingulate gyri, albeit to a lesser extent. Importantly, relative to healthy controls, patients exhibited a significantly smaller age-related cortical thickness in the anterior cingulate, inferior temporal, and insular gyri in the right hemisphere. These results provide evidence supporting the existence of neurodegenerative processes in schizophrenia and suggest that these processes already occur in the early stage of the illness.

Association of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A With Clinical Features of Youth-Onset Schizophrenia

We investigated the associations of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A with youth-onset schizophrenia in the Russian population in a case-control study, and the role of the genotype in the severity of clinical features. The association between rs7322347 and schizophrenia (p = 0.0001) is described for the first time. Furthermore, we found a link with rs6280 and rs4680 in females (p = 0.001 and p = 0.02 respectively) and with rs7322347 in males (p = 0.002). Clinical symptoms were assessed on three scales: the Clinician-Rated Dimensions of Psychosis Symptom Severity scale, Positive and Negative Syndrome Scale, and Frontal Assessment Battery. Gender differences in clinical features are of particular interest. In our study we found gender differences in the severity of clinical features-higher scores for delusions (Positive and Negative Syndrome Scale and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) in males and higher scores for depression, delusions, somatic concern, motor retardation, poor attention were found in females.

Connectome development and a novel extension to the neurodevelopmental model of schizophrenia

The brain is the ultimate adaptive system, a complex network organized across multiple levels of spatial and temporal resolution that is sculpted over several decades via its interactions with the environment. This review sets out to examine how fundamental biological processes in early and late neurodevelopment, in interaction with environmental inputs, guide the formation of the brain's network and its ongoing reorganization throughout the course of development. Moreover, we explore how disruptions in these processes could lead to abnormal brain network architecture and organization and thereby give rise to schizophrenia. Arguing that the neurodevelopmental trajectory leading up to the manifestation of psychosis may best be understood from the sequential trajectory of connectome formation and maturation, we propose a novel extension to the neurodevelopmental model of the illness that posits that schizophrenia is a disorder of connectome development.

Risk factors in early and late onset schizophrenia

BACKGROUND

This study looks at key risk factors in patients with schizophrenia to identify trends according to age of onset, comparing presentations prior to 26years (youth onset), between 26 and 40years (middle onset), and after 40years of age (late onset).

METHODS

The early psychosis program at St Vincent's Hospital Melbourne treats patients presenting in the early stages of psychosis between 16 and 65years of age. A database was developed to capture key risk factors in all patients with an eventual diagnosis of schizophrenia (n=225). Risk factor profiles were then generated and compared for patients based on age of onset.

RESULTS

Older age of onset was associated with weaker family history of schizophrenia, lower rates of substance use, better early psychosocial functioning and higher educational achievement. Female preponderance and comorbid physical health problems were particularly notable in the late onset cohort. Later life schizophrenia also showed a relatively greater association with psychosocial factors proximal to psychosis onset, such as unemployment.

DISCUSSION

Clear trends are noticeable with age. Older patients have characteristic differences in their background risk factors compared to youth onset patients, including less hereditary influence and relatively more emphasis on later life risk factors. Identifying the roles of specific risk factors in these distinct age-onset groups can enhance our understanding of underlying aetiology and facilitate service development to meet the needs of each specific age group.

Induced Pluripotent Stem Cells Reveal Common Neurodevelopmental Genome Deprograming in Schizophrenia

Schizophrenia is a neurodevelopmental disorder characterized by complex aberrations in the structure, wiring, and chemistry of multiple neuronal systems. The abnormal developmental trajectory of the brain is established during gestation, long before clinical manifestation of the disease. Over 200 genes and even greater numbers of single nucleotide polymorphisms and copy number variations have been linked with schizophrenia. How does altered function of such a variety of genes lead to schizophrenia? We propose that the protein products of these altered genes converge on a common neurodevelopmental pathway responsible for the development of brain neural circuit and neurotransmitter systems. The results of a multichanneled investigation using induced pluripotent stem cell (iPSCs)- and embryonic stem cell (ESCs)-derived neuronal committed cells (NCCs) indicate an early (preneuronal) developmental-genomic etiology of schizophrenia and that the dysregulated developmental gene networks are common to genetically unrelated cases of schizophrenia. The results support a "watershed" mechanism in which mutations within diverse signaling pathways affect the common pan-ontogenic mechanism, integrative nuclear (n)FGFR1 signaling (INFS). Dysregulation of INFS in schizophrenia NCCs deconstructs coordinated gene networks and leads to formation of new networks by the dysregulated genes. This genome deprograming affects critical gene programs and pathways for neural development and functions. Studies show that the genomic deprograming reflect an altered nFGFR1-genome interactions and deregulation of miRNA genes by nFGFR1. In addition, changes in chromatin topology imposed by nFGFR1 may play a role in coordinate gene dysregulation in schizophrenia.

Schizotypal traits and cognitive performance in siblings of patients with psychosis

INTRODUCTION

Schizotypy has been proposed to be the expression of genetic vulnerability to schizophrenia. The available literature shows cognitive similarities between schizotypy and schizophrenia, with mildly impaired performance being associated with schizotypy. This study aims to determine the relationship between schizotypy and cognitive performance in siblings of patients with psychosis.

METHODS

Schizotypal features and cognitive performance on a neuropsychological battery were compared between 48 siblings of patients with psychosis and 44 healthy controls. The relationships between schizotypy and cognitive performance were analysed by controlling the condition of being a sibling.

RESULTS

Siblings showed poorer performance on vigilance/sustained attention (M = 37.6; SD = 7.1) and selective attention/interference control/working memory (M = 23.28; SD = 2.7) tasks. The variance in vigilance/sustained attention performance was explained, at 30%, by the interpersonal factor of schizotypy on the suspiciousness dimension and the condition of being a sibling.

CONCLUSIONS

Interpersonal features of schizotypy in siblings of patients with psychosis are associated with deficits in vigilance/sustained attention performance.

Barbara Fish and a Short History of the Neurodevelopmental Hypothesis of Schizophrenia

The neurodevelopmental hypothesis of schizophrenia has become a paradigm broadly accepted in today's research in schizophrenia and its spectrum. This article traces the historical development of the neurodevelopmental hypothesis of schizophrenia up until the time of its explicit formulation in 1987, by Weinberger and by Murray and Lewis, with a main focus on the seminal contribution of Barbara Fish to its conception and elaboration.

Sex differences in auditory verbal hallucinations in early, middle and late adolescence: results from a survey of 17 451 Japanese students aged 12-18 years

OBJECTIVES

Women have higher rates of auditory verbal hallucinations (AVH) than men; however, less is known about sex differences in the prevalence of AVH in early, middle and late adolescence. We sought to elucidate the differences in the prevalence of AVH and to examine the degree to which these differences could be explained by differences in levels of depressive symptoms.

DESIGN

We used a cross-sectional design and a self-reported questionnaire.

SETTING

Participants were recruited from public junior and senior high schools in Tsu, Mie Prefecture and Kochi Prefecture, Japan.

PARTICIPANTS

In total, 19 436 students were contacted and 18 250 participated. Responses from 17 451 students with no missing data were analysed (aged 12-18 years, M_age=15.2 years (SD=1.7), 50.6% girls).

MEASURES

AVH were assessed through one of four items adopted from the schizophrenia section of the Japanese version of the Diagnostic Interview Schedule for Children. Depressive symptoms were assessed using the 12-item General Health Questionnaire.

RESULTS

The prevalence of AVH was 7.0% among early adolescents (aged 12-13 years), 6.2% among middle adolescents (aged 14-15 years) and 4.8% among late adolescents (aged 16-18 years). Being female was significantly associated with a higher prevalence of AVH through adolescence (OR=1.71, 95% CI 1.31 to 2.23 in early adolescence; OR=1.42, 95% CI 1.14 to 1.76 in middle adolescence; OR=1.52, 95% CI 1.23 to 1.87 in late adolescence); however, these differences became non-significant after adjusting for depressive symptoms (OR=1.21, 95% CI 0.92 to 1.60; OR=1.00, 95% CI 0.80 to 1.25; OR=1.16, 95% CI 0.93 to 1.44, respectively).

CONCLUSIONS

Sex differences in auditory hallucinations are seen in both adult and youth populations. The higher rates of auditory verbal hallucinations seen in girls may be secondary to the differences in the rate of depressive symptoms.

Metabolic abnormality in the right dorsolateral prefrontal cortex in patients with obsessive-compulsive disorder: proton magnetic resonance spectroscopy

OBJECTIVE

Proton magnetic resonance spectroscopy (1H-MRS) was used to evaluate metabolic changes in the dorsolateral prefrontal cortex (DLPFC) in patients with obsessive-compulsive disorder (OCD).

METHODS

In total, 14 OCD patients (mean age 28.9±7.2 years) and 14 healthy controls (mean age 32.6±7.1 years) with no history of neurological and psychiatric illness participated in this study. Brain metabolite concentrations were measured from a localised voxel on the right DLPFC using a 3-Tesla 1H-MRS.

RESULTS

The metabolic concentration of myo-inositol in patients with OCD increased significantly by 52% compared with the healthy controls, whereas glutamine/glutamate was decreased by 11%. However, there were no significant differences in N-acetylaspartate, choline, lactate and lipid between the two groups.

CONCLUSION

These findings would be helpful to understand the pathophysiology of OCD associated with the brain metabolic abnormalities in the right DLPFC.

The "polyenviromic risk score": Aggregating environmental risk factors predicts conversion to psychosis in familial high-risk subjects

BACKGROUND

Young relatives of individuals with schizophrenia (i.e. youth at familial high-risk, FHR) are at increased risk of developing psychotic disorders, and show higher rates of psychiatric symptoms, cognitive and neurobiological abnormalities than non-relatives. It is not known whether overall exposure to environmental risk factors increases risk of conversion to psychosis in FHR subjects.

METHODS

Subjects consisted of a pilot longitudinal sample of 83 young FHR subjects. As a proof of principle, we examined whether an aggregate score of exposure to environmental risk factors, which we term a 'polyenviromic risk score' (PERS), could predict conversion to psychosis. The PERS combines known environmental risk factors including cannabis use, urbanicity, season of birth, paternal age, obstetric and perinatal complications, and various types of childhood adversity, each weighted by its odds ratio for association with psychosis in the literature.

RESULTS

A higher PERS was significantly associated with conversion to psychosis in young, familial high-risk subjects (OR=1.97, p=0.009). A model combining the PERS and clinical predictors had a sensitivity of 27% and specificity of 96%.

CONCLUSION

An aggregate index of environmental risk may help predict conversion to psychosis in FHR subjects.

Neurological soft signs: Effects of trait schizotypy, psychological distress and auditory hallucination predisposition

Schizotypy is regarded as a trait vulnerability for psychotic disorders, yet alone is insufficient for development of a diagnosable disorder. Additional symptoms and psychological distress are necessary for help seeking and transition from an at risk mental state to a clinical diagnosis. The present study investigated the interaction between trait schizotypy, state auditory verbal hallucination (AVH) predisposition, distress and handedness for the expression of neurological soft signs (NSS), a neurodevelopmental vulnerability factor for psychosis. Cluster analysis formed schizotypy groups statistically across the dimensions captured by the SPQ. It was hypothesized that schizotypy and AVH predisposition would interact, resulting in significantly greater NSS. Psychological distress and handedness were hypothesized to be significant covariates, accounting for some variance in the expression of NSS between the groups. A sample of University students (n = 327) completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, General Health Questionnaire and the Neurological Evaluation Scale (NES). Cluster Analysis revealed four schizotypy groups. Distress was not a significant covariate in any analysis. As expected, those with high overall schizotypy and high AVH predisposition expressed significantly greater Motor-Coordination NSS compared to those with high schizotypy and low AVH predisposition. Within the Mixed Interpersonal and Cognitive-Perceptual Schizotypy cluster, those with low AVH predisposition expressed significantly more Motor-Coordination NSS than those with high AVH predisposition. These findings suggest motor coordination NSS are detectable in schizotypy, and AVH predisposition appears to interact with these traits. This study highlights the importance of considering both trait and subclinical state risk factors when investigating risk for psychosis.

Immunoadolescence: Neuroimmune development and adolescent behavior

The brain is increasingly appreciated to be a constantly rewired organ that yields age-specific behaviors and responses to the environment. Adolescence in particular is a unique period characterized by continued brain maturation, superimposed with transient needs of the organism to traverse a leap from parental dependence to independence. Here we describe how these needs require immune maturation, as well as brain maturation. Our immune system, which protects us from pathogens and regulates inflammation, is in constant communication with our nervous system. Together, neuro-immune signaling regulates our behavioral responses to the environment, making this interaction a likely substrate for adolescent development. We review here the identified as well as understudied components of neuro-immune interactions during adolescence. Synaptic pruning, neurite outgrowth, and neurotransmitter release during adolescence all regulate-and are regulated by-immune signals, which occur via blood-brain barrier dynamics and glial activity. We discuss these processes, as well as how immune signaling during this transitional period of development confers differential effects on behavior and vulnerability to mental illness.

Reduced Sleep Spindles in Schizophrenia: A Treatable Endophenotype That Links Risk Genes to Impaired Cognition?

Although schizophrenia (SZ) is defined by waking phenomena, abnormal sleep is a common feature. In particular, there is accumulating evidence of a sleep spindle deficit. Sleep spindles, a defining thalamocortical oscillation of non-rapid eye movement stage 2 sleep, correlate with IQ and are thought to promote long-term potentiation and enhance memory consolidation. We review evidence that reduced spindle activity in SZ is an endophenotype that impairs sleep-dependent memory consolidation, contributes to symptoms, and is a novel treatment biomarker. Studies showing that spindles can be pharmacologically enhanced in SZ and that increasing spindles improves memory in healthy individuals suggest that treating spindle deficits in patients with SZ may improve cognition. Spindle activity is highly heritable, and recent large-scale genome-wide association studies have identified SZ risk genes that may contribute to spindle deficits and illuminate their mechanisms. For example, the SZ risk gene CACNA1I encodes a calcium channel that is abundantly expressed in the thalamic spindle generator and plays a critical role in spindle activity based on a mouse knockout. Future genetic studies of animals and humans can delineate the role of this and other genes in spindles. Such cross-disciplinary research, by forging empirical links in causal chains from risk genes to proteins and cellular functions to endophenotypes, cognitive impairments, symptoms, and diagnosis, has the potential to advance the mechanistic understanding, treatment, and prevention of SZ. This review highlights the importance of deficient sleep-dependent memory consolidation among the cognitive deficits of SZ and implicates reduced sleep spindles as a potentially treatable mechanism.

Gene × Environment Interactions in Schizophrenia: Evidence from Genetic Mouse Models

The study of gene × environment, as well as epistatic interactions in schizophrenia, has provided important insight into the complex etiopathologic basis of schizophrenia. It has also increased our understanding of the role of susceptibility genes in the disorder and is an important consideration as we seek to translate genetic advances into novel antipsychotic treatment targets. This review summarises data arising from research involving the modelling of gene × environment interactions in schizophrenia using preclinical genetic models. Evidence for synergistic effects on the expression of schizophrenia-relevant endophenotypes will be discussed. It is proposed that valid and multifactorial preclinical models are important tools for identifying critical areas, as well as underlying mechanisms, of convergence of genetic and environmental risk factors, and their interaction in schizophrenia.

Attachment, Neurobiology, and Mentalizing along the Psychosis Continuum

In this review article, we outline the evidence linking attachment adversity to psychosis, from the premorbid stages of the disorder to its clinical forms. To better understand the neurobiological mechanisms through which insecure attachment may contribute to psychosis, we identify at least five neurobiological pathways linking attachment to risk for developing psychosis. Besides its well documented influence on the hypothalamic-pituary-adrenal (HPA) axis, insecure attachment may also contribute to neurodevelopmental risk through the dopaminergic and oxytonergic systems, as well as bear influence on neuroinflammation and oxidative stress responses. We further consider the neuroscientific and behavioral studies that underpin mentalization as a suite of processes potentially moderating the risk to transition to psychotic disorders. In particular, mentalization may help the individual compensate for endophenotypical impairments in the integration of sensory and metacognitive information. We propose a model where embodied mentalization would lie at the core of a protective, resilience response mitigating the adverse and potentially pathological influence of the neurodevelopmental cascade of risk for psychosis.

Dysregulations of Synaptic Vesicle Trafficking in Schizophrenia

Schizophrenia is a serious psychiatric illness which is experienced by about 1 % of individuals worldwide and has a debilitating impact on perception, cognition, and social function. Over the years, several models/hypotheses have been developed which link schizophrenia to dysregulations of the dopamine, glutamate, and serotonin receptor pathways. An important segment of these pathways that have been extensively studied for the pathophysiology of schizophrenia is the presynaptic neurotransmitter release mechanism. This set of molecular events is an evolutionarily well-conserved process that involves vesicle recruitment, docking, membrane fusion, and recycling, leading to efficient neurotransmitter delivery at the synapse. Accumulated evidence indicate dysregulation of this mechanism impacting postsynaptic signal transduction via different neurotransmitters in key brain regions implicated in schizophrenia. In recent years, after ground-breaking work that elucidated the operations of this mechanism, research efforts have focused on the alterations in the messenger RNA (mRNA) and protein expression of presynaptic neurotransmitter release molecules in schizophrenia and other neuropsychiatric conditions. In this review article, we present recent evidence from schizophrenia human postmortem studies that key proteins involved in the presynaptic release mechanism are dysregulated in the disorder. We also discuss the potential impact of dysfunctional presynaptic neurotransmitter release on the various neurotransmitter systems implicated in schizophrenia.

Interaction of BDNF with cytokines in chronic schizophrenia

Brain-derived neurotrophic factor (BDNF) interacts with cytokines. Although both BDNF and cytokines occur at abnormal levels in schizophrenia patients, their interactions have not yet been examined. We therefore compared serum BDNF, TNF-α, interleukin (IL)-2, IL-6, and IL-8 levels in 92 chronically medicated schizophrenia patients and 60 healthy controls. We correlated these serum levels within these subject groups with each other and with clinical symptoms assessed according to the Positive and Negative Syndrome Scale (PANSS). Compared to the control group, the schizophrenia patients had significantly lower BDNF and TNF-α levels, and higher IL-2, IL-6, and IL-8 levels. The patients also showed a significant positive correlation between BDNF and both IL-2 and IL-8 levels, and low BDNF and TNF-α levels together were associated with poor performance on the PANSS cognitive factor. Thus, an interaction between cytokines and neurotrophic factors may be implicated in the pathophysiology of chronic schizophrenia. In particular, the cytokine TNF-α may interact with BNDF causing cognitive impairment.

Sex/gender differences in the brain and cognition in schizophrenia

The early conceptualizations of schizophrenia have noted some sex/gender differences in epidemiology and clinical expression of the disorder. Over the past few decades, the interest in differences between male and female patients has expanded to encompass brain morphology and neurocognitive function. Despite some variability and methodological shortcomings, a few patterns emerge from the available literature. Most studies of gross neuroanatomy show more enlarged ventricles and smaller frontal lobes in men than in women with schizophrenia; finding reflecting normal sexual dimorphism. In comparison, studies of brain asymmetry and specific corticolimbic structures, suggest a disturbance in normal sexual dimorphism. The neurocognitive findings are somewhat consistent with this picture. Studies of cognitive functions mediated by the lateral frontal network tend to show sex differences in patients which are in the same direction as those observed in the general population, whereas studies of processes mediated by the corticolimbic system more frequently reveal reversal of normal sexual dimorphisms. These trends are faint and future research would need to delineate neurocognitive differences between men and women with various subtypes of schizophrenia (e.g., early versus late onset), while taking into consideration hormonal status and gender of tested participants.

Glutamatergic dysfunction linked to energy and membrane lipid metabolism in frontal and anterior cingulate cortices of never treated first-episode schizophrenia patients

BACKGROUND

Glutamatergic dysfunction and altered membrane lipid and energy metabolism have been repeatedly demonstrated in the frontal/prefrontal and anterior cingulate cortex (ACC) in schizophrenia. Though having been already studied in animals, the presumed link between glutamatergic function and structural plasticity has not been investigated directly in the human brain yet. We measured glutamate (Glu), focal energy metabolism, and membrane phospholipid turnover to investigate main pathologies in those key brain regions of schizophrenia.

METHODS

(1)H- and (31)P-Chemical Shift Imaging (CSI) was combined in a single session to assess Glu and markers of energy (PCr, ATP) and membrane lipid (PME, PDE) metabolism in 31 neuroleptic-naïve first acute onset psychosis patients and 31 matched healthy controls. Multivariate analyses of covariance were used to assess disease effects on Glu and to investigate the impact of Glu alterations on phospholipid and energy metabolites.

RESULTS

Glu levels of patients were increased in the frontal and prefrontal cortex bilaterally and in the ACC. Higher Glu was associated with increased left frontal/prefrontal PME and right frontal/prefrontal PDE in patients, which was not observed in healthy controls. In contrast, higher Glu levels were associated with lower PCr or ATP values in the frontal/prefrontal cortex bilaterally and in the right ACC of controls. This was not observed in the right ACC and left frontal/prefrontal cortex of patients.

CONCLUSION

Frontal glutamatergic hyperactivity is disconnected from physiologically regulated energy metabolism and is associated with increased membrane breakdown in right and increased membrane restoration in left frontal and prefrontal cortical regions. As indicated by previous findings, this pathology is likely dynamic during the course of first acute illness and possibly associated with negative symptoms and cognitive impairment. Our findings underline the importance of further research on neuroprotective treatment options during the early acute or even better for the ultra-high risk state of psychotic illness.