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

Role of T helper lymphokines in the immune-inflammatory pathophysiology of schizophrenia: Systematic review and meta-analysis

BACKGROUND

Schizophrenia is highly complex multifactorial psychiatric disorder with poorly defined etiopathophysiology, which also has manifestations in the immune system.

AIMS

The aim of this review is to meta-analyze the available evidence regarding the role of immune activation indicated by the T helper cells in order to evaluate etiopathophysiological links between the immune system and schizophrenia.

METHODS

A literature search was performed in multiple electronic databases for relevant research papers published between 1990 and May 2014. Meta-analyses were conducted under both random- (REM) and fixed-effect models (FEM) by calculating weighted mean differences with 95% confidence intervals. Heterogeneity was assessed with the I(2) index.

RESULTS

Twenty-one studies were selected after observing inclusion and exclusion criteria. In vitro interferon-gamma (INF-γ) and interleukin (IL)-2 production was significantly lower in the schizophrenic patients compared with non-schizophrenic control individuals under both FEM and REM. Serum levels of IL-2 and serum/in vitro IL-4 were not significantly different in both groups under both FEM and REM. Overall Th1:Th2 ratio (INF-γ:IL-4 and IL-2:IL-4) in the serum samples was significantly deflected towards Th2 under both models in the serum samples (- 0.33 [- 0.59 to - 0.06]; P < 0.03, FEM and - 2.44 [- 4.27 to - 0.60]; P < 0.009, REM) but in vitro production Th1:Th2 ratio (INF-γ:IL-4 and IL-2:IL-4) was deflected towards Th1 under both the models (1.11 [0.45-1.78]; P < 0.002, FEM and 6.68 [0.72-12.64]; P < 0.03, REM).

CONCLUSIONS

Whereas the Th1:Th2 ratio in the serum samples deflected towards T2, in vitro Th1:Th2 ratio favored Th1 when the individual study data were meta-analyzed.

Dysplasticity, metaplasticity, and schizophrenia: Implications for risk, illness, and novel interventions

In this paper, we review the history of the concept of neuroplasticity as it relates to the understanding of neuropsychiatric disorders, using schizophrenia as a case in point. We briefly review the myriad meanings of the term neuroplasticity, and its neuroscientific basis. We then review the evidence for aberrant neuroplasticity and metaplasticity associated with schizophrenia as well as the risk for developing this illness, and discuss the implications of such understanding for prevention and therapeutic interventions. We argue that the failure and/or altered timing of plasticity of critical brain circuits might underlie cognitive and deficit symptoms, and may also lead to aberrant plastic reorganization in other circuits, leading to affective dysregulation and eventually psychosis. This "dysplastic" model of schizophrenia can suggest testable etiology and treatment-relevant questions for the future.

Body mass, cardiovascular risk and metabolic characteristics of young persons presenting for mental healthcare in Sydney, Australia

OBJECTIVES

To determine the body mass, cardiovascular and metabolic characteristics of young people presenting for mental healthcare.

DESIGN

Cross-sectional assessments of body mass, cardiovascular and metabolic risk factors.

SETTING

Two primary-care based sites in Sydney, Australia for young people in the early stages of mental disorders.

PARTICIPANTS

A clinical sample of young people (12-30 years) with mental health problems.

OUTCOME MEASURES

Daily smoking rates, body mass index (BMI), blood glucose and lipids, blood pressure (BP) and pulse rate.

RESULTS

Of 1005 young people who had their BMI determined (62% female; 19.0±3.5 years), three quarters (739/1005) also had BP recordings and one-third (298/1005) had blood sampling. Clinically, 775 were assigned to one of three diagnostic categories (anxious-depression: n=541; mania-fatigue, n=104; developmental-psychotic n=130). The profile of BMI categories approximated that of the comparable segments of the Australian population. Older age, lower levels of social functioning and higher systolic BP were all associated with high BMI. In a subset (n=129), current use of any psychotropic medication was associated (p<0.05) with increased BMI. Almost one-third of cases were current daily smokers (compared to population rate of 11%). Males had a higher proportion of raised glucose and high-density lipoprotein (HDL) compared to females (9.3% and 34.1% vs 2.1% and 5.9%, respectively). Overall, there was no relationship between BMI and fasting glucose but significant relationships with triglycerides and HDL were noted. Furthermore, there were no significant relationships between diagnostic subgroup and metabolic profiles.

CONCLUSIONS

Daily smoking rates are increased among young people presenting for mental healthcare. However, these young people do not demonstrate adverse cardiometabolic profiles. The high levels of smoking, and association of BMI with adverse social circumstances, suggest that risk factors for chronic disease are already present and likely to be compounded by medication and social disadvantage.

Childhood residential mobility, schizophrenia, and bipolar disorder: a population-based study in Denmark

INTRODUCTION

Childhood adversity is gaining increasing attention as a plausible etiological factor in the development of psychotic disorders. Childhood residential mobility is a potential risk factor that has received little attention in this context.

METHODS

We used registry data to estimate associations of residential mobility with narrow and broad schizophrenia and bipolar disorder across the course of childhood among 1.1 million individuals born in Denmark 1971-1991 and followed from age 15 through 2010. We assessed effect modification by sex, family history of mental disorder, the presence of siblings close in age, and distance moved.

RESULTS

In individual-year models adjusted for family history, urbanicity at birth, and parental age, mobility at all ages except the year of birth was associated with heightened risk of narrow and broad schizophrenia, and risk increased with age at moving and with the number of moves. Further adjustment for mobility at all ages 0-15 revealed associations mainly during the latter half of childhood, which were strongest during adolescence. Associations between mobility and bipolar disorder were fewer and weaker compared to schizophrenia. There was modest evidence of interaction with family history of psychiatric diagnosis, but little evidence for interaction by sex, the presence of closely-aged siblings, or distance moved. Schizophrenia associations did not appear attributable to increased mobility among adolescents with earlier onset.

CONCLUSIONS

Mobility may increase risk for psychotic disorders, particularly schizophrenia. Children may be especially vulnerable during adolescence. Future research should investigate the importance of school changes and the potential for interaction with genetic risk.

Fetal programming of schizophrenia: select mechanisms

Mounting evidence indicates that schizophrenia is associated with adverse intrauterine experiences. An adverse or suboptimal fetal environment can cause irreversible changes in brain that can subsequently exert long-lasting effects through resetting a diverse array of biological systems including endocrine, immune and nervous. It is evident from animal and imaging studies that subtle variations in the intrauterine environment can cause recognizable differences in brain structure and cognitive functions in the offspring. A wide variety of environmental factors may play a role in precipitating the emergent developmental dysregulation and the consequent evolution of psychiatric traits in early adulthood by inducing inflammatory, oxidative and nitrosative stress (IO&NS) pathways, mitochondrial dysfunction, apoptosis, and epigenetic dysregulation. However, the precise mechanisms behind such relationships and the specificity of the risk factors for schizophrenia remain exploratory. Considering the paucity of knowledge on fetal programming of schizophrenia, it is timely to consolidate the recent advances in the field and put forward an integrated overview of the mechanisms associated with fetal origin of schizophrenia.

The extent of diffusion MRI markers of neuroinflammation and white matter deterioration in chronic schizophrenia

In a previous study we have demonstrated, using a novel diffusion MRI analysis called free-water imaging, that the early stages of schizophrenia are more likely associated with a neuroinflammatory response and less so with a white matter deterioration or a demyelination process. What is not known is how neuroinflammation and white matter deterioration change along the progression of the disorder. In this study we apply the free-water measures on a population of 29 chronic schizophrenia subjects and compare them with 25 matching controls. Our aim was to compare the extent of free-water imaging abnormalities in chronic subjects with the ones previously obtained for subjects at their first psychotic episode. We find that chronic subjects showed a limited extent of abnormal increase in the volume of the extracellular space, suggesting a less extensive neuroinflammatory response relative to patients at the onset of schizophrenia. At the same time, the chronic schizophrenia subjects had greater extent of reduced fractional anisotropy compared to the previous study, suggesting increased white matter deterioration along the progression of the disease. Our findings substantiate the role of neuroinflammation in the earlier stages of the disorder, and the effect of neurodegeneration that is worsening in the chronic phase.

NMDA receptor-deficient mice display sexual dimorphism in the onset and severity of behavioural abnormalities

N-methyl-d-aspartate (NMDA) receptor-deficient mice can be used to understand the role that NMDA receptors (NMDARs) play in the pathophysiology of neurodevelopmental disorders such as schizophrenia. Genetically modified mice with low levels of NR1 subunit (NR1 knockdown mice) have reduced receptor levels throughout development, and have robust abnormalities in behaviours that are relevant to schizophrenia. We traced the onset and severity of these behaviours at three developmental stages to understand when in development the underlying circuits depend on intact NMDAR function. We examined social behaviour, working memory, executive function, locomotor activity and stereotypy at 3, 6 and 12 weeks of age in NR1 knockdown mice and their wild-type littermates. We discovered that each of these behaviours had a unique developmental trajectory in mutant mice, and males showed an earlier onset and severity than females in several behaviours. Hyperlocomotion was most substantial in juvenile mice and plateaued in adult mice, whereas stereotypy progressively worsened with age. Impairments in working memory and sociability were sexually dimorphic, with deficits first detected in peri-adolescent males but only detected in adult females. Interestingly, executive function was most impaired in peri-adolescent mice of either sex. Furthermore, while juvenile mutant mice had some ability to problem solve in the puzzle box test, the same mice lost this ability when tested 4 weeks later. Our studies highlight key developmental periods for males and females in the expression of behaviours that are relevant to psychiatric disorders.

Sleep spindle deficits in antipsychotic-naïve early course schizophrenia and in non-psychotic first-degree relatives

INTRODUCTION

Chronic medicated patients with schizophrenia have marked reductions in sleep spindle activity and a correlated deficit in sleep-dependent memory consolidation. Using archival data, we investigated whether antipsychotic-naïve early course patients with schizophrenia and young non-psychotic first-degree relatives of patients with schizophrenia also show reduced sleep spindle activity and whether spindle activity correlates with cognitive function and symptoms.

METHOD

Sleep spindles during Stage 2 sleep were compared in antipsychotic-naïve adults newly diagnosed with psychosis, young non-psychotic first-degree relatives of schizophrenia patients and two samples of healthy controls matched to the patients and relatives. The relations of spindle parameters with cognitive measures and symptom ratings were examined.

RESULTS

Early course schizophrenia patients showed significantly reduced spindle activity relative to healthy controls and to early course patients with other psychotic disorders. Relatives of schizophrenia patients also showed reduced spindle activity compared with controls. Reduced spindle activity correlated with measures of executive function in early course patients, positive symptoms in schizophrenia and IQ estimates across groups.

CONCLUSIONS

Like chronic medicated schizophrenia patients, antipsychotic-naïve early course schizophrenia patients and young non-psychotic relatives of individuals with schizophrenia have reduced sleep spindle activity. These findings indicate that the spindle deficit is not an antipsychotic side-effect or a general feature of psychosis. Instead, the spindle deficit may predate the onset of schizophrenia, persist throughout its course and be an endophenotype that contributes to cognitive dysfunction.

The role of untreated psychosis in neurodegeneration: a review of hypothesized mechanisms of neurotoxicity in first-episode psychosis

For over 20 years, studies have tried to measure the association between the duration of untreated psychosis (DUP) and changes in brain morphology. A hypothesis that untreated psychosis is neurotoxic has been postulated, but the mechanisms of that toxicity have not been described. We re-analyzed papers collected for a systematic review to extract data on the hypotheses that have been generated on the potential mechanisms by which DUP could impact brain morphology in first-episode psychosis. Dopaminergic hyperactivity, prolonged hypothalamic-pituitary-adrenal activation, and persistent activity of catecholamines have been hypothesized as mechanisms to explain these associations. However, the question remains as to whether the observed structural changes are permanent or may be reversed via antipsychotic treatment.

Epigenetics, stress, and their potential impact on brain network function: a focus on the schizophrenia diatheses

The recent sociodevelopmental cognitive model of schizophrenia/psychosis is a highly influential and compelling compendium of research findings. Here, we present logical extensions to this model incorporating ideas drawn from epigenetic mediation of psychiatric disease, and the plausible effects of epigenetics on the emergence of brain network function and dysfunction in adolescence. We discuss how gene-environment interactions, effected by epigenetic mechanisms, might in particular mediate the stress response (itself heavily implicated in the emergence of schizophrenia). Next, we discuss the plausible relevance of this framework for adolescent genetic risk populations, a risk group characterized by vexing and difficult-to-explain heterogeneity. We then discuss how exploring relationships between epigenetics and brain network dysfunction (a strongly validated finding in risk populations) can enhance understanding of the relationship between stress, epigenetics, and functional neurobiology, and the relevance of this relationship for the eventual emergence of schizophrenia/psychosis. We suggest that these considerations can expand the impact of models such as the sociodevelopmental cognitive model, increasing their explanatory reach. Ultimately, integration of these lines of research may enhance efforts of early identification, intervention, and treatment in adolescents at-risk for schizophrenia.

Evaluating differential developmental trajectories to adolescent-onset mood and psychotic disorders

BACKGROUND

It is an open question as to whether differential developmental trajectories, potentially representing underlying pathophysiological processes, can form the basis of a more useful typology in young persons who present for mental health care.

METHODS

A cohort of 605 young people was recruited from youth mental health services that target the early phases of anxiety, mood or psychotic disorders. Participants were assigned to one of three clinical sub-types (anxious-depression; mania-fatigue; developmental-psychotic) according to putative developmental trajectories.

RESULTS

The distribution of subtypes was: 51% anxiety-depression, 25% mania-fatigue and 24% developmental-psychotic, with key differences in demographic, clinical, family history and neuropsychological characteristics. When analyses were limited to 286 cases with 'attenuated' or sub-threshold syndromes, the pattern of differences was similar. Multinomial logistic regression demonstrated that compared to the developmental-psychotic subtype, both the mania-fatigue and anxiety-depression subtypes were younger and more depressed at presentation, but less functionally impaired. Other discriminating variables between the developmental-psychotic and mania-fatigue sub-types were that the latter were significantly more likely to have a family history of bipolar disorder but have less likelihood of impaired verbal learning; whilst the anxious-depression group were more anxious, more likely to have a family history of depression, and had a higher premorbid IQ level.

CONCLUSIONS

This cross-sectional evaluation provides preliminary support for differing developmental trajectories in young persons presenting for mental health care. Prospective follow-up is needed to examine the predictive validity of this approach and its relationships to underlying pathophysiological mechanisms.

Altered asymmetry of the anterior cingulate cortex in subjects at genetic high risk for psychosis

OBJECTIVE

Many studies have reported that patients with schizophrenia often have structural abnormalities of the anterior cingulate cortex (ACC) and that some of these seem to be of genetic origin, therefore predating the onset of illness. The present study aimed to investigate whether these alterations in the ACC are genetic in origin by comparing the morphological patterns of three groups: normal controls, subjects at genetic high risk (GHR) for psychosis, and patients with schizophrenia. The relationships between morphological variations and executive function were also investigated.

METHODS

This study examined the magnetic resonance images of cingulate sulcus/paracingulate sulcus (CS/PCS) folding patterns in 222 subjects (103 normal subjects, 30 individuals at GHR, and 89 patients with schizophrenia) and evaluated differences in the morphological and asymmetrical patterns of the ACC among groups. Neurocognitive tests were then performed and differences in cognitive performance were analyzed according to morphological variation.

RESULTS

Differences in PCS folding were detected; the control group was significantly more likely than were other groups to show a well-developed left PCS (p=0.009) and leftward asymmetry of the PCS (p<0.001). However, neither GHR subjects (p=0.346) nor patients (p=0.784) showed this leftward asymmetry. No statistically significant differences in CS continuity were observed. A more prominent left PCS (p=0.031) and leftward PCS asymmetry (p=0.030) were both associated with higher scores on the working memory task.

CONCLUSION

The results suggest that GHR subjects have distinct neurodevelopmental anomalies that resemble those of patients with schizophrenia even though they do not display any psychotic symptoms. Certain developmental alterations in the ACC, such as the loss of leftward sulcal asymmetry in patients with schizophrenia, might be related to genetic factors. Additionally, this morphological alteration might partly account for the impaired executive function in schizophrenia.

A review of neuroimaging studies of young relatives of individuals with schizophrenia: a developmental perspective from schizotaxia to schizophrenia

In an effort to identify the developing abnormalities preceding psychosis, Dr. Ming T. Tsuang and colleagues at Harvard expanded Meehl's concept of "schizotaxia," and examined brain structure and function in families affected by schizophrenia (SZ). Here, we systematically review genetic (familial) high-risk (HR) studies of SZ using magnetic resonance imaging (MRI), examine how findings inform models of SZ etiology, and suggest directions for future research. Neuroimaging studies of youth at HR for SZ through the age of 30 were identified through a MEDLINE (PubMed) search. There is substantial evidence of gray matter volume abnormalities in youth at HR compared to controls, with an accelerated volume reduction over time in association with symptoms and cognitive deficits. In structural neuroimaging studies, prefrontal cortex (PFC) alterations were the most consistently reported finding in HR. There was also consistent evidence of smaller hippocampal volume. In functional studies, hyperactivity of the right PFC during performance of diverse tasks with common executive demands was consistently reported. The only longitudinal fMRI study to date revealed increasing left middle temporal activity in association with the emergence of psychotic symptoms. There was preliminary evidence of cerebellar and default mode network alterations in association with symptoms. Brain abnormalities in structure, function and neurochemistry are observed in the premorbid period in youth at HR for SZ. Future research should focus on the genetic and environmental contributions to these alterations, determine how early they emerge, and determine whether they can be partially or fully remediated by innovative treatments.

Convergence of genetic and environmental factors on parvalbumin-positive interneurons in schizophrenia

Schizophrenia etiology is thought to involve an interaction between genetic and environmental factors during postnatal brain development. However, there is a fundamental gap in our understanding of the molecular mechanisms by which environmental factors interact with genetic susceptibility to trigger symptom onset and disease progression. In this review, we summarize the most recent findings implicating oxidative stress as one mechanism by which environmental insults, especially early life social stress, impact the development of schizophrenia. Based on a review of the literature and the results of our own animal model, we suggest that environmental stressors such as social isolation render parvalbumin-positive interneurons (PVIs) vulnerable to oxidative stress. We previously reported that social isolation stress exacerbates many of the schizophrenia-like phenotypes seen in a conditional genetic mouse model in which NMDA receptors (NMDARs) are selectively ablated in half of cortical and hippocampal interneurons during early postnatal development (Belforte et al., 2010). We have since revealed that this social isolation-induced effect is caused by impairments in the antioxidant defense capacity in the PVIs in which NMDARs are ablated. We propose that this effect is mediated by the down-regulation of PGC-1α, a master regulator of mitochondrial energy metabolism and anti-oxidant defense, following the deletion of NMDARs (Jiang et al., 2013). Other potential molecular mechanisms underlying redox dysfunction upon gene and environmental interaction will be discussed, with a focus on the unique properties of PVIs.

Altered cognitive development in the siblings of individuals with schizophrenia

The goal of the current study was to further investigate the late neurodevelopmental hypothesis of schizophrenia by examining cross-sectional, age-related changes in cognitive function among young adult: 1) siblings of individuals with schizophrenia (N = 66); (2) healthy control participants (N = 77); and (3) the siblings of healthy controls (N = 77). All subjects participated in a battery of tasks in four domains: 1) IQ; 2) working memory; 3) episodic memory; and 4) executive function. We found significant group differences in the relationships between age and performance in working memory and episodic memory, with similar patterns for executive function and verbal IQ. The siblings of individuals with schizophrenia showed impaired performance in working memory, episodic memory, and executive function. In addition, healthy controls and/or their siblings showed age-related improvements in all four cognitive domains, while the siblings of individuals with schizophrenia only showed this for verbal IQ.

Interleukin 18 and cognitive impairment in first episode and drug naïve schizophrenia versus healthy controls

Alterations in the inflammatory and immune systems have been documented to occur from the earliest stages of schizophrenia, and have been associated with neurodevelopmental changes. Cognitive impairment is a core feature in the pathology of schizophrenia, and recent studies showed a significant increase in serum IL-18 in schizophrenia, and a putative role of IL-18 in neuroprogression and thus neurocognitive defects. The purpose of this study was to examine the association of IL-18 with cognitive deficits in schizophrenia. We recruited 77 first episode and drug naïve schizophrenic patients and 75 healthy control subjects and examined the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and serum IL-18 in both groups. Schizophrenic symptoms were assessed using the positive and negative syndrome scale (PANSS). We found that IL-18 levels were non-significantly higher in patients than controls (206.0±92.9 pg/ml vs 193.2±41.8 pg/ml, p=0.28). Cognitive scores on the RBANS and nearly all of its five subscales (all p<0.05) except for the Visuospatial/Constructional index (p>0.05) were significantly lower in schizophrenic patients than normal controls. For the patients, IL-18 was positively associated with the Visuospatial/Constructional domain of cognitive deficits in schizophrenia. Our findings suggest that cognitive deficits occur during the acute stage of a schizophrenic episode, and IL-18 may be involved in Visuospatial/Constructional deficits of these patients.

Relapse duration, treatment intensity, and brain tissue loss in schizophrenia: a prospective longitudinal MRI study

OBJECTIVE

Longitudinal structural MRI studies have shown that patients with schizophrenia have progressive brain tissue loss after onset. Recurrent relapses are believed to play a role in this loss, but the relationship between relapse and structural MRI measures has not been rigorously assessed. The authors analyzed longitudinal data to examine this question.

METHODS

The authors studied data from 202 patients drawn from the Iowa Longitudinal Study of first-episode schizophrenia for whom adequate structural MRI data were available (N=659 scans) from scans obtained at regular intervals over an average of 7 years. Because clinical follow-up data were obtained at 6-month intervals, the authors were able to compute measures of relapse number and duration and relate them to structural MRI measures. Because higher treatment intensity has been associated with smaller brain tissue volumes, the authors also examined this countereffect in terms of dose-years.

RESULTS

Relapse duration was related to significant decreases in both general (e.g., total cerebral volume) and regional (e.g., frontal) brain measures. Number of relapses was unrelated to brain measures. Significant effects were also observed for treatment intensity.

CONCLUSIONS

Extended periods of relapse may have a negative effect on brain integrity in schizophrenia, suggesting the importance of implementing proactive measures that may prevent relapse and improve treatment adherence. By examining the relative balance of effects, that is, relapse duration versus antipsychotic treatment intensity, this study sheds light on a troublesome dilemma that clinicians face. Relapse prevention is important, but it should be sustained using the lowest possible medication dosages that will control symptoms.

Neurodevelopment and inflammatory patterns in schizophrenia in relation to pathophysiology

As for other major psychoses, the etiology of schizophrenia still remains poorly understood, involving genetic and epigenetic mechanisms, as well as environmental contributions. In addition, immune alterations have been widely reported in schizophrenic patients, involving both the unspecific and specific pathways of the immune system, and suggesting that infectious/autoimmune processes play an important role in the etiopathogenesis of the disorder. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system. In this perspective, even though mixed results have been reported, it seems that schizophrenia is associated with an imbalance in inflammatory cytokines. Alterations in the inflammatory and immune systems, moreover, seem to be already present in the early stages of schizophrenia and connected to the neurodevelopmental hypothesis of the disorder, identifying its roots in brain development abnormalities that do not manifest themselves until adolescence or early adulthood. At the same time, neuropathological and longitudinal studies in schizophrenia also support a neurodegenerative hypothesis and, more recently, a novel mixed hypothesis, integrating neurodevelopmental and neurodegenerative models, has been put forward. The present review aims to provide an updated overview of the connections between the immune and inflammatory alterations and the aforementioned hypotheses in schizophrenia.

Developmental neuroinflammation and schizophrenia

There is increasing interest in and evidence for altered immune factors in the etiology and pathophysiology of schizophrenia. Stimulated by various epidemiological findings reporting elevated risk of schizophrenia following prenatal exposure to infection, one line of current research aims to explore the potential contribution of immune-mediated disruption of early brain development in the precipitation of long-term psychotic disease. Since the initial formulation of the "prenatal cytokine hypothesis" more than a decade ago, extensive epidemiological research and remarkable advances in modeling prenatal immune activation effects in animal models have provided strong support for this hypothesis by underscoring the critical role of cytokine-associated inflammatory events, together with downstream pathophysiological processes such as oxidative stress, hypoferremia and zinc deficiency, in mediating the short- and long-term neurodevelopmental effects of prenatal infection. Longitudinal studies in animal models further indicate that infection-induced developmental neuroinflammation may be pathologically relevant beyond the antenatal and neonatal periods, and may contribute to disease progression associated with the gradual development of full-blown schizophrenic disease. According to this scenario, exposure to prenatal immune challenge primes early pre- and postnatal alterations in peripheral and central inflammatory response systems, which in turn may disrupt the normal development and maturation of neuronal systems from juvenile to adult stages of life. Such developmental neuroinflammation may adversely affect processes that are pivotal for normal brain maturation, including myelination, synaptic pruning, and neuronal remodeling, all of which occur to a great extent during postnatal brain maturation. Undoubtedly, our understanding of the role of developmental neuroinflammation in progressive brain changes relevant to schizophrenia is still in infancy. Identification of these mechanisms would be highly warranted because they may represent a valuable target to attenuate or even prevent the emergence of full-blown brain and behavioral pathology, especially in individuals with a history of prenatal complications such as in-utero exposure to infection and/or inflammation.

The presentation of dermatoglyphic abnormalities in schizophrenia: a meta-analytic review

Within a neurodevelopmental model of schizophrenia, prenatal developmental deviations are implicated as early signs of increased risk for future illness. External markers of central nervous system maldevelopment may provide information regarding the nature and timing of prenatal disruptions among individuals with schizophrenia. One such marker is dermatoglyphic abnormalities (DAs) or unusual epidermal ridge patterns. Studies targeting DAs as a potential sign of early developmental disruption have yielded mixed results with regard to the strength of the association between DAs and schizophrenia. The current study aimed to resolve these inconsistencies by conducting a meta-analysis examining the six most commonly cited dermatoglyphic features among individuals with diagnoses of schizophrenia. Twenty-two studies published between 1968 and 2012 were included. Results indicated significant but small effects for total finger ridge count and total A-B ridge count, with lower counts among individuals with schizophrenia relative to controls. Other DAs examined in the current meta-analysis did not yield significant effects. Total finger ridge count and total A-B ridge count appear to yield the most reliable dermatoglyphic differences between individuals with and without schizophrenia.

A plausible model of schizophrenia must incorporate psychological and social, as well as neuro developmental, risk factors

Subtle alterations in brain development caused by genes or early environmental hazards, such as obstetric complications, play a role in projecting some individuals on a trajectory toward schizophrenia. High-risk and cohort studies demonstrate that children destined to develop schizophrenia tend to have delayed milestones and subtle neuromotor and cognitive impairments (particularly in coordination and language). These neurocognitive problems lead to difficulties in interpersonal relations, and their progressive alienation makes these at-risk children more likely to harbor odd or paranoid ideas. This cascade of increasingly deviant development may then be compounded by brain maturational changes during adolescence with a resultant lability of the dopaminergic response to stress. As a result, the individual is more susceptible to the effects of the abuse of dopamine-releasing drugs, and to other risk factors such as migration or stressful life events; social isolation may be a common pathway underlying several of the social risk factors.

Early prefrontal functional blockade in rats results in schizophrenia-related anomalies in behavior and dopamine

Growing evidence suggests schizophrenia may arise from abnormalities in early brain development. The prefrontal cortex (PFC) stands out as one of the main regions affected in schizophrenia. Latent inhibition, an interesting cognitive marker for schizophrenia, has been found in some studies to be reduced in acute patients. It is generally widely accepted that there is a dopaminergic dysfunctioning in schizophrenia. Moreover, several authors have reported that the psychostimulant, D-amphetamine (D-AMP), exacerbates symptoms in patients with schizophrenia. We explored in rats the effects in adulthood of neonatal transient inactivation of the PFC on behavioral and neurochemical anomalies associated with schizophrenia. Following tetrodotoxin (TTX) inactivation of the left PFC at postnatal day 8, latent inhibition-related dopaminergic responses and dopaminergic reactivity to D-AMP were monitored using in vivo voltammetry in the left core part of the nucleus accumbens in adult freely moving rats. Dopaminergic responses and behavioral responses were followed in parallel. Prefrontal neonatal inactivation resulted in disrupted behavioral responses of latent inhibition and latent inhibition-related dopaminergic responses in the core subregion. After D-AMP challenge, the highest dose (1.5 mg/kg i.p.) induced a greater dopamine increase in the core in rats microinjected with TTX, and a parallel increase in locomotor activity, suggesting that following prefrontal neonatal TTX inactivation animals display a greater behavioral and dopaminergic reactivity to D-AMP. Transitory inactivation of the PFC early in the postnatal developmental period leads to behavioral and neurochemical changes in adulthood that are meaningful for schizophrenia modeling. The data obtained may help our understanding of the pathophysiology of this disabling disorder.

The immune system and developmental programming of brain and behavior

The brain, endocrine, and immune systems are inextricably linked. Immune molecules have a powerful impact on neuroendocrine function, including hormone-behavior interactions, during health as well as sickness. Similarly, alterations in hormones, such as during stress, can powerfully impact immune function or reactivity. These functional shifts are evolved, adaptive responses that organize changes in behavior and mobilize immune resources, but can also lead to pathology or exacerbate disease if prolonged or exaggerated. The developing brain in particular is exquisitely sensitive to both endogenous and exogenous signals, and increasing evidence suggests the immune system has a critical role in brain development and associated behavioral outcomes for the life of the individual. Indeed, there are associations between many neuropsychiatric disorders and immune dysfunction, with a distinct etiology in neurodevelopment. The goal of this review is to describe the important role of the immune system during brain development, and to discuss some of the many ways in which immune activation during early brain development can affect the later-life outcomes of neural function, immune function, mood and cognition.

Glutamatergic changes in the cerebral white matter associated with schizophrenic exacerbation

OBJECTIVE

Glutamatergic dysfunction in the brain has been implicated in the pathophysiology of schizophrenia. This study was aimed to examine several brain chemical mediators, including Glx (glutamate + glutamine), using (1)H magnetic resonance spectroscopy (MRS) in medicated patients with schizophrenia, with and without psychotic exacerbation.

METHOD

(1)H MRS was acquired in 24 patients with schizophrenia, with psychotic exacerbation; 22 patients without exacerbation; and 27 age- and sex-matched healthy volunteers. The levels of metabolites were measured in the left frontal and inferior parietal white matter and compared across the three groups.

RESULTS

The Glx level was significantly elevated in the left inferior parietal white matter in the patients with psychotic exacerbation in comparison with that in the healthy volunteers and the patients without exacerbation (P < 0.05). We also detected that there was a significant correlation between Positive and Negative Syndrome Scale-positive scale and Glx level in the left parietal white matter (r = 0.51, P < 0.001).

CONCLUSION

Higher than normal Glx levels indicate glutamatergic overactivity in the left inferior parietal white matter with schizophrenic exacerbation, a finding that is in accordance with the glutamatergic hypothesis in schizophrenia. The Glx level measured by (1)H MRS could be a biomarker for exacerbation in schizophrenia.

Examining the course of hallucinatory experiences in children and adolescents: a systematic review

BACKGROUND

Childhood and adolescence represent the periods during which hallucinatory experiences occur at the greatest prevalence, and also constitute a critical window of vulnerability for the pathogenesis of psychotic disorders. The longitudinal course of hallucinatory experiences during late childhood and adolescence, as well as their relationship to psychotic disorders, has never been the subject of review.

METHODS

We followed the PRISMA guidelines for conducting systematic reviews and combined the use of electronic and manual systematic search methods. Data were extracted upon pre-defined requested items and were analyzed using several epidemiological measures. The interpretation of the results was conducted in relation to the study design variables.

RESULTS

A total of 11 datasets (6 epidemiological and 5 clinical) were reviewed. The baseline prevalence of hallucinatory experiences ranged from 4.9% to 9%. Discontinuation occurred in between 58.7% and 94.5% of the cases, and person-year discontinuation rates ranged from 3% to 40.7% and appeared to be related to the duration of follow-up. Despite low person-year incidence rate, incident cases constituted between 27.7% and 83.3% of outcome samples. 2 of 3 studies showed evidence to predict transition to psychosis with likelihood ratios of 2.5 and 6.6.

CONCLUSIONS

Hallucinatory experiences are a common experience during childhood and adolescence. A review of the current literature suggests that there is a considerable turnover of incident-discontinuing cases and that most cases discontinue in the short term. A subset of the cases was at risk for persistence or transition to psychosis, probably related to indicators of severity of the hallucinatory experience.

Occlusal dysesthesia: a qualitative systematic review of the epidemiology, aetiology and management

Occlusal dysesthesia refers to a persistent complaint of uncomfortable bite sensation with no obvious occlusal discrepancy. This systematic review aimed to draw a picture of such patients, to present an agreement of previously reported diagnostic criteria and to analyse the evidence level of the recommended management approaches. An electronic search for all relevant reports on occlusal dysesthesia was thoroughly performed based on previous nomenclatures (e.g. phantom bite, occlusal hyperawareness) in PubMed and The Cochrane Library in July, 2011. A total of 84 reports were matched, among which only 11 studies were included after a two-step (abstract and detailed full-text revision) screening process. Additionally, a thorough manual review of reference lists of the included reports enabled the inclusion of two additional studies. Data analysis revealed that 37 occlusal dysesthesia patients presented a mean age of 51.7 ± 10.6 years and were predominantly women (male/female: 1/5.1) with symptom duration of more than 6 years (average: 6.3 ± 7.5 years) and with concomitant psychological disturbances (e.g. mood disorders, somatoform disorders, personality disorders). Only four authors presented diagnostic criteria for occlusal dysesthesia, which served as the basis for an agreement in the diagnostic criteria. Treatment approaches included psychotherapy, cognitive/behaviour therapy, splint therapy and prescription of anti-depressants or anti-anxiety drugs. Classification of evidence level of management approaches, however, revealed that most of them were expert opinions with single- or multiple-case report(s). Future studies are necessary for a deeper understanding of the mechanisms behind the occlusal dysesthesia symptoms, and consequently, for improvements in evidence-based management approaches.

WITHDRAWN: Anatomic differences in first episode schizophrenia: a deformation-based morphometry MRI Study

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Magnetic resonance spectroscopy of limbic structures displays metabolite differences in young unaffected relatives of schizophrenia probands

Imaging studies of schizophrenia patients showed fronto-temporal brain volume deficits, while magnetic resonance spectroscopy (MRS) studies of patients and unaffected biological relatives have found a decrement of the neuronal marker N-acetyl-aspartate (NAA) in the hippocampus and frontal lobes, and increased choline-containing phospholipids. Using a 3T MR scanner, we determined the metabolite profile within limbic regions (anterior cingulate cortex (ACC) and left hippocampus) of 36 unaffected, adolescent/young adult relatives of schizophrenia probands (first-degree=16, second-degree=20) and 25 healthy controls with no family history of schizophrenia. Significant main effects of group were found on NAA/Cho ratios for both the left hippocampus (F = 6.11, p ≤ 0.02) and ACC (F = 4.89, p ≤ 0.03) as well as for the left hippocampus Cho/Cr ratio (F = 5.55, p ≤ 0.02). Compared to age and sex matched healthy controls without a family history of schizophrenia, first-degree relatives of probands had greater MRS metabolite deviations than second-degree relatives. Greater familial proximity to the schizophrenia proband (or higher schizophrenia susceptibility) among biological relatives was associated with stepwise lowering of NAA/Cho and elevations in Cho/Cr ratios. The observed limbic metabolite changes among young, nonpsychotic biological relatives are likely related to shared genetic vulnerability factors, and may assist in the early identification of schizophrenia for primary and secondary prevention.

Integrative etiopathogenetic models of psychotic disorders: methods, evidence and concepts

Integrative models of the etiopathogesnesis of psychotic disorders are needed since a wealth of information from such diverse fields as neurobiology, psychology, and the social sciences is currently changing the concepts of mental disorders. Several approaches to integrate these streams of information into coherent concepts of psychosis are feasible and will need to be assessed in future experimental studies. Common to these concepts are the notion of psychotic disorders as brain disorders and a polythetic approach in that it is increasingly realized that a multitude of interindividually partially different pathogenetic factors interact in individual persons in a complex fashion resulting in the clinical symptoms of psychosis.

Neuroendocrine markers of high risk for psychosis: salivary testosterone in adolescent boys with prodromal symptoms

BACKGROUND

The peak in age of onset of psychotic disorders such as schizophrenia during puberty and early adulthood suggests a relationship between the expression of psychopathology and the changes in the brain and body that take place during this dynamic maturational period, including a dramatic increase in circulating oestrogens and androgens. This study examined levels of salivary testosterone and oestradiol in adolescents with prepsychotic, prodromal symptoms, as this may mediate risk for psychosis by having an impact on brain development.

METHOD

In 21 male adolescents with prodromal symptoms and 21 male non-clinical controls levels of testosterone and oestradiol were measured in saliva. Tanner pubertal stage and prodromal symptoms were also assessed.

RESULTS

Levels of testosterone were significantly lower in adolescents with prodromal symptoms as compared with non-clinical controls. No group differences in oestradiol were found. In the total sample, level of testosterone was significantly correlated with age and Tanner pubertal stage.

CONCLUSIONS

Our observations are in line with current hypotheses stressing the role of neuroendocrine factors during adolescence in the expression of psychotic symptoms. From a developmental perspective, susceptibility to psychotic disorders increases during adolescence. Our data suggest that testosterone might, in part, mediate this increased vulnerability. Further research is needed to assess the mediating, neural, mechanisms through which testosterone may have an impact on the development of psychotic symptoms. In the search for early risk markers for psychosis, studying neuroendocrine factors might increase our understanding of 'at-risk' developmental pathways.

Tracing the development of psychosis and its prevention: what can be learned from animal models

Schizophrenia (SCZ) is a neurodevelopmental disorder manifested symptomatically after puberty whose pharmacotherapy remains unsatisfactory. In recent years, longitudinal structural neuroimaging studies have revealed that neuroanatomical aberrations occur in this disorder and in fact precede symptom onset, raising the exciting possibility that SCZ can be prevented. There is some evidence that treatment with atypical antipsychotic drugs (APDs) prior to the development of the full clinical phenotype reduces the risk of transition to psychosis, but results remain controversial. It remains unknown whether progressive structural brain aberrations can be halted. Given the diagnostic, ethical, clinical and methodological problems of pharmacological and imaging studies in patients, getting such information remains a major challenge. Animal neurodevelopmental models of SCZ are invaluable for investigating such questions because they capture the notion that the effects of early brain damage are progressive. In recent years, data derived from such models have converged on key neuropathological and behavioral deficits documented in SCZ attesting to their strong validity, and making them ideal tools for evaluating progression of pathology following in-utero insults as well as its prevention. We review here our recent studies that use longitudinal in vivo structural imaging to achieve this aim in the prenatal immune stimulation model that is based on the association of prenatal infection and increased risk for SCZ. Pregnant rats were injected on gestational day 15 with the viral mimic polyriboinosinic-polyribocytidylic acid (poly I:C) or saline. Male and female offspring were imaged and tested behaviorally on postnatal days (PNDs) 35, 46, 56, 70 and 90. In other experiments, offspring of poly I:C- and saline-treated dams received the atypical antipsychotic drugs (APDs) clozapine or risperidone in two developmental windows: PND 34-47 and PND 48-61, and underwent behavioral testing and imaging at adulthood. Prenatal poly I:C-induced interference with fetal brain development led to aberrant postnatal brain development as manifested in structural abnormalities in the hippocampus, the striatum, the prefrontal cortex and lateral ventricles (LV), as seen in SCZ. The specific trajectories were region-, age- and sex-specific, with females having delayed onset of pathology compared to males. Brain pathology was accompanied by development of behavioral abnormalities phenotypic of SCZ, attentional deficit and hypersensitivity to amphetamine, with same sex difference. Hippocampal volume loss and LV volume expansion as well as behavioral abnormalities were prevented in the offspring of poly I:C mothers who received clozapine or risperidone during the asymptomatic period of adolescence (PND 34-47). Administration at a later window, PNDs 48-61, exerted sex-, region- and drug- specific effects. Our data show that prenatal insult leads to progressive postnatal brain pathology, which gradually gives rise to "symptoms"; that treatment with atypical APDs can prevent both brain and behavioral pathology; and that the earlier the intervention, the more pathological outcomes can be prevented.

Postural control in bipolar disorder: increased sway area and decreased dynamical complexity

Structural, neurochemical, and functional abnormalities have been identified in the brains of individuals with bipolar disorder, including in key brain structures implicated in postural control, i.e. the cerebellum, brainstem, and basal ganglia. Given these findings, we tested the hypothesis that postural control deficits are present in individuals with bipolar disorder. Sixteen participants with bipolar disorder (BD) and 16 age-matched non-psychiatric healthy controls were asked to stand as still as possible on a force platform for 2 minutes under 4 conditions: (1) eyes open-open base; (2) eyes closed-open base; (3) eyes open-closed base; and (4) eyes closed-closed base. Postural sway data were submitted to conventional quantitative analyses of the magnitude of sway area using the center of pressure measurement. In addition, data were submitted to detrended fluctuation analysis, a nonlinear dynamical systems analytic technique that measures complexity of a time-series, on both the anterior-posterior and medio-lateral directions. The bipolar disorder group had increased sway area, indicative of reduced postural control. Decreased complexity in the medio-lateral direction was also observed for the bipolar disorder group, suggesting both a reduction in dynamic range available to them for postural control, and that their postural corrections were primarily dominated by longer time-scales. On both of these measures, significant interactions between diagnostic group and visual condition were also observed, suggesting that the BD participants were impaired in their ability to make corrections to their sway pattern when no visual information was available. Greater sway magnitude and reduced complexity suggest that individuals with bipolar disorder have deficits in sensorimotor integration and a reduced range of timescales available on which to make postural corrections.

Schizophrenia, "Just the Facts" 6. Moving ahead with the schizophrenia concept: from the elephant to the mouse

The current construct of schizophrenia as a unitary disease is far from satisfactory, and is in need of reconceptualization. The first five papers in our "facts" series reviewed what is known about schizophrenia to date, and a limited number of key facts appear to stand out. Schizophrenia is characterized by persistent cognitive deficits, positive and negative symptoms typically beginning in youth, substantive heritability, and brain structural, functional and neurochemical alterations including dopaminergic dysregulation. Several pathophysiological models have been proposed with differing interpretations of the illness, like the fabled six blind Indian men groping different parts of an elephant coming up with different conclusions. However, accumulating knowledge is integrating the several extant models of schizophrenia etiopathogenesis into unifying constructs; we discuss an example, involving a neurodevelopmental imbalance in excitatory/inhibitory neural systems leading to impaired neural plasticity. This imbalance, which may be proximal to clinical manifestations, could result from a variety of genetic, epigenetic and environmental causes, as well as pathophysiological processes such as inflammation and oxidative stress. Such efforts to "connect the dots" (and visualizing the elephant) are still limited by the substantial clinical, pathological, and etiological heterogeneity of schizophrenia and its blurred boundaries with several other psychiatric disorders leading to a "fuzzy cluster" of overlapping syndromes, thereby reducing the content, discriminant and predictive validity of a unitary construct of this illness. The way ahead involves several key directions: a) choosing valid phenotype definitions increasingly derived from translational neuroscience; b) addressing clinical heterogeneity by a cross-diagnostic dimensional and a staging approach to psychopathology; c) addressing pathophysiological heterogeneity by elucidating independent families of "extended" intermediate phenotypes and pathophysiological processes (e.g. altered excitatory/inhibitory, salience or executive circuitries, oxidative stress systems) that traverse structural, functional, neurochemical and molecular domains; d) resolving etiologic heterogeneity by mapping genomic and environmental factors and their interactions to syndromal and specific pathophysiological signatures; e) separating causal factors from consequences and compensatory phenomena; and f) formulating or reformulating hypotheses that can be refuted/tested, perhaps in the mouse or other experimental models. These steps will likely lead to the current entity of schizophrenia being usefully deconstructed and reconfigured into phenotypically overlapping, but etiopathologically unique and empirically testable component entities (similar to mental retardation, epilepsy or cancer syndromes). The mouse may be the way to rescue the trapped elephant!

Early and broadly defined psychosis risk mental states

Current definitions of the prodromal (or at-risk mental state) phase of schizophrenia include attenuated and/or transient psychotic symptoms as well as a combination of different risk indicators and a recent significant deterioration in global functioning. Data accumulated to date suggest rates of conversion to frank psychosis within two years in 25 to 40% of cases supporting the validity of these criteria. However, at this late phase of illness, functional deterioration is often already pronounced, highlighting the need for earlier identification. Moreover, negative symptoms and social impairments, cognitive deficits, other non-psychotic psychopathology and/or functional decline and non-specific biological indicators, often can be detected well before the at-risk mental state as currently defined; indicating that a broad characterization of an earlier stage may be possible. Identifying specific criteria to define this group of individuals, starting from the framework of familial high-risk, can help define a broader group of people, including earlier at-risk mental states, for future research. The hope is that this research will help facilitate intervention at earlier stages that may in turn minimize functional deterioration, and delay, attenuate or even prevent transition to psychosis. The disadvantages as well as the potential benefits of this approach are discussed.

Progressive alterations of the auditory association areas in young non-psychotic offspring of schizophrenia patients

BACKGROUND

Schizophrenia may involve progressive alterations of structure and hemispheric lateralization of auditory association areas (AAA) within the superior temporal gyrus. These alterations may be greater in male patients. It is unclear if these deficits are state-dependent or whether they predate illness onset and reflect familial diathesis.

AIMS

We sought to compare AAA cortical thickness, surface area and lateralization across adolescent and young adult non-psychotic offspring of schizophrenia patients (OS) and healthy controls at baseline and one year follow-up. We also assessed the moderating effect of gender on these measures.

METHODS

Fifty-six OS and thirty-six control subjects were assessed at baseline and at follow-up on AAA surface area and thickness using FreeSurfer to process T1-MRI-images. We used repeated measures ANCOVAs, controlling intra cranial volume and age with assessment-time and side as within-subject factors and gender and study group as between-subject factors.

RESULTS

Surface area deficit in OS was greater on the left than on the right, as reflected in a lower surface area laterality-index (left-right/left + right × 100) in OS compared to controls. Left, but not right surface area and surface area laterality-index showed a longitudinal decline in OS compared to controls. Male OS declined more than controls on surface area and thickness.

CONCLUSIONS

Left AAA surface area may progressively decline in young non-psychotic offspring at familial diathesis for schizophrenia causing a continuing reversal of the leftward AAA lateralization. Progressive surface area reduction and thinning of AAA may be more prominent in young non-psychotic male offspring at risk for schizophrenia.

Stochastic tractography study of Inferior Frontal Gyrus anatomical connectivity in schizophrenia

BACKGROUND

Abnormalities within language-related anatomical structures have been associated with clinical symptoms and with language and memory deficits in schizophrenia. Recent studies suggest disruptions in functional connectivity within the Inferior Frontal Gyrus (IFG) network in schizophrenia. However, due to technical challenges, anatomical connectivity abnormalities within this network and their involvement in clinical and cognitive deficits have not been studied.

MATERIAL AND METHODS

Diffusion and anatomical scans were obtained from 23 chronic schizophrenia patients and 23 matched controls. The IFG was automatically segmented, and its white matter connections extracted and measured with newly-developed stochastic tractography tools. Correlations between anatomical structures and measures of semantic processing were also performed.

RESULTS

White Matter connections between the IFG and posterior brain regions followed two distinct pathways: dorsal and ventral. Both demonstrated left lateralization, but ventral pathway abnormalities were only found in schizophrenia. IFG volumes also showed left lateralization and abnormalities in schizophrenia. Further, despite similar laterality and abnormality patterns, IFG volumes and white matter connectivity were not correlated with each other in either group. Interestingly, measures of semantic processing correlated with white matter connectivity in schizophrenia and with gray matter volumes in controls. Finally, hallucinations were best predicted by both gray matter and white matter measures together.

CONCLUSIONS

Our results suggest abnormalities within the ventral IFG network in schizophrenia, with white matter abnormalities better predicting semantic deficits. The lack of a statistical relationship between coexisting gray and white matter deficits might suggest their different origin and the necessity for a multimodal approach in future schizophrenia studies.

To poly(I:C) or not to poly(I:C): advancing preclinical schizophrenia research through the use of prenatal immune activation models

The neurodevelopmental hypothesis of schizophrenia has been highly influential in shaping our current thinking about modeling the disease in animals. Based on the findings provided by human epidemiological studies, a great deal of recent interest has been centered upon the establishment of neurodevelopmental rodent models in which the basic experimental manipulation takes the form of prenatal exposure to infection and/or immune activation. One such model is based on prenatal treatment with the inflammatory agent poly(I:C) (=polyriboinosinic-polyribocytidilic acid), a synthetic analog of double-stranded RNA. Since its initial establishment and application to basic schizophrenia research, the poly(I:C) model has made a great impact on researchers concentrating on the neurodevelopmental and neuroimmunological basis of complex human brain disorders such as schizophrenia, and as a consequence, the model now enjoys wide recognition in the international scientific community. The present article emphasizes that the poly(I:C) model has gained such impact because it successfully accounts for several aspects of schizophrenia epidemiology, pathophysiology, symptomatology, and treatment. The numerous features of this experimental system make the poly(I:C) model a very powerful neurodevelopmental animal model of schizophrenia-relevant brain disease which is expected to be capable of critically advancing our knowledge of how the brain, following an (immune-associated) triggering event in early life, can develop into a "schizophrenia-like brain" over time. Furthermore, the poly(I:C) model seems highly suitable for the exploration of novel pharmacological and neuro-immunomodulatory strategies for both symptomatic and preventive treatments against psychotic disease, as well as for the identification of neurobiological mechanisms underlying gene-environment and environment-environment interactions presumably involved in the etiology of schizophrenia and related disorders.

Diffusion tensor imaging in the early phase of schizophrenia: what have we learned?

The dysconnectivity model suggests that disturbed integration of neural communication is central to schizophrenia. The integrity of macro-structural brain circuits can be examined with diffusion tensor imaging (DTI), an MRI application sensitive to microstructural abnormalities of brain white matter. DTI studies in first-episode schizophrenia patients and individuals at high-risk of psychosis can provide insight into the role of structural dysconnectivity in the liability, onset and early course of psychosis. This review discusses (i) views on the role of white matter abnormalities in schizophrenia, (ii) DTI and its application in schizophrenia, (iii) DTI findings in first-episode patients and subjects at high-risk of psychosis; their timing, anatomical location and early course, (iv) the hypothesized underlying pathological substrate and possible causes of DTI white matter alterations, including effects of adolescent cannabis use, and (v) some methodological issues and future recommendations. In summary, there is evidence that DTI abnormalities convey a liability for psychosis and additional abnormalities occur around onset of psychosis. However, findings in first-episode patients are less robust than in chronic patients, and progression of disturbances may occur in the early course of poor-outcome patients. In addition, acceleration of the normal aging process may occur. Adolescent cannabis use has specific effects on DTI measures. An unresolved issue is the underlying pathology of DTI abnormalities, and combining DTI with other MRI indices can provide more insight. More research is needed on which genetic and environmental factors play a role in the variability of current results.

Gamma oscillation deficits and the onset and early progression of schizophrenia

A fascinating convergence of evidence in recent years has implicated the disturbances of neural synchrony in the gamma frequency band (30-100 Hz) as a major pathophysiologic feature of schizophrenia. Evidence suggests that reduced glutamatergic neurotransmission via the N-methyl-D-aspartate (NMDA) receptors that are localized to inhibitory interneurons, perhaps especially the fast-spiking cells that contain the calcium-binding protein parvalbumin (PV), may contribute to gamma band synchrony deficits. These deficits may underlie the brain's failure to integrate information and hence the manifestations of many symptoms and deficits of schizophrenia. Furthermore, because gamma oscillations are thought to provide the temporal structure that is necessary for synaptic plasticity, gamma oscillation deficits may disturb the developmental synaptic reorganization process that is occurring during the period of late adolescence and early adulthood. This disturbance may contribute to the onset of schizophrenia and the functional deterioration that is characteristic of the early stage of the illness. Finally, reduced NMDA neurotransmission on inhibitory interneurons, including the PV-containing cells, may inflict excitotoxic or oxidative injury to downstream pyramidal neurons, leading to further loss of synapses and dendritic branchings. Hence, a key element in the conceptualization of rational early-intervention and prevention strategies for schizophrenia may involve correcting the abnormal NMDA neurotransmission on inhibitory interneurons-possibly that on the PV-containing neurons, in particular-thereby normalizing gamma oscillation deficits and attenuating downstream neuronal pathology.

Decreased BDNF in patients with antipsychotic naïve first episode schizophrenia

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is a key factor known to mediate neuronal proliferation, differentiation, survival and response to stress. Decreases in BDNF levels have been reported in schizophrenia, but studies in treatment naïve patients are few. Herein we report on serum BDNF levels in a series of patients with first-episode treatment naïve psychoses in comparison to age matched healthy controls.

METHOD

Fasting serum BDNF levels were measured in 41 patients with treatment naive first episode psychosis (24 with schizophrenia, schizoaffective disorder or schizophreniform disorder, and 17 with non-schizophrenia psychotic disorders) and 41 age-matched healthy controls.

RESULTS

A three group analyses of covariance (ANCOVA) showed a diagnosis effect (p=.038) in which patients with schizophrenia had lesser serum BDNF levels than patient with non-schizophrenia psychosis, who in turn had lesser BDNF levels than matched healthy controls. Planned two-group ANCOVAs suggested that patients with schizophrenia had lower serum BDNF level than matched controls (p=.016), whereas patients with non-schizophrenia psychosis did not differ from controls. There were no age effects on BDNF, but there was a trend (p=.08) for a gender by group interaction with greater reductions in female patients with schizophrenia. The BDNF levels did not correlate with magnitude of smoking, body mass index, severity of positive and negative symptoms or overall functioning.

CONCLUSIONS

Serum BDNF may be reduced at the onset of psychosis but its role in the pathogenesis of schizophrenia remains unclear. Elucidating the role of BDNF in schizophrenia and related psychotic disorders may provide an important therapeutic target. Further studies are also needed to examine if patients with schizophrenia have more pronounced reductions in BDNF than those with affective psychosis.

What is schizophrenia: A neurodevelopmental or neurodegenerative disorder or a combination of both? A critical analysis

The etiology of schizophrenia has been the focus of intensive research for a long time. Perspectives have changed drastically with the development of new investigative techniques. Clinical observations made by Kraepelin, Clouston, Bender, and Watt are now being complemented by neuroimaging and genetic studies to prove the neurodevelopmental hypothesis. At the same time, neuropathological and longitudinal studies of schizophrenia often support a neurodegenerative hypothesis. To provide a theoretical basis to the available evidence, another hypothesis called the progressive neurodevelopmental model has also emerged. This review presents some key evidence supporting each of these theories followed by a critical analysis of each.

Subjective effects of cannabis before the first psychotic episode

OBJECTIVE

The aim of the present study was to gain more insight into the positive and negative effects of cannabis in the prodromal phase of schizophrenia and in the ultra-high-risk (UHR) state for psychosis.

METHOD

A theory-driven questionnaire was used to examine subjective effects in the prodromal phase in male subjects with a recent onset of schizophrenia or related disorder (n = 52) and in the UHR state in help-seeking male subjects screened for being at UHR for psychosis (n = 17); both groups were compared to cannabis-using controls from the general population (n=52).

RESULTS

Recent-onset patients and UHR subjects reported feeling more anxious, depressed and suspicious immediately after cannabis use. Some patients also reported feeling less depressed after cannabis use. Recent-onset patients reported increased visual and acoustic hallucinations, and confusion after cannabis use. Of the recent-onset patients 37% reported that their very first psychotic symptoms occurred during cannabis intoxication. Long-term effects of cannabis reported more often by both patient groups were depression, less control over thoughts and social problems.

CONCLUSIONS

These results suggest that schizophrenia patients in the prodromal phase and subjects at UHR for psychosis are more sensitive to some negative effects of cannabis, in particular psychotic effects, compared to cannabis users from the general population. Although limited by the retrospective design in the recent-onset patients, the present study adds qualitative evidence to longitudinal studies that suggest that cannabis is a component cause in the onset of the first psychotic episode. Further studies are needed on the objective and subjective effects of cannabis in UHR subjects.

Striatal metabolic alterations in non-psychotic adolescent offspring at risk for schizophrenia: a (1)H spectroscopy study

In vivo proton ((1)H) Magnetic Resonance spectroscopy ((1)H MRS) has shown abnormalities in young first-episode patients with schizophrenia. It is unclear whether these abnormalities reflect trait related vs. state related alterations in schizophrenia. We compared young first-degree relatives of schizophrenia patients and healthy controls using (1)H MRS. We hypothesized alterations in the (1)H MRS metabolites N-acetyl aspartate (NAA) and glutamate in corticostriatal and thalamic brain regions. We obtained multi-voxel, short-TE (1)H MRS measurements at 1.5 Tesla in 40 consenting adolescent offspring at risk for schizophrenia (HR), and 48 age matched healthy controls (HC). Absolute levels of NAA, phosphocreatine plus creatine (PCr+Cr), choline-containing compounds (GPC+PC), myo-inositol and glutamate plus glutamine (Glu+Gln) were obtained from the seven different anatomical brain areas (nominal voxel size of 4.5cm(3) each) and corrected for tissue voxel composition. HR subjects showed NAA (p=.0049), PCr+Cr (p=0.028) and GPC+PC (p=0.0086) reductions in the caudate compared with HC subjects. Male HR subjects had significant Glu+Gln reductions compared to male HC subjects (p=.0022). HR subjects had increased NAA in prefrontal white matter. NAA levels in the prefrontal white matter and Glu+Gln levels in the inferior parietal/occipital region were both increased in HR without psychopathology compared with HC subjects. Lower NAA, PCr+Cr and GPC+PC levels may reflect an overall reduction in cellular processes in the caudate of HC subjects, perhaps related to decreases in cell density, or synaptic overpruning. Further studies are needed to examine the pathophysiologic significance of these observations, and their potential predictive value for schizophrenia related psychopathology that may emerge in these at risk relatives during adolescence and early adulthood.

Predictors of 10-year outcome of first-episode psychosis

BACKGROUND

Predictors of outcome for psychosis are poorly understood. Duration of untreated psychosis (DUP) appears to predict short-term outcome although its medium- to long-term role remains unclear. Neurodevelopmental indices such as pre-morbid function and/or neurological soft signs may predict longer-term outcome. We aimed to assess the impact of a range of clinical and demographic variables on long-term outcome of a geographically defined, epidemiological first-episode psychosis cohort.

METHOD

A 10-year follow-up was undertaken of a consecutively presenting sample of 109 cases of first-episode psychosis aged 16-50 years. Baseline assessments included positive, negative and depression symptoms, DUP, neurological soft signs and pre-morbid functioning. Multi-dimensional outcomes were assessed blind to baseline data.

RESULTS

All participants were traced at a mean of 10.5 years post-index admission: 11 had died, 10 from non-natural causes. Of the surviving cases, 70% were comprehensively re-assessed by interview. Summary data on the remainder were collected from their family practitioner and chart review. Poor 10-year outcomes were predicted independently by poor pre-morbid functioning, baseline negative symptoms and longer DUP. The same measures, plus neurological soft signs, appeared to predict outcomes in a DSM-IV schizophrenia/schizo-affective subgroup.

CONCLUSIONS

Poor pre-morbid functioning, baseline symptoms, DUP and neurological soft signs at onset independently predict poor long-term outcome in first-episode psychosis.