Meta-analysis of brain weight in schizophrenia

Automatic Segmentation and Alignment of Uterine Shapes from 3D Ultrasound Data

BACKGROUND

The uterus is the most important organ in the female reproductive system. Its shape plays a critical role in fertility and pregnancy outcomes. Advances in medical imaging, such as 3D ultrasound, have significantly improved the exploration of the female genital tract, thereby enhancing gynecological healthcare. Despite well-documented data for organs like the liver and heart, large-scale studies on the uterus are lacking. Existing classifications, such as VCUAM and ESHRE/ESGE, provide different definitions for normal uterine shapes but are not based on real-world measurements. Moreover, the lack of comprehensive datasets significantly hinders research in this area. Our research, part of the larger NURSE study, aims to fill this gap by establishing the shape of a normal uterus using real-world 3D vaginal ultrasound scans. This will facilitate research into uterine shape abnormalities associated with infertility and recurrent miscarriages.

METHODS

We developed an automated system for the segmentation and alignment of uterine shapes from 3D ultrasound data, which consists of two steps: automatic segmentation of the uteri in 3D ultrasound scans using deep learning techniques, and alignment of the resulting shapes with standard geometrical approaches, enabling the extraction of the normal shape for future analysis. The system was trained and validated on a comprehensive dataset of 3D ultrasound images from multiple medical centers. Its performance was evaluated by comparing the automated results with manual annotations provided by expert clinicians.

RESULTS

The presented approach demonstrated high accuracy in segmenting and aligning uterine shapes from 3D ultrasound data. The segmentation achieved an average Dice similarity coefficient (DSC) of 0.90. Our method for aligning uterine shapes showed minimal translation and rotation errors compared to traditional methods, with the preliminary average shape exhibiting characteristics consistent with expert findings of a normal uterus.

CONCLUSION

We have presented an approach to automatically segment and align uterine shapes from 3D ultrasound data. We trained a deep learning nnU-Net model that achieved high accuracy and proposed an alignment method using a combination of standard geometrical techniques. Additionally, we have created a publicly available dataset of 3D transvaginal ultrasound volumes with manual annotations of uterine cavities to support further research and development in this field. The dataset and the trained models are available at https://github.com/UL-FRI-LGM/UterUS.

A thermodynamical model of non-deterministic computation in cortical neural networks

Neuronal populations in the cerebral cortex engage in probabilistic coding, effectively encoding the state of the surrounding environment with high accuracy and extraordinary energy efficiency. A new approach models the inherently probabilistic nature of cortical neuron signaling outcomes as a thermodynamic process of non-deterministic computation. A mean field approach is used, with the trial Hamiltonian maximizing available free energy and minimizing the net quantity of entropy, compared with a reference Hamiltonian. Thermodynamic quantities are always conserved during the computation; free energy must be expended to produce information, and free energy is released during information compression, as correlations are identified between the encoding system and its surrounding environment. Due to the relationship between the Gibbs free energy equation and the Nernst equation, any increase in free energy is paired with a local decrease in membrane potential. As a result, this process of thermodynamic computation adjusts the likelihood of each neuron firing an action potential. This model shows that non-deterministic signaling outcomes can be achieved by noisy cortical neurons, through an energy-efficient computational process that involves optimally redistributing a Hamiltonian over some time evolution. Calculations demonstrate that the energy efficiency of the human brain is consistent with this model of non-deterministic computation, with net entropy production far too low to retain the assumptions of a classical system.

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.

Finite Element Analysis of Glucose Diffusivity in Cellulose Nanofibril Peripheral Nerve Conduits

Peripheral neuropathy arising from physical trauma is estimated to afflict 20 million people in the United States alone. In one common surgical intervention, neural conduits are placed over the nerve stumps to bridge the gap and create a microenvironment conducive to regeneration. It has been proposed that a biocompatible material such as cellulose nanofiber may serve as a viable conduit material, providing a non-inflammatory and mechanically stable system. Preliminary studies have shown that cellulose nanofiber conduits successfully aid neural regeneration and further, that the dimensions of the conduit relative to the nerve gap have an impact on efficacy in murine models. It has been hypothesized that the reliance of regeneration upon the physical dimensions of the conduit may be related to modified modes of diffusion and/or distances of key cellular nutrients and waste metabolites to/from the injury site. The present work investigates the concentration profile of glucose within the conduit via finite element analysis as a function of the physical dimensions of the conduit. It was determined that the magnitude of glucose diffusion was greater through the conduit walls than through the luminal space between the nerve and the inner wall of the conduit, and that as such radial diffusion is dominant over axial diffusion.

PCM1 is necessary for focal ciliary integrity and is a candidate for severe schizophrenia

The neuronal primary cilium and centriolar satellites have functions in neurogenesis, but little is known about their roles in the postnatal brain. We show that ablation of pericentriolar material 1 in the mouse leads to progressive ciliary, anatomical, psychomotor, and cognitive abnormalities. RNAseq reveals changes in amine- and G-protein coupled receptor pathways. The physiological relevance of this phenotype is supported by decreased available dopamine D2 receptor (D2R) levels and the failure of antipsychotic drugs to rescue adult behavioral defects. Immunoprecipitations show an association with Pcm1 and D2Rs. Finally, we sequence PCM1 in two human cohorts with severe schizophrenia. Systematic modeling of all discovered rare alleles by zebrafish in vivo complementation reveals an enrichment for pathogenic alleles. Our data emphasize a role for the pericentriolar material in the postnatal brain, with progressive degenerative ciliary and behavioral phenotypes; and they support a contributory role for PCM1 in some individuals diagnosed with schizophrenia.

The role of ciliary/centriolar components in the postnatal brain is unclear. Here, the authors show via ablation of Pcm1 in mice that degenerative ciliary/centriolar phenotypes induce neuroanatomical and behavioral changes. Sequencing of PCM1 in human cohorts and zebrafish in vivo complementation suggests PCM1 mutations can contribute to schizophrenia.

Neuroanatomical Differences Among Sexual Offenders: A Targeted Review with Limitations and Implications for Future Directions

As sexual assault and child sexual abuse continue to be worldwide public health concerns, research has continued to explore factors associated with sexual offending. Structural and functional neuroanatomical brain differences have been examined in an effort to differentiate sexual offenders and their behavior. This targeted review searched PubMed and Google Scholar for empirical studies using brain imaging techniques to examine possible structural or functional differences among control groups compared with at least one group of sexual offenders with contact offenses. This targeted review summarizes the structural and functional findings of 15 brain imaging studies (i.e., computed tomography, diffusion tensor imaging, magnetic resonance imaging, positron emission tomography, and functional magnetic resonance imaging), which suggest possible differences in brain size and gray matter volume, cortical thickness, white matter connectivity, and specific structural and functional differences among brain regions (fronto-temporal region, amygdala, prefrontal cortex, etc.). The methodological limitations of brain imaging studies and the associated findings with regard to sexual offenders are highlighted, as research indicates that many of the proposed differences in brain structure and function are not unique to this population. We further highlight several limitations to using neuroimaging studies to examine this population of interest, including publication bias, small sample size, underpowered studies, and all-male samples. As these results are mixed and findings are not seemingly unique to sexual offenders, we suggest future sexual offender research may benefit from focusing on more financially feasible options, such as neuropsychological assessment approaches, to assess for and attend to offenders' criminogenic and rehabilitative/therapeutic needs in alignment with the risk-need-responsivity model.

Gray matter abnormalities in language processing areas and their associations with verbal ability and positive symptoms in first-episode patients with schizophrenia spectrum psychosis

BACKGROUND

Impaired verbal communication is a prominent feature in patients with schizophrenia. Verbal communication difficulties adversely affect psychosocial outcomes and worsen schizophrenia's clinical manifestation. In the present study, we aimed to investigate associations among gray matter (GM) volumes in language processing areas (LPAs), verbal ability, and positive symptoms in first-episode patients (FEPs) with schizophrenia spectrum psychosis.

METHODS

We enrolled 94 FEPs and 52 healthy controls (HCs) and subjected them to structural magnetic resonance imaging. The GM volumes of the bilateral pars opercularis (POp), pars triangularis (PTr), planum temporale (PT), Heschl's gyrus (HG), insula, and fusiform gyrus (FG), were estimated and compared between the FEPs and HCs. Verbal intelligence levels and positive symptom severity were examined for correlations with the left LPA volumes.

RESULTS

The GM volumes of the left POp, HG, and FG were significantly smaller in the FEPs than in the HCs, while the right regions showed no significant between-group difference. A multiple linear regression model revealed that larger left PT volume was associated with better verbal intelligence in FEPs. In exploratory correlation analysis, several LPAs showed significant correlations with the severity of positive symptoms in FEPs. The left FG volume had a strong inverse correlation with the severity of auditory verbal hallucinations, while the left PT volume was inversely associated with the severity of positive formal thought disorder and delusions. Moreover, the volume of the left insula was positively associated with the severity of bizarre behavior.

CONCLUSIONS

The present study suggests that GM abnormalities in the LPAs, which can be detected during the early stage of illness, may underlie impaired verbal communication and positive symptoms in patients with schizophrenia spectrum psychosis.

Mapping cortical surface features in treatment resistant schizophrenia with in vivo structural MRI

Decreases in cortical volume (CV), thickness (CT) and surface area (SA) have been reported in individuals with schizophrenia by in vivo MRI studies. However, there are few studies that examine these cortical measures as potential biomarkers of treatment resistance (TR) and treatment response (NTR) in schizophrenia. This study used structural MRI to examine differences in CV, CT, and SA in 42 adults with schizophrenia (TR = 21, NTR = 21) and 23 healthy controls (HC) to test the hypothesis that individuals with TR schizophrenia have significantly greater reductions in these cortical measures compared to individuals with NTR schizophrenia. We found that individuals with TR schizophrenia showed significant reductions in CV and CT compared to individuals with NTR schizophrenia in right frontal and precentral regions, right parietal and occipital cortex, left temporal cortex and bilateral cingulate cortex. In line with previous literature, the temporal lobe and cingulate gyrus in both patient groups showed significant reductions of all three measures when compared to healthy controls. Taken together these results suggest that regional changes in CV and CT may index mechanisms specific to TR schizophrenia and potentially identify patients with TR schizophrenia for earlier treatment.

State-associated changes in longitudinal [18F]-PBR111 TSPO PET imaging of psychosis patients: Evidence for the accelerated ageing hypothesis?

OBJECTIVE

To determine whether state-associated changes in microglial activity, measured with translocator-protein positron emission tomography (TSPO PET), can be identified in psychosis patients through longitudinal evaluation of their regional tracer uptake over the clinical course from acute psychosis to post-treatment follow-up, and comparison to healthy controls. We also evaluated the relation between tracer uptake, clinical symptoms and peripheral immunological markers.

METHOD

Second-generation radioligand [¹⁸F]-PBR111 TSPO PET-CT was used for longitudinal dynamic imaging in 14 male psychosis patients and 17 male age-matched healthy control subjects. Patients were first scanned during an acute psychotic episode followed by a second scan after treatment. Prior genotyping of subjects for the rs6917 polymorphism distinguished high- and mixed-affinity binders. The main outcome was regional volume of distribution (V_T), representing TSPO binding. Plasma concentrations of CRP, cytokines and kynurenines were measured at each timepoint.

RESULTS

We found a significant three-way interaction between time of scan, age and cohort (cortical grey matter F6.50, p.020). Age-dependent differences in V_T existed between cohorts during the psychotic state, but not at follow-up. Patients' relative change in V_T over time correlated with age (cortical grey matter Pearson's r.574). PANSS positive subscale scores correlated with regional V_T during psychosis (cortical grey matter r.767). Plasma CRP and quinolinic acid were independently associated with lower V_T.

CONCLUSIONS

We identified a differential age-dependent pattern of TSPO binding from psychosis to follow-up in our cohort of male psychosis patients. We recommend future TSPO PET studies in psychosis patients to differentiate between clinical states and consider potential age-related effects.

Sudden spinal hemorrhage in a pediatric case with total body irradiation-induced cavernous hemangioma

Compared to cerebral radiation-induced cavernous hemangiomas (RICHs), little is known about intraspinal RICHs. A 13-year-old male suddenly developed symptomatic spinal hemorrhage eight years after hematopoietic stem cell transplantation using a total body irradiation (TBI) based myeloablative regimen. A solitary small hemangioma was detected on follow-up T2 star weighted magnetic resonance imaging of the spine. His neurological symptoms gradually improved with supportive treatment and rehabilitation, although he experienced rebleeding 2 years later. Intraspinal RICH is very rare but should be recognized as a possible late adverse effect in pediatric patients who received TBI.

PKBγ/AKT3 loss-of-function causes learning and memory deficits and deregulation of AKT/mTORC2 signaling: Relevance for schizophrenia

Psychiatric genetic studies have identified genome-wide significant loci for schizophrenia. The AKT3/1q44 locus is a principal risk region and gene-network analyses identify AKT3 polymorphisms as a constituent of several neurobiological pathways relevant to psychiatric risk; the neurobiological mechanisms remain unknown. AKT3 shows prenatal enrichment during human neocortical development and recurrent copy number variations involving the 1q43-44 locus are associated with cortical malformations and intellectual disability, implicating an essential role in early brain development. Here, we investigated the role of AKT3 as it relates to aspects of learning and memory and behavioral function, relevant to schizophrenia and cognitive disability, utilizing a novel murine model of Akt3 genetic deficiency. Akt3 heterozygous (Akt3^-/+) or null mice (Akt3^-/-) were assessed in a comprehensive test battery. Brain biochemical studies were conducted to assess the impact of Akt3 deficiency on cortical Akt/mTOR signaling. Akt3^-/+ and Akt3^-/- mice exhibited selective deficits of temporal order discrimination and spatial memory, tasks critically dependent on intact prefrontal-hippocampal circuitry, but showed normal prepulse inhibition, fear conditioned learning, memory for novel objects and social function. Akt3 loss-of-function, reduced brain size and dramatically impaired cortical Akt Ser⁴⁷³ activation in an allele-dose dependent manner. Such changes were observed in the absence of altered Akt1 or Akt2 protein expression. Concomitant reduction of the mTORC2 complex proteins, Rictor and Sin1 identifies a potential mechanism. Our findings provide novel insight into the neurodevelopmental role of Akt3, identify a non-redundant role for Akt3 in the development of prefrontal cortical-mediated cognitive function and show that Akt3 is potentially the dominant regulator of AKT/mTOR signaling in brain.

Microglia and Brain Plasticity in Acute Psychosis and Schizophrenia Illness Course: A Meta-Review

OBJECTIVE

Schizophrenia poses a tremendous health, social, and economic burden upon patients and society, indicating current treatment options remain inadequate. Recent findings from several lines of evidence have pointed to the importance of immune system involvement in not only premorbid neurodevelopmental but also subsequent symptom generation and aging processes of brain change in schizophrenia. In this meta-review, we use the summarized evidence from recent quantitative systematic reviews (SRs) and meta-analyses of several subspecialties to critically evaluate the hypothesis that immune-related processes shape the symptomatic presentation and illness course of schizophrenia, both directly and indirectly through altered neuroplasticity.

METHODS

We performed a data search in PubMed for English language SRs and meta-analyses from 2010 to 2017. The methodological quality of the SRs was assessed with the AMSTAR instrument. In addition, we review in this paper 11 original publications on translocator protein (TSPO) positron emission tomography (PET) imaging in schizophrenia.

RESULTS

We reviewed 26 SRs and meta-analyses. Evidence from clinical observational studies of inflammatory or immunological markers and randomized controlled drug trials of immunomodulatory compounds as add-on in the treatment of schizophrenia suggests psychotic exacerbations are accompanied by immunological changes different from those seen in non-acute states, and that the symptoms of schizophrenia can be modified by compounds such as non-steroidal anti-inflammatory drug and minocycline. Information derived from post-mortem brain tissue analysis and PET neuroimaging studies to evaluate microglial activation have added new perspectives to the available evidence, yet these results are very heterogeneous. Each research domain comes with unique opportunities as well as inherent limitations. A better understanding of the (patho-)physiology of microglial cells and their role in neuroplasticity is key to interpreting the immune-related findings in the context of schizophrenia illness exacerbations and progression.

CONCLUSION

Evidence from clinical studies analyzing patients' blood and cerebrospinal fluid samples, neuroimaging and post-mortem brain tissue suggests that aberrant immune responses may define schizophrenia illness' course through altered neuroplasticity representing abnormal aging processes. Most findings are however prone to bias and confounding, and often non-specific to schizophrenia, and a multidisciplinary translational approach is needed to consolidate these findings and link them to other schizophrenia hypotheses.

How much do we know about schizophrenia and how well do we know it? Evidence from the Schizophrenia Library

BACKGROUND

True findings about schizophrenia remain elusive; many findings are not replicated and conflicting results are common. Well-conducted systematic reviews have the ability to make robust, generalizable conclusions, with good meta-analyses potentially providing the closest estimate of the true effect size. In this paper, we undertake a systematic approach to synthesising the available evidence from well-conducted systematic reviews on schizophrenia.

METHOD

Reviews were identified by searching Medline, EMBASE, CINAHL, Current Contents and PsycINFO. The decision to include or exclude reviews, data extraction and quality assessments were conducted in duplicate. Evidence was graded as high quality if reviews contained large samples and robust results; and as moderate quality if reviews contained imprecision, inconsistency, smaller samples or study designs that may be prone to bias.

RESULTS

High- and moderate-quality evidence shows that numerous psychosocial and biomedical treatments are effective. Patients have relatively poor cognitive functioning, and subtle, but diverse, structural brain alterations, altered electrophysiological functioning and sleep patterns, minor physical anomalies, neurological soft signs, and sensory alterations. There are markers of infection, inflammation or altered immunological parameters; and there is increased mortality from a range of causes. Risk for schizophrenia is increased with cannabis use, pregnancy and birth complications, prenatal exposure to Toxoplasma gondii, childhood central nervous system viral infections, childhood adversities, urbanicity and immigration (first and second generation), particularly in certain ethnic groups. Developmental motor delays and lower intelligence quotient in childhood and adolescence are apparent.

CONCLUSIONS

We conclude that while our knowledge of schizophrenia is very substantial, our understanding of it remains limited.

Structural alterations of the social brain: a comparison between schizophrenia and autism

Autism spectrum disorder and schizophrenia share a substantial number of etiologic and phenotypic characteristics. Still, no direct comparison of both disorders has been performed to identify differences and commonalities in brain structure. In this voxel based morphometry study, 34 patients with autism spectrum disorder, 21 patients with schizophrenia and 26 typically developed control subjects were included to identify global and regional brain volume alterations. No global gray matter or white matter differences were found between groups. In regional data, patients with autism spectrum disorder compared to typically developed control subjects showed smaller gray matter volume in the amygdala, insula, and anterior medial prefrontal cortex. Compared to patients with schizophrenia, patients with autism spectrum disorder displayed smaller gray matter volume in the left insula. Disorder specific positive correlations were found between mentalizing ability and left amygdala volume in autism spectrum disorder, and hallucinatory behavior and insula volume in schizophrenia. Results suggest the involvement of social brain areas in both disorders. Further studies are needed to replicate these findings and to quantify the amount of distinct and overlapping neural correlates in autism spectrum disorder and schizophrenia.

Impact of neonatal NOS-1 inhibitor exposure on neurobehavioural measures and prefrontal-temporolimbic integration in the rat nucleus accumbens

Nitric oxide (NO) is a gaseous neurotransmitter that plays a significant role in the establishment and refinement of functional neural circuits. Genetic and post-mortem studies have suggested that neuronal NO synthase (NOS-1) activity may be compromised in frontal and temporal lobes, and related structures, in schizophrenia. The goal of this study was to determine if there is a link between neonatal disruptions in NO signalling and disturbances in the development and function of prefrontal-temporolimbic circuits. Neonatal rats were injected on postnatal days PD3-5 with the selective NOS-1 inhibitor Nω-propyl-L-arginine (NPA) and tested in adulthood (≥PD60) or as juveniles (PD30). Adult rats treated with NPA as neonates exhibited increased amphetamine-induced locomotion compared to animals receiving vehicle as neonates, whereas this was not observed in juvenile rats treated with NPA as neonates. Adult rats exposed to NPA as neonates also exhibited deficits in social interaction and short-term recognition memory, as well as reduced brain weight, compared to vehicle-treated controls. Finally, neonatal NPA exposure increased the responsiveness of nucleus accumbens neurons to prefrontal cortical input and disrupted the modulation of cortico-accumbens circuits by hippocampal afferents that is normally observed in adult animals. These results show for the first time that neonatal inhibition of NOS-1 during a critical neurodevelopmental period leads to aberrant behaviours that manifest in adulthood, as well as electrophysiological abnormalities in prefrontal-temporolimbic circuits. Greater understanding of the role of NOS-1 in the development of these circuits will shed light on how developmental insults translate to pathophysiology associated with schizophrenia.

Age-related brain trajectories in schizophrenia: a systematic review of structural MRI studies

Using the Pubmed database, we performed a detailed literature search for structural magnetic resonance imaging studies on patients with schizophrenia, investigating the relationship between macroscopic and microscopic structural parameters and age, to delineate an age-related trajectory. Twenty-six studies were considered for the review, from January 2000 to June 2012. Research results are heterogeneous because of the multifactorial features of schizophrenia and the multiplicity of the methodological approaches adopted. Some areas, within the amygdala-hippocampus complex, which are affected early in life by schizophrenia, age in a physiological way. Other regions, such as the superior temporal gyrus, appear already impaired at the onset of symptoms, undergo a worsening in the acute phase but later stabilize, progressing physiologically over years. Finally, there are regions, such as the uncinate fasciculus, which are not altered early in life, but are affected around the onset of schizophrenia, with their impairment continuously worsening over time. Further extensive longitudinal studies are needed to understand the timing and the possible degenerative characteristics of structural impairment associated with schizophrenia.

Periadolescent maturation of the prefrontal cortex is sex-specific and is disrupted by prenatal stress

The prefrontal cortex (PFC) undergoes dramatic, sex-specific maturation during adolescence. Adolescence is a vulnerable window for developing mental illnesses that show significant sexual dimorphisms. Gestational stress is associated with increased risk for both schizophrenia, which is more common among men, and cognitive deficits. We have shown that male, but not female, rats exposed to prenatal stress develop postpubertal deficits in cognitive behaviors supported by the prefrontal cortex. Here we tested the hypothesis that repeated variable prenatal stress during the third week of rat gestation disrupts periadolescent development of prefrontal neurons in a sex-specific fashion. Using Golgi-Cox stained tissue, we compared dendritic arborization and spine density of prelimbic layer III neurons in prenatally stressed and control animals at juvenile (day 20), prepubertal (day 30), postpubertal (day 56), and adult (day 90) ages (N = 115). Dendritic ramification followed a sex-specific pattern that was disrupted during adolescence in prenatally stressed males, but not in females. In contrast, the impact of prenatal stress on the female PFC was not evident until adulthood. Prenatal stress also caused reductions in brain and body weights, and the latter effect was more pronounced among males. Additionally, there was a trend toward reduced testosterone levels for adult prenatally stressed males. Our findings indicate that, similarly to humans, the rat PFC undergoes sex-specific development during adolescence and furthermore that this process is disrupted by prenatal stress. These findings may be relevant to both the development of normal sex differences in cognition as well as differential male-female vulnerability to psychiatric conditions.

Epigenetic signatures may explain the relationship between socioeconomic position and risk of mental illness: preliminary findings from an urban community-based sample

Low socioeconomic position (SEP) has previously been linked to a number of negative health indicators, including poor mental health. The biologic mechanisms linking SEP and mental health remain poorly understood. Recent work suggests that social exposures influence DNA methylation in a manner salient to mental health. We conducted a pilot investigation to assess whether SEP, measured as educational attainment, modifies the association between genomic methylation profiles and traumatic stress in a trauma-exposed sample. Results show that methylation × SEP interactions occur preferentially in genes pertaining to nervous system function, suggesting a plausible biological pathway by which SEP may enhance sensitivity to stress and, in turn, risk of posttraumatic stress disorder.[Supplementary materials are available for this article. Go to the publisher's online edition of Biodemography and Social Biology for the following free supplemental resource: Supplementary tables of full model and functional annotation clustering results.].

Epigenetic and genetic variation at the IGF2/H19 imprinting control region on 11p15.5 is associated with cerebellum weight

IGF2 is a paternally expressed imprinted gene with an important role in development and brain function. Allele-specific expression of IGF2 is regulated by DNA methylation at three differentially methylated regions (DMRs) spanning the IGF2/H19 domain on human 11p15.5. We have comprehensively assessed DNA methylation and genotype across the three DMRs and the H19 promoter using tissue from a unique collection of well-characterized and neuropathologically-dissected post-mortem human cerebellum samples (n = 106) and frontal cortex samples (n = 51). We show that DNA methylation, particularly in the vicinity of a key CTCF-binding site (CTCF3) in the imprinting control region (ICR) upstream of H19, is strongly correlated with cerebellum weight. DNA methylation at CTCF3 uniquely explains ~25% of the variance in cerebellum weight. In addition, we report that genetic variation in this ICR is strongly associated with cerebellum weight in a parental-origin specific manner, with maternally-inherited alleles associated with a 16% increase in cerebellum weight compared with paternally-inherited alleles. Given the link between structural brain abnormalities and neuropsychiatric disease, an understanding of the epigenetic and parent-of-origin specific genetic factors associated with brain morphology provides important clues about the etiology of disorders such as schizophrenia and autism.

How does the social environment 'get into the mind'? Epigenetics at the intersection of social and psychiatric epidemiology

The social environment plays a considerable role in determining major psychiatric disorders. Emerging evidence suggests that features of the social environment modify gene expression independently of the primary DNA sequence through epigenetic processes. Accordingly, dysfunction of epigenetic mechanisms offers a plausible mechanism by which an adverse social environment gets "into the mind" and results in poor mental health. The purpose of this review is to provide an overview of the studies suggesting that epigenetic changes introduced by the social environment then manifest as psychological consequences. Our goal is to build a platform to discuss the ways in which future epidemiologic studies may benefit from including epigenetic measures. We focus on schizophrenia, major depressive disorder, post-traumatic stress disorder, anorexia nervosa, and substance dependence as examples that highlight the ways in which social environmental exposures, mediated through epigenetic processes, affect mental health.

Stereological approaches to identifying neuropathology in psychosis

The challenges involved in identifying the neuropathological substrates of the clinical syndrome recognized as schizophrenia are well known. Stereological sampling provides a means to obtain accurate and precise quantitative estimates of components of neural circuits and thus offers promise of an enhanced capacity to detect subtle alterations in brain structure associated with schizophrenia. In this review, we 1) consider the importance and rationale for robust quantitative measures of brain abnormalities in postmortem studies of schizophrenia; 2) provide a brief overview of stereological methods for obtaining such measures; 3) discuss the methodological details that should be reported to document the robustness of a stereological study; 4) given the constraints of postmortem human studies, suggest how to approach the limitations of less robust designs; and 5) present an overview of methodologically sound stereological estimates from postmortem studies of schizophrenia.

Human brain weight is correlated with expression of the 'housekeeping genes' beta-2-microglobulin (β2M) and TATA-binding protein (TBP)

AIMS

Many variables affect mRNA measurements in post mortem human brain tissue. Brain weight has not hitherto been considered to be such a factor. This study examined whether there is any relationship between brain weight and mRNA abundance.

METHODS

We investigated quantitative real-time RT-PCR data for five 'housekeeping genes' using the 104 adult brains of the Stanley Microarray Consortium series. Eleven data sets were analysed, from cerebellum, hippocampus, and anterior cingulate cortex. We used a specified sequence of correlations, partial correlations and multiple regression analyses.

RESULTS

Brain weight correlated with the 'raw' (i.e. non-normalized) data for two mRNAs, β2-microglobulin and TATA-binding protein, measured in cerebellum and hippocampus, respectively. In hippocampus, the geometric mean of three housekeeping gene transcripts also correlated with brain weight. The correlations were significant after adjusting for age, sex and other confounders, and the effect of brain weight was confirmed using multiple regression. No correlations with brain weight were seen in the anterior cingulate cortex, nor for the other mRNAs examined.

CONCLUSIONS

The findings were not anticipated; they need replication in another brain series, and a more systematic survey is indicated. In the interim, we suggest that quantitative gene expression studies in human brain should inspect for a potential influence of brain weight, especially as the affected transcripts are commonly used as reference genes for normalization purposes in studies of neurological and psychiatric disorders. The relationship of brain weight with β2-microglobulin mRNA may reflect the roles of major histocompatibility complex class I genes in synapse formation and plasticity.

Markers of glutamate synaptic transmission and plasticity are increased in the anterior cingulate cortex in bipolar disorder

BACKGROUND

Cortical glutamate levels are elevated in bipolar disorder, but the interpretation of this increase is unclear because glutamate has metabolic as well as neurotransmitter roles. We investigated this by measuring vesicular glutamate transporter 1 (VGluT1) expression, which reflects activity at glutamate synapses. We also measured netrin-G1 and netrin-G2 messenger RNAs because these genes are involved in the formation and plasticity of glutamatergic connections.

METHODS

Using quantitative polymerase chain reaction, we quantified transcripts for VGluT1, netrin-G1 (isoforms G1c, G1d, and G1f), and netrin-G2 in the anterior cingulate cortex from subjects with bipolar disorder (n = 34), schizophrenia (n = 35), and healthy control subjects (n = 35).

RESULTS

Vesicular glutamate transporter 1, netrin-G2, and netrin-G1d and G1f were increased in bipolar disorder but not in schizophrenia. Netrin-G1c did not differ between groups. Netrin-G1c and netrin-G1f expression showed left-right asymmetries. Vesicular glutamate transporter 1 messenger RNA correlated with brain weight.

CONCLUSIONS

Increased VGluT1 expression is supportive of elevated glutamate neurotransmission in the anterior cingulate cortex in bipolar disorder. The netrin-G1 and netrin-G2 findings suggest there may be an underlying difference in the plasticity of the affected circuitry.

Exploring the knowledge contained in neuroimages: statistical discriminant analysis and automatic segmentation of the most significant changes

OBJECTIVE

The aim of this article is to propose an integrated framework for extracting and describing patterns of disorders from medical images using a combination of linear discriminant analysis and active contour models.

METHODS

A multivariate statistical methodology was first used to identify the most discriminating hyperplane separating two groups of images (from healthy controls and patients with schizophrenia) contained in the input data. After this, the present work makes explicit the differences found by the multivariate statistical method by subtracting the discriminant models of controls and patients, weighted by the pooled variance between the two groups. A variational level-set technique was used to segment clusters of these differences. We obtain a label of each anatomical change using the Talairach atlas.

RESULTS

In this work all the data was analysed simultaneously rather than assuming a priori regions of interest. As a consequence of this, by using active contour models, we were able to obtain regions of interest that were emergent from the data. The results were evaluated using, as gold standard, well-known facts about the neuroanatomical changes related to schizophrenia. Most of the items in the gold standard was covered in our result set.

CONCLUSIONS

We argue that such investigation provides a suitable framework for characterising the high complexity of magnetic resonance images in schizophrenia as the results obtained indicate a high sensitivity rate with respect to the gold standard.

Selection of Reference Gene Expression in a Schizophrenia Brain Cohort

OBJECTIVE

In order to conduct postmortem human brain research into the neuropatho-logical basis of schizophrenia, it is critical to establish cohorts that are well-characterized and well-matched. The aim of the present study was therefore to determine if specimen characteristics including: diagnosis, age, postmortem interval (PMI), brain acidity (pH), and/or the agonal state of the subject at death related to RNA quality, and to determine the most appropriate reference gene mRNAs.

METHODS

A matched cohort was selected of 74 subjects (schizophrenia/schizoaffective disorder, n = 37; controls, n = 37). Middle frontal gyrus tissue was pulverized, tissue pH was measured, RNA isolated for cDNA from each case, and RNA integrity number (RIN) measurements were assessed. Using quantitative reverse transcription-polymerase chain reaction, nine housekeeper genes were measured and a geomean calculated per case in each diagnostic group.

RESULTS

The RINs were very good (mean = 7.3) and all nine housekeeper control genes were significantly correlated with RIN. Seven of nine housekeeper genes were also correlated with pH; two clinical variables, agonal state and duration of illness, did have an effect on some control mRNAs. No major impact of PMI or freezer time on housekeeper mRNAs was detected. The results show that people with schizophrenia had significantly less PPIA and SDHA mRNA and tended to have less GUSB and B2M mRNA, suggesting that these control genes may not be good candidates for normalization.

CONCLUSIONS

In the present cohort <10% variability in RINs was detected and the diagnostic groups were well matched overall. The cohort was adequately powered (0.80-0.90) to detect mRNA differences (25%) due to disease. The study suggests that multiple factors should be considered in mRNA expression studies of human brain tissues. When schizophrenia cases are adequately matched to control cases subtle differences in gene expression can be reliably detected.

Volumes of brain, grey and white matter and cerebrospinal fluid in schizophrenia in the Northern Finland 1966 Birth Cohort: an epidemiological approach to analysis

Magnetic resonance imaging (MRI) studies in schizophrenia have seldom involved a general population birth cohort or other epidemiological samples. We studied the Northern Finland 1966 Birth Cohort and identified all people with psychotic disorders. Along with an unaffected age-matched control sample (n = 100) from the cohort, 54 subjects with schizophrenia underwent MRI brain scan at age 33-35 years from which we defined volumes of whole brain, grey and white matter and intracranial cerebrospinal fluid (CSF). Whole brain, grey and white matter volumes were 2-3% smaller in the schizophrenia subjects, who showed a 7% increase in CSF volume. These volume changes were independent of the effects of gender, family history of psychosis, perinatal risks or age at onset of illness. Moreover, there was no evidence that the effects were due to particular subgroups of cases having very low or high values. Rather, there were linear trends in the associations between whole brain and grey matter volume measures and schizophrenia. Our study replicates the previous findings of brain volume differences in schizophrenia on a general population level.

Schizophrenia, brain disease and meta-analyses: integrating the pieces and testing Fusar-Poli's hypothesis

This paper aims to discuss and test the hypothesis raised by Fusar-Poli [Fusar-Poli P. Can neuroimaging prove that schizophrenia is a brain disease? A radical hypothesis. Medical Hypotheses in press, corrected proof] that "on the basis of the available imaging literature there is no consistent evidence to reject the radical and provocative hypothesis that schizophrenia is not a brain disease". To achieve this goal, all meta-analyses on 'fMRI and schizophrenia' published during the current decade and indexed in Pubmed were summarized, as much as some other useful information, e.g., meta-analyses on genetic risk factors. Our main conclusion is that the literature fully supports the hypothesis that schizophrenia is a syndrome (not a disease) associated with brain abnormalities, despite the fact that there is no singular and reductionist pathway from the nosographic entity (schizophrenia) to its causes. This irreducibility is due to the fact that the syndrome has more than one dimension (e.g., cognitive, psychotic and negative) and each of them is related to abnormalities in specific neuronal networks. A psychiatric diagnosis is a statistical procedure; these dimensions are not identically represented in each diagnosticated case and this explains the existence of more than one pattern of brain abnormalities related to schizophrenia. For example, chronification is associated with negativism while the first psychotic episode is not; in that sense, the same person living with schizophrenia may reveal different symptoms and fMRI patterns along the course of his life, and this is precisely what defines schizophrenia since the time when it was called Dementia Praecox (first by pick then by Kraepelin). It is notable that 100% of the collected meta-analyses on 'fMRI and schizophrenia' reveal positive findings. Moreover, all meta-analyses that found positive associations between schizophrenia and genetic risk factors have to do with genes (SNPs) especially activated in neuronal tissue of the central nervous system (CNS), suggesting that, to the extent these polymorphisms are related to schizophrenia's etiology, they are also related to abnormal brain activity.

Altered volume and hemispheric asymmetry of the superficial cortical layers in the schizophrenia planum temporale

In vivo structural MRI studies in schizophrenia auditory cerebral cortex have reported smaller volumes and, less consistently, have reported altered hemispheric asymmetry of volumes. We used autopsy brains from 19 schizophrenia and 18 nonpsychiatric male subjects to measure the volume asymmetry of the planum temporal (PT). We then used the most recently autopsied 11 schizophrenia and 10 nonpsychiatric brains to measure the widths and fractional volumes of the upper (I-III) and lower (IV-VI) layers. Measurements of whole PT gray matter volumes did not show significant changes in schizophrenia. Nevertheless, laminar volume measurements revealed that the upper layers of the PT comprise a smaller fraction of the total cortex in schizophrenia than in nonpsychiatric brains. Subdivision of the PT showed that this change was especially prominent caudally, beyond Heschl's gyrus, whereas similar but less pronounced changes were found in the rostral PT and Heschl's gyrus. Complementary measures of laminar widths showed that the altered fractional volume in the caudal left PT was due mainly to approximately 8% thinner upper layers. However, the caudal right PT had a different profile, with thicker lower layers and comparatively unchanged upper layers. Thus, in the present study, laminar measurements provided a more sensitive method for detecting changes than measurement of whole PT volumes. Besides findings in schizophrenia, our cortical width measurements revealed normal hemispheric asymmetries consistent with previous reports. In schizophrenia, the thinner upper layers of the caudal PT suggest disrupted corticocortical processing, possibly affecting the multisensory integration and phonetic processing of this region.

Schizophrenia, "Just the Facts": what we know in 2008 part 1: overview

For every disorder, there is a set of established findings and accepted constructs upon which further understanding is built. The concept of schizophrenia as a disease entity has been with us for a little more than a century, although descriptions resembling this condition predate this conceptualization. In 1988, for the inaugural issue of Schizophrenia Research, at the invitation of the founding editors, a senior researcher, since deceased (RJ Wyatt) published a summary of generally accepted ideas about the disorder, which he termed "the facts" of schizophrenia. Ten years later, in conjunction with two of the authors (MSK, RT), he compiled a more extensive set of "facts" for the purpose of evaluating conceptual models or theoretical constructs developed to understand the nature of schizophrenia. On the 20th anniversary of this journal, we update and substantially expand our effort to periodically summarize the current body of information about schizophrenia. We compile a body of seventy-seven representative major findings and group them in terms of their specific relevance to schizophrenia -- etiologies, pathophysiology, clinical manifestations, and treatments. We rate each such "fact" on a 0-3 scale for measures of reproducibility, whether primary to schizophrenia, and durability over time. We also pose one or more critical questions with reference to each "fact", answers to which might help better elucidate the meaning of that finding for our understanding of schizophrenia. We intend to follow this paper with the submission to the journal of a series of topic-specific articles, critically reviewing the evidence.

Brain structure and function changes during the development of schizophrenia: the evidence from studies of subjects at increased genetic risk

This article reviews the evidence for changes in the structure and function of the brain in subjects at high risk of schizophrenia for genetic reasons during the genesis of the disorder. We first highlight the structural and functional abnormalities in schizophrenia and whether any similar or lesser abnormalities are apparent in unaffected relatives. There is good evidence for subtle abnormalities of hippocampal and ventricle volume in relatives that are not as marked as the deficits in schizophrenia. In addition, the functional imaging literature suggests that prefrontal cortex function may deteriorate in those at risk who go on to develop the disorder. We then review the findings from longitudinal imaging studies of those at high risk, particularly the Edinburgh High-Risk Study, which report gray matter density reductions in medial and lateral temporal lobe because people develop schizophrenia, as well as functional abnormalities which precede onset. We conclude by quoting our own and others' imaging studies of the associations of genetic and other risk factors for schizophrenia, including stressful life events and cannabis use, which provide mechanistic examples of how these changes may be brought about. Overall, the literature supports the view that there are measurable changes in brain structure and function during the genesis of the disorder, which provide opportunities for early detection and intervention.

Neuroimaging and molecular genetics of schizophrenia: pathophysiological advances and therapeutic potential

There is impressive evidence for the involvement of several genetic risk factors in the aetiopathogenesis of schizophrenia. Most of these genes impact on neuropharmacological systems. Examining their relationship with brain imaging indices is arguably the best currently available method of examining these effects in vivo. In a sample of young, initially healthy people at high genetic risk of schizophrenia brain structure was measured with structural magnetic resonance imaging (sMRI) and brain function was indexed with neuropsychological tests and functional MRI. Regular detailed clinical assessments established whether subjects had developed psychotic symptoms and/or schizophrenia itself. The Catechol-O-Methyl Transferase (COMT) Val allele increased the risk of schizophrenia in this cohort in a dose-dependent manner. Subjects with this allele had reduced grey matter density in anterior cingulate cortex and increased fMRI activation in lateral prefrontal cortex and anterior and posterior cingulate. The risk allele in the Neuregulin 1 (NRG1) promoter region, on the other hand, was associated with the development of psychotic symptoms, decreased premorbid IQ and decreased activation of pre-frontal and temporal lobe regions. The NRG1 gene appears to be a risk factor for an extended or intermediate phenotype, while the COMT Val allele, which decreases the rate at which cortical dopamine is degraded compared to the Met allele, is associated with an increased risk of schizophrenia in subjects at increased familial risk. We provide examples of how these advances in our knowledge could lead to the development of new treatments for psychosis.

Progressive brain volume loss in schizophrenia over the course of the illness: evidence of maturational abnormalities in early adulthood

BACKGROUND

Considering the magnitude of the reported changes in brain volume over time in first-episode patients it is unlikely that these changes are constant over the life-span of the schizophrenic illness. Thus, one would expect the progression in brain volume change in schizophrenia to follow a more complex trajectory over time.

METHODS

Two magnetic resonance imaging brain scans were obtained over a 5-year interval of 96 schizophrenia patients and 113 healthy subjects between ages 16 to 56.

RESULTS

The trajectory of brain volume change differed between patients with schizophrenia and healthy individuals. Before the age of 45 years cerebral and gray matter loss and lateral ventricle increase were excessive in patients relative to controls, representing approximately the first 20 years of illness. Patients showed an excessive third ventricle volume increase over time. In addition, poor outcome patients showed more brain tissue loss during the follow-up interval than good outcome patients.

CONCLUSIONS

Cerebral (gray) matter volume loss in the patients was mainly characterized by the absence of the normal curved trajectory of volume change with age that was present in healthy subjects. Later in life, the degree of volume change in patients is similar to that observed with normal aging. Independently of age, larger brain volume changes appear clinically relevant.

Regional thinning of the cerebral cortex in schizophrenia: effects of diagnosis, age and antipsychotic medication

Morphological abnormalities of the cerebral cortex have been reported in a number of MRI-studies in schizophrenia. Uncertainty remains regarding cause, mechanism and progression of the alterations. It has been suggested that antipsychotic medication reduces total gray matter volumes, but results are inconsistent. In the present study differences in regional cortical thickness between 96 patients with a DSM-IV diagnosis of schizophrenia (n=81) or schizoaffective disorder (n=15) and 107 healthy subjects (mean age 42 years, range 17-57 years) were investigated using MRI and computer image analysis. Cortical thickness was estimated as the shortest distance between the gray/white matter border and the pial surface at numerous points across the entire cortical mantle. The influence of age and antipsychotic medication on variation in global and regional cortical thickness was explored. Thinner cortex among patients than controls was found in prefrontal and temporal regions of both hemispheres, while parietal and occipital regions were relatively spared. Some hemispheric specificity was noted, as regions of the prefrontal cortex were more affected in the right hemisphere, and regions of the temporal cortex in the left hemisphere. No significant interaction effect of age and diagnostic group on variation in cortical thickness was demonstrated. Among patients, dose or type of antipsychotic medication did not affect variation in cortical thickness. The results from this hitherto largest study on the topic show that prefrontal and temporal cortical thinning in patients with schizophrenia compared to controls is as pronounced in older as in younger subjects. The lack of significant influence from antipsychotic medication supports that regional cortical thinning is an inherent feature of the neurobiological disease process in schizophrenia.

Measuring brain volume by MR imaging: impact of measurement precision and natural variation on sample size requirements

BACKGROUND AND PURPOSE

To determine the sample size needed to provide adequate statistical power in studies of brain volume by MR imaging, we examined the precision and variability of measurements in healthy controls.

MATERIALS AND METHODS

A cohort of 52 people (mean age, 25.1 years) was examined at weeks 0 and 12 at 1.5 T. We used an axial multisection T1-weighted sequence and a contiguous proton-attenuation/T2-weighted sequence. Data were registered to a probabilistic brain atlas, and an automated atlas-based program was used to segment brain tissue by type and by lobe. We assumed that there were no changes in volume because there were no intervening neurologic events. Sample sizes required to yield 80% statistical power in detecting a significant difference in volume were calculated for various experimental designs, assuming a patient-control volume difference of 5% or 2%.

RESULTS

The precision of most measurements was excellent, but required sample sizes were larger than anticipated. If the goal was to detect a 5% difference in whole brain volume in a 2-sample cross-sectional study, the required sample was 73 patients and 73 controls because brain volume varies between individuals in a way that is not informative about disease effects. For a similar 2-sample longitudinal study, the required sample size was just 5 patients and 5 controls.

CONCLUSIONS

Our results argue strongly for longitudinal studies in preference to cross-sectional studies, especially as research budgets decline. Our findings also suggest that there may be more uncertainty than expected in published MR imaging brain volume studies.

2-D DIGE analysis of liver and red blood cells provides further evidence for oxidative stress in schizophrenia

The molecular disease mechanisms associated with schizophrenia remain largely unknown. Although primarily considered a disorder of the brain, there is evidence of a peripheral component to schizophrenia. In this study, we investigated liver tissue and red blood cells (RBC) from schizophrenia patients and controls using 2-D DIGE proteomic analysis. Fourteen proteins were significantly altered in liver samples from schizophrenia patients (n = 15) compared to healthy controls (n = 15). Analysis of the schizophrenia RBC proteome revealed 8 proteins significantly altered in samples from schizophrenia patients (13 antipsychotic-treated and 7 drug-naïve) compared to controls (n = 20). Six of the altered proteins in the liver and four of the altered RBC proteins are related to oxidative stress. These results corroborate our earlier findings obtained from post-mortem brain studies and substantiate our hypothesis that metabolic alterations leading to oxidative stress are linked to the schizophrenia disease process. Our results also suggest that at least some of the pathological processes associated with the schizophrenia disease process can be traced in peripheral tissue. If peripheral cells can be used as a disease surrogate, promising new investigative avenues could be explored.

Deconstructing psychosis with human brain imaging

This review synthesizes our current knowledge on the neurobiology of psychosis from an array of in vivo brain-imaging studies. The evidence base consists of hundreds of studies of patients with schizophrenia and fewer on bipolar disorder but rarely providing direct comparisons between the disorders or integration across methods. Replicated findings in schizophrenia include reduced whole-brain and hippocampal volume as potential vulnerability markers, with further progression at onset; reduced N-acetyl aspartate concentrations in hippocampus and prefrontal cortex; striatal dopamine D(2) receptors upregulation; and alteration in the relation between frontal and temporal activation. These findings are not attributable to medication effects but are of unclear specificity and may apply across the psychosis spectrum. There are consistently replicated associations of psychotic symptoms and cognitive impairment in both structural and functional imaging in schizophrenia but not, as yet, in bipolar disorder. Therefore, it would be premature to dispense with current diagnostic categories because direct comparisons among them are rare, insufficient studies have examined longitudinal changes, and long-term imaging outcome studies in first-episode psychosis have not yet been done. To address these issues and make neuroimaging "clinically relevant," investigators will need to standardize their approaches to data acquisition and analysis, and construct the necessary range of "human brain maps," to implement studies that are sufficiently powered to provide reliable data pertinent to deconstructing psychosis.

Primary visual cortex volume and total neuron number are reduced in schizophrenia

A number of studies that assessed the visual system in subjects with schizophrenia found impairments in early visual processing. Furthermore, functional imaging studies suggested changes in primary visual cortex activity in subjects with schizophrenia. Interestingly, postmortem studies of subjects with schizophrenia reported an increased density of neurons in the primary visual cortex (Brodmann's area 17, BA17). The observed changes in visual processing may thus be reflected in structural changes in the circuitry of BA17. To characterize the structural changes further we used stereological methods based on unbiased principles of sampling (Cavalieri's principle and the optical fractionator) to estimate the total volume and neuron number of BA17 in postmortem brains from 10 subjects with schizophrenia and 10 matched normal comparison subjects. In addition, we assessed cortical thickness. We found a marked and significant reduction in total neuron number (25%) and volume (22%) of BA17 in the schizophrenia group relative to the normal comparison subjects. In contrast, we found no changes in neuronal density or cortical thickness between the two groups. Subjects with schizophrenia therefore have a smaller cortical area allocated to primary visual perception. This finding suggests the existence of a schizophrenia-related change in cortical parcellation.

Meta-analysis in the assessment of treatment outcome

Randomized clinical trials provide the most reliable estimates of the benefits and harms of treatments. Limited sample sizes restrict their power to allow informative analyses of secondary outcomes, or patient subgroups. The overall results of trials only apply to the average patient and clinical application ignores the individual patient differences.Meta-analysis in the context of a systematic review can produce more precise estimates of effect by combining the results of primary studies. This is particularly valuable for investigating rare, but important outcomes such as suicide. Variations between the trial-specific results can be investigated by meta-regression. Individual patient data meta-analyses (IPDMAs) are potentially much more powerful designs because they allow analysis of patient-level variables. As more genetic factors are identified that might account for treatment variability between individuals, IPDMAs offer a powerful strategy that can be used on existing trial data sets. Despite practical difficulties, IPDMAs are increasingly being conducted.

Brain volume in first-episode schizophrenia: systematic review and meta-analysis of magnetic resonance imaging studies

BACKGROUND

Studies of people with schizophrenia assessed using magnetic resonance imaging (MRI) usually include patients with first-episode and chronic disease, yet brain abnormalities may be limited to those with chronic schizophrenia.

AIMS

To determine whether patients with a first episode of schizophrenia have characteristic brain abnormalities.

METHOD

Systematic review and meta-analysis of 66 papers comparing brain volume in patients with a first psychotic episode with volume in healthy controls.

RESULTS

A total of 52 cross-sectional studies included 1424 patients with a first psychotic episode; 16 longitudinal studies included 465 such patients. Meta-analysis suggests that whole brain and hippocampal volume are reduced (both P<0.0001) and that ventricular volume is increased (P<0.0001) in these patients relative to healthy controls.

CONCLUSIONS

Average volumetric changes are close to the limit of detection by MRI methods. It remains to be determined whether schizophrenia is a neurodegenerative process that begins at about the time of symptom onset, or whether it is better characterised as a neurodevelopmental process that produces abnormal brain volumes at an early age.

Investigating the neurodevelopmental hypothesis of schizophrenia

1. An optimal intra-uterine environment is critical for normal development of the brain. It is now thought that abnormal development in a compromised prenatal and/or early postnatal environment may be a risk factor for several neurological disorders that manifest postnatally, such as cerebral palsy, schizophrenia and epilepsy. 2. The present review examines some of the effects of abnormal prenatal brain development and focuses on one disorder that has been hypothesized to have, at least in part, an early neurodevelopmental aetiology: schizophrenia. 3. The key neuropathological alterations and changes in some of the neurotransmitter systems observed in patients with schizophrenia are reviewed. Evidence in support of a neurodevelopmental hypothesis for schizophrenia is examined. 4. A summary of the animal models that have been used by researchers in an attempt to elucidate the origins of this disorder is presented. Although no animal model of a complex human disorder is ever likely to emulate deficits in all aspects of structure and function observed in patients with a neuropsychiatric illness, our findings and those of others give support to the early neurodevelopmental hypothesis. 5. Thus, it is possible that an adverse event in utero disrupts normal brain development and creates a vulnerability of the brain that predisposes an already at-risk individual (e.g. genetic inheritance) to develop the disorder later in life.

The influence of chronic exposure to antipsychotic medications on brain size before and after tissue fixation: a comparison of haloperidol and olanzapine in macaque monkeys

It is unclear to what degree antipsychotic therapy confounds longitudinal imaging studies and post-mortem studies of subjects with schizophrenia. To investigate this problem, we developed a non-human primate model of chronic antipsychotic exposure. Three groups of six macaque monkeys each were exposed to oral haloperidol, olanzapine or sham for a 17-27 month period. The resulting plasma drug levels were comparable to those seen in subjects with schizophrenia treated with these medications. After the exposure, we observed an 8-11% reduction in mean fresh brain weights as well as left cerebrum fresh weights and volumes in both drug-treated groups compared to sham animals. The differences were observed across all major brain regions (frontal, parietal, temporal, occipital, and cerebellum), but appeared most robust in the frontal and parietal regions. Stereological analysis of the parietal region using Cavalieri's principle revealed similar volume reductions in both gray and white matter. In addition, we assessed the subsequent tissue shrinkage due to standard histological processing and found no evidence of differential shrinkage due to drug exposure. However, we observed a pronounced general shrinkage effect of approximately 20% and a highly significant variation in shrinkage across brain regions. In conclusion, chronic exposure of non-human primates to antipsychotics was associated with reduced brain volume. Antipsychotic medication may confound post-mortem studies and longitudinal imaging studies of subjects with schizophrenia that depend upon volumetric measures.

An animal model of chronic placental insufficiency: relevance to neurodevelopmental disorders including schizophrenia

Evidence now suggests that compromised prenatal brain development may increase the risk for the manifestation of neurological disorders such as schizophrenia. We present a guinea-pig model which mimics a condition of human pregnancy, namely, chronic placental insufficiency. Previously we reported that at term there are changes in the brains of these offspring which are relevant to changes in patients with schizophrenia. The aim of this study was to examine whether deficits in brain structure persist to adolescence and young adulthood (8-12 weeks) and have implications for behavioral function. Reduced uteroplacental blood flow was induced via unilateral ligation of the uterine artery at mid-gestation. The brain was examined in control and prenatally compromised (PC) animals 8 weeks after birth using morphometric and immunohistochemical markers. In a separate cohort of animals, prepulse inhibition (PPI) of the acoustic startle response was assessed at 4, 8 and 12 weeks of age. Brain neurochemistry was examined by determining the concentrations of dopamine and its metabolite, dihydroxyphenylacetic acid (DOPAC), at 12 weeks using high performance liquid chromatography. In PC animals compared with controls there was a reduction in brain weight, persistent enlargement of the lateral ventricles, a reduction in the volume of the basal ganglia and septal region and no evidence of gliosis. No differences were observed in concentration of catecholamines in any brain region examined. At 12, but not 4 or 8, weeks of age, PPI was reduced in PC animals compared with controls. The findings of reduced brain weight, ventriculomegaly, reduced basal ganglia volume and absence of astrogliosis in the PC guinea-pig brain at adolescence parallel some of the changes observed in patients with schizophrenia. The impairment of PPI is comparable to sensorimotor gating deficits observed in patients with schizophrenia. These results indicate that adverse prenatal conditions lead to long-term alterations in brain structure and function which resemble alterations seen in patients with schizophrenia and therefore support the early neurodevelopmental hypothesis of schizophrenia.

Schizophrenia genes, gene expression, and neuropathology: on the matter of their convergence

This review critically summarizes the neuropathology and genetics of schizophrenia, the relationship between them, and speculates on their functional convergence. The morphological correlates of schizophrenia are subtle, and range from a slight reduction in brain size to localized alterations in the morphology and molecular composition of specific neuronal, synaptic, and glial populations in the hippocampus, dorsolateral prefrontal cortex, and dorsal thalamus. These findings have fostered the view of schizophrenia as a disorder of connectivity and of the synapse. Although attractive, such concepts are vague, and differentiating primary events from epiphenomena has been difficult. A way forward is provided by the recent identification of several putative susceptibility genes (including neuregulin, dysbindin, COMT, DISC1, RGS4, GRM3, and G72). We discuss the evidence for these and other genes, along with what is known of their expression profiles and biological roles in brain and how these may be altered in schizophrenia. The evidence for several of the genes is now strong. However, for none, with the likely exception of COMT, has a causative allele or the mechanism by which it predisposes to schizophrenia been identified. Nevertheless, we speculate that the genes may all converge functionally upon schizophrenia risk via an influence upon synaptic plasticity and the development and stabilization of cortical microcircuitry. NMDA receptor-mediated glutamate transmission may be especially implicated, though there are also direct and indirect links to dopamine and GABA signalling. Hence, there is a correspondence between the putative roles of the genes at the molecular and synaptic levels and the existing understanding of the disorder at the neural systems level. Characterization of a core molecular pathway and a 'genetic cytoarchitecture' would be a profound advance in understanding schizophrenia, and may have equally significant therapeutic implications.

The distribution and morphology of prefrontal cortex pyramidal neurons identified using anti-neurofilament antibodies SMI32, N200 and FNP7. Normative data and a comparison in subjects with schizophrenia, bipolar disorder or major depression

Alterations in the density and size of pyramidal neurons in the prefrontal cortex have been described in schizophrenia and mood disorder. However, the changes are generally modest and have not always been replicated. We investigated the possibility that specific pyramidal neuron sub-populations, defined by their immunoreactivity with the anti-neurofilament antibodies SMI32, N200, and FNP7, are differentially affected in these disorders. First, we assessed the distribution and characteristics of pyramidal neurons labelled by the antibodies in the human dorsolateral prefrontal cortex (Brodmann areas 9, 32, 46), using single and double label immunocytochemistry and immunofluorescence. Three largely separate sub-populations of pyramidal neurons were identified, although with more substantial overlap between SMI32- and FNP7-positive neurons in lamina V. We then determined the density, size and shape of the three pyramidal neuron sub-populations in area 9 in patients with schizophrenia, bipolar disorder, or major depressive disorder, compared to controls (n=15 in each group). We found a lower density of lamina III N200-positive neurons in major depressive disorder than in schizophrenia or bipolar disorder. There were no other overall differences in neuronal density, or in neuronal size or shape, although a planned secondary analysis supported the previously reported decrease of neuronal size in lamina V in bipolar disorder. In summary, our study illustrates a conceptual and methodological approach which may be of value for investigating the differential neuropathological involvement of pyramidal neuron sub-populations. However, we found no clear evidence that the prefrontal neuropathology of schizophrenia or mood disorders preferentially affects SMI32-, N200- or FNP7-immunoreactive pyramidal neurons.