Cognitive clustering in schizophrenia patients, their first-degree relatives and healthy subjects is associated with anterior cingulate cortex volume

Cognitive impairments are a core feature in schizophrenia patients (SCZ) and are also observed in first-degree relatives (FR) of SCZ. However, substantial variability in the impairments exists within and among SCZ, FR and healthy controls (HC). A cluster-analytic approach can group individuals based on profiles of traits and create more homogeneous groupings than predefined categories. Here, we investigated differences in the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychological battery (six subscales) among SCZ, unaffected FR and HC. To identify three homogeneous and meaningful cognitive groups regardless of categorical diagnoses (SCZ, FR and HC), cognitive clustering was performed, and differences in the BACS subscales among the cognitive cluster groups were investigated. Finally, the effects of diagnosis and cognition on brain volumes were examined. As expected, there were significant differences in the five BACS subscales among the diagnostic groups. The cluster-analytic approach generated three meaningful subgroups: (i) neuropsychologically normal, (ii) intermediate impaired and (iii) widespread impaired. The cognitive subgroups were mainly affected by the clinical diagnosis, and significant differences in all BACS subscales among clusters were found. The effects of the diagnosis and cognitive clusters on brain volumes overlapped in the frontal, temporal and limbic regions. Frontal and temporal volumes were mainly affected by the diagnosis, whereas the anterior cingulate cortex (ACC) volumes were affected by the additive effects of diagnosis and cognition. Our findings demonstrate a cognitive continuum among SCZ, FR and HC and support the concept of cognitive impairment and the related ACC volumes as intermediate phenotypes in SCZ.

Spatial and temporal expression patterns of genes around nine neuroticism-associated loci

Neuroticism is a high-order personality trait. Individuals with higher neuroticism have increased risks of various psychiatric disorders and physical health outcomes. Neuroticism is related to physiological differences in the brain. A recent genome-wide association study identified nine distinct genomic loci that contribute to neuroticism. Brain development and function depend on the precise regulation of gene expression, which is differentially regulated across brain regions and developmental stages. Using multiple publicly available human post-mortem databases, we investigated, in brain and non-brain tissues and across several developmental life stages, the spatial and temporal expression patterns of genes arising from nine neuroticism-associated loci. Functional gene-network analysis for neuroticism-associated genes was performed. The spatial expression analysis revealed that the nearest genes (GRIK3, SRP9, KLHL2, PTPRD, ELAVL2, CRHR1 and CELF4) from index single-nucleotide polymorphisms (SNPs) at the nine loci were intensively enriched in the brain compared with their representation in non-brain tissues (p<1.56×10^-3). The nearest genes associated with the glutamate receptor activity network consisted mainly of GRIK3 (FDR q=4.25×10^-2). The temporal expression analysis revealed that the neuroticism-associated genes were divided into three expression patterns: KLHL2, CELF4 and CRHR1 were preferentially expressed during postnatal stages; PTPRD, ELAVL2 and MFHAS1 were expressed during prenatal stages; and the other three genes were not expressed during specific life stages. These findings suggest that the glutamate network might be a target for investigating the neurobiological mechanisms underlying susceptibilities to higher neuroticism and several psychiatric disorders and that neuroticism is mediated by genes specifically expressed in the brain during several developmental stages.

Olfactory function in neuropsychiatric disorders

Recent clinical studies have identified olfactory dysfunction in patients with neuropsychiatric disorders. Although these studies showed differences in olfactory function between healthy individuals and neuropsychiatric patients, no studies have compared the differences in olfactory function among neuropsychiatric disorders. The aim of the present study was to investigate olfactory function among various neuropsychiatric disorders. Three-hundred and eighteen outpatients diagnosed according to the ICD-10 code participated in the study. Olfactory function was assessed using the Open Essence test. The differences in olfactory function among disorders were compared by analyses of (co-)variance. As expected, olfactory function was significantly affected by the age and marginally affected by the gender. We investigated the differences in olfactory function among patients with different neuropsychiatric disorders (F0-F9). Olfactory function significantly differed among the diagnostic groups. Post hoc analysis showed that patients with F0 had decreased olfactory function compared to patients from the other diagnostic groups. In particular, patients with Alzheimer's disease (AD) had significantly poorer olfactory function compared to patients with other neuropsychiatric disorders. There were no differences among the other groups. These findings suggest that patients with AD had poorer olfactory function compared not only to healthy subjects but also to patients with several other neuropsychiatric disorders.

Response to benzodiazepines and the clinical course in malignant catatonia associated with schizophrenia: A case report

BACKGROUND

Malignant catatonia (MC) is a disorder consisting of catatonic symptoms, hyperthermia, autonomic instability, and altered mental status. Neuroleptic malignant syndrome (NMS) caused by antipsychotics is considered a variant of MC. Benzodiazepine (BZD) medications are safe and effective treatments providing rapid relief from MC. This case study reports a detailed clinical course of a case of MC associated with schizophrenia initially diagnosed as NMS that responded successfully to BZDs but not to dantrolene.

CASE PRESENTATION

A 53-year-old man with schizophrenia was admitted to the psychiatric hospital because of excitement, monologue, muscle rigidity, and insomnia. In the 3 days before admission, the patient had discontinued his medications after his family member's death. He presented with hyperthermia, tachycardia, hypertension, excessive sweating, and an elevated serum creatine phosphokinase (CPK) level. On the basis of these features, he was suspected to have NMS. The patient was treated with dantrolene for 7 days without improvement despite having a normalized serum CPK level. The patient was transferred to our university hospital for an in-depth examination and treatment of his physical status. Infection and pulmonary embolism were excluded as possible causes. To treat his excitement and auditory hallucination, an intravenous drip (IVD) of haloperidol was initiated, but this treatment increased the patient's catatonic and psychotic symptoms, although his serum CPK level had remained within a normal range. As a result, the treatment was changed to diazepam. After an IVD of diazepam, the patient's symptoms rapidly improved, and the IVD was subsequently replaced with oral administration of lorazepam. Eventually, the patient was diagnosed with MC associated with schizophrenia. BZD therapy was dramatically effective.

CONCLUSION

Catatonia, MNS, and MC may be due to a common brain pathophysiology and these conditions may be in a spectrum, although uncertainty in the boundaries among conditions, and the BZD treatment may be useful. Most importantly, catatonia has not been described as a subtype of schizophrenia on the basis of the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria, and the medications for catatonia and schizophrenia are different. Antipsychotics are not effective in relieving catatonia, or they may induce NMS, whereas BZDs are effective for treating both MC and NMS.

Possible factors influencing the duration of hospital stay in patients with psychiatric disorders attempting suicide by jumping

BACKGROUND

Patients with psychiatric disorders have a high rate of suicide. The present study investigated factors influencing hospital stays for Japanese patients with psychiatric disorders attempting suicide by jumping.

METHODS

We diagnosed all suicide attempts (n = 113) by jumping based on the International Classification of Diseases 10th Revision (ICD-10) and investigated the mean hospital stays of patients with each diagnosis based on the ICD-10 code. We then analyzed differences in the demographic and clinical characteristics between the diagnostic groups to identify factors influencing the duration of hospital stay.

RESULTS

Patients diagnosed with schizophrenia (F2 code) were the most frequent (32.7%) of all diagnoses; therefore, we divided the diagnostic groups into schizophrenia group (n = 37) and other psychiatric diagnoses group (n = 76). The patients with schizophrenia showed a significantly longer hospital stay (125.7 ± 63.9 days) compared with the patients with other psychiatric diagnoses (83.6 ± 63.2) (β ± SE = 42.1 ± 12.7, p = 0.0013), whereas there was no difference in the jump height between the two groups (the average was the 3rd to 4th floor; p > 0.05). The number of injured parts, particularly lower-limb fractures, was significantly higher (p = 0.017) in patients with schizophrenia than in patients with other psychiatric diagnoses. The duration of psychiatric treatment in patients with schizophrenia were significantly longer (z = 3.4, p = 0.001) than in patients with other psychiatric diagnoses.

CONCLUSION

Our findings indicate that the number of injuries and the body parts injured in patients with schizophrenia are associated with a longer duration of hospital stay following a suicide attempt by jumping. The current use of antipsychotics and a longer duration of taking antipsychotics might contribute to the risk of bone fracture via hyperprolactinemia. Further cognitive impairment in patients with schizophrenia might prevent rehabilitation for the management of lower-limb fractures. From these results, we suggest that clinicians should monitor the level of prolactin and cognitive function in patients with schizophrenia in future studies on managing of lower-limb fractures.

Differences in social functioning among patients with major psychiatric disorders: Interpersonal communication is impaired in patients with schizophrenia and correlates with an increase in schizotypal traits

Impaired social functioning is a hallmark of major psychiatric disorders. The purpose of this study was to detect a disorder-specific factor of social dysfunction among patients with major psychiatric disorders (PSY), including schizophrenia (SCZ), bipolar disorder (BIP) and major depressive disorder (MDD). Social functioning was assessed in patients with SCZ (n=80), BIP (n=27) or MDD (n=29) and healthy controls (HC, n=68) using the Social Functioning Scale (SFS). Compared to HC, the SCZ, BIP and MDD patient groups showed lower total SFS scores. No differences in the total scores for social functioning were observed between patient groups. We next investigated seven subscales of the SFS among PSY and observed significant diagnostic effects on all subscales of the SFS. Notably, patients with SCZ have poorer interpersonal communication than patients with MDD. Furthermore, the poorer interpersonal communication score was significantly correlated with an increase in schizotypal personality traits, as assessed by the Schizotypal Personality Questionnaire (SPQ) in HC. Although there were no differences in overall social functioning among PSY, disorder-specific factors, such as interpersonal communication, were evident in SCZ. The correlation between poor interpersonal communication and the increase in schizotypal traits suggests that poor interpersonal communication may be an intermediate phenotype of SCZ.

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg=-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness.

Novel genetic loci underlying human intracranial volume identified through genome-wide association

Intracranial volume reflects the maximally attained brain size during development, and remains stable with loss of tissue in late life. It is highly heritable, but the underlying genes remain largely undetermined. In a genome-wide association study of 32,438 adults, we discovered five previously unknown loci for intracranial volume and confirmed two known signals. Four of the loci were also associated with adult human stature, but these remained associated with intracranial volume after adjusting for height. We found a high genetic correlation with child head circumference (ρgenetic = 0.748), which indicates a similar genetic background and allowed us to identify four additional loci through meta-analysis (Ncombined = 37,345). Variants for intracranial volume were also related to childhood and adult cognitive function, and Parkinson's disease, and were enriched near genes involved in growth pathways, including PI3K-AKT signaling. These findings identify the biological underpinnings of intracranial volume and their link to physiological and pathological traits.

Pharmacogenomic Study of Clozapine-Induced Agranulocytosis/Granulocytopenia in a Japanese Population

BACKGROUND

Clozapine-induced agranulocytosis (CIA)/clozapine-induced granulocytopenia (CIG) (CIAG) is a life-threatening event for schizophrenic subjects treated with clozapine.

METHODS

To examine the genetic factor for CIAG, a genome-wide pharmacogenomic analysis was conducted using 50 subjects with CIAG and 2905 control subjects.

RESULTS

We identified a significant association in the human leukocyte antigen (HLA) region (rs1800625, p = 3.46 × 10(-9), odds ratio [OR] = 3.8); therefore, subsequent HLA typing was performed. We detected a significant association of HLA-B*59:01 with CIAG (p = 3.81 × 10(-8), OR = 10.7) and confirmed this association by comparing with an independent clozapine-tolerant control group (n = 380, p = 2.97 × 10(-5), OR = 6.3). As we observed that the OR of CIA (OR: 9.3~15.8) was approximately double that in CIG (OR: 4.4~7.4), we hypothesized that the CIG subjects were a mixed population of those who potentially would develop CIA and those who would not develop CIA (non-CIA). This hypothesis allowed the proportion of the CIG who were non-CIA to be calculated, enabling us to estimate the positive predictive value of the nonrisk allele on non-CIA in CIG subjects. Assuming this model, we estimated that 1) ~50% of CIG subjects would be non-CIA; and 2) ~60% of the CIG subjects without the risk allele would be non-CIA and therefore not expected to develop CIA.

CONCLUSIONS

Our results suggest that HLA-B*59:01 is a risk factor for CIAG in the Japanese population. Furthermore, if our model is true, the results suggest that rechallenging certain CIG subjects with clozapine may not be always contraindicated.

Abnormal asymmetries in subcortical brain volume in schizophrenia

Subcortical structures, which include the basal ganglia and parts of the limbic system, have key roles in learning, motor control and emotion, but also contribute to higher-order executive functions. Prior studies have reported volumetric alterations in subcortical regions in schizophrenia. Reported results have sometimes been heterogeneous, and few large-scale investigations have been conducted. Moreover, few large-scale studies have assessed asymmetries of subcortical volumes in schizophrenia. Here, as a work completely independent of a study performed by the ENIGMA consortium, we conducted a large-scale multisite study of subcortical volumetric differences between patients with schizophrenia and controls. We also explored the laterality of subcortical regions to identify characteristic similarities and differences between them. T1-weighted images from 1680 healthy individuals and 884 patients with schizophrenia, obtained with 15 imaging protocols at 11 sites, were processed with FreeSurfer. Group differences were calculated for each protocol and meta-analyzed. Compared with controls, patients with schizophrenia demonstrated smaller bilateral hippocampus, amygdala, thalamus and accumbens volumes as well as intracranial volume, but larger bilateral caudate, putamen, pallidum and lateral ventricle volumes. We replicated the rank order of effect sizes for subcortical volumetric changes in schizophrenia reported by the ENIGMA consortium. Further, we revealed leftward asymmetry for thalamus, lateral ventricle, caudate and putamen volumes, and rightward asymmetry for amygdala and hippocampal volumes in both controls and patients with schizophrenia. Also, we demonstrated a schizophrenia-specific leftward asymmetry for pallidum volume. These findings suggest the possibility of aberrant laterality in neural pathways and connectivity patterns related to the pallidum in schizophrenia.

The Five-Factor Model personality traits in schizophrenia: A meta-analysis

Personality is one of important factors in the pathogenesis of schizophrenia because it affects patients' symptoms, cognition and social functioning. Several studies have reported specific personality traits in patients with schizophrenia compared with healthy subjects. However, the results were inconsistent among studies. The NEO Five-Factor Inventory (NEO-FFI) measures five personality traits: Neuroticism (N), Extraversion (E), Openness (O), Agreeableness (A) and Conscientiousness (C). Here, we performed a meta-analysis of these personality traits assessed by the NEO-FFI in 460 patients with schizophrenia and 486 healthy subjects from the published literature and investigated possible associations between schizophrenia and these traits. There was no publication bias for any traits. Because we found evidence of significant heterogeneity in all traits among the studies, we applied a random-effect model to perform the meta-analysis. Patients with schizophrenia showed a higher score for N and lower scores for E, O, A and C compared with healthy subjects. The effect sizes of these personality traits ranged from moderate to large. These differences were not affected by possible moderator factors, such as gender distribution and mean age in each study, expect for gender effect for A. These findings suggest that patients with schizophrenia have a different personality profile compared with healthy subjects.

A human-specific AS3MT isoform and BORCS7 are molecular risk factors in the 10q24.32 schizophrenia-associated locus

Genome-wide association studies (GWASs) have reported many single nucleotide polymorphisms (SNPs) associated with psychiatric disorders, but knowledge is lacking regarding molecular mechanisms. Here we show that risk alleles spanning multiple genes across the 10q24.32 schizophrenia-related locus are associated in the human brain selectively with an increase in the expression of both BLOC-1 related complex subunit 7 (BORCS7) and a previously uncharacterized, human-specific arsenite methyltransferase (AS3MT) isoform (AS3MT(d2d3)), which lacks arsenite methyltransferase activity and is more abundant in individuals with schizophrenia than in controls. Conditional-expression analysis suggests that BORCS7 and AS3MT(d2d3) signals are largely independent. GWAS risk SNPs across this region are linked with a variable number tandem repeat (VNTR) polymorphism in the first exon of AS3MT that is associated with the expression of AS3MT(d2d3) in samples from both Caucasians and African Americans. The VNTR genotype predicts promoter activity in luciferase assays, as well as DNA methylation within the AS3MT gene. Both AS3MT(d2d3) and BORCS7 are expressed in adult human neurons and astrocytes, and they are upregulated during human stem cell differentiation toward neuronal fates. Our results provide a molecular explanation for the prominent 10q24.32 locus association, including a novel and evolutionarily recent protein that is involved in early brain development and confers risk for psychiatric illness.

Structural alterations of the superior temporal gyrus in schizophrenia: Detailed subregional differences

BACKGROUND

Reduced gray matter volumes in the superior temporal gyrus (STG) have been reported in patients with schizophrenia. Such volumetric abnormalities might denote alterations in cortical thickness, surface area, local gyrification or all of these factors. The STG can be anatomically divided into five subregions using automatic parcellation in FreeSurfer: lateral aspect of the STG, anterior transverse temporal gyrus of Heschl gyrus (HG), planum polare (PP) of the STG, planum temporale (PT) of the STG and transverse temporal sulcus.

METHODS

We acquired magnetic resonance imaging (MRI) 3T scans from 40 age- and sex-matched patients with schizophrenia and 40 healthy subjects, and the scans were automatically processed using FreeSurfer. General linear models were used to assess group differences in regional volumes and detailed thickness, surface area and local gyrification.

RESULTS

As expected, patients with schizophrenia had significantly smaller bilateral STG volumes than healthy subjects. Of the five subregions in the STG, patients with schizophrenia showed significantly and marginally reduced volumes in the lateral aspect of the STG and PT of the STG bilaterally compared with healthy subjects. The volumetric alteration in bilateral lateral STG was derived from both the cortical thickness and surface area but not local gyrification. There was no significant laterality of the alteration in the lateral STG between patients and controls and no correlation among the structures and clinical characteristics.

CONCLUSIONS

These findings suggest that of five anatomical subregions in the STG, the lateral STG is one of the most meaningful regions for brain pathophysiology in schizophrenia.

A comprehensive meta-analysis of ZNF804A SNPs in the risk of schizophrenia among Asian populations

Common variants in ZNF804A increased the risk of schizophrenia (and bipolar disorder), with low effect sizes in Europeans, which is in line with the polygenic nature of the illnesses, and implies that genetic analyses in small samples may not be sufficient to detect stable results. This notion is supported by the inconsistent replications of ZNF804A variations among individual small Asian samples, indicating the absence of definitive conclusions in this population. We collected psychiatric phenotypic and genetic data from Asian genome-wide association (GWA) and individual replication studies, which include up to 13,452 cases, 17,826 healthy controls, and 680 families, that is, the largest-scale study on ZNF804A in Asian populations to date. The European GWAS risk single nucleotide polymorphism (SNP) rs1344706 was nominally associated with schizophrenia in these Asian samples (one-tailed P = 4.26 × 10(-2) , odds ratio [OR] = 1.048), and the association was further strengthened when bipolar disorder data was also included (one-tailed P = 1.85 × 10(-2) , OR = 1.057). Besides, a non-synonymous SNP rs1366842 in the exon 4 of ZNF804A was also associated with schizophrenia (P = 9.96 × 10(-3) , OR = 1.095). We additionally analyzed other 163 SNPs covering ZNF804A region, but none of them showed any evidence of association. Though the two SNPs did not remain significant if we applied multiple corrections, our analysis should be interpreted as a primary replication study with in prior hypothesis, and rs1344706 and rs1366842 might confer a small but detectable risk of schizophrenia (and bipolar disorder) in Asians. Moreover, the current data suggest the necessity of replication analyses in a large enough scale samples.

Predicting employment status and subjective quality of life in patients with schizophrenia

Although impaired social functioning, particularly poor employment status, is a cardinal feature of patients with schizophrenia and leads to decreased quality of life (QOL), few studies have addressed the relationship between these two clinical issues. The aim of this study was to determine whether employment status predicts subjective QOL and to evaluate a model in which functional capacity mediates the relationship between general cognitive performance and employment status. Ninety-three patients with schizophrenia were administered a comprehensive battery of cognitive tests, the UCSD Performance-based Skills Assessment-Brief version (UPSA-B), the Social Functioning Scale (SFS), and the Subjective Quality of Life Scale (SQLS). First, we evaluated a model for predicting the employment/occupation subscale score of the SFS using path analysis, and the model fitted well (χ2 (4) = 3.6, p = 0.46; CFI = 1.0; RMSEA < 0.001, with 90% CIs: 0-0.152). Employment status was predicted by negative symptoms and functional capacity, which was in turn predicted by general cognitive performance. Second, we added subjective QOL to this model. In a final path model, QOL was predicted by negative symptoms and employment status. This model also satisfied good fit criteria (χ2 (7) = 10.3, p = 0.17; CFI = 0.987; RMSEA = 0.072, with 90% CIs: 0-0.159). The UPSA-B and SFS scores were moderately correlated with most measures of cognitive performance. These results support the notion that better employment status enhances subjective QOL in patients with schizophrenia.

The Piccolo Intronic Single Nucleotide Polymorphism rs13438494 Regulates Dopamine and Serotonin Uptake and Shows Associations with Dependence-Like Behavior in Genomic Association Study

Piccolo (PCLO) inhibits methamphetamine-induced neuropharmacological effects via modulation of dopamine (DA) uptake and regulation of the transport of synaptic vesicles in neuronal cells. Clinical studies have recently suggested that the single nucleotide polymorphism (SNP) rs13438494 in the intron 24 of the PCLO gene is associated with psychiatric disorder, in the meta-analysis of GWAS. Therefore, in this study, we attempted to evaluate the possible role of the PCLO SNP in the mechanisms of uptake of monoamines. To characterize rs13438494 in the PCLO gene, we constructed plasmids carrying either the C or A allele of the SNP and transiently transfected them into SH-SY5Y cells to analyze genetic effects on the splicing of PCLO mRNA. The C and A allele constructs produced different composition of the transcripts, indicating that the intronic SNP does affect the splicing pattern. We also transfected DA and serotonin (5-hydroxytryptamine; 5- HT) transporters into cells and analyzed their uptakes to elucidate the association to psychiatric disorders. In the cells transfected with the C allele, both the DA and 5-HT uptake were enhanced compared to the A allele. We also conducted a clinical study, in order to clarify the genetic associations. PCLO rs13438494 exhibits a relationship with the symptoms of drug dependence or related parameters, such as the age of first exposure to methamphetamine, eating disorders, tobacco dependence and fentanyl requirement. Our findings suggest that rs13438494 is associated with drug abuse and contributes to the pathogenesis of psychiatric disorders via modulation of neurotransmitter turnover.

Emerging roles of ARHGAP33 in intracellular trafficking of TrkB and pathophysiology of neuropsychiatric disorders

Intracellular trafficking of receptor proteins is essential for neurons to detect various extracellular factors during the formation and refinement of neural circuits. However, the precise mechanisms underlying the trafficking of neurotrophin receptors to synapses remain elusive. Here, we demonstrate that a brain-enriched sorting nexin, ARHGAP33, is a new type of regulator for the intracellular trafficking of TrkB, a high-affinity receptor for brain-derived neurotrophic factor. ARHGAP33 knockout (KO) mice exhibit reduced expression of synaptic TrkB, impaired spine development and neuropsychiatric disorder-related behavioural abnormalities. These deficits are rescued by specific pharmacological enhancement of TrkB signalling in ARHGAP33 KO mice. Mechanistically, ARHGAP33 interacts with SORT1 to cooperatively regulate TrkB trafficking. Human ARHGAP33 is associated with brain phenotypes and reduced SORT1 expression is found in patients with schizophrenia. We propose that ARHGAP33/SORT1-mediated TrkB trafficking is essential for synapse development and that the dysfunction of this mechanism may be a new molecular pathology of neuropsychiatric disorders.

The molecular mechanisms of neurotrophin receptor trafficking are only partially understood. Here the authors show that ARHGAP33 interacts with SORT1 to regulate TrkB trafficking, the dysfunction of which impairs synapse development and leads to schizophrenia-related behavioural abnormalities in mice.

Sensory cognitive abnormalities of pain in autism spectrum disorder: a case-control study

BACKGROUND

The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) recently included sensory processing abnormalities in the diagnostic criteria for individuals with autism spectrum disorder (ASD). However, there is no standard method for evaluating sensory abnormalities in individuals with ASD.

METHODS

Fifteen individuals with ASD and 15 age- and sex-matched controls were enrolled in this study. We compared objective pain sensitivity by measuring the pain detection threshold and pain tolerance to three different stimuli (electricity, heat, and cold). Then, we compared both subjective pain sensitivity, assessed by the visual analog scale (VAS), and quality of pain, assessed by the short-form McGill Pain Questionnaire (SF-MPQ), to determine the maximum tolerable pain intensities of each stimulation.

RESULTS

The pain detection threshold and pain tolerance of individuals with ASD were not impaired, indicating that there were no differences in the somatic perception of pain between groups. However, individuals with ASD were hyposensitive to subjective pain intensity compared to controls (VAS; electrical: p = 0.044, cold: p = 0.011, heat: p = 0.042) and hyposensitive to affective aspects of pain sensitivity (SF-MPQ; electrical: p = 0.0071, cold: p = 0.042).

CONCLUSIONS

Our results suggest that the cognitive pathways for pain processing are impaired in ASD and, furthermore, that our methodology can be used to assess pain sensitivity in individuals with ASD. Further investigations into sensory abnormalities in individuals with ASD are needed to clarify the pathophysiologic processes that may alter sensory processing in this disorder.

Imaging genetics and psychiatric disorders

Imaging genetics is an integrated research method that uses neuroimaging and genetics to assess the impact of genetic variation on brain function and structure. Imaging genetics is both a tool for the discovery of risk genes for psychiatric disorders and a strategy for characterizing the neural systems affected by risk gene variants to elucidate quantitative and mechanistic aspects of brain function implicated in psychiatric disease. Early studies of imaging genetics included association analyses between brain morphology and single nucleotide polymorphisms whose function is well known, such as catechol-Omethyltransferase (COMT) and brain-derived neurotrophic factor (BDNF). GWAS of psychiatric disorders have identified genes with unknown functions, such as ZNF804A, and imaging genetics has been used to investigate clues of the biological function of these genes. The difficulty in replicating the findings of studies with small sample sizes has motivated the creation of largescale collaborative consortiums, such as ENIGMA, CHARGE and IMAGEN, to collect thousands of images. In a genome-wide association study, the ENIGMA consortium successfully identified common variants in the genome associated with hippocampal volume at 12q24, and the CHARGE consortium replicated this finding. The new era of imaging genetics has just begun, and the next challenge we face is the discovery of small effect size signals from large data sets obtained from genetics and neuroimaging. New methods and technologies for data reduction with appropriate statistical thresholds, such as polygenic analysis and parallel independent component analysis (ICA), are warranted. Future advances in imaging genetics will aid in the discovery of genes and provide mechanistic insight into psychiatric disorders.

Assessment of a multi-assay biological diagnostic test for mood disorders in a Japanese population

The current diagnostic tests for mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD), have limitations. Inflammatory markers, growth factors, and oxidative stress markers are involved in the pathophysiology of mood disorders. A multi-assay biological diagnostic test combining these biomarkers might improve diagnostic efficiency. The plasma levels of soluble tumor necrosis factor receptor 2 (sTNFR2), epidermal growth factor (EGF), and myeloperoxidase were measured in 40 MDD patients, 40 BD patients and 40 controls in a Japanese population. We also investigated the plasma levels of these markers in 40 patients with schizophrenia to determine the utility of these markers in differential diagnosis. The plasma levels of sTNFR2 were significantly higher in BD and schizophrenia patients than in controls. The plasma levels of EGF and myeloperoxidase were significantly higher in patients with BD than in controls. The correct classification rate obtained from discriminant analysis with sTNFR2 and EGF between controls and mood disorders was 69.2%, with a sensitivity and specificity of 62.5% and 82.5%, respectively. The correct classification rate obtained from discriminant analysis with sTNFR2 and EGF between controls and BD was 85.0%, with a sensitivity and specificity of 77.6% and 92.5%, respectively. Our results suggest that sTNFR2 and EGF could be biological markers of BD. Further studies are needed to determine the utility of these markers in diagnostic tests for mood disorders.

Whole-exome sequencing and neurite outgrowth analysis in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex group of clinically heterogeneous neurodevelopmental disorders with unclear etiology and pathogenesis. Genetic studies have identified numerous candidate genetic variants, including de novo mutated ASD-associated genes; however, the function of these de novo mutated genes remains unclear despite extensive bioinformatics resources. Accordingly, it is not easy to assign priorities to numerous candidate ASD-associated genes for further biological analysis. Here we developed a convenient system for identifying an experimental evidence-based annotation of candidate ASD-associated genes. We performed trio-based whole-exome sequencing in 30 sporadic cases of ASD and identified 37 genes with de novo single-nucleotide variations (SNVs). Among them, 5 of those 37 genes, POGZ, PLEKHA4, PCNX, PRKD2 and HERC1, have been previously reported as genes with de novo SNVs in ASD; and consultation with in silico databases showed that only HERC1 might be involved in neural function. To examine whether the identified gene products are involved in neural functions, we performed small hairpin RNA-based assays using neuroblastoma cell lines to assess neurite development. Knockdown of 8 out of the 14 examined genes significantly decreased neurite development (P<0.05, one-way analysis of variance), which was significantly higher than the number expected from gene ontology databases (P=0.010, Fisher's exact test). Our screening system may be valuable for identifying the neural functions of candidate ASD-associated genes for further analysis and a substantial portion of these genes with de novo SNVs might have roles in neuronal systems, although further detailed analysis might eliminate false positive genes from identified candidate ASD genes.