Magnetic resonance imaging findings in schizophrenia and atypical psychoses

Genome-wide association study of atypical psychosis

Atypical psychosis with a periodic course of exacerbation and features of major psychiatric disorders [schizophrenia (SZ) and bipolar disorder (BD)] has a long history in clinical psychiatry in Japan. Based upon the new criteria of atypical psychosis, a Genome-Wide Association Study (GWAS) was conducted to identify the risk gene or variants. The relationships between atypical psychosis, SZ and BD were then assessed using independent GWAS data. Forty-seven patients with solid criteria of atypical psychosis and 882 normal controls (NCs) were scanned using an Affymetrics 6.0 chip. GWAS SZ data (560 SZ cases and 548 NCs) and GWAS BD (107 cases with BD type 1 and 107 NCs) were compared using gene-based analysis. The most significant SNPs were detected around the CHN2/CPVL genes (rs245914, P = 1.6 × 10(-7)) , COL21A1 gene (rs12196860, P = 2.45 × 10(-7) ), and PYGL/TRIM9 genes (rs1959536, P = 7.73 × 10(-7) ), although none of the single-nucleotide polymorphisms exhibited genome-wide significance (P = 5 × 10(-8) ). One of the highest peaks was detected on the major histocompatibility complex region, where large SZ GWASs have previously disclosed an association. The gene-based analysis suggested significant enrichment between SZ and atypical psychosis (P = 0.01), but not BD. This study provides clues about the types of patient whose diagnosis lies between SZ and BD. Studies with larger samples are required to determine the causal variant.

A magnetic resonance imaging study of adhesio interthalamica in clinical subtypes of schizophrenia

CONTEXT

Previous studies have suggested subtle anatomical brain differences between patients with schizophrenia and healthy control subjects. However, the results are inconsistent and there is no study investigating the various subtypes of this mental disorder separately.

AIM

This study was conducted to compare the rate of absence of adhesio interthalamica (AI), a midline brain structure, between 3 subtypes of schizophrenia (paranoid, undifferentiated, and residual) and healthy control group, using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A total of 29 schizophrenia patients (21 men, 8 women) of three subtypes (paranoid, undifferentiated, and residual) were compared with 29 age- and gender-matched healthy controls. All subjects underwent 3-D brain MRI of full coronal series, 1.5-mm slices without interslice gaps. If the grey matter band connecting the thalami could not be identified on two or more coronal adjacent slices, the AI was considered as absent. The results were statistically analyzed.

RESULTS

The incidence rate of AI absence in patients with heterogenous subtypes of schizophrenia was was similar to control group, even when patients and controls of each gender were compared separately (P>0.05). In residual subtype, patients showed a significant priority in AI absence in comparison with the control group (P=0.041), which was not seen in paranoid and undifferentiated subtypes (P>0.05).

CONCLUSION

Residual subtype of schizophrenia is associated with higher rate of AI absence in this study. Subsequent studies are required to determine if the absence of AI is a cause of residual schizophrenia or an effect.

An association study of the signal transducer and activator of transcription 6 gene with periodic psychosis

OBJECTIVE

Recent molecular and genetic investigations have suggested that the current nosology for major psychiatric disorders, based on the "two-entities-principal" is not accurate with respect to clinical observations; patient groups that do not fit to the current operative diagnostic boundaries are readily identified. We aimed to perform an investigation of the signal transducer and activator of transcription 6 (STAT6) gene (located on 12q13), which has an important role in the apoptotic cascade, with patients suffering from periodic psychosis.

METHODS

Genetic association study has been employed for the current work. Investigated six tag-SNPs were chosen from Hapmap database.

RESULTS

Among six tag-SNPs, one marker (rs10783813), located in the STAT6 gene, showed modest association (p<0.05), although no marker or haplotype block showed association after Bonferroni's correction.

CONCLUSION

Future studies will reveal the etiological role of STAT6, and of other genes of the apoptotic cascade, in major psychiatric disorders.

Quantification of frontal and temporal lobe brain-imaging findings in schizophrenia: a meta-analysis

Magnetic resonance imaging (MRI) and positron emission tomography (PET) studies of the frontal and temporal lobes in schizophrenia patients and healthy controls have proliferated over the past 2 decades, but there have been relatively few attempts to quantify the evidence. In this meta-analytic review, 155 studies on frontal and temporal lobe neurobiology were synthesized, reflecting results from 4043 schizophrenia patients and 3977 normal controls. Cohen's d was used to quantify case-control differences, and moderator variable analysis indexed the relation of sample and imaging characteristics to the magnitude of these differences. Frontal metabolic and blood flow deficiencies in conjunction with cognitive activation tasks ("hypofrontality") emerged as the strongest body of evidence, demonstrating abnormalities that distinguish approximately half of schizophrenia patients from healthy people. Most case-control comparisons with structural and functional imaging yield small and in many cases unstable findings. Technical scanning parameters like slice thickness and magnet strength did not vary with case-control differences consistently across the meta-analyses. However, patient sample characteristics including sample size, handedness and gender composition emerged frequently as moderators of brain-imaging effect sizes.