Kang Sim

Subjective quality of life in first episode schizophrenia spectrum disorders with comorbid depression

Previous studies have reported high prevalence rates of depressive symptoms or syndromes in subjects with first episode psychosis, but data are lacking on the quality of life (QOL) in these subjects. This cross-sectional study seeks to compare the subjective QOL of these individuals with and without a comorbid depressive syndrome at baseline. Using the Structured Clinical Interview to Diagnose DSM IV-Axis I Disorders, the Scale to Assess Unawareness of Mental Disorders (SUMD), Positive and Negative Syndrome Scale (PANSS), Hamilton Rating Scale for Depression (HAM-D), and the World Health Organization Quality of Life-Bref Scale (WHOQOL-BREF), we evaluated 66 consecutive subjects with first episode schizophrenia spectrum disorders (schizophrenia, schizoaffective and schizophreniform disorders) in our Early Psychosis Intervention Program. We found that subjects with a comorbid depressive syndrome had greater awareness of their mental illness, its social consequences and treatment efficacy, but poorer overall QOL, especially in the physical, psychological health, social relationships and environmental domains. The poorer QOL in subjects with a comorbid depressive syndrome may be explained by the greater degree of insight in these patients and their attributing their troubles to poor health, unsatisfactory social support and negative environment. Alternative explanations are also possible, providing possible foci for psychological support and intervention.

Genetic association studies of glutamate, GABA and related genes in schizophrenia and bipolar disorder: A decade of advance

Schizophrenia (SZ) and bipolar disorder (BD) are debilitating neurobehavioural disorders likely influenced by genetic and non-genetic factors and which can be seen as complex disorders of synaptic neurotransmission. The glutamatergic and GABAergic neurotransmission systems have been implicated in both diseases and we have reviewed extensive literature over a decade for evidence to support the association of glutamate and GABA genes in SZ and BD. Candidate-gene based population and family association studies have implicated some ionotrophic glutamate receptor genes (GRIN1, GRIN2A, GRIN2B and GRIK3), metabotropic glutamate receptor genes (such as GRM3), the G72/G30 locus and GABAergic genes (e.g. GAD1 and GABRB2) in both illnesses to varying degrees, but further replication studies are needed to validate these results. There is at present no consensus on specific single nucleotide polymorphisms or haplotypes associated with the particular candidate gene loci in these illnesses. The genetic architecture of glutamate systems in bipolar disorder need to be better studied in view of recent data suggesting an overlap in the genetic aetiology of SZ and BD. There is a pressing need to integrate research platforms in genomics, epistatic models, proteomics, metabolomics, neuroimaging technology and translational studies in order to allow a more integrated understanding of glutamate and GABAergic signalling processes and aberrations in SZ and BD as well as their relationships with clinical presentations and treatment progress over time.

Antipsychotic drug prescription for schizophrenia in East Asia: rationale for change

Abstract  The purpose of this international collaborative study was to investigate the prescription patterns of antipsychotic drugs for schizophrenia in East Asia and to analyze factors that affect these patterns. Prescription patterns for patients admitted for treatment of schizophrenia were surveyed using a standardized protocol from six East‐Asian region/countries: China, Hong Kong, Japan, Korea, Singapore and Taiwan. Patients’ social and clinical characteristics, psychiatric symptoms, course of illness, and adverse effects of medications were systematically assessed and recorded. Prescriptions of the first‐ and second‐generation antipsychotic drugs were compared. A total of 2399 patients were recruited. The second‐generation drugs comprised 28.1% of all prescribed antipsychotics, and 46% of the antipsychotic prescriptions were in the context of polypharmacy. The mean dosage of antipsychotics for the whole sample was 675.3 + 645.1 mg chlorpromazine equivalents. Japan had a high frequency of prescribing high doses and polypharmacy; Singapore had a high utilization of depot injections while China had a higher prescription of clozapine. Using multiple logistic regression analysis, distinctions in the prescription patterns of antipsychotic drugs were found: first‐generation drugs were mainly for controlling aggressive behavior, while second‐generation drugs were targeted at the alleviation of positive, negative psychotic symptoms as well as disruptive behavior in schizophrenia. The present collaborative study highlighted differences in the prescription patterns, especially the under‐utilization of second‐generation antipsychotic drugs in East Asia. The pattern of antipsychotic medication use varied from country to country and is likely to be influenced by the prevailing health‐care system, the availability and cost of the drugs.

Longitudinal neuroimaging and neuropsychological changes in bipolar disorder patients: review of the evidence.

Longitudinal studies of biological domains in bipolar disorder (BD) are crucial in determining if such baseline changes are progressive. We reviewed reported studies of longitudinal brain structural/functional magnetic resonance imaging (MRI) and neuropsychological changes in BD through November 2012. Longitudinal brain structural MRI studies suggest cortical and subcortical abnormalities within networks subserving emotional regulation. There is evidence of neuroprogressive loss of gray matter volume in prefrontal and anterior cingulate cortex and the subgenual region, with less consistent findings in temporal and subcortical regions. Abnormal amygdala neurodevelopment is noted in adolescent onset BD and possible changes in hippocampus require further evaluation. The fewer reported longitudinal functional MRI studies suggest neurobiological changes in activation patterns involving fronto-limbic circuitry which relate to different illness phase and mood states. Early onset pediatric/adolescent BD may signify a more malignant course of illness in which extensive and executive neurocognitive deficits are found early and may persist, with some potential for improvement during remission and perhaps with treatment. Future studies should include larger samples, combine investigational modalities, incorporate genetic profiles, consider standardization of assessments and collaborative ventures across institutions, selection of more homogeneous subgroups and track neurobiological changes longer to clarify trajectories of changes.

White matter abnormalities in major depression: Evidence from post-mortem, neuroimaging and genetic studies

BACKGROUND Until more recently, most studies have examined the changes in brain gray matter in major depressive disorder (MDD) with less studies focusing on understanding white matter pathology in MDD. Studies of brain white matter volume changes, connectivity disruptions, as well as genetic factors affecting myelination can throw light on the nature of white matter abnormalities underpinning MDD. METHODS We review the state of the art understanding of white matter changes in MDD from the extant neuropathology, neuroimaging and neurogenetic studies. RESULTS Overall, data are sparse and mostly conducted in older patients with MDD. Post-mortem studies have highlighted pathology of white matter in prefrontal brain region in terms of decreased oligodendrocyte density, reductions in the expression of genes related to oligodendrocyte function, molecular changes in intercellular cell adhesion molecule (ICAM) expression levels and suggestion of possible mechanism of ischemia. Structural magnetic resonance imaging studies have revealed deep white matter hyperintensities which are associated with clinical severity, and treatment responsiveness. LIMITATIONS There is a particular dearth of genetic studies related to white matter pathology, studies of younger depressed subjects and specifically probing cortical and subcortical white matter pathology together in MDD. CONCLUSIONS Future investigations would want to study white matter changes in different cerebral regions and incorporate multimodal and longitudinal levels of examination in order to better grasp the neural basis of this condition.

Genome wide association studies (GWAS) and copy number variation (CNV) studies of the major psychoses: what have we learnt?

Schizophrenia (SZ) and bipolar disorder (BPD) have high heritabilities and are clinically and genetically complex. Genome wide association studies (GWAS) and studies of copy number variations (CNV) in SZ and BPD have allowed probing of their underlying genetic risks. In this systematic review, we assess extant genetic signals from published GWAS and CNV studies of SZ and BPD up till March 2011. Risk genes associated with SZ at genome wide significance level (p value<7.2 × 10(-8)) include zinc finger binding protein 804A (ZNF804A), major histocompatibility (MHC) region on chromosome 6, neurogranin (NRGN) and transcription factor 4 (TCF4). Risk genes associated with BPD include ankyrin 3, node of Ranvier (ANK3), calcium channel, voltage dependent, L type, alpha 1C subunit (CACNA1C), diacylglycerol kinase eta (DGKH), gene locus on chromosome 16p12, and polybromo-1 (PBRM1) and very recently neurocan gene (NCAN). Possible common genes underlying psychosis include ZNF804A, CACNA1C, NRGN and PBRM1. The CNV studies suggest that whilst CNVs are found in both SZ and BPD, the large deletions and duplications are more likely found in SZ rather than BPD. The validation of any genetic signal is likely confounded by genetic and phenotypic heterogeneities which are influenced by epistatic, epigenetic and gene-environment interactions. There is a pressing need to better integrate the multiple research platforms including systems biology computational models, genomics, cross disorder phenotyping studies, transcriptomics, proteomics, metabolomics, neuroimaging and clinical correlations in order to get us closer to a more enlightened understanding of the genetic and biological basis underlying these potentially crippling conditions.

Testing models of thalamic dysfunction in schizophrenia using neuroimaging

Summary.Neural models of schizophrenia have implicated the thalamus in deficits of early sensory processing and multimodal integration. We have reviewed the existing neuroimaging literature for evidence in support of models that propose abnormalities of thalamic relay nuclei, the mediodorsal thalamic nucleus, and large-scale cortico-thalamic networks. Thalamic volume reduction was found in some but not all studies. Studies of the early stages of schizophrenia suggest that thalamic volume reduction is present early in the course of the illness. Functional imaging studies have revealed task related abnormalities in several cortical and subcortical areas including the thalamus, suggesting a disruption of distributed thalamocortical networks. Chemical imaging studies have provided evidence for a loss of thalamic neuronal integrity in schizophrenia.There is, at present, inadequate data to support the hypothesis that schizophrenia is associated with abnormalities of sensory relay or association nuclei. There is evidence for a perturbation of cortico-thalamic networks, but further research is needed to elucidate the underlying mechanisms at the cellular and systems levels. The challenges ahead include better delineation of thalamic structure and function in vivo, the combination of genetic and imaging techniques to elucidate the genetic contributions to a thalamic phenotype of schizophrenia, and longitudinal studies of thalamic structure and function.

Regionally Specific White Matter Disruptions of Fornix and Cingulum in Schizophrenia

Limbic circuitry disruptions have been implicated in the psychopathology and cognitive deficits of schizophrenia, which may involve white matter disruptions of the major tracts of the limbic system, including the fornix and the cingulum. Our study aimed to investigate regionally specific abnormalities of the fornix and cingulum in schizophrenia using diffusion tensor imaging (DTI). We determined the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) profiles along the fornix and cingulum tracts using a fibertracking technique and a brain mapping algorithm, the large deformation diffeomorphic metric mapping (LDDMM), in the DTI scans of 33 patients with schizophrenia and 31 age-, gender-, and handedness-matched healthy controls. We found that patients with schizophrenia showed reduction in FA and increase in RD in bilateral fornix, and increase in RD in left anterior cingulum when compared to healthy controls. In addition, tract-based analysis revealed specific loci of these white matter differences in schizophrenia, that is, FA reductions and AD and RD increases occur in the region of the left fornix further from the hippocampus, FA reductions and RD increases occur in the rostral portion of the left anterior cingulum, and RD and AD increases occur in the anterior segment of the left middle cingulum. In patients with schizophrenia, decreased FA in the specific loci of the left fornix and increased AD in the right cingulum adjoining the hippocampus correlated with greater severity of psychotic symptoms. These findings support precise disruptions of limbic-cortical integrity in schizophrenia and disruption of these structural networks may contribute towards the neural basis underlying the syndrome of schizophrenia and clinical symptomatology.

Neurobiological evidence for thalamic, hippocampal and related glutamatergic abnormalities in bipolar disorder: a review and synthesis.

The thalamus, hippocampus and related glutamatergic neurotransmission pathways have been implicated in the pathophysiology of bipolar disorder. We have reviewed the existing literature over approximately two decades from 1990 to March 2008 for evidence that support structural, functional and chemical neuroimaging abnormalities as well as glutamatergic aberrations of the thalamus and the hippocampus in bipolar disorder. Available structural neuroimaging studies suggest a predominance of negative findings in terms of hippocampal and thalamic volumetric changes in bipolar disorder. Many functional neuroimaging studies however have found activation changes within the thalami, medial temporal lobes, prefrontal regions, and basal ganglia suggesting abnormal limbic-thalamo-cortical circuitry in bipolar disorder. The pattern of findings suggests abnormalities in the regulation of neuronal activity without fixed lesions in the thalamus or hippocampus. This could be related to factors such as cohort heterogeneity, image resolution and whether specific nuclei are examined, or that bipolar disorder is associated with greater neural inefficiency and greater reactivity to emotional stimuli. Chemical neuroimaging studies in bipolar disorder also implicate altered excitatory glutamate neurotransmission as well as cellular and membrane metabolism, especially pronounced within the hippocampus. Within the hippocampus, abnormalities of the ionotropic glutamate receptors were found in bipolar disorder with metabotropic glutamate receptors being relatively understudied. The few immunohistochemical studies performed on the thalamus also suggest the possibility of disturbances of glutamatergic neurotransmission involving intracellular signaling and trafficking processes in bipolar disorder. Overall, the emerging trends from these findings highlight the need for further research to unravel underlying neurobiological changes and clinical correlates of thalamic and hippocampal dysfunction in bipolar disorder.

White matter abnormalities in first-episode schizophrenia: a combined structural MRI and DTI study.

This study examined white matter volume change and integrity jointly in patients with first-episode schizophrenia using an empirically derived region of interest approach and novel Diffusion Tensor Imaging (DTI) geometric indices. Structural images from 103 individuals comprising of 39 patients with first-episode schizophrenia and 64 healthy controls were examined for regions of white matter volume change using voxel-based morphometry (VBM). These regions were then further interrogated for group differences employing geometric indices in addition to fractional anisotropy (FA).VBM analyses revealed that patients with first-episode schizophrenia had lower white matter volume in the right temporal-occipital region (p<0.005) corresponding to the inferior longitudinal fasciculus. Further analyses of diffusion anisotropy in the right temporal-occipital region revealed lower planar anisotropy, and higher linear anisotropy (p=0.012) in patients. FA in the implicated region was also found to be correlated with severity of delusions (r=0.47, p=0.004).We confirmed previous findings of lower white matter volume in the region of inferior longitudinal fasciculus. The presence of changes in geometric diffusion indices in the implicated white matter region suggested that pathophysiological processes which underlie cerebral white matter volume reduction may not be reflected by changes in FA. Further research is needed to better understand the nature of these white matter changes and its progression in schizophrenia over time.