Resting-state functional connectivity correlates of antipsychotic treatment in unmedicated schizophrenia

BACKGROUND

Antipsychotics may modulate the resting state functional connectivity(rsFC) to improve clinical symptoms in schizophrenia(Sz). Existing literature has potential confounders like past medication effects and evaluating preselected regions/networks. We aimed to evaluate connectivity pattern changes with antipsychotics in unmedicated Sz using Multivariate pattern analysis(MVPA), a data-driven technique for whole-brain connectome analysis.

METHODS

Forty-seven unmedicated patients with Sz(DSM-IV-TR) underwent clinical evaluation and neuroimaging at baseline and after 3-months of antipsychotic treatment. Resting-state functional MRI was analysed using group-MVPA to derive 5-components. The brain region with significant connectivity pattern changes with antipsychotics was identified, and post-hoc seed-to-voxel analysis was performed to identify connectivity changes and their association with symptom changes.

RESULTS

Connectome-MVPA analysis revealed the connectivity pattern of a cluster localised to left anterior cingulate and paracingulate gyri (ACC/PCG) (peak coordinates:x = -04,y = +30,z = +26;k = 12;cluster-p_FWE=0.002) to differ significantly after antipsychotics. Specifically, its connections with clusters of precuneus/posterior cingulate cortex(PCC) and left inferior temporal gyrus(ITG) correlated with improvement in positive and negative symptoms scores, respectively.

CONCLUSION

ACC/PCG, a hub of the default mode network, seems to mediate the antipsychotic effects in unmedicated Sz. Evaluating causality models with data from randomised controlled design using the MVPA approach would further enhance our understanding of therapeutic connectomics in Sz.

Analyzing biomarker discovery: Estimating the reproducibility of biomarker sets

Many researchers try to understand a biological condition by identifying biomarkers. This is typically done using univariate hypothesis testing over a labeled dataset, declaring a feature to be a biomarker if there is a significant statistical difference between its values for the subjects with different outcomes. However, such sets of proposed biomarkers are often not reproducible – subsequent studies often fail to identify the same sets. Indeed, there is often only a very small overlap between the biomarkers proposed in pairs of related studies that explore the same phenotypes over the same distribution of subjects. This paper first defines the Reproducibility Score for a labeled dataset as a measure (taking values between 0 and 1) of the reproducibility of the results produced by a specified fixed biomarker discovery process for a given distribution of subjects. We then provide ways to reliably estimate this score by defining algorithms that produce an over-bound and an under-bound for this score for a given dataset and biomarker discovery process, for the case of univariate hypothesis testing on dichotomous groups. We confirm that these approximations are meaningful by providing empirical results on a large number of datasets and show that these predictions match known reproducibility results. To encourage others to apply this technique to analyze their biomarker sets, we have also created a publicly available website, https://biomarker.shinyapps.io/BiomarkerReprod/, that produces these Reproducibility Score approximations for any given dataset (with continuous or discrete features and binary class labels).

Factors associated with SARS-CoV-2 test positivity in long-term care homes: A population-based cohort analysis using machine learning

BACKGROUND

SARS-Cov-2 infection rates are high among residents of long-term care (LTC) homes. We used machine learning to identify resident and community characteristics predictive of SARS-Cov-2 infection.

METHODS

We linked 26 population-based health and administrative databases to identify the population of all LTC residents tested for SARS-Cov-2 infection in Ontario, Canada. Using ensemble-based algorithms, we examined 484 factors, including individual-level demographics, healthcare use, comorbidities, functional status, and laboratory results; and community-level characteristics to identify factors predictive of infection. Analyses were performed separately for January to April (early wave 1) and May to August (late wave 1).

FINDINGS

Among 80,784 LTC residents, 64,757 (80.2%) were tested for SARS-Cov-2 (median age 86 (78-91) years, 30.6% male), of whom 10.2% of 33,519 and 5.2% of 31,238 tested positive in early and late wave 1, respectively. In the late phase (when restriction of visitors, closure of communal spaces, and universal masking in LTC were routine), regional-level characteristics comprised 33 of the top 50 factors associated with testing positive, while laboratory values and comorbidities were also predictive. The c-index of the final model was 0.934, and sensitivity was 0.887. In the highest versus lowest risk quartiles, the odds ratio for infection was 114.3 (95% CI 38.6-557.3). LTC-related geographic variations existed in the distribution of observed infection rates and the proportion of residents at highest risk.

INTERPRETATION

Machine learning informed evaluation of predicted and observed risks of SARS-CoV-2 infection at the resident and LTC levels, and may inform initiatives to improve care quality in this setting.

FUNDING

Funded by a Canadian Institutes of Health Research, COVID-19 Rapid Research Funding Opportunity grant (# VR4 172736) and a Peter Munk Cardiac Centre Innovation Grant. Dr. D. Lee is the Ted Rogers Chair in Heart Function Outcomes, University Health Network, University of Toronto. Dr. Austin is supported by a Mid-Career investigator award from the Heart and Stroke Foundation. Dr. McAlister is supported by an Alberta Health Services Chair in Cardiovascular Outcomes Research. Dr. Kaul is the CIHR Sex and Gender Science Chair and the Heart & Stroke Chair in Cardiovascular Research. Dr. Rochon holds the RTO/ERO Chair in Geriatric Medicine from the University of Toronto. Dr. B. Wang holds a CIFAR AI chair at the Vector Institute.

Predictors of mortality among long-term care residents with SARS-CoV-2 infection

BACKGROUND

While individuals living in long-term care (LTC) homes have experienced adverse outcomes of SARS-CoV-2 infection, few studies have examined a broad range of predictors of 30-day mortality in this population.

METHODS

We studied residents living in LTC homes in Ontario, Canada, who underwent PCR testing for SARS-CoV-2 infection from January 1 to August 31, 2020, and examined predictors of all-cause death within 30 days after a positive test for SARS-CoV-2. We examined a broad range of risk factor categories including demographics, comorbidities, functional status, laboratory tests, and characteristics of the LTC facility and surrounding community were examined. In total, 304 potential predictors were evaluated for their association with mortality using machine learning (Random Forest).

RESULTS

A total of 64,733 residents of LTC, median age 86 (78, 91) years (31.8% men), underwent SARS-CoV-2 testing, of whom 5029 (7.8%) tested positive. Thirty-day mortality rates were 28.7% (1442 deaths) after a positive test. Of 59,702 residents who tested negative, 2652 (4.4%) died within 30 days of testing. Predictors of mortality after SARS-CoV-2 infection included age, functional status (e.g., activity of daily living score and pressure ulcer risk), male sex, undernutrition, dehydration risk, prior hospital contacts for respiratory illness, and duration of comorbidities (e.g., heart failure, COPD). Lower GFR, hemoglobin concentration, lymphocyte count, and serum albumin were associated with higher mortality. After combining all covariates to generate a risk index, mortality rate in the highest risk quartile was 48.3% compared with 7% in the first quartile (odds ratio 12.42, 95%CI: 6.67, 22.80, p < 0.001). Deaths continued to increase rapidly for 15 days after the positive test.

CONCLUSIONS

LTC residents, particularly those with reduced functional status, comorbidities, and abnormalities on routine laboratory tests, are at high risk for mortality after SARS-CoV-2 infection. Recognizing high-risk residents in LTC may enhance institution of appropriate preventative measures.

Antisaccade task performance in obsessive-compulsive disorder and its clinical correlates

OBJECTIVE

Obsessive-Compulsive Disorder (OCD) is characterized by abnormalities in the cortico-striato-thalamo-cortical (CSTC) circuitry of the brain. Antisaccade eye movement tasks measure aspects of the voluntary control of behaviour that are sensitive to CSTC circuitry dysfunction.

METHOD

In this study, we examined antisaccade eye movement parameters of OCD patients in comparison with healthy controls (HC). In addition, we also examined the relationship between the antisaccade eye movement parameters and the severity of OCD. Antisaccade performance among right handed OCD patients (N = 65) was compared to matched right handed HC (N = 57). Eye tracking data during the task performance were collected using an Eye-Link eye-tracker at 1000-Hz sampling rate. OCD symptom severity was evaluated using Yale-Brown obsessive compulsive scale.

RESULTS

The antisaccade error percentage was significantly greater in OCD patients than HC (p < 0.001). In addition, OCD patients had less accurate final eye position compared to HC (p < 0.001). There were no significant correlation between antisaccade parameters and OCD severity measures.

CONCLUSION

Deficient performance in antisaccade task supports CSTC abnormality in OCD and this appears to be independent of the illness severity. Examining this in remitted participants with OCD and in unaffected first degree relatives could help ascertaining their endophenotype validity.

Impact of NRG1 HapICE gene variants on digit ratio and dermatoglyphic measures in schizophrenia

Multiple lines of evidence have suggested a potential role of Neuregulin-1 (NRG1) in the neurodevelopmental pathogenesis of schizophrenia. Interaction between genetic risk variants present within NRG1 locus and non-specific gestational putative insults can significantly impair crucial processes of brain development. Such genetic effects can be analyzed through the assessment of digit ratio and dermatoglyphic patterns. We examined the role of two well-replicated polymorphisms of NRG1 (SNP8NRG221533 and SNP8NRG243177) on schizophrenia risk and its probable impact on the digit ratio and dermatoglyphic measures in patients (N = 221) and healthy controls (N = 200). In schizophrenia patients, but not in healthy controls, a significant association between NRG1 SNP8NRG221533 C/C genotype with lower left 2D:4D ratio, as well as with higher FA_T_bcRC and DA_T_bcRC. The substantial effect of SNP8NRG221533 on both digit ratio and dermatoglyphic measures suggest a potential role for NRG1 gene variants on neurodevelopmental pathogenesis of schizophrenia.

Tolerance of transcranial direct current stimulation in psychiatric disorders: An analysis of 2000+ sessions

Transcranial direct current stimulation (tDCS), a non-invasive, neuromodulatory technique, is being increasingly applied to several psychiatric disorders. In this study, we describe the side-effect profile of repeated tDCS sessions (N = 2005) that were administered to 171 patients (156 adults and 15 adolescents) with different psychiatric disorders [schizophrenia [N = 109], obsessive-compulsive disorder [N = 28], alcohol dependence syndrome [N = 13], mild cognitive impairment [N = 10], depression [N = 6], dementia [N = 2] and other disorders [N = 3]]. tDCS was administered at a constant current strength of 2 mA with additional ramp-up and ramp-down phase of 20 s each at the beginning and end of the session, respectively. Other tDCS protocol parameters were: schizophrenia and obsessive-compulsive disorder: 5-days of twice-daily 20-min sessions with an inter-session interval of 3-h; Mild cognitive impairment/dementia and alcohol dependence syndrome: at least 5-days of once-daily 20-min session; Depression: 10-days of once-daily 30 min session. At the end of each tDCS session, any adverse event observed by the administrator and/or reported by the patient was systematically assessed using a comprehensive questionnaire. The commonly reported adverse events during tDCS included burning sensations (16.2%), skin redness (12.3%), scalp pain (10.1%), itching (6.7%), and tingling (6.3%). Most of the adverse events were noted to be mild, transient and well-tolerated. In summary, our observations suggest that tDCS is a safe mode for therapeutic non-invasive neuromodulation in psychiatric disorders in adults as well as the adolescent population.

Differential impact of interleukin-6 promoter gene polymorphism on hippocampal volume in antipsychotic-naïve schizophrenia patients

BACKGROUND

Differential susceptibility model hypothesizes that a genotype need not be unfavorable all the time as postulated in stress-diathesis model but can be beneficial in a supportive context. Single-nucleotide polymorphism (SNP) (rs18000795) within the promoter region of interleukin-6 (IL-6) gene was earlier noted to have a differential susceptibility on hippocampal volume in schizophrenia (SCZ).

MATERIALS AND METHODS

We examined antipsychotic-naïve/free SCZ patients (n = 35) in comparison with healthy controls (n = 68). Hippocampus volumes were assessed in 3 Tesla magnetic resonance imaging using voxel-based morphometry. Region of interest analysis was done using hippocampus mask. IL-6 SNP (rs1800795) was genotyped using TaqMan allelic discrimination assay.

RESULTS

A significantly deficient right (T = 3.03; K _E= 392; P _SVC-FWE= 0.04) and left (T = 3.03; K _E= 47; P _uncorr= 0.03) hippocampal gray matter volumes were noted in SCZ patients after controlling for the potential confounding effects of age, sex, and total brain volume. There was a significant diagnosis x rs1800795 genotype interaction involving both left (T = 2.17, K _E= 95, P _uncorr= 0.02) and right (T = 1.82, K _E= 29, P _uncorr= 0.04) hippocampal volumes. Patients with GG (left: F =5.78; P = 0.02; right: F =6.21; P = 0.01) but not GC/CC genotype (left: F =0.89; P = 0.34; right: F <0.01; P = 0.95) had volume depletion.

CONCLUSION

A paradoxical smaller hippocampal volume with GG genotype was noted in SCZ. Further elucidation of its mechanistic basis might have translational implications.

4941Machine learning based automated diagnosis of ischemic vs non-ischemic dilated cardiomyopathy using 3D myocardial deformation analysis

Background

Late Gadolinium Enhancement (LGE) imaging is a reference standard technique for the differentiation of ischemic cardiomyopathy (ICM) from non-ischemic dilated cardiomyopathy (NIDCM) in patients with heart failure and reduced ejection fraction (HFrEF). 3D myocardial deformation analysis (3D-MDA) offers highly reproducible phenotypic assessments of regional architecture and function that may provide value for artificial-intelligence-assisted cardiomyopathy diagnosis without need for LGE imaging.

Purpose

In this study, we trained and validated a machine-learning-based model to enable automated diagnosis of ischemic versus non-ischemic dilated cardiomyopathy exclusively using regional patterns of deformation among patients otherwise matched by age, sex and global contractile dysfunction.

Methods

100 ICM and 100 NIDCM patients matched for age, sex, and LVEF underwent standard cine SSFP and LGE imaging. Patient diagnoses were established using a combination of clinical and LGE-based criteria. 3D-MDA was performed using validated software (GIUSEPPE) to compute regional 3D strain measures at each cardiac phase in both conventional and principal strain directions. Principal Component Analysis (PCA) was performed on the composite 3D-MDA dataset. The first 20 components were chosen, accounting for approximately 65% of the population variance. Subsequently, a support-vector-machine-based algorithm was used with 10-fold cross-validation to discriminate ICM from NIDCM.

Results

Patients were 63±10 years (ICM: 63±10 years, NIDCM: 63±10 years, p=0.955), 74% male (ICM: 74%, NIDCM: 74%, p=1.000), and had a mean LVEF of 27±8% (ICM: 27±7%, NIDCM: 28±7%, p=0.688). Global time to peak strain was significantly shorter in ICM patients relative to NIDCM patients across all surfaces and in all directions (p<0.05). The highest single-variable Area Under the Curve (AUC) achieved for the classification of ICM versus NIDCM from global data was for minimum principal strain (ICM: 43.7±7.8, NIDCM: 48.3±7.5, p<0.001, AUC: 0.682) (Figure 1). However, a multi-feature machine-learning-based model exposed to all available regional 3D deformation data achieved an AUC of 0.903 (sensitivity 87.7%, specificity 75.5%).

Conclusions

Machine learning-based analyses of3D regionaldeformation patterns allows for robust discrimination of ICM versus NIDCM. Further expansion of the presented findings is planned on a wider, multi-centre cohort.

Acknowledgement/Funding

Dr. White was supported by an award from Heart and Stroke Foundation of Alberta. This study was funded in part by Calgary Health Trust.

Neuro-hemodynamic endophenotypes of emotional interference in OCD: fMRI study using emotion counting stroop task

BACKGROUND

We sought to examine the endophenotype pattern of neuro-hemodynamic substrates of emotion counting Stroop (ecStroop) paradigm in patients with OCD, their unaffected siblings [first degree relatives-FDR] and healthy controls (HC).

METHODS

OCD patients (medication naïve)[N = 16], their unaffected siblings(FDR)[N = 16] and HC [N = 24] were compared using an established ecStroop paradigm in a 3-Tesla fMRI. The relative BOLD signals corresponding to the three types of conditions (neural words-N, words with negative emotional salience-E and words with salience for OCD-O) were examined in the apriori hypothesized brain regions.

RESULTS

Both in O minus N contrast and O minus E contrast, the groups demonstrated significant differential activation of right insula (BA 13). The post-hoc analyses showed in patients and FDRs relative to HC the following: significant hyperactivation of insula in O minus E contrast; significant hyperactivation of right insula and right DLPFC (BA 9) in O minus N contrast.

CONCLUSIONS

The neuro-hemodynamic responses corresponding to the obsessive words in insula and DLPFC could be potential endophenotypes. "Threat relatedness" might thus have a vulnerability meaning in the pathogenesis and neurobiological basis of OCD.

Telomere length and its association with hippocampal gray matter volume in antipsychotic-naïve/free schizophrenia patients

Accelerated ageing processes are postulated to underlie schizophrenia pathogenesis. This postulate is supported by observations of reduced telomere length in schizophrenia patients. Hippocampus, one of the most important brain regions implicated in schizophrenia, is shown to atrophy at a faster rate in aging. In this study, telomere length (TL) was measured in 30 antipsychotic-naive/free schizophrenia patients and 60 healthy controls using quantitative PCR assay. Hippocampus volume was measured using voxel-based morphometry. Schizophrenia was associated with differential TL between sexes [Status × Sex; F(1,85) = 5.9, p = 0.017, η² = 0.065]. Male schizophrenia patients had significantly lower relative TL than female patients [F(1,85) = 7.38, p = 0.008], while such sex difference was not observed in healthy controls [F(1,85) = 0.16, p = 0.69]. Schizophrenia patients showed a significant sex-by-telomere interaction with both right & left hippocampus, with male patients showing positive association of telomere length with volume, while female patients showed negative association. Telomere shortening and the positive association of telomere length with hippocampus volume was observed only in male patients with schizophrenia. Since correlational observations in this cross-sectional study does not necessarily support definitive causal relationship, further longitudinal studies examining hippocampus volume and telomere in schizophrenia patients are needed.

Construction of population-specific Indian MRI brain template: Morphometric comparison with Chinese and Caucasian templates

OBJECTIVE

Spatial normalization of brain MR images is highly dependent on the choice of target brain template. Morphological differences caused by factors like genetic and environmental exposures, generates a necessity to construct population specific brain templates. Brain image analysis performed using brain templates from Caucasian population may not be appropriate for non-Caucasian population. In this study, our objective was to construct an Indian brain template from a large population (N = 157 subjects) and compare the morphometric parameters of this template with that of Chinese-56 and MNI-152 templates. In addition, using an independent MRI data of 15 Indian subjects, we also evaluated the potential registration accuracy differences using these three templates.

METHODS

Indian brain template was constructed using iterative routines as per established procedures. We compared our Indian template with standard MNI-152 template and Chinese template by measuring global brain features. We also examined accuracy of registration by aligning 15 new Indian brains to Indian, Chinese and MNI templates. Furthermore, we supported our measurement protocol with inter-rater and intra-rater reliability analysis.

RESULTS

Our results showed that there were significant differences in global brain features of Indian template in comparison with Chinese and MNI brain templates. The results of registration accuracy analysis revealed that fewer deformations are required when Indian brains are registered to Indian template as compared to Chinese and MNI templates.

CONCLUSION

This study concludes that population specific Indian template is likely to be more appropriate for structural and functional image analysis of Indian population.

Efficacy of fronto-temporal transcranial direct current stimulation for refractory auditory verbal hallucinations in schizophrenia: A randomized, double-blind, sham-controlled study

Persistent auditory verbal hallucinations (AVH) that are refractory to antipsychotic medications are reported in about 20-30% of schizophrenia patients. Transcranial Direct Current Stimulation (tDCS), a non-invasive and safe neuromodulatory technique, has attracted significant interest as an add-on treatment for refractory AVH in schizophrenia. Studies examining the efficacy of tDCS for refractory AVH in schizophrenia have reported inconsistent findings. In this study, using a randomized, double-blind, sham-controlled design (RCT), we sought to examine the effect of add-on tDCS [anode corresponding to left dorsolateral prefrontal cortex and cathode to left temporo-parietal junction; 2-mA, twice-daily sessions for 5-days] to treat refractory AVH in schizophrenia patients (N=25); following this RCT phase, patients that had <30% reduction in AVH severity were offered an open-label extension (OLE) active stimulation to evaluate the effect of cross-over to verum tDCS. In the RCT phase, repeated measures ANOVA with tDCS type [verum (N=12) vs. sham (N=13)] as between subjects factor demonstrated a significant tDCS-type X time-point interaction [F=21.5, p<0.001, partial-η2=0.48] with significantly greater reduction of AVH score in verum tDCS group as compared to sham group. In the OLE phase, sham-to-verum crossed over patients (N=13) showed significantly greater reduction in AVH severity than their corresponding change during RCT phase (t=2.9; p=0.01). Together, these observations add further support to the beneficial effects of add-on tDCS to treat refractory AVH schizophrenia.

Neural Effects of Transcranial Direct Current Stimulation in Schizophrenia: A Case Study using Functional Near-infrared Spectroscopy

Schizophrenia is a severe neuropsychiatric disorder characterized by delusions, hallucinations, behavioral symptoms, and cognitive deficits. Roughly, 70%-80% of schizophrenia patients experience auditory verbal hallucinations (AVHs), with 25%-30% demonstrating resistance to conventional antipsychotic medications. Studies suggest a promising role for add-on transcranial direct current stimulation (tDCS) in the treatment of medication-refractory AVHs. The mechanisms through which tDCS could be therapeutic in such cases are unclear, but possibly involve neuroplastic effects. In recent years, functional near-infrared spectroscopy (fNIRS) has been used successfully to study tDCS-induced neuroplastic changes. In a double-blind, sham-controlled design, we applied fNIRS to measure task-dependent cerebral blood flow (CBF) changes as a surrogate outcome of single session tDCS-induced effects on neuroplasticity in a schizophrenia patient with persistent auditory hallucinations. The observations are discussed in this case report.

Neural Correlates of a Perspective-taking Task Using in a Realistic Three-dimmensional Environment Based Task: A Pilot Functional Magnetic Resonance Imaging Study

Objective

Perspective-taking ability is an essential spatial faculty that is of much interest in both health and neuropsychiatric disorders. There is limited data on the neural correlates of perspective taking in the context of a realistic three-dimensional environment. We report the results of a pilot study exploring the same in eight healthy volunteers.

Methods

Subjects underwent two runs of an experiment in a 3 Tesla magnetic resonance imaging (MRI) involving alternate blocks of a first-person perspective based allocentric object location memory task (OLMT), a third-person perspective based egocentric visual perspective taking task (VPRT), and a table task (TT) that served as a control. Difference in blood oxygen level dependant response during task performance was analyzed using Statistical Parametric Mapping software, version 12. Activations were considered significant if they survived family-wise error correction at the cluster level using a height threshold of p＜0.001, uncorrected at the voxel level.

Results

A significant difference in accuracy and reaction time based on task type was found. Subjects had significantly lower accuracy in VPRT compared to TT. Accuracy in the two active tasks was not significantly different. Subjects took significantly longer in the VPRT in comparison to TT. Reaction time in the two active tasks was not significantly different. Functional MRI revealed significantly higher activation in the bilateral visual cortex and left temporoparietal junction (TPJ) in VPRT compared to OLMT.

Conclusion

The results underscore the importance of TPJ in egocentric manipulation in healthy controls in the context of reality-based spatial tasks.

Neurocognitive Impairments in Unaffected First-degree Relatives of Schizophrenia

BACKGROUND

Neurocognitive impairments of attention and executive functioning are trait abnormalities in schizophrenia, and these are considered to be endophenotypes. These deficits have been convincingly linked to prefrontal cortical functioning. In this study, we examined the cognitive performance in the domains of attention and executive functioning among first-degree relatives of Indian people with schizophrenia (high-risk [HR] patients) compared to healthy controls (HC).

MATERIALS AND METHODS

Siblings of patients with DSM-IV schizophrenia, HR patients (n = 17), were compared with HC (n = 30) (matched as a group for age, sex, years of education, and handedness) using the following neurocognitive tests for attention and executive function - digit span test (DST), trail making test, letter-number sequencing (LNS), and spatial span test.

RESULTS

HR patients had significantly deficient performance in attention and executive function tasks (DST-forward [P < 0.001], DST-backward [P < 0.001], spatial span-forward [P < 0.001], spatial span-backward [P < 0.001], and LNS [P < 0.001]).

CONCLUSIONS

This study replicates the findings that neurocognitive deficits involving executive function task performance, attention, and working memory, which are considered as principal features in patients with schizophrenia, are also significantly present in the first-degree relatives of patients. Thus, these neurocognitive parameters can be considered as potential endophenotypes in schizophrenia.

Auditory false perception in schizophrenia: Development and validation of auditory signal detection task

Auditory hallucinations constitute an important symptom component in 70-80% of schizophrenia patients. These hallucinations are proposed to occur due to an imbalance between perceptual expectation and external input, resulting in attachment of meaning to abstract noises; signal detection theory has been proposed to explain these phenomena. In this study, we describe the development of an auditory signal detection task using a carefully chosen set of English words that could be tested successfully in schizophrenia patients coming from varying linguistic, cultural and social backgrounds. Schizophrenia patients with significant auditory hallucinations (N=15) and healthy controls (N=15) performed the auditory signal detection task wherein they were instructed to differentiate between a 5-s burst of plain white noise and voiced-noise. The analysis showed that false alarms (p=0.02), discriminability index (p=0.001) and decision bias (p=0.004) were significantly different between the two groups. There was a significant negative correlation between false alarm rate and decision bias. These findings extend further support for impaired perceptual expectation system in schizophrenia patients.

The impact of IL10 polymorphisms and sHLA-G levels on the risk of schizophrenia

Early life immune aberrations have strongly been associated with the risk of schizophrenia. Amongst them, inflammation induced neurodevelopmental origin has emerged as one of the widely recognized underlying mechanisms. Interleukin-10 (IL-10) is an important anti-inflammatory and immunoregulatory cytokine. It modulates the expression of another immuno-inhibitory molecule, Human Leukocyte Antigen-G (HLA-G), predominantly expressed at the feto-maternal interface. Under physiological conditions, IL-10 and HLA-G molecules regulate the feto-maternal immune homeostasis by limiting the inflammatory states and influence the outcome of pregnancy. The aberrant expression of these molecules can cause pregnancy complications, which are known to confer strong risk to schizophrenia in the offspring. However, there is a considerable lack of information on the effect of the functional interactions between IL-10 and HLA-G on the risk of schizophrenia. We therefore examined the impact of possible correlation between IL-10 genetic variations and the plasma levels of soluble HLA-G (sHLA-G) on schizophrenia risk. Genotyping of IL10 (-592 C>A, -1082 A>G) single nucleotide polymorphisms (SNPs) was performed by PCR-RFLP method in 219 schizophrenia patients and 197 healthy subjects and levels of sHLA-G were estimated by ELISA in 46 patients and 44 healthy subjects. There was no significant difference in the genotype and allele frequencies between the groups for both the IL10 SNPs analyzed. However, we observed a correlation between IL10 genetic variation and plasma levels of sHLA-G in schizophrenia patients. Patients carrying CC genotype of IL10 -592C>A polymorphism had significantly lower sHLA-G levels compared to CA and AA genotypes. Our findings suggest the impact of possible correlation between IL-10 and HLA-G on schizophrenia risk.

Cerebellar volume deficits in medication-naïve obsessive compulsive disorder

Even though conventional neurobiological models of obsessive compulsive disorder (OCD) commonly demonstrate abnormalities involving fronto-striatal circuits, there is emerging evidence regarding the role of posterior brain structures such as cerebellum. In this study, we examined the cerebellar regional volume in a large sample of medication-naïve OCD patients compared to matched healthy controls (HC). In 49 medication naïve right handed OCD patients and 39 age and sex matched HC, sub-region wise volume of cerebellum was extracted from the T1 weighted images using Spatially Unbiased Infra tentorial Template (SUIT) toolbox and compared using hypothesis driven, region of interest approach after clinical assessment with standard scales. After controlling for age, sex and ICV, the subjects with OCD had significantly smaller cerebellum compared to HC, especially in the posterior lobe sub-regions - lobule VI and left crus 1. This study gives preliminary evidence for region specific cerebellar volumetric deficits in the pathophysiological of OCD. Regional cerebellar volume deficits conform to the abnormal connectivity of cerebellum to specific cortical regions and it is indicative of involvement of regions outside the conventional fronto-striatal circuitry. This might be important in the context of cognitive deficits seen in OCD.

The impact of HLA-G 3' UTR variants and sHLA-G on risk and clinical correlates of schizophrenia

The Major Histocompatibility Complex (MHC)/Human Leukocyte Antigen (HLA) is known to influence the pathogenesis of several complex human diseases resulting from gene-environmental interactions. Recently, it has emerged as one of the risk determinants of schizophrenia. The HLA-G protein (a non-classical MHC class I molecule), encoded by the HLA-G gene, is shown to play important role in embryonic development. Importantly, its genetic variations and aberrant expression have been implicated in pregnancy complications like preeclampsia, inflammation, and autoimmunity. Converging evidence implicates these phenomena as risk mechanisms of schizophrenia. However, the functional implications of HLA-G in schizophrenia are yet to be empirically examined. The impact of two functional polymorphisms [14bp Insertion/Deletion (INDEL) and +3187 A>G] and soluble HLA-G (sHLA-G) levels on schizophrenia risk was evaluated. In this exploratory study, the Ins/Ins genotype of 14bp INDEL was found to confer a strong risk for schizophrenia. Further, low levels of sHLA-G were shown to have a significant impact on Clinical Global Impression (CGI) severity in people with schizophrenia.

Impact of antipsychotic medication on transcranial direct current stimulation (tDCS) effects in schizophrenia patients

Transcranial direct current stimulation (tDCS) has generated interest as a treatment modality for schizophrenia. Dopamine, a critical pathogenetic link in schizophrenia, is also known to influence tDCS effects. We evaluated the influence of antipsychotic drug type (as defined by dopamine D2 receptor affinity) on the impact of tDCS in schizophrenia. DSM-IV-TR-diagnosed schizophrenia patients [N=36] with persistent auditory hallucinations despite adequate antipsychotic treatment were administered add-on tDCS. Patients were divided into three groups based on the antipsychotic's affinity to D2 receptors. An auditory hallucinations score (AHS) was measured using the auditory hallucinations subscale of the Psychotic Symptom Rating Scales (PSYRATS). Add-on tDCS resulted in a significant reduction inAHS. Antipsychotic drug type had a significant effect on AHS reduction. Patients treated with high affinity antipsychotics showed significantly lesser improvement compared to patients on low affinity antipsychotics or a mixture of the two. Furthermore, a significant sex-by-group interaction occurred; type of medication had an impact on tDCS effects only in women. Improvement differences could be due to the larger availability of the dopamine receptor system in patients taking antipsychotics with low D2 affinity. Sex-specific differences suggest potential estrogen-mediated effects. This study reports a first-time observation on the clinical utility of antipsychotic drug type in predicting tDCS effects in schizophrenia.

Pituitary volume in medication-naïve adults with obsessive compulsive disorder

Pituitary volume is considered to reflect hypothalamic-pituitary-adrenal axis dysregulation, and this has been studied in various psychiatric disorders. This study demonstrates that pituitary volume as assessed through the region of interest manual tracing method in 50 medication-naïve adult patients with obsessive-compulsive disorder was not significantly different compared with 40 healthy control subjects (687.80 ± 126.60 versus 694.73 ± 131.59, F=0.55, p=0.46). The authors also compared the patients with obsessive-compulsive disorder without any comorbid axis I conditions (N=35) with healthy control subjects and found no difference in the pituitary volumes (681.62 ± 130.85 versus 694.72 ± 131.59, F=0.90, p=0.35). This emphasizes the need to examine hypothalamo-pituitary axis structures after taking into consideration various potential confounders such as medications and depression.

Clinical correlates of superior temporal gyrus volume abnormalities in antipsychotic-naïve schizophrenia

In this study, the authors report superior temporal gyrus (STG) and Heschl's gyrus (HG) volume deficits in a large sample of medication-naïve patients with schizophrenia (N=55) in comparison with healthy control subjects (N=45) with structural MRI using voxel-based morphometry. Patients had significantly smaller volumes of left HG [X=-41, Y=-22, Z=11; Brodmann's area (BA)-41), right HG (X=47, Y=-18, Z=11; BA-41), and left STG (X=-50, Y=-34, Z=11; BA-42] compared with healthy control subjects. In addition, Positive and Negative Syndrome Scale positive score had a significant negative correlation with left HG. Findings observed in a large sample of antipsychotic-naive patients with schizophrenia emphasize the role of HG and STG in the pathophysiology of schizophrenia.

Dermatoglyphic correlates of hippocampus volume: Evaluation of aberrant neurodevelopmental markers in antipsychotic-naïve schizophrenia

Schizophrenia is a disorder of aberrant neurodevelopment is marked by abnormalities in brain structure and dermatoglyphic traits. However, the link between these two (i.e. dermatoglyphic parameters and brain structure) which share ectodermal origin and common developmental window has not been explored extensively. The current study examined dermatoglyphic correlates of hippocampal volume in antipsychotic-naïve schizophrenia patients in comparison with matched healthy controls. Ridge counts and asymmetry measures for palmar inter-digital areas (a-b, b-c, c-d) were obtained using high resolution digital scans of palms from 89 schizophrenia patients [M:F=48:41] and 48 healthy controls [M:F=30:18]. Brain scans were obtained for subset of subjects including 26 antipsychotic-naïve patients [M:F=13:13] and 29 healthy controls [M:F=19:10] using 3 T-MRI. Hippocampal volume and palmar ridge counts were measured by blinded raters with good inter-rater reliability using valid methods. Directional asymmetry (DA) of b-c and bilateral hippocampal volume were significantly lower in patients than controls. Significant positive correlation was found between DA and ridge count of b-c with bilateral anterior hippocampal volume. Study demonstrates the utility of dermatoglyphic markers in identifying structural changes in the brain which may form the basis for neurodevelopmental pathogenesis in schizophrenia.

A Voxel Based Morphometry Study of Brain Gray Matter Volumes in Juvenile Obsessive Compulsive Disorder

INTRODUCTION

Adult patients with Obsessive Compulsive Disorder (OCD) have been shown to have gray matter (GM) volume differences from healthy controls in multiple regions - the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), medial frontal gyri (MFG), striatum, thalamus, and superior parietal lobule. However, there is paucity of data with regard to juvenile OCD. Hence, we examined GM volume differences between juvenile OCD patients and matched healthy controls using voxel based morphometry (VBM) with the above apriori regions of interest.

METHOD

Fifteen right handed juvenile patients with OCD and age- sex- handedness- matched healthy controls were recruited after administering the Mini International Neuropsychiatric Interview-KID and the Children's Yale-Brown Obsessive Compulsive Scale, and scanned using a 3 Tesla magnetic resonance imaging scanner. VBM methodology was followed.

RESULTS

In comparison with healthy controls, patients had significantly smaller GM volumes in left ACC. YBOCS total score (current) showed significant negative correlation with GM volumes in bilateral OFC, and left superior parietal lobule.

CONCLUSION

These findings while reiterating the important role of the orbito-fronto-striatal circuitry, also implicate in the parietal lobe - especially the superior parietal lobule as an important structure involved in the pathogenesis of OCD.

Cognitive mapping deficits in schizophrenia: Evidence from clinical correlates of visuospatial transformations

The 'cognitive mapping' component of spatial cognition, namely - the allocentric/egocentric function and its relation to symptoms in schizophrenia is relatively unexplored. In this study, we compared schizophrenia patients (N=44) to demographically-matched healthy controls (N=43) using computer-administered visuospatial transformation tasks with egocentric and allocentric components and analyzed their correlation with symptoms. Significant diagnosis X task-type interaction effect was seen on task accuracy. Patients performed significantly worse than controls in the allocentric letter rotation task (LRT) but not in the egocentric people rotation task (PRT). Accuracy in the LRT was significantly lesser than in PRT among patients but not among controls. Patients were significantly slower as compared to controls in both tasks. Both groups took longer to perform PRT as compared to LRT. LRT accuracy showed significant negative correlation with total positive symptoms as well as negative symptoms scores. Angle of rotation, perspective (front-facing/back-facing), orientation (mirrored/normal), and stimulus type (letter/number) were found to significantly influence performance in both groups of subjects. The present data support the finding that there is a differential impairment of allocentric abilities in schizophrenia patients. Further systematic research in this area may facilitate better understanding of schizophrenia pathogenesis.

Serum vitamin D and hippocampal gray matter volume in schizophrenia

Disparate lines of evidence including epidemiological and case-control studies have increasingly implicated vitamin D in the pathogenesis of schizophrenia. Vitamin D deficiency can lead to dysfunction of the hippocampus--a brain region hypothesized to be critically involved in schizophrenia. In this study, we examined for potential association between serum vitamin D level and hippocampal gray matter volume in antipsychotic-naïve or antipsychotic-free schizophrenia patients (n = 35). Serum vitamin D level was estimated using 25-OH vitamin D immunoassay. Optimized voxel-based morphometry was used to analyze 3-Tesla magnetic resonance imaging (MRI) (1-mm slice thickness). Ninety-seven percent of the schizophrenia patients (n = 34) had sub-optimal levels of serum vitamin D (83%, deficiency; 14%, insufficiency). A significant positive correlation was seen between vitamin D and regional gray matter volume in the right hippocampus after controlling for age, years of education and total intracranial volume (Montreal Neurological Institute (MNI) coordinates: x = 35, y = -18, z = -8; t = 4.34 pFWE(Corrected) = 0.018). These observations support a potential role of vitamin D deficiency in mediating hippocampal volume deficits, possibly through neurotrophic, neuroimmunomodulatory and glutamatergic effects.

Corpus callosum abnormalities in medication-naïve adult patients with obsessive compulsive disorder

Emerging evidence demonstrates widespread abnormalities involving white matter (WM) tracts connecting different cortical regions in obsessive-compulsive disorder (OCD). The corpus callosum (CC), the largest inter-hemispheric tract connecting the association cortices, has been shown to be affected in OCD. This study examines CC abnormalities in a large sample of medication-naïve OCD patients in comparison to matched healthy controls (HCs). We examined the mid-sagittal area of the CC in medication-naïve OCD patients (n=49) in comparison with age-, sex-, and handedness-matched HCs (n=38). Witelson's method was used to measure the sub-regions of the CC - namely, the genu, body, isthmus and splenium - with good inter-rater reliability. The area of the body of the CC and total CC area were significantly larger in OCD patients than in HCs after controlling for age, sex and intracranial area. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) compulsion score had a significant negative correlation with the areas of the isthmus and splenium of the CC in addition to the total CC area. The region-specific differences in the body of the CC and the region-specific association of severity score with posterior regions of the CC might be indicative of the involvement of additional areas like the dorsolateral prefrontal cortex, posterior parietal areas, occipital and association cortices in OCD that extend beyond the conventional orbito-fronto-striatal circuitry that is often posited to be involved in OCD.

Volumetric analysis of hippocampal sub-regions in late onset depression: a 3 tesla magnetic resonance imaging study

BACKGROUND

While many studies have reported reduced volume of hippocampus in late onset depression (LOD), the status of hippocampus sub-regions (anterior/posterior) is yet to be explored. Evaluating hippocampal sub-regions might facilitate better elucidation of the neurobiological basis of LOD.

METHODS

Twenty five elderly subjects with LOD (mean age=65.28yr, SD=5.73, 15 females) and 20 healthy controls (mean age=65.35yr, SD=5.67, 7 females) were examined using 3-tesla magnetic resonance imaging (MRI). They were also evaluated with Montgomery Asberg Depression Rating Scale (MADRS) and Hindi Mental State Examination (HMSE). We examined the difference in volume of Hippocampal sub-regions between the LOD group and control group controlling for the age, sex and intracranial volume.

RESULTS

Left posterior hippocampus volume was significantly smaller in LOD group than the control group (1.01±0.19ml vs 1.16±0.25ml, F=7.50, p=0.009). There was a similar trend for the right posterior hippocampus (1.08±0.19ml vs 1.18±0.27ml, F=3.18, p=0.082). Depression severity (mean MADRS score=20.64±8.99) had a significant negative correlation with volumes of right posterior hippocampus (r=-0.37, p=0.012) and left posterior hippocampus (r=-0.46, p=0.001) in the LOD group.

CONCLUSIONS

Specific reduction of posterior hippocampus volume and its relationship with depression severity indicates sub region specific hippocampal volumetric abnormalities in LOD. Future studies need to evaluate sub region specific hippocampal volume in LOD longitudinally for better understanding of the pathogenesis of LOD in view of the functional differences between anterior and posterior hippocampus.

Clinical correlates of parametric digit-symbol substitution test in schizophrenia

Processing speed deficit, ascertained by digit-symbol substitution test (DSST), is considered as a fundamental impairment in schizophrenia. Clinical correlates of processing speed abnormalities, especially using the parametric version of DSST is yet to be evaluated comprehensively. In this study, we examined schizophrenia patients (N=66) and demographically matched healthy controls (N=72) using computer-administered parametric DSST (pDSST) with fixed (pDSSTF) as well as random (pDSSTR) conditions and analysed the relationship between pDSST performance and clinical symptoms. Psychopathology was assessed using Scale for Assessment of Positive Symptoms (SAPS)/Negative Symptoms (SANS) with good inter-rater reliability. In comparison with healthy controls, patients demonstrated significantly lesser number of correct responses (CN) in pDSSTF (t=8.0; p<0.001) and pDSSTR (t=7.8; p<0.001) as well as significantly prolonged reaction time in pDSSTF (t=7.1; p<0.001) and pDSSTR (t=7.0; p<0.001). The difference in CN between pDSSTF and pDSSTR [ΔCN] was significantly lesser in patients than healthy controls (t=2.61; p=0.01). The pDSST reaction time had significant positive correlation with negative syndrome scores as well as bizarre behaviour score. Significantly greater processing speed deficits in pDSST suggest potential relational memory/visual scanning abnormalities in schizophrenia. Furthermore, pDSST deficits demonstrated a significant association with the psychopathology, especially with the various negative symptoms and bizarre behaviour.

Cognitive mapping deficits in schizophrenia: a critical overview

Hippocampal deficits are an established feature of schizophrenia and are complementary with recent evidences of marked allocentric processing deficits being reported in this disorder. By "Cognitive mapping" we intend to refer to the concepts from the seminal works of O'Keefe and Nadel (1978) that led to the development of cognitive map theory of hippocampal function. In this review, we summarize emerging evidences and issues that indicate that "Cognitive mapping deficits" form one of the important cognitive aberrations in schizophrenia. The importance has been placed upon hippocampally mediated allocentric processing deficits and their role in pathology of schizophrenia, for spatial/representational cognitive deficits and positive symptoms in particular. It is modestly summarized that emerging evidences point toward a web of spatial and cognitive representation errors concurrent with pronounced hippocampal dysfunction. In general, it can be stated that there are clear and consistent evidences that favor the cognitive mapping theory in explaining certain deficits of schizophrenia and for drawing out a possible and promising endophenotype/biomarkers. Further research in this regard demands attention.

Transcranial direct current stimulation in schizophrenia

Transcranial direct current stimulation (tDCS) is an upcoming treatment modality for patients with schizophrenia. A series of recent observations have demonstrated improvement in clinical status of schizophrenia patients with tDCS. This review summarizes the research work that has examined the effects of tDCS in schizophrenia patients with respect to symptom amelioration, cognitive enhancement and neuroplasticity evaluation. tDCS is emerging as a safe, rapid and effective treatment for various aspects of schizophrenia symptoms ranging from auditory hallucinations-for which the effect is most marked, to negative symptoms and cognitive symptoms as well. An interesting line of investigation involves using tDCS for altering and examining neuroplasticity in patients and healthy subjects and is likely to lead to new insights into the neurological aberrations and pathophysiology of schizophrenia. The mechanistic aspects of the technique are discussed in brief. Future work should focus on establishing the clinical efficacy of this novel technique and on evaluating this modality as an adjunct to cognitive enhancement protocols. Understanding the mechanism of action of tDCS as well as the determinants and neurobiological correlates of clinical response to tDCS remains an important goal, which will help us expand the clinical applications of tDCS for the treatment of patients with schizophrenia.

Yoga increases the volume of the hippocampus in elderly subjects

CONTEXT

The neurobiological effect of yoga on the cortical structures in the elderly is as yet unknown.

MATERIALS AND METHODS

Seven healthy elderly subjects received yoga intervention as an add-on life-style practice. Magnetic resonance imaging scans were obtained before and 6 months later. Voxel-based-morphometric analyses compared the brains before and after the yoga.

RESULTS

Yoga group was found to have increases in hippocampal, but not in occipital gray matter.

CONCLUSION

Yoga has potential to reduce neuro-senescence. Small sample size and absence of the control group prevent generalization of the findings limiting its translational value.

A Longitudinal Study of Relation between Side-effects and Clinical Improvement in Schizophrenia: Is There a Neuro-metabolic Threshold for Second Generation Antipsychotics?

Objective

Classical studies demonstrated Neuroleptic Induced Extrapyramidal Side-effects (NIES; Neuroleptic threshold) to correlate with the efficacy of first generation antipsychotics. Second generation antipsychotics (SGAs), in addition to the extrapyramidal side effects, are also associated with metabolic side effects. This prospective study on antipsychotic-naïve schizophrenia patients, for the first-time, examined concurrently the relationship between clinical improvement and these side-effects NIES and Neuroleptic Induced Metabolic Side-effects.

Methods

Thirty six-antipsychotic-naïve schizophrenia (DSM-IV) patients were examined at baseline and after 5 weeks of treatment with antipsychotics. At baseline and follow-up, we recorded the body mass index (BMI) and assessed psychopathology using Scale for Assessment of Positive-symptoms (SAPS) and Scale for Assessment of Negative-symptoms (SANS), extrapyramidal symptoms using Simpson-Angus Extra Pyramidal Scale (SAEPS) and improvement using Clinical Global Impression Improvement (CGI).

Results

After treatment, patients showed significant reduction in SAPS (baseline, 27.97±14.47; follow-up, 14.63±13.25; p<0.001) and SANS total scores (baseline, 63.77±28.96; follow-up, 49.30±28.77; p=0.001) and a significant increase in BMI (baseline, 18.5±3.37; follow-up, 19.13±3.17; p<0.001). At follow-up CGI-Improvement score was (2.55±0.65) and SAEPS score was (0.8±1.32). CGI-Improvement score had a significant negative correlation with magnitude of increase in BMI (r_s=-0.39; p=0.01) and SAEPS symptom score at follow-up (r_s=-0.58; p<0.001). In addition, magnitude of increase in BMI showed positive correlation with the magnitude of reduction in SAPS total score (r_s=0.33; p=0.04).

Conclusion

The study findings suggest a possible relation between clinical improvement and antipsychotic-induced neuroleptic as well as metabolic side-effects in schizophrenia. Though the mechanism of this relation is yet to be elucidated, insulin signaling pathways and lipid homeostasis are potential mechanisms in addition to the established neurotransmitter hypothesis. Theoretically findings support the novel hypothetical construct of 'Neuro-Metabolic threshold' in the treatment of schizophrenia.

Evolutionary genetic analyses of MEF2C gene: implications for learning and memory in Homo sapiens

MEF2C facilitates context-dependent fear conditioning (CFC) which is a salient aspect of hippocampus-dependent learning and memory. CFC might have played a crucial role in human evolution because of its advantageous influence on survival of species. In this study, we analyzed 23 orthologous mammalian gene sequences of MEF2C gene to examine the evidence for positive selection on this gene in Homo sapiens using Phylogenetic Analysis by Maximum Likelihood (PAML) and HyPhy software. Both PAML Bayes Empirical Bayes (BEB) and HyPhy Fixed Effects Likelihood (FEL) analyses supported significant positive selection on 4 codon sites in H. sapiens. Also, haplotter analysis revealed significant ongoing positive selection on this gene in Central European population. The study findings suggest that adaptive selective pressure on this gene might have influenced human evolution. Further research on this gene might unravel the potential role of this gene in learning and memory as well as its pathogenetic effect in certain hippocampal disorders with evolutionary basis like schizophrenia.

Thalamic shape abnormalities in antipsychotic naïve schizophrenia

BACKGROUND

Neurodevelopmental hypothesis of schizophrenia states abnormal pruning as one of the pathogenetic mechanism in schizophrenia. Though thalamic volume abnormalities have been documented, the shape differences of thalamus in antipsychotic-free schizophrenia in comparison with age- and sex-matched healthy volunteers need validation.

MATERIALS AND METHODS

We examined antipsychotic naïve schizophrenia patients (n=60) and age- and sex-matched healthy volunteers (n=44). The thalamic shape abnormalities were analyzed from their coded structural magnetic resonance imaging (MRI) data using three-dimensional automated image analysis software, FMRIB's (Oxford Center for the functional MRI of the brain) tools-FIRST (FMRIB's Integrated Registration and Segmentation Tool) by creating deformable mesh model. Correlation with the psychopathology scores was carried out using F-statistics.

RESULTS

Patients with schizophrenia showed significant inward deformations in the regions corresponding to anterior, ventromedial, mediodorsal, and pulvinar nuclei. There was a direct correlation between negative syndrome score and the deformation in the right mediodorsal and right pulvinar nuclei.

CONCLUSION

The inward deformations of thalamus in antipsychotic naive schizophrenia patients correspond to those nuclei which have reciprocal connections with frontal, superior temporal, and anterior cingulate regions and support the neurodevelopmental hypothesis of schizophrenia.

Family history correlates of digit ratio abnormalities in schizophrenia

BACKGROUND

The differences in digit ratio are proposed to arise due to differential effects of sex steroids on the growth of finger bones. In this study, we sought to examine the sex differences and the influence of family history of psychosis on digit ratio in patients with schizophrenia compared to matched healthy controls (HCs).

MATERIALS AND METHODS

Digit ratio (2D: 4D) was examined for a large sample of schizophrenia patients (n=200) and HC (n=177) to evaluate the potential effects of family history.

RESULTS

The right hand 2D: 4D digit ratio was lesser in schizophrenia patients compared to HC (0.97±0.05 vs 0.98±0.04, t=2.2, P=0.02). There was a significant difference in the right hand 2D: 4D digit ratio of female patients with schizophrenia when compared to female HCs (0.96±0.05 vs 0.98±0.03, t=2.1, P=0.03) while males showed no such difference on either hands. On the contrary, family history‑positive males showed a significantly greater digit ratio for the left hand (FH present (0.99±0.04) vs HC (0.97±0.04), t=2.15, P=0.03), while there was no difference between family history‑positive females and HC.

CONCLUSION

Overall, in patients, reversal of expected "directionality" in digit ratio was observed in our study with greater left 2D: 4D in male patients having a family history of schizophrenia being a novel finding. Reversal of sexual dimorphism has been linked to the pathogenesis of schizophrenia. It is possible that such reversal might have a putative genetic basis, perhaps only in men with schizophrenia.

Volume and asymmetry abnormalities of insula in antipsychotic-naive schizophrenia: a 3-tesla magnetic resonance imaging study

CONTEXT

Insula, which is a vital brain region for self-awareness, empathy, and sensory stimuli processing, is critically implicated in schizophrenia pathogenesis. Existing studies on insula volume abnormalities report inconsistent findings potentially due to the evaluation of 'antipsychotic-treated' schizophrenia patients as well as suboptimal methodology.

AIM

To understand the role of insula in schizophrenia.

MATERIALS AND METHODS

In this first-time 3-T magnetic resonance imaging study, we examined antipsychotic-naive schizophrenic patients (N=30) and age-, sex-, handedness- and education-matched healthy controls (N=28). Positive and negative symptoms were scored with good interrater reliability (intraclass correlation coefficient (ICC)>0.9) by using the scales for negative and positive symptoms. Gray matter volume of insula and its anterior/posterior subregions were measured by using a three-dimensional, interactive, semiautomated software based on the valid method with good interrater reliability (ICC>0.85). Intracranial volume was automatically measured by using the FreeSurfer software.

RESULTS

Patients had significantly deficient gray matter volumes of left (F=33.4; P<0.00001) and right (F=11.9; P=0.001) insula after controlling for the effects of age, sex, and intracranial volume. Patients with predominantly negative symptoms had a significantly deficient right posterior insula volume than those with predominantly positive symptoms (F=6.3; P=0.02). Asymmetry index analysis revealed anterior insular asymmetry to be significantly reversed (right>left) in male patients in comparison with male controls (left>right) (t=2.7; P=0.01).

CONCLUSIONS

Robust insular volume deficits in antipsychotic-naive schizophrenia support intrinsic role for insula in pathogenesis of this disorder. The first-time demonstration of a relationship between right posterior insular deficit and negative symptoms is in tune with the background neurobiological literature. Another novel observation of sex-specific anterior insular asymmetry reversal in patients supports evolutionary postulates of schizophrenia pathogenesis.

Entorhinal Cortex Volume in Antipsychotic-naïve Schizophrenia

BACKGROUND

Entorhinal cortex (ERC), a multimodal sensory relay station for the hippocampus, is critically involved in learning, emotion, and novelty detection. One of the pathogenetic mechanistic bases in schizophrenia is proposed to involve aberrant information processing in the ERC. Several studies have looked at cytoarchitectural and morphometric changes in the ERC, but results have been inconsistent possibly due to the potential confounding effects of antipsychotic treatment.

MATERIALS AND METHODS

In this study, we have examined the entorhinal cortex volume in antipsychotic-naïve schizophrenia patients (n=40; M:F=22:18) in comparison with age, sex, and handedness, matched (as a group) with healthy subjects (n=42; M:F=25:17) using a valid method. 3-Tesla MR images with 1-mm sections were used and the data was analyzed using the SPSS software.

RESULTS

Female schizophrenia patients (1.25±0.22 mL) showed significant volume deficit in the right ERC in comparison with female healthy controls (1.45±0.34 mL) (F=4.9; P=0.03), after controlling for the potential confounding effects of intracranial volume. However, male patients did not differ from male controls. The left ERC volume did not differ between patients and controls.

CONCLUSIONS

Consistent with the findings of a few earlier studies we found a reduction in the right ERC volume in patients. However, this was limited to women. Contextually, our study finding supports the role for ERC deficit in schizophrenia pathogenesis - perhaps mediated through aberrant novelty detection. Sex-differential observation of ERC volume deficit in schizophrenia needs further studies.

Neurohemodynamic correlates of 'OM' chanting: A pilot functional magnetic resonance imaging study

Background:

A sensation of vibration is experienced during audible ‘OM’ chanting. This has the potential for vagus nerve stimulation through its auricular branches and the effects on the brain thereof. The neurohemodynamic correlates of ‘OM’ chanting are yet to be explored.

Materials and Methods:

Using functional Magnetic Resonance Imaging (fMRI), the neurohemodynamic correlates of audible ‘OM’ chanting were examined in right-handed healthy volunteers (n=12; nine men). The ‘OM’ chanting condition was compared with pronunciation of “ssss” as well as a rest state. fMRI analysis was done using Statistical Parametric Mapping 5 (SPM5).

Results:

In this study, significant deactivation was observed bilaterally during ‘OM’ chanting in comparison to the resting brain state in bilateral orbitofrontal, anterior cingulate, parahippocampal gyri, thalami and hippocampi. The right amygdala too demonstrated significant deactivation. No significant activation was observed during ‘OM’ chanting. In contrast, neither activation nor deactivation occurred in these brain regions during the comparative task – namely the ‘ssss’ pronunciation condition.

Conclusion:

The neurohemodynamic correlates of ‘OM’ chanting indicate limbic deactivation. As similar observations have been recorded with vagus nerve stimulation treatment used in depression and epilepsy, the study findings argue for a potential role of this ‘OM’ chanting in clinical practice.

Orbitofrontal Lobe Volume Deficits in Antipsychotic-Naïve Schizophrenia: A 3-Tesla MRI study

BACKGROUND

Prefrontal cortex deficits have been consistently demonstrated in schizophrenia. The orbitofrontal lobe (OFL), a critical component of the prefrontal cortex, subserves social and neuro-cognitive functions. While these functional impairments are established in schizophrenia, the OFL volume deficits have not been well studied, especially in antipsychotic-naïve patients.

AIM

To study OFL volume deficits in antipsychotic-naïve schizophrenia patients in comparison with matched healthy controls using high-resolution 3-tesla (3T) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Fourteen antipsychotic-naïve schizophrenia patients (DSM-IV) and 14 age-, sex-, handedness- and education-matched healthy controls were scanned using 3T MRI. Psychopathology was assessed in the patient group using the scale for assessment of negative symptoms and the scale for assessment of positive symptoms (SAPS). The OFL volume was measured using Region of Interest (ROI)-based manual morphometry technique, with good inter-rater reliability (intra-class correlation coefficient = 0.98).

RESULTS

Total OFL volume was significantly smaller in schizophrenia patients (43.3 ± 9.6 mL) in comparison with healthy controls (52.1 ± 12.2 mL) after controlling for the potential confounding effects of age, sex and intracranial volume (F = 5.3, P = .03). Duration of untreated psychosis did not correlate significantly with OFL volumes. There was a trend towards significant negative correlation between the left and total OFL volumes and SAPS scores (r = -0.49, P = .06).

CONCLUSION

OFL volume deficits might underlie the pathogenesis of schizophrenia symptoms with possible neuro-developmental origins.