A Neuregulin-1 schizophrenia susceptibility variant causes perihippocampal fiber tract anomalies in healthy young subjects

Cognitive Impairments Related to COMT and Neuregulin 1 Phenotypes as Transdiagnostic Markers in Schizophrenia Spectrum Patients

Background: Research on the interaction between antipsychotic treatment and cognitive dysfunction in schizophrenia spectrum disorders (SSDs) is extensive, yet the role of genetic polymorphisms in catechol-O-methyltransferase (COMT) and neuregulin 1 (NRG1) remains underexplored. Methods: This study evaluates the impact of COMT (rs4680) and NRG1 (rs3924999 and rs35753505) polymorphisms on cognitive functions in SSD patients. A cross-sectional study was conducted with fifty-four patients, assessed using the Positive and Negative Syndrome Scale (PANSS) and the CNS Vital Signs battery. Results: Significant cognitive function differences were observed across SSD diagnostic categories (p < 0.001). The NRG1 rs35753505 TT genotype was significantly associated with better verbal memory performance compared to the CC genotype (p = 0.03), while no significant differences were observed for other genotypes. The NRG1 rs3924999 AA genotype showed superior reasoning performance compared to AG and GG genotypes (p = 0.01), with AG and GG associated with lower scores (p = 0.01 and p = 0.02, respectively). Additionally, the COMT Val158Met genotype significantly influenced processing speed, with patients at the first episode of psychosis showing higher scores than chronic patients (p = 0.01). Conclusions: These findings suggest that NRG1 and COMT polymorphisms may influence cognitive domains in schizophrenia spectrum disorders, potentially informing personalized treatment and cognitive rehabilitation strategies.

Building better brains: the pleiotropic function of neurotrophic factors in postnatal cerebellar development

The cerebellum is a multifunctional brain region that controls diverse motor and non-motor behaviors. As a result, impairments in the cerebellar architecture and circuitry lead to a vast array of neuropsychiatric and neurodevelopmental disorders. Neurotrophins and neurotrophic growth factors play essential roles in the development as well as maintenance of the central and peripheral nervous system which is crucial for normal brain function. Their timely expression throughout embryonic and postnatal stages is important for promoting growth and survival of both neurons and glial cells. During postnatal development, the cerebellum undergoes changes in its cellular organization, which is regulated by a variety of molecular factors, including neurotrophic factors. Studies have shown that these factors and their receptors promote proper formation of the cerebellar cytoarchitecture as well as maintenance of the cerebellar circuits. In this review, we will summarize what is known on the neurotrophic factors' role in cerebellar postnatal development and how their dysregulation assists in developing various neurological disorders. Understanding the expression patterns and signaling mechanisms of these factors and their receptors is crucial for elucidating their function within the cerebellum and for developing therapeutic strategies for cerebellar-related disorders.

Correlation of rs35753505 polymorphism in Neuregulin 1 gene with psychopathology and intelligence of people with schizophrenia

BACKGROUND AND AIM

Schizophrenia is one of the most severe psychiatric disorders. About 0.5 to 1% of the world's population suffers from this non-Mendelian disorder. Environmental and genetic factors seem to be involved in this disorder. In this article, we investigate the alleles and genotypic correlation of mononucleotide rs35753505 polymorphism of Neuregulin 1 (NRG1), one of the selected genes of schizophrenia, with psychopathology and intelligence.

MATERIALS AND METHODS

102 independent and 98 healthy patients participated in this study. DNA was extracted by the salting out method and the polymorphism (rs35753505) were amplified by polymerase chain reaction (PCR). Sanger sequencing was performed on PCR products. Allele frequency analysis was performed using COCAPHASE software, and genotype analysis was performed using Clump22 software.

RESULTS

According to our study's statistical findings, all case samples from the three categories of men, women, and overall participants significantly differed from the control group in terms of the prevalence of allele C and the CC risk genotype. The rs35753505 polymorphism significantly raised Positive and Negative Syndrome Scale (PANSS) test results, according to a correlation analysis between the two variables. However, this polymorphism led to a significant decrease in overall intelligence in case samples compared to control samples.

CONCLUSION

In this study, it seems that the rs35753505 polymorphism of NRG1 gene has a significant role in the sample of patients with schizophrenia in Iran and also in psychopathology and intelligence disorders.

Brain Network Simulations Indicate Effects of Neuregulin-1 Genotype on Excitation-Inhibition Balance in Cortical Dynamics

Neuregulin-1 (NRG1) represents an important factor for multiple processes including neurodevelopment, brain functioning or cognitive functions. Evidence from animal research suggests an effect of NRG1 on the excitation-inhibition (E/I) balance in cortical circuits. However, direct evidence for the importance of NRG1 in E/I balance in humans is still lacking. In this work, we demonstrate the application of computational, biophysical network models to advance our understanding of the interaction between cortical activity observed in neuroimaging and the underlying neurobiology. We employed a biophysical neuronal model to simulate large-scale brain dynamics and to investigate the role of polymorphisms in the NRG1 gene (rs35753505, rs3924999) in n = 96 healthy adults. Our results show that G/G-carriers (rs3924999) exhibit a significant difference in global coupling (P = 0.048) and multiple parameters determining E/I-balance such as excitatory synaptic coupling (P = 0.047), local excitatory recurrence (P = 0.032) and inhibitory synaptic coupling (P = 0.028). This indicates that NRG1 may be related to excitatory recurrence or excitatory synaptic coupling potentially resulting in altered E/I-balance. Moreover, we suggest that computational modeling is a suitable tool to investigate specific biological mechanisms in health and disease.

Genetic variation in NRG 1 gene and risk of post-traumatic stress disorders in patients with hepatocellular carcinoma

Objective

Neuregulin 1 (NRG1) was proved to play an important role in numerous neurodevelopmental processes. In our study, we aimed to investigate the relationship between the NRG1 gene polymorphism and the cognitive function of patients with hepatocellular carcinoma (HCC) complicated with post‐traumatic stress disorders (PTSD) before and after the psychological intervention.

Methods

Mini‐mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) were used for cognitive function assessment. Serum level of NRG1 was detected by ELISA, and the correlation between NRG1 level and cognitive function was analyzed. The difference of cognitive function score of patients with HCC complicated with PTSD before and after psychological intervention was compared, and the relationship between rs35753505 and rs3924999 polymorphism with the score was analyzed.

Results

Patients with HCC complicated with PTSD showed decreased serum NRG1 level. NRG1 levels of patients in the HCC + PTSD group were positively correlated with MMSE, MoCA, and LOTCA scores. In rs35753505, the CC genotype was a risk factor for the occurrence of PTSD in patients with HCC, while in rs3924999, the GG genotype was a risk factor for the occurrence of PTSD in patients with HCC. After psychological intervention, the CC genotype at rs35753505 and the GG genotype at rs3924999 were susceptible genotypes.

Conclusion

CC genotype at rs35753505 and GG genotype at rs3924999 of NRG1 gene increased the risk of PTSD in patients with HCC. CC and GG genotypes were susceptible after psychological intervention.

Causes of Sudden Unexpected Death in Schizophrenia Patients: A Forensic Autopsy Population Study

BACKGROUND

Schizophrenia is a detrimental psychiatric disorder, with an increased mortality from natural and nonnatural causes.

METHODS

This study was a retrospective review of autopsy cases of all the individuals with history of schizophrenia investigated by the Office of the Chief Medical Examiner, State of Maryland, for a 5-year period from 2008 to 2012.

RESULT

A total of 391 schizophrenia patients were autopsied at the Office of the Chief Medical Examiner because they died suddenly and unexpectedly. Their age ranged from 15 to 100 years with the mean age of 49.5 years. Of the 391 deaths, 191 (48.8%) were white, 185 (47.3%) were African American, and 15 (3.9%) were either Hispanic or Asian. The male and female ratio was 1.5:1. The majority of deaths (64.2%) were caused by natural diseases, 12.0% deaths were accidents, 11.5% deaths were suicides, and 9.7% deaths were homicides. The manner of death remained undetermined in 38 cases (9.7%). Of the 251 natural deaths, 198 cases (78.9%) were owing to cardiovascular diseases. Cause of death was listed as cardiac arrhythmia in 11 cases. This diagnosis of cardiac arrhythmia was made by exclusion based on death scene investigation, review of medical history, complete autopsy, and toxicological tests. Drug intoxication was the second most common cause of death.

CONCLUSIONS

The study shows high fatality caused by cardiovascular diseases and drug intoxication among schizophrenia patients, which calls attention of the medical community to closely monitor the high risk factors of sudden death among schizophrenia patients.

Discoidin domain receptor 1 gene variants are associated with decreased white matter fractional anisotropy and decreased processing speed in schizophrenia

DDR1 has been linked to schizophrenia (SZ) and myelination. Here, we tested whether DDR1 variants in people at risk for SZ influence white matter (WM) structural variations and cognitive processing speed (PS). First, following a case-control design (Study 1), SZ patients (N = 1193) and controls (N = 1839) were genotyped for rs1264323 and rs2267641 at DDR1, and the frequencies were compared. We replicated the association between DDR1 and SZ (rs1264323, adjusted P = 0.015). Carriers of the rs1264323AA combined with the rs2267641AC or CC genotype are at risk to develop SZ compared to the other genotype combinations. Second, SZ patients (Study 2, N = 194) underwent an evaluation of PS using the Trail Making Test (TMT) and DDR1 genotyping. To compare PS between DDR1 genotype groups, we conducted an analysis of covariance (including rs1264323 as a covariate) and found that SZ patients with the rs2267641CC genotype had decreased PS compared to patients with the AA and AC genotypes. Third, 54 patients (Study 3) from Study 2 were selected based on rs1264323 genotype to undergo reevaluation, including a DTI-MRI brain scan. To test for associations between PS, WM microstructure and DDR1 genotype, we first localized those WM regions where fractional anisotropy (FA) was correlated with PS and tested whether FA showed differences between the rs1264323 genotypes. SZ patients with the rs1264323AA genotype showed decreased FA in WM regions associated with decreased PS. We conclude that DDR1 variants may confer a risk of SZ through WM microstructural alterations leading to cognitive dysfunction.

Gene polymorphisms and response to transcranial direct current stimulation for auditory verbal hallucinations in schizophrenia

OBJECTIVE

Recent observations demonstrate a significant ameliorative effect of add-on transcranial direct current stimulation (tDCS) on auditory verbal hallucinations (AVHs) in schizophrenia. Of the many SNPs, NRG1 rs35753505 and catechol-o-methyl transferase (COMT) rs4680 polymorphisms have shown to have a strong association with neuroplasticity effect in schizophrenia.

METHODS

Schizophrenia patients (n=32) with treatment resistant auditory hallucinations were administered with an add-on tDCS. The COMT (rs4680) and NRG1 (rs35753505) genotypes were determined. The COMT genotypes were categorised into Val group (GG; n=15) and Met group (GG/AG; n=17) and NRG1 genotypes were categorised into AA group (n=12) and AG/GG group (n=20).

RESULTS

The reduction in auditory hallucination sub-scale score was significantly affected by COMT-GG genotype [Time×COMT interaction: F(1,28)=10.55, p=0.003, ɳ2=0.27]. Further, COMT-GG effect was epistatically influenced by the co-occurrence of NRG1-AA genotype [Time×COMT×NRG1 interaction: F(1,28)=8.09, p=0.008, ɳ2=0.22]. Irrespective of genotype, females showed better tDCS response than males [Time×Sex interaction: F(1,21)=4.67, p=0.04, ɳ2=0.18].

CONCLUSION

COMT-GG and NRG1-AA genotypes aid the tDCS-induced improvement in AVHs in schizophrenia patients. Our preliminary observations need replication and further systematic research to understand the neuroplastic gene determinants that modulate the effect of tDCS.

Neuregulin-1 (NRG1) polymorphisms linked with psychosis transition are associated with enlarged lateral ventricles and white matter disruption in schizophrenia

BACKGROUND

Two single-nucleotide polymorphisms (SNPs) (rs4281084 and rs12155594) within the neuregulin-1 (NRG1) gene have been associated with psychosis transition. However, the neurobiological changes associated with these SNPs remain unclear. We aimed to determine what relationship these two SNPs have on lateral ventricular volume and white matter integrity, as abnormalities in these brain structures are some of the most consistent in schizophrenia.

METHODS

Structural (n = 370) and diffusion (n = 465) magnetic resonance imaging data were obtained from affected and unaffected individuals predominantly of European descent. The SNPs rs4281084, rs12155594, and their combined allelic load were examined for their effects on lateral ventricular volume, fractional anisotropy (FA) as well as axial (AD) and radial (RD) diffusivity. Additional exploratory analyses assessed NRG1 effects on gray matter volume, cortical thickness, and surface area throughout the brain.

RESULTS

Individuals with a schizophrenia age of onset ⩽25 and a combined allelic load ⩾3 NRG1 risk alleles had significantly larger right (up to 50%, p adj = 0.01) and left (up to 45%, p adj = 0.05) lateral ventricle volumes compared with those with allelic loads of less than three. Furthermore, carriers of three or more risk alleles, regardless of age of onset and case status, had significantly reduced FA and elevated RD but stable AD in the frontal cortex compared with those carrying fewer than three risk alleles.

CONCLUSIONS

Our findings build on a growing body of research supporting the functional importance of genetic variation within the NRG1 gene and complement previous findings implicating the rs4281084 and rs12155594 SNPs as markers for psychosis transition.

Polymorphisms of dopamine pathway genes NRG1 and LMX1A are associated with cognitive performance in bipolar disorder

OBJECTIVES

LIM homeobox transcription factor 1, alpha (LMX1A) and neuregulin 1 (NRG1) are susceptibility genes for schizophrenia that have been implicated in the dopaminergic pathway and have been associated with altered cognitive functioning. We hypothesized that single nucleotide polymorphisms (SNPs) in LMX1A and NRG1 would be associated with cognitive functioning in bipolar disorder.

METHODS

In total, four SNPs were directly genotyped. Regression models with five aggregated cognitive domains and intelligence quotient (IQ) score were run using risk variants of LMX1A (rs11809911, rs4657412, rs6668493) and NRG1 (rs35753505) as predictors. Models were performed in a clinical sample of patients with bipolar disorder (n = 114) and healthy controls (n = 104).

RESULTS

The risk variants of the rs11809911 SNP in LMX1A were negatively associated with IQ score and memory/learning, whereas the risk variants of rs35753505 in NRG1 were positively associated with IQ score (adjusted R(2) = 0.17, Q = 0.006) and memory/learning (adjusted R(2) = 0.24, Q = 0.001). The risk variants of the rs35753505 SNP in NRG1 were positively associated with language (adjusted R(2) = 0.11, Q = 0.006), visuospatial functions (adjusted R(2) = 0.23, Q = 0.001), and attention/speed (adjusted R(2) = 0.25, Q = 0.001). Results could not be replicated in controls.

CONCLUSIONS

The risk variants of the rs35753505 SNP were associated with increased performance in several cognitive domains and IQ, whereas the risk variants of the rs11809911 SNP in LMX1A was associated with reduced IQ and memory/learning.

Neuregulin-1 protects against acute optic nerve injury in rat model

OBJECTIVES

In this study, we employed a rat model and examined the expression pattern of neuregulin-1 (NRG-1) in optic nerve and retinal ganglion cells (RGCs) in response to optic nerve injury to understand the role of NRG-1 in conferring protection against acute optic nerve injury.

METHOD

Forty-eight male rats were randomly divided into two groups, the sham-operation group (n=24) and optic nerve injury group (n=24). Flash visual evoked potentials (FVEP) and fundography images were acquired at different time points following optic nerve injury (2h, 1d, 2d, 7d, 14d and 28d). Semi-quantitative analysis of NGR-1 expression pattern was performed by immunohistochemistry (IHC) staining. In a related experiment, 100 male rats were randomly divided into NGR-1 treatment group (n=60) (treated with increasing dose of NGR-1 at 0.5μg, 1μg and 3μg), normal saline (NS) group (n=20) and negative control group (n=20). Optic nerve injury was induced in all the animals and in situ cell death was measured by detecting the apoptosis rates using TUNEL assay.

RESULTS

Fundus photography results revealed no detectable differences between the sham-operation group and optic nerve injury group at 2h, 1d, 2d and 7d. However at 2weeks, the optic discs turned pale in all animals in the optic nerve injury group. NRG-1 expression increased significantly at all time points in the optic nerve injury group (P<0.05), compared to the sham-operation group, with NRG-1 expression peaking at 14d and gradually declining by 28d. Statistically significant differences in amplitude and latency of P100 wave were also detected between the optic nerve injury and sham-operation group (P<0.05). In related experiment, compared to NS group, treatment with 1μg and 3μg of recombinant human NRG-1 resulted in statistically significant FVEP-P100 amplitude values (all P<0.05). Further, compared to the NS group, ganglion cell apoptosis was dramatically reduced in the NRG-1 group at all time points and the reduction was statistically significant in 3μg NRG-1 treatment group at 7d, 14d and 28d (all P<0.05).

CONCLUSION

Our results strongly suggest that NRG-1 is highly effective in preserving normal optic nerve function and is essential for tissue repair following optic nerve injury. Thus, NRG-1 expression confers protection against acute optic nerve injury in a dose-dependent manner.

Genetic variation in the G72 gene is associated with increased frontotemporal fiber tract integrity

G72 (syn. DAOA, D-amino acid oxidase activator) is a susceptibility gene for both schizophrenia and bipolar disorder. Diffusion tensor imaging studies hint at changes in fiber tract integrity in both disorders. We aimed to investigate whether a G72 susceptibility haplotype causes changes in fiber tract integrity in young healthy subjects. We compared fractional anisotropy in 47 subjects that were either homozygous for the M23/M24 risk haplotype (n = 20) or homozygous for M23(rs3918342)/M24(rs1421292) wild type (n = 27) using diffusion tensor imaging with 3 T. Tract-based spatial statistics, a method especially developed for diffusion data analysis, was used to delineate the major fiber tracts. We found clusters of increased FA values in homozygous risk haplotype carriers in the right periinsular region and in the right inferior parietal lobe (IPL). We did not find clusters indicating decreased FA values. The insula and the IPL have been implicated in both schizophrenia and bipolar pathophysiology. Increased FA values might reflect changes in dendritic morphology as previously described by in vitro studies. These findings further corroborate the hypothesis that a shared gene pool between schizophrenia and bipolar disorder might lead to neuroanatomic changes that confer an unspecific vulnerability for both disorders.