COMT, neuropsychological function and brain structure in schizophrenia: a systematic review and neurobiological interpretation

Meta-analysis of structural and functional brain abnormalities in early-onset schizophrenia

Background

Previous studies based on resting-state functional magnetic resonance imaging(rs-fMRI) and voxel-based morphometry (VBM) have demonstrated significant abnormalities in brain structure and resting-state functional brain activity in patients with early-onset schizophrenia (EOS), compared with healthy controls (HCs), and these alterations were closely related to the pathogenesis of EOS. However, previous studies suffer from the limitations of small sample sizes and high heterogeneity of results. Therefore, the present study aimed to effectively integrate previous studies to identify common and specific brain functional and structural abnormalities in patients with EOS.

Methods

The PubMed, Web of Science, Embase, Chinese National Knowledge Infrastructure (CNKI), and WanFang databases were systematically searched to identify publications on abnormalities in resting-state regional functional brain activity and gray matter volume (GMV) in patients with EOS. Then, we utilized the Seed-based d Mapping with Permutation of Subject Images (SDM-PSI) software to conduct a whole-brain voxel meta-analysis of VBM and rs-fMRI studies, respectively, and followed by multimodal overlapping on this basis to comprehensively identify brain structural and functional abnormalities in patients with EOS.

Results

A total of 27 original studies (28 datasets) were included in the present meta-analysis, including 12 studies (13 datasets) related to resting-state functional brain activity (496 EOS patients, 395 HCs) and 15 studies (15 datasets) related to GMV (458 EOS patients, 531 HCs). Overall, in the functional meta-analysis, patients with EOS showed significantly increased resting-state functional brain activity in the left middle frontal gyrus (extending to the triangular part of the left inferior frontal gyrus) and the right caudate nucleus. On the other hand, in the structural meta-analysis, patients with EOS showed significantly decreased GMV in the right superior temporal gyrus (extending to the right rolandic operculum), the right middle temporal gyrus, and the temporal pole (superior temporal gyrus).

Conclusion

This meta-analysis revealed that some regions in the EOS exhibited significant structural or functional abnormalities, such as the temporal gyri, prefrontal cortex, and striatum. These findings may help deepen our understanding of the underlying pathophysiological mechanisms of EOS and provide potential biomarkers for the diagnosis or treatment of EOS.

Early- and late-phase changes of brain activity and early-phase neuromodulation in the posttraumatic stress disorder rat model

Posttraumatic stress disorder (PTSD) is a complex syndrome that may occur after life-threatening events. Fear memory abnormalities may play vital roles in the pathogenesis of PTSD. Previous work has found that fear memories are not rigid; the retrieval of fear memories may change over time. Furthermore, prior studies suggest that theta wave (4 Hz) activity is highly correlated with fear expression in an animal model. However, the relationship between pathological fear memory and potential brain wave features in PTSD remains largely uncharacterized. Here, we hypothesized that after traumatic stress exposure, the longitudinal dynamics of abnormal fears in PTSD animal models could be reflected by the measurement of local field potentials (LFPs). Using a well-established modified single-prolonged stress and footshock (SPS & FS) PTSD rat model, animals were restrained for 2 h and subsequently subjected to 20 min of forced swimming, then exposed to diethyl ether until they lost consciousness and placed in a conditioning chamber for fear conditioning. To characterize the temporal changes, we characterized freezing behavior brain wave features during the conditioning chamber re-exposure in the early (10 and 30 min; 2, 4, and 6 h) and late (day 1, 3, 7, and 14) phases after traumatic stress exposure. Our results indicate that SPS & FS rats showed co-morbid PTSD phenotypes including significantly higher levels of anxiety-, depression-, and anhedonia-like behaviors, and impaired fear extinction. Delta wave (0.5-4 Hz) suppression in the medial prefrontal cortex, amygdala, and ventral hippocampus occurred 10 and 30 min after traumatic stress, followed by continuous delta wave activity from 2 h to day 14, correlating with fear levels. tDCS reduced delta activity and alleviated PTSD-like phenotypes in the SPS & FS group. In this study, profiling abnormal fears with brain wave correlates may improve our understanding of time-dependent pathological fear memory retrieval in PTSD and facilitate the development of effective intervention strategies.

COMT Val158Met and BDNF Val66Met Single-Nucleotide Polymorphisms Are Not Associated With Emotional Distress One Year After Moderate-Severe Traumatic Brain Injury

Emotional distress is a common, but poorly addressed, feature of moderate-severe traumatic brain injury (TBI). Previously identified sociodemographic, psychological, and injury-related factors account for only a small proportion of the variability in emotional distress post-TBI. Genetic factors may help to further understand emotional distress in this population. The catechol-O-methyltransferase (COMT) Val158 and brain-derived neurotrophic factor (BDNF) 66Met single-nucleotide polymorphisms (SNPs) have been identified as possible contributory factors to outcomes after TBI. We investigated whether the COMT Val158 and BDNF 66Met SNPs were associated with emotional distress 1 year after moderate-severe TBI, and whether these associations were moderated by age, sex, and TBI severity (as measured by the duration of post-traumatic amnesia [PTA]). Moderate-severe TBI survivors (COMT, n = 391; BDNF, n = 311) provided saliva samples after admission to a TBI rehabilitation hospital. At a follow-up interview ∼1 year after injury, participants completed a self-report measure of emotional distress (Hospital Anxiety and Depression Scale; HADS). Multiple linear regression models were constructed for each SNP to predict total scores on the HADS. Neither COMT Val158 nor BDNF 66Met carriage status (carrier vs. non-carrier) significantly predicted emotional distress (COMT, p = 0.49; BDNF, p = 0.66). Interactions of SNP × age (COMT, p = 0.90; BDNF, p = 0.93), SNP × sex (COMT, p = 0.09; BDNF, p = 0.60), SNP × injury severity (COMT, p = 0.53; BDNF, p = 0.87), and SNP × sex × age (COMT, p = 0.08; BDNF, p = 0.76) were also non-significant. Our null findings suggest that COMT Val158 and BDNF 66Met SNPs do not aid the prediction of emotional distress 1 year after moderate-severe TBI, neither in isolation nor in interaction with age, sex and injury severity. The reporting of null findings such as ours is important to avoid publication bias and prompt researchers to consider the challenges of single-gene candidate studies in understanding post-TBI outcomes. Analyses in larger samples that incorporate multiple genetic factors and their relevant moderating factors may provide a greater understanding of the role of genetics in post-TBI emotional distress.

Prognostic and immunomodulatory roles of schizophrenia-associated genes HTR2A, COMT, and PRODH in pan-cancer analysis and glioma survival prediction model

Background

The shortened life expectancy in schizophrenia (SCZ) patients may be correlated with most cancers, yet there is heterogeneity in the studies examining these correlations. This study explored the expression of SCZ-related genes (HTR2A, COMT, and PRODH) in pan-cancer analysis. It helped to enhance the mechanistic understanding of the SCZ-cancer relationship and their immune mechanisms at the genetic level. Additionally, this study established a survival prediction model for glioblastoma and low-grade glioma (GBMLGG).

Methods and results

SCZ-associated genes (HTR2A, COMT, and PRODH) were subjected to pan-cancer analysis. COX regression analysis and survival analysis were carried out for differentially expressed genes in multiple cancers, and finally, GBMLGG was derived as the focus for further detailed analysis. The immune scores and immune cell infiltration analyses were performed. All three genes were considerably linked with immune infiltration in GBMLGG, consistent with survival analysis. Based on the immunocyte analysis, it was observed that CD8+ T cells might be critically involved in the survival of GBMLGG. Genomic heterogeneity studies identified correlations of three genes with GBMLGG in tumor mutational burden (TMB) and mutant-allele tumor heterogeneity (MATH). HTR2A and COMT were significantly negatively correlated in TMB. Furthermore, it was found that HTR2A had a significant positive correlation with MATH, whereas PRODH had a significant negative correlation with MATH. Accordingly, a survival prediction model was constructed for GBMLGG using these three genes and clinical data, with better results obtained when evaluated in two separate datasets. Finally, gene expression validation and further immunocyte analysis were carried out in the single-cell RNA sequencing (scRNA-seq) data of glioma.

Conclusion

SCZ-associated genes (HTR2A, COMT, and PRODH) were significantly differentially expressed in the carcinogenesis and survival of multiple cancers. The up or downregulation of gene expression varied across cancer types. In the GBMLGG analysis, upregulation of HTR2A and COMT was significantly positively correlated with carcinogenesis, while the opposite was noted for PRODH. Furthermore, a negative correlation was found between the upregulation of HTR2A and COMT and the survival of GBMLGG, and the opposite was also noted for PRODH. As reflected in the immunocyte analysis, abnormal expression of the three genes might be linked with CD8+ T cell infiltration, which might be critically involved in the survival of GBMLGG patients. The expression of HTR2A and COMT may inversely affect the efficacy of immunotherapy through the TMB pathway and further affect the prognosis of patient survival. The expression of HTR2A might positively indicate the degree of tumor heterogeneity through MATH and further affect the survival and prognosis of patients. The negative correlation of PRODH led to the opposite effect. Finally, the constructed survival prediction model demonstrated good predictive value, which was well validated in scRNA-seq analysis.

Pharmacogenetic Guided Opioid Therapy Improves Chronic Pain Outcomes and Comorbid Mental Health: A Randomized, Double-Blind, Controlled Study

Interindividual variability in analgesic response is at least partly due to well-characterized polymorphisms that are associated with opioid dosing and adverse outcomes. The Clinical Pharmacogenetics Implementation Consortium (CPIC) has put forward recommendations for the CYP2D6 phenotype, but the list of studied drug-gene pairs continues to grow. This clinical trial randomized chronic pain patients (n = 60), referred from primary care to pain unit care into two opioid prescribing arms, one guided by CYP2D6, μ-opioid receptor (OPRM1), and catechol-O-methyl transferase (COMT) genotypes vs. one with clinical routine. The genotype-guided treatment reduced pain intensity (76 vs. 59 mm, p < 0.01) by improving pain relief (28 vs. 48 mm, p < 0.05), increased quality of life (43 vs. 56 mm p < 0.001), and lowered the incidence of clinically relevant adverse events (3 [1-5] vs. 1 [0-2], p < 0.01) and 42% opioid dose (35 [22-61] vs. 60 [40-80] mg/day, p < 0.05) as opposed to usual prescribing arm. The final health utility score was significantly higher (0.71 [0.58-0.82] vs. 0.51 [0.13-0.67] controls, p < 0.05) by improving sleepiness and depression comorbidity, with a significant reduction of 30-34% for headache, dry mouth, nervousness, and constipation. A large-scale implementation analysis could help clinical translation, together with a pharmaco-economic evaluation.

COMT but Not 5HTTLPR Gene Is Associated with Depression in First-Episode Psychosis: The Role of Stressful Life Events

Serotonergic and dopaminergic systems are involved in the regulation of mood and reactivity to psychological stress. This study explores, in a sample of first episode psychosis (FEP) patients, whether more severe depressive symptoms were found in those who: (1) experienced a major stressful event in the 6 months preceding illness onset; and (2) were homozygous for the COMT Val158 allele or carrying the S allele of 5-HTTLPR. A total of 186 FEP patients recruited were assessed using the Hamilton Rating Scale for Depression (HAMD) for depressive symptoms. Stressful life events (SLEs) were collected by the List of Events Scale. The genotypes of 5-HTTLPR, rs25531, and COMT Val158 Met were performed. It has been found that higher levels of depression is associated with the presence of SLEs (p = 0.019) and with COMT Val158 allele homozygosity (p = 0.029), but not with carrying the S allele of 5-HTTLPR. The COMT gene moderates the association between depression and SLEs as Val158 allele homozygote patients experiencing SLEs had the highest level of depressive symptoms compared to the others (p = 0.002). The present study provides initial evidence for an effect of the COMT Val158 homozygosity and severe stressful life events on the severity of depressive symptoms in first episode psychosis.

Effects of psychosis-associated genetic markers on brain volumetry: a systematic review of replicated findings and an independent validation

BACKGROUND

Given psychotic illnesses' high heritability and associations with brain structure, numerous neuroimaging-genetics findings have been reported in the last two decades. However, few findings have been replicated. In the present independent sample we aimed to replicate any psychosis-implicated SNPs (single nucleotide polymorphisms), which had previously shown at least two main effects on brain volume.

METHODS

A systematic review for SNPs showing a replicated effect on brain volume yielded 25 studies implicating seven SNPs in five genes. Their effect was then tested in 113 subjects with either schizophrenia, bipolar disorder, 'at risk mental state' or healthy state, for whole-brain and region-of-interest (ROI) associations with grey and white matter volume changes, using voxel-based morphometry.

RESULTS

We found FWER-corrected (Family-wise error rate) (i.e. statistically significant) associations of: (1) CACNA1C-rs769087-A with larger bilateral hippocampus and thalamus white matter, across the whole brain; and (2) CACNA1C-rs769087-A with larger superior frontal gyrus, as ROI. Higher replication concordance with existing literature was found, in decreasing order, for: (1) CACNA1C-rs769087-A, with larger dorsolateral-prefrontal/superior frontal gyrus and hippocampi (both with anatomical and directional concordance); (2) ZNF804A-rs11681373-A, with smaller angular gyrus grey matter and rectus gyri white matter (both with anatomical and directional concordance); and (3) BDNF-rs6265-T with superior frontal and middle cingulate gyri volume change (with anatomical and allelic concordance).

CONCLUSIONS

Most literature findings were not herein replicated. Nevertheless, high degree/likelihood of replication was found for two genome-wide association studies- and one candidate-implicated SNPs, supporting their involvement in psychosis and brain structure.

The effects of catechol-O-methyltransferase single nucleotide polymorphisms on positive and negative symptoms of schizophrenia: A systematic review and meta-analysis

The catechol-O-methyltransferase (COMT) gene is thought to have an important role in the etiopathogenesis of schizophrenia, but there are conflicting results regarding its role in clinical presentation. We aimed to elucidate the relationship between the single nucleotide polymorphisms (SNPs) in the COMT gene and the severity of positive and negative symptoms. In order to investigate the relationship, the PubMed, PubMed Central, Scopus, and Cochrane CENTRAL databases were screened for eligible articles. Thirty-eight studies, including 4443 adult patients with schizophrenia, were included in the quantitative analyses, and four studies were qualitatively assessed. Quantitative analyses were performed for acutely ill and clinically stable patient subgroups regarding the different genotypes of rs4680 SNP. Our results showed that the severity of negative symptoms was higher in patients who were rs4680 Met homozygous compared to Val/Met heterozygotes only in acutely ill samples. There was no other significant difference between genotypes. Meta-regression did not reveal any significant moderator effect on the difference in negative symptoms. General psychopathology, positive, negative, and total psychotic symptom levels also were similar between Val homozygotes and Met carriers. Nonetheless, there are some limitations in the study. First, SNPs except for rs4680 were under-researched because of the limited number of studies. Second, high heterogeneity across studies was the main concern. Our results suggested that the COMT rs4680 Met allele was associated with higher levels of negative symptoms within acutely ill patients. Future studies should focus on specific patient subgroups to reveal the moderating effects of SNPs.

Prefrontal abnormalities, executive dysfunction and symptoms severity are modulated by COMT Val158Met polymorphism in first episode psychosis

INTRODUCTION

Core dysfunctions proposed for psychotic disorders include prefrontal cortex (PFC) dopaminergic hypoactivity, executive function (EF) deficits and reduced gray matter in the PFC. The Val variant of COMT Val₁₅₈Met polymorphism is associated with reduced dopaminergic signaling in the PFC. However, it is unclear how COMT Val₁₅₈Met modulates PFC gray matter reduction, EF deficits and symptom severity at the time of the first psychotic episode.

METHODS

The effect of COMT on both EF performance and prefrontal volume (PFC-VOL) was tested in 158 first episode psychosis (FEP) patients and 141 healthy controls (HC) matched for age (range 9-35 years), sex, ethnicity, handedness and COMT Val₁₅₈Met distribution. EF and PFC-VOL were compared between FEP and HC groups within each polymorphism status (Met/Met versus Val carriers) to assess whether COMT influenced diagnostic differences. Next, correlations between PFC-VOL and EF performance were computed, as well as between both variables and other clinical characteristics of interest (PANSS scores, PAS infancy and premorbid IQ) in the FEP sample.

RESULTS

COMT influenced the diagnostic differences mainly in PFC-VOL, but also in EF performance. FEP-Val carriers showed lower EF scores and reduced PFC-VOL compared to the HC group but also poorer EF performance than FEP Met/Met. Poorer EF performance was associated with smaller PFC-VOL, and both were related to increased severity of negative symptoms, poorer premorbid adjustment, and lower estimated premorbid IQ in FEP patients.

CONCLUSIONS

Our findings suggest that COMT Val₁₅₈Met polymorphism might contribute to PFC-VOL reductions, executive dysfunctions and symptom severity in FEP patients.

Genetics of menstrual migraine and their association with female hormonal factors

Perimenopause is linked to increased migraine (Mg), especially menstrual Mg (MMg), influenced by hormonal changes. Compared to nonmenstrual attacks, menstrual attacks are more disabling and less responsive to treatment. Women with perimenstrual estrogen withdrawal have been linked to Mg during menstruation, whereas Mg during perimenopause has been linked to unpredictable fluctuations in estrogen levels. It has been widely established that female sex hormones play a role in Mg, but how it occurs remains unclear. This narrative review was identified using Medline and PubMed searches between 1946 and 2021. Search terms included “headache,” “migraine,” “menstrual migraine,” “menstruation,” “menopause,” “perimenopause,” “estrogen,” and “progesterone.” This article focuses on the candidate genes and female hormones that play a role in MMg. More study is necessary to understand better the environmental components that play a critical role in disease development. Currently, there is insufficient clinical evidence to support the function of menstrual Mg. The specific research facts examined MMg unique candidate genes and female hormonal factors that support their association and found MMg etiologic processes for generating an early diagnostic marker.

A Systematic Review of Cognition-Brain Morphology Relationships on the Schizophrenia-Bipolar Disorder Spectrum

The nature of the relationship between cognition and brain morphology in schizophrenia-spectrum disorders (SSD) and bipolar disorder (BD) is uncertain. This review aimed to address this, by providing a comprehensive systematic investigation of links between several cognitive domains and brain volume, cortical thickness, and cortical surface area in SSD and BD patients across early and established illness stages. An initial search of PubMed and Scopus databases resulted in 1486 articles, of which 124 met inclusion criteria and were reviewed in detail. The majority of studies focused on SSD, while those of BD were scarce. Replicated evidence for specific regions associated with indices of cognition was minimal, however for several cognitive domains, the frontal and temporal regions were broadly implicated across both recent-onset and established SSD, and to a lesser extent BD. Collectively, the findings of this review emphasize the significance of both frontal and temporal regions for some domains of cognition in SSD, while highlighting the need for future BD-related studies on this topic.

An Integrated Account of Expert Perspectives on Functioning in Schizophrenia

An integrated and interdisciplinary care system for individuals with schizophrenia is essential, which implies the need for a tool that assesses the difficulties and contextual factors of relevance to their functioning, and facilitates coordinated working across the different professions involved in their care. The International Classification of Functioning, Disability and Health Core Sets (ICF-CS) cover these requirements. This study aimed to evaluate the content validity of the ICF-CSs for schizophrenia from the perspective of experts. Six three-round Delphi studies were conducted with expert panels from different professional backgrounds which have played a significant role in the treatment of individuals with schizophrenia (psychiatry, psychology, nursing, occupational therapy, social work and physiotherapy). In total, 790 experts from 85 different countries participated in the first round. In total, 90 ICF categories and 28 Personal factors reached expert consensus (reached consensus from four or more professional perspectives). All the categories in the brief version of the ICF-CS for schizophrenia reached consensus from all the professional perspectives considered. As for the comprehensive version, 89.7% of its categories reached expert consensus. The results support the worldwide content validity of the ICF-CSs for schizophrenia from an expert perspective and underline the importance of assessing functioning by considering all the components implied.

Critical review of the evidence base regarding theories conceptualising the aetiology of psychosis

A critical review of literature related to the aetiology of psychosis was conducted with specific emphasis on genetics. It was found that, although many published articles were retrieved via database searches, the format of the information was disparate in presentation leading to unnecessary inconsistences. This suggests the need for insightful collaboration by authors and standardisation of published articles to prevent academic and specialism barriers remaining as a discouragement to non-specialists wishing to access this information.

Interacting Roles of COMT and GAD1 Genes in Patients with Treatment-Resistant Schizophrenia: a Genetic Association Study of Schizophrenia Patients and Healthy Controls

The projection from dopaminergic neurons to gamma-aminobutyric acid (GABA) interneurons in the prefrontal cortex is involved in the etiology of schizophrenia. The impact of interacting effects between dopamine signals and the expression of GABA on the clinical phenotypes of schizophrenia has not been studied. Since these interactions could be closely involved in prefrontal cortex functions, patients with specific alleles of these relevant molecules (which lead to lower or vulnerable genetic functions) may develop treatment-refractory symptoms. We conducted a genetic association study focusing on COMT and GAD1 genes for a treatment-resistant schizophrenia (TRS) group (n=171), a non-TRS group (n=592), and healthy controls (HC: n=447), and we examined allelic combinations specific to TRS. The results revealed that the percentage of subjects with Met allele of rs4680 on the COMT gene and C/C homozygote of rs3470934 on the GAD1 gene was significantly higher in the TRS group than the other two groups. There was no significant difference between the non-TRS group and HC groups. Considering the direction of functions of these single-nucleotide polymorphisms revealed by previous studies, we speculate that subjects with the Met/CC allelic combination could have a higher dopamine level and a lower expression of GABA in the prefrontal cortex. Our results suggest that an interaction between the dopaminergic signal and GABA signal intensities could differ between TRS patients and patients with other types of schizophrenia and healthy subjects.

The Gene Polymorphism of VMAT2 Is Associated with Risk of Schizophrenia in Male Han Chinese

OBJECTIVE

To investigate the association between gene polymorphism of vesicular monoamine transporter type 2(VMAT2) and schizophrenia in Han Chinese population.

METHODS

430 patients with schizophrenia and 470 age-sex matched controls were recruited from four mental health centers. All patients were diagnosed by two psychiatrists based on the Structured Clinical Interview for DSM Disorders (SCID). The ligase detection reactions (LDR) method was used to assess the polymorphism of the two SNPs (rs363371 and rs363324) of VMAT2.

RESULTS

No associations of two SNPs with schizophrenia was found. When we stratified males and females for the analysis, we found that that in the recessive model of rs363371, there was an obvious significant association between rs363371 and schizophrenia in males (OR=0.564, 95% CI=0.357-0.892, p=0.014) but not females. For the association between rs363324 and schizophrenia, no association was found in either males or females. No association was found when stratifying early-onset schizophrenia and late-onset schizophrenia.

CONCLUSION

Our findings indicate that both rs363371 and rs363324 were not associated with schizophrenia, while it seemed that the AA genotype of rs363371 plays a protective effect in male Chinese in developing schizophrenia.

Effects of caffeic acid on epigenetics in the brain of rats with chronic unpredictable mild stress

The present study hypothesized that caffeic acid (3,4-dihydroxycinnamic acid; CaA) may exert antidepressant-like effects in rats with chronic unpredictable mild stress via epigenetic mechanisms, such as DNA methylation and hydroxymethylation. The chronic unpredictable mild stress (CUMS) model was used to analyze the effects of CaA on behavioral phenotypes, and to evaluate the distribution of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in the hippocampus and prefrontal cortex using immunohistochemistry and immunofluorescence. mRNA levels of the genes encoding brain-derived neurotropic factor (BDNF) and catechol-O-methyltransferase (COMT), and key enzymes regulating DNA methylation [DNA methyltransferase (DNMT)1 and DNMT3A] and hydroxymethylation [Ten-eleven translocation (TET)1-3] were examined using quantitative (q)PCR. Furthermore, enrichment of 5mC and 5hmC at the promotor regions of the Bdnf and Comt genes was quantified using chromatin immunoprecipitation-qPCR. Behavioral data showed that CaA exerted a slight antidepressant-like effect. Bdnf and Comt genes showed differential expression patterns due to CUMS. CaA intervention induced different Dnmt1/Dnmt3a and Tet1/Tet2 mRNA levels in the hippocampus and prefrontal cortex, respectively. CaA regulated the ratio of 5mC/5hmC at the promotor region of the Bdnf and Comt genes and therefore influenced gene expression, which may be a valuable therapeutic option for major depressive disorder (MDD). In conclusion, there were epigenetic changes in the hippocampus and prefrontal cortex in CUMS rats, and CaA may function as a modulator of DNA methylation to regulate gene transcription, thus providing a mechanistic basis for the use of this phytochemical agent in the treatment of MDD.

Auditory cognitive training improves prepulse inhibition in serine racemase mutant mice

Evidence indicates that neuroplasticity-based cognitive training can improve cognition in patients with schizophrenia, but the individual response to training varies greatly between subjects. Hence, there is a need to understand the neurological underpinnings of cognitive training to reveal predictors of treatment response. D-serine is a crucial modulator of neuroplasticity, and decreased levels of D-serine may contribute to deficits in neuroplasticity in schizophrenia. Interestingly, we observed that training mice to identify auditory oddballs increased extracellular levels of D-serine in the hippocampus during training. Serine racemase (Srr) is the only source of brain D-serine; thus, it is possible that Srr may mediate the response to training. To test this hypothesis, we trained mice that have a mutated version of Srr (SrrY269*/SrrY269*) and reduced levels of D-serine in the same auditory training. SrrY269*/SrrY269* mice showed decreased performance during auditory training (defined as the capacity to discriminate an oddball during a sequence of tones). Importantly, auditory training improved prepulse inhibition (PPI) in SrrY269*/SrrY269* but not in wild-type mice. Finally, D-serine (100 mg/kg i.p.) given 30 min before training sessions to SrrY269*/SrrY269* mice improved training performance, but it did not enhance PPI. Taken together, our results show that D-serine is involved in the response to neuroplasticity-based auditory training and that PPI deficits can be improved by auditory oddball training even in the presence of neuroplasticity deficits.

Association of COMT Val158Met Polymorphism With Delirium Risk and Outcomes After Traumatic Brain Injury

OBJECTIVE

The authors investigated the association of the catechol-o-methyltransferase (COMT) gene Val¹⁵⁸Met polymorphism with delirium risk and functional and cognitive outcomes among patients with complicated mild to moderate traumatic brain injury (TBI).

METHODS

In a prospective observational cohort study, patients were monitored for occurrence of delirium during the first 4 days of admission by using the Confusion Assessment Method. Functional and cognitive outcomes were evaluated with the Glasgow Outcome on Discharge Scale and the Montreal Cognitive Assessment test, respectively. Eighty-nine patients were included in the study; of these, 17 (19%) were diagnosed with delirium.

RESULTS

The COMT Val¹⁵⁸/Val¹⁵⁸ polymorphism was associated with increased risk of delirium in multivariable regression analyses adjusted for alcohol misuse, history of neurological disorder, age, and admission Glasgow Coma Scale score (odds ratio=4.57, 95% CI=1.11, 18.9, p=0.036). The COMT Met¹⁵⁸ allele was associated with better functional outcomes in univariate analysis (odds ratio=2.82, 95% CI=1.10, 7.27, p=0.031) but not in multivariable analysis (odds ratio=2.33, 95% CI=0.89, 6.12, p=0.085). Cognitive outcomes were not associated with the COMT Val¹⁵⁸Met polymorphism in univariate regression analysis (p=0.390). Delirium was a significant predictor of worse functional and cognitive outcomes in multivariable regression analyses adjusted for other risk factors (odds ratio=0.04, 95% CI=0.01, 0.16, p<0.001, and β=-3.889, 95% CI=-7.55, -0.23, p=0.038, respectively).

CONCLUSIONS

The COMT genotype is important in delirium risk and functional outcomes of patients with mild to moderate TBI. Whether the COMT genotype is associated with outcomes through incident delirium remains to be determined in larger studies.

Association of Genetic Variants of Dopamine and Serotonin In Schizophrenia

BACKGROUND

Several studies indicated that antipsychotic treatment response and side effect manifestation can be different due to inter-individual variability in genetic variations.

AIM OF THE STUDY

Here we perform a case-control study to explore a potential association between schizophrenia and variants within the antipsychotic drug molecular targets (DRD1, DRD2, DRD3, HTR2A, HTR6) and metabolizing enzymes (CYP2D6, COMT) genes in Armenian population including also analysis of their possible relationship with disease clinical symptoms.

METHODS

A total of 18 SNPs was studied in patients with schizophrenia (n = 78) and healthy control subjects (n = 77) using MassARRAY genotyping.

RESULTS

We found that two studied genetic variants, namely DRD2 rs4436578*C and HTR2A rs6314*A are underrepresented in the group of patients compared to healthy subjects. After the correction for multiple testing, the rs4436578*C variant remained significant while the rs6314*A reported borderline significance. No significant differences in minor allele frequencies for other studied variants were identified. Also, a relationship between the genotypes and age of onset as well as disease duration has been detected.

CONCLUSIONS

The DRD2 rs4436578*C genetic variant might have protective role against schizophrenia, at least in Armenians.

Genetic polymorphism in catechol-O-methyltransferase associated with the functional connectivity of frontostriatal circuits in first episode schizophrenia patients

Negative symptoms in schizophrenia have been associated with functional changes in frontostriatal pathways. Dysregulation of the dopamine signal in frontostriatal pathways leads to the symptomology observed in schizophrenia. Although the catechol-O-methyltransferase (COMT) gene, one of the susceptibility genes for schizophrenia, has been associated with dopamine activities in prefrontal and striatal regions, it is still unclear whether the disease state and COMT val¹⁵⁸ met genotype have an interaction effect on the functional connectivity of frontostriatal pathways. In this study, we evaluated the possible interactions between COMT val¹⁵⁸ met variations and the disease state on the resting-state functional connectivity (RSFC) of frontostriatal pathways in fifty-one first episode schizophrenia (FES) patients (val/val: 29, met +: 22) with prominent negative symptoms and forty-eight healthy controls (val/val: 31, met +: 17). Regions of interest were defined by the result of a meta-analysis of frontostriatal pathways using the Neurosynth database. We found a significant genotype × disease interaction effect on the RSFC between the bilateral anterior cingulate (ACC) and right caudate, which overlapped with the main effect of the disease state. Behavioural regression analysis suggested that RSFC between the right ACC and right caudate correlated with the severity of SANS avolition-apathy scores in patients who were met carriers but not in patients who were val homozygous. Our findings suggest that the RSFC of frontostriatal pathways may differentially affected by an individual's COMT val¹⁵⁸ met genotype.

The role of genetics in cognitive remediation in schizophrenia: A systematic review

The role of genetics in cognitive remediation therapies in schizophrenia has not been completely understood yet. Different genes involved in neurotrophic, dopaminergic and serotonin systems have reported to influence cognitive functioning in schizophrenia. These genetic factors could also be contributing to the variability in responsiveness to cognitive treatments. No comprehensive synthesis of the literature of the role of genetics in the context of cognitive remediation has been conducted until now. We aimed to systematically review the published works through three electronic database searches: PubMed, Scopus, and the Cochrane Library. Eligible studies revealed a rising interest in the field although the number of published studies was rather small (n = 10). Eventually, promising results showing a relationship between some phenotypic variations based on different polymorphisms and different levels of responsivity to cognitive remediation therapies have been described although results are still inconclusive. In case those findings will be replicated, they could be guiding future research and informing clinical decision-making in the next future.

Functioning in schizophrenia from the perspective of psychologists: A worldwide study

Schizophrenia is a severe mental disorder associated with impairment in functioning. A multidisciplinary approach is essential to help individuals with this health condition, and psychological interventions are considered a priority. The International Classification of Functioning, Disability and Health (ICF) offers a theoretical framework for assessing functioning and disability. The ICF Core Sets for schizophrenia are a list of ICF categories describing the most common problems in functioning of persons affected by this health condition. This study aimed to explore the content validity of these ICF Core Sets and to identify the most common problems in people with schizophrenia from the perspective of psychologists. Psychologists with experience of schizophrenia treatment were recruited for a three-round Delphi study in order to gather their views regarding the problems commonly presented by these patients. A total of 175 psychologists from 46 countries covering the six WHO regions answered the first-round questionnaire, and 137 completed all three rounds. The 7,526 concepts extracted from first-round responses were linked to 412 ICF categories and 53 personal factors. Consensus (≥75% agreement) was reached for 76 ICF categories and 28 personal factors. Seventy-three of the 97 ICF categories that form the Comprehensive ICF Core Set for schizophrenia achieved consensus, and only three categories that yielded consensus do not feature in this Core Set. These results support the content validity of these ICF Core Sets from the perspective of psychologists. This provides further evidence of the suitability of the ICF framework for describing functioning and disability in persons with schizophrenia.

COMT polymorphism regulates the hippocampal subfield volumes in first-episode, drug-naive patients with major depressive disorder

Purpose: Compared with healthy subjects (HS), patients with major depressive disorder (MDD) exhibit volume differences that affect the volume changes in several areas such as the limbic, cortical, subcortical, and white matter. Catechol-O-methyltransferase (COMT) is a methylation enzyme that catalyzes endogenous catecholamines. The Val158Met polymorphism of COMT has been reported to affect the dopamine (DA) levels, which plays an important role in psychiatric diseases. However, the relationships among both DA levels, COMT genotype, and brain morphology are complicated and controversial. In previous studies that investigated the hippocampal subfields, the greatest brain abnormalities in MDD patients were observed in Cornu Ammonis (CA)1 and the subiculum, followed by that in CA2-3. We have prospectively demonstrated the relationship between the single-nucleotide polymorphism of the Val158Met COMT gene (rs4680) and the hippocampal subfields in drug-naive MDD patients. Patients and methods: In this study, we compared 27 MDD patients and 42 HS who were divided into groups based on their COMT genotype. The effects of the diagnosis, genotype, and genotype-diagnosis interaction related to CA1 and the subiculum volumes, as well as the whole-brain cortical thickness, were evaluated by performing a FreeSurfer statistical analysis of high-resolution magnetic resonance imaging (MRI) findings. Results: The results revealed that there was a statistically significant interaction between the effects of diagnosis and genotype on the right subiculum (a component of the hippocampus). Conclusion: This Val158Met COMT polymorphism may influence the subiculum volume in drug-naive, first-episode MDD patients.

COMT and GAD1 gene polymorphisms are associated with impaired antisaccade task performance in schizophrenic patients

Genetic influences modulating executive functions engaging prefrontal cortical brain systems were investigated in 141 male subjects. The effects of variations in two genes implicated in dopamine and GABA activities in the prefrontal cortex: rs4680 (Val158/Met polymorphism of the catechol-o-methyltransferase gene-COMT) and rs3749034 (C/T) substitution in the promoter region of the glutamic acid decarboxylase gene (GAD1) were studied on antisaccade (AS) performance in healthy subjects and schizophrenic patients. Genotyping revealed a trend towards a reduced proportion of COMT Val/Met heterozygotes and a significantly increased frequency of the GAD1 rs3749034 C allele in schizophrenic patients relative to controls. Patients had elevated error rates, increased AS latencies and increased latency variability (coefficient of variation) compared to controls. The influence of polymorphisms was observed only in patients but not in controls. A substantial effect of the COMT genotype was noted on the coefficient of variation in latency, and this measure was higher in Val homozygotes compared to Met allele carriers (p < 0.05) in the patient group. The outcome from rs3749034 was also disclosed on the error rate (higher in T carriers relative to C homozygotes, p < 0.01) and latency (increased in C homozygotes relative to T carriers, p < 0.01). Binary logistic regression showed that inclusion of the genotype factor (i.e., selective estimation of antisaccade measures in CC carriers) considerably increased the validity of the diagnostic model based on the AS measures. These findings may well be derived from specific genetic associations with prefrontal cortex functioning in schizophrenia.

Association between catechol-O-methyltransferase genetic variation and functional connectivity in patients with first-episode schizophrenia

Dopamine in the prefrontal cortex (PFC) plays an important role in cognitive performance and regulates by catechol-O-methyltransferase (COMT) expression. To clarify the effect of COMT genotype on cognitive function in patients with schizophrenia, we performed DNA genotyping, cognitive evaluations, and functional magnetic resonance imaging (fMRI) in antipsychotic-naïve patients with first-episode schizophrenia (FES) and matched healthy control subjects. We found that all cognitive domains were impaired in patients with FES compared with healthy subjects. Moreover, COMT genotype influenced the verbal learning performance in healthy subjects, but not in patients with FES. Resting-state fMRI data revealed that patients with FES exhibited higher functional connectivity degree centrality in the medial PFC and lower degree centrality in the parietal-occipital junction than healthy subjects. Furthermore, patients with FES who were COMT Met allele carriers had higher degree centrality in the medial PFC than those with the Val/Val genotype. In contrast, in healthy controls, Met allele carriers exhibited higher degree centrality than healthy controls with the Val/Val genotype in the left hippocampus and left amygdala. There was a negative correlation between the degree centrality value in medial PFC and score of the Hopkins Verbal Learning Test-Revised (HVLT-R) in FES patients with the Met allele. Our findings suggest that COMT genotype differentially influences pathways related to cognitive performance in patients with FES versus healthy individuals, providing an important insight into schizophrenia pathophysiology.

The link between schizophrenia and substance use disorder: A unifying hypothesis

Substance use disorders occur commonly in patients with schizophrenia and dramatically worsen their overall clinical course. While the exact mechanisms contributing to substance use in schizophrenia are not known, a number of theories have been put forward to explain the basis of the co-occurrence of these disorders. We propose here a unifying hypothesis that combines recent evidence from epidemiological and genetic association studies with brain imaging and pre-clinical studies to provide an updated formulation regarding the basis of substance use in patients with schizophrenia. We suggest that the genetic determinants of risk for schizophrenia (especially within neural systems that contribute to the risk for both psychosis and addiction) make patients vulnerable to substance use. Since this vulnerability may arise prior to the appearance of psychotic symptoms, an increased use of substances in adolescence may both enhance the risk for developing a later substance use disorder, and also serve as an additional risk factor for the appearance of psychotic symptoms. Future studies that assess brain circuitry in a prospective longitudinal manner during adolescence prior to the appearance of psychotic symptoms could shed further light on the mechanistic underpinnings of these co-occurring disorders while identifying potential points of intervention for these difficult-to-treat co-occurring disorders.

Differential effects of physical activity and sleep duration on cognitive function in young adults

PURPOSE

Although exercise and sleep duration habits are associated with cognitive function, their beneficial effects on cognitive function remain unclear. We aimed to examine the effect of sleep duration and daily physical activity on cognitive function, elucidating the neural mechanisms using near-infrared spectroscopy (NIRS).

METHODS

A total of 23 healthy young adults (age 22.0 ± 2.2 years) participated in this study. Exercise amount was assessed using a uniaxial accelerometer. We evaluated total sleep time (TST) and sleep efficiency by actigraphy. Cognitive function was tested using the N-back task, the Wisconsin Card Sorting Test (WCST), and the Continuous Performance Test-Identical Pairs (CPT-IP), and the cortical oxygenated hemoglobin levels during a word fluency task were measured with NIRS.

RESULTS

Exercise amount was significantly correlated with reaction time on 0- and 1-back tasks (r = -0.602, p = 0.002; r = -0.446, p = 0.033, respectively), whereas TST was significantly correlated with % corrects on the 2-back task (r = 0.486, p = 0.019). Multiple regression analysis, including exercise amount, TST, and sleep efficiency, revealed that exercise amount was the most significant factor for reaction time on 0- and 1-back tasks (β = -0.634, p = 0.002; β = -0.454, p = 0.031, respectively), and TST was the most significant factor for % corrects on the 2-back task (β = 0.542, p = 0.014). The parameter measured by WCST and CPT-IP was not significantly correlated with TST or exercise amount. Exercise amount, but not TST, was significantly correlated with the mean area under the NIRS curve in the prefrontal area (r = 0.492, p = 0.017).

CONCLUSION

Exercise amount and TST had differential effects on working memory and cortical activation in the prefrontal area. Daily physical activity and appropriate sleep duration may play an important role in working memory.

The effect of interactions between genetics and cannabis use on neurocognition. A review

BACKGROUND

Cannabis is one of the most widely-used drugs in industrialized countries. It is now well established that cannabis use impacts neurocognition. In the intoxication period time episodic memory, working memory and attention are impacted and impulsivity is increased. The long-term effects of cannabis use tend to be similar. Various internal factors, such as sex differences, modulate this impact. It is unclear whether genetic variations can also influence the impact of cannabis on neurocognition. We set out to examine the impact of genetic variations on neurocognition in cannabis users.

METHOD

We conducted a search via the PubMed, Web of Science, and ScienceDirect databases to identify studies measuring neurocognition and assessing genotypes in the context of cannabis use.

RESULTS

We included 13 articles. We found that working memory, verbal and visual memory and sustained attention are more impacted during intoxication in subjects with the Val COMT allele. COMT gene could also modulate sustained attention in regular use. The CNR1, AKT1, DBH and 5-HTT/SLC6A4 genes may also modulate effects.

CONCLUSION

Most of these genes are linked to schizophrenia. A fuller understanding of their impact on the effects of cannabis on neurocognition would thus help elucidate the mechanisms linking cannabis and psychosis. However, evidence is still scant, and more research is needed.

Association between COMT Val158Met and psychiatric disorders: A comprehensive meta-analysis

Catechol-O-methyltransferase (COMT) Val158Met is widely regarded as potentially important for understanding the genetic etiology of many different psychiatric disorders. The present study appears to be the first comprehensive meta-analysis of COMT genetic association studies to cover all psychiatric disorders for which there were available data, published in any language, and with an emphasis on investigating disorder subtypes (defined clinically or by demographic or other variables). Studies were included if they reported one or more datasets (i.e., some studies examined more than one clinical group) in which there were sufficient information to compute effect sizes. A total of 363 datasets were included, consisting of 56,998 cases and 74,668 healthy controls from case control studies, and 2,547 trios from family based studies. Fifteen disorders were included. Attention-deficit hyperactivity disorder and panic disorder were associated with the Val allele for Caucasian samples. Substance-use disorder, defined by DSM-IV criteria, was associated with the Val allele for Asian samples. Bipolar disorder was associated with the Met allele in Asian samples. Obsessive-compulsive disorder tended to be associated with the Met allele only for males. There was suggestive evidence that the Met allele is associated with an earlier age of onset of schizophrenia. Results suggest pleiotropy and underscore the importance of examining subgroups-defined by variables such as age of onset, sex, ethnicity, and diagnostic system-rather than examining disorders as monolithic constructs.

Genetic Variants Within Molecular Targets of Antipsychotic Treatment: Effects on Treatment Response, Schizophrenia Risk, and Psychopathological Features

Schizophrenia (SCZ) is a common and severe mental disorder. Genetic factors likely play a role in its pathophysiology as well as in treatment response. In the present study, we investigated the effects of several single nucleotide polymorphisms (SNPs) within 9 genes involved with antipsychotic (AP) mechanisms of action. Two independent samples were recruited. The Korean sample included 176 subjects diagnosed with SCZ and 326 healthy controls, while the Italian sample included 83 subjects and 194 controls. AP response as measured by the positive and negative syndrome scale (PANSS) was the primary outcome, while the secondary outcome was the SCZ risk. Exploratory analyses were performed on (1) symptom clusters response (as measured by PANSS subscales); (2) age of onset; (3) family history; and (4) suicide history. Associations evidenced in the primary analyses did not survive to the FDR correction. Concerning SCZ risk, we partially confirmed the associations among COMT and MAPK1 genetic variants and SCZ. Finally, our exploratory analysis suggested that CHRNA7 and HTR2A genes may modulate both positive and negative symptoms responses, while PLA2G4A and SIGMAR1 may modulate respectively positive and negative symptoms responses. Moreover, GSK3B, HTR2A, PLA2G4A, and S100B variants may determine an anticipation of SCZ age of onset. Our results did not support a primary role for the genes investigated in AP response as a whole. However, our exploratory findings suggested that these genes may be involved in symptom clusters response.

Gene-environment interaction as a predictor of early adjustment in first episode psychosis

BACKGROUND

This study aims to explore the gene-environment interaction hypothesis applied to pre-symptomatic neurodevelopmental phenotypes of first episode psychosis (FEP), that is, genetic factors might increase vulnerability to the effects of environmental adverse conditions occurring at later stages of development.

METHODS

We constructed a schematic 'two-hit' model, with Val/Val homozygosity for the catechol-O-methyltransferase (COMT) Val158Met polymorphism as the 'first hit' and history of obstetric complications and parental socioeconomic status as 'second hits'. Early adjustment, measured using the Premorbid Adjustment Scale, was considered the main outcome. The study population comprised 221 adolescents and adults with FEP and 191 sex- and age-matched controls.

RESULTS

The interaction between the Val/Val COMT genotype and a positive history of obstetric complications plus low parental socioeconomic status was significantly associated with poorer early adjustment. These results were observed both in FEP individuals and in controls, and remained significant after controlling for age, sex, and diagnosis.

CONCLUSIONS

Individuals carrying Val/Val seem to be more sensitive to the synergistic effect of environmental factors acting early in neurodevelopment, which leads to vulnerability phenotypes such as impaired early adjustment.

Differential Associations between Cortical Thickness and Striatal Dopamine in Treatment-Naïve Adults with ADHD vs. Healthy Controls

Alterations in catecholamine signaling and cortical morphology have both been implicated in the pathophysiology of attention deficit/hyperactivity disorder (ADHD). However, possible links between the two remain unstudied. Here, we report exploratory analyses of cortical thickness and its relation to striatal dopamine transmission in treatment-naïve adults with ADHD and matched healthy controls. All participants had one magnetic resonance imaging (MRI) and two [¹¹C]raclopride positron emission tomography scans. Associations between frontal cortical thickness and the magnitude of d-amphetamine-induced [¹¹C]raclopride binding changes were observed that were divergent in the two groups. In the healthy controls, a thicker cortex was associated with less dopamine release; in the ADHD participants the converse was seen. The same divergence was seen for baseline D2/3 receptor availability. In healthy volunteers, lower D2/3 receptor availability was associated with a thicker cortex, while in the ADHD group lower baseline D2/3 receptor availability was associated with a thinner cortex. Individual differences in cortical thickness in these regions correlated with ADHD symptom severity. Together, these findings add to the evidence of associations between dopamine transmission and cortical morphology, and suggest that these relationships are altered in treatment-naïve adults with ADHD.

Pharmacodynamic genetic polymorphisms affect adverse drug reactions of haloperidol in patients with alcohol-use disorder

Background

Antipsychotic action of haloperidol is due to blockade of D₂ receptors in the mesolimbic dopamine pathway, while the adverse drug reactions are associated with striatal D₂ receptor blockade. Contradictory data concerning the effects of genetic polymorphisms of genes encoding these receptors and associated structures (catechol-O-methyltransferase [COMT], glycine transporter and gene encoding the density of D₂ receptors on the neuronal membrane) are described.

Objective

The objectives of this study were to evaluate the correlation between DRD2, SLC6A3 (DAT) and COMT genetic polymorphisms and to investigate their effect on the development of adverse drug reactions in patients with alcohol-use disorder who received haloperidol.

Patients and methods

The study included 64 male patients (average age 41.38 ± 10.14 years, median age 40 years, lower quintile [LQ] 35 years, upper quintile [UQ] 49 years). Bio-Rad CFX Manager™ software and “SNP-Screen” sets of “Syntol” (Russia) were used to determine polymorphisms rs4680, rs1800497, rs1124493, rs2242592, rs2298826 and rs2863170. In every “SNP-Screen” set, two allele-specific hybridizations were used, which allowed to determine two alleles of studied polymorphism separately on two fluorescence channels.

Results

Results of this study detected a statistically significant difference in the adverse drug reaction intensity in patients receiving haloperidol with genotypes 9/10 and 10/10 of polymorphic marker SLC6A3 rs28363170. In patients receiving haloperidol in tablets, the increases in the UKU Side-Effect Rating Scale (UKU) score of 9.96 ± 2.24 (10/10) versus 13 ± 2.37 (9/10; p < 0.001) and in the Simpson-Angus Scale (SAS) score of 5.04 ± 1.59 (10/10) versus 6.41 ± 1.33 (9/10; p = 0.006) were revealed.

Conclusion

Polymorphism of the SCL6A3 gene can affect the safety of haloperidol, and this should be taken into account during the choice of drug and its dosage regimen.

Does COMT val158met polymorphism influence P50 sensory gating, eye tracking or saccadic inhibition dysfunctions in schizophrenia?

Three electrophysiological endophenotypes are routinely studied in schizophrenia (SCZ): smooth pursuit eye movement (SPEM) dysfunction, deficits in P50 auditory-evoked potential inhibition, and saccadic inhibition deficits. The current study aimed to investigate the relationship between the COMT val158met polymorphism and these three endophenotypes. One hundred four SCZ patients (DSM-IV-R criteria) and 89 healthy controls were included in this study. P50 auditory-evoked potential inhibition, antisaccade paradigm and SPEM were analyzed. All individuals were genotyped for the COMT val158met. SCZ patients showed a higher rate of deficits measured by the SPEM, antisaccade and P50 inhibition paradigms without association with COMT val158met. However, in our control group, we have found an association between the Val polymorphism and the smoking status. More importantly, we have found a higher accuracy of saccades during the predictive pursuit task associated to the Met polymorphism in controls but not in SCZ patients who were receiving antidopaminergic medications. This result is in line with the hypothesis of the relationship between the Met polymorphism of the COMT gene, a higher level of dopamine in the prefrontal cortex and the role of the fronto-cerebellar loop in smooth predictive pursuit.

COMT val158met polymorphism and molecular alterations in the human dorsolateral prefrontal cortex: Differences in controls and in schizophrenia

The single nucleotide val158met polymorphism in catechol o-methyltransferase (COMT) influences prefrontal cortex function. Working memory, dependent on the dorsolateral prefrontal cortex (DLPFC), has been repeatedly shown to be influenced by this COMT polymorphism. The high activity COMT val isoform is associated with lower synaptic dopamine levels. Altered synaptic dopamine levels are expected to lead to molecular adaptations within the synapse and within DLPFC neural circuitry. In this human post mortem study using high quality DLPFC tissue, we first examined the influence of the COMT val158met polymorphism on markers of dopamine neurotransmission, N-methyl-d-aspartate (NMDA) receptor subunits and glutamatic acid decarboxylase 67 (GAD67), all known to be critical to DLPFC circuitry and function. Next, we compared target gene expression profiles in a cohort of control and schizophrenia cases, each characterized by COMT genotype. We find that the COMT val allele in control subjects is associated with significant upregulation of GluN2A and GAD67 mRNA levels compared to met carriers. Comparisons between control and schizophrenia groups reveal that GluN2A, GAD67 and DRD2 are differentially regulated between diagnostic groups in a genotype specific manner. Chronic antipsychotic treatment in rodents did not explain these differences. These data demonstrate an association between COMTval158met genotype and gene expression profile in the DLPFC of controls, possibly adaptations to maintain DLPFC function. In schizophrenia val homozygotes, these adaptations are not seen and could reflect pathophysiologic mechanisms related to the known poorer performance of these subjects on DLPFC-dependent tasks.

RNA splicing is a primary link between genetic variation and disease

Noncoding variants play a central role in the genetics of complex traits, but we still lack a full understanding of the molecular pathways through which they act. We quantified the contribution of cis-acting genetic effects at all major stages of gene regulation from chromatin to proteins, in Yoruba lymphoblastoid cell lines (LCLs). About ~65% of expression quantitative trait loci (eQTLs) have primary effects on chromatin, whereas the remaining eQTLs are enriched in transcribed regions. Using a novel method, we also detected 2893 splicing QTLs, most of which have little or no effect on gene-level expression. These splicing QTLs are major contributors to complex traits, roughly on a par with variants that affect gene expression levels. Our study provides a comprehensive view of the mechanisms linking genetic variation to variation in human gene regulation.

Disorder-specific genetic factors in obsessive-compulsive disorder: A comprehensive meta-analysis

Much remains to be learned about the etiology of obsessive-compulsive disorder (OCD). Twin studies suggest that it arises from both disorder-specific and non-specific genetic factors. To understand the etiology of OCD per se, it is necessary to identify disorder-specific factors. Previous research shows that OCD is associated with serotonin-related polymorphisms (5-HTTLPR coded as triallelic and HTR2A rs6311/rs6313) and, in males, a polymorphism involved in catecholamine modulation; COMT (rs4680). The present study is the first comprehensive meta-analysis to investigate whether these polymorphisms are specific to OCD. A meta-analysis was conducted for genetic association studies of OCD or any other psychiatric disorder, published in any language, in any country. A total of 551 studies were examined, of which 290 were included, consisting of 47,358 cases and 68,942 controls from case control studies, and 2,443 trios from family based studies. The main meta-analysis was limited to those disorders in which there were at least five datasets (studies or sub-studies) per disorder. Results confirmed that OCD is associated with polymorphisms of 5-HTTLPR, HTR2A, and, in males only, COMT. These polymorphisms were not associated with almost all other forms of psychopathology, including unipolar mood disorders, bipolar disorder, panic disorder, schizophrenia, and alcohol dependence. OCD, compared to most other disorders, had a significantly stronger association with particular alleles of each of the polymorphisms. Results did not differ across ancestral groups (Asian vs. Caucasian), designs (case control vs. family based), or diagnostic systems. Results suggest that the polymorphisms investigated in this study are relatively specific to OCD.

Transcranial direct current stimulation and neuroplasticity genes: implications for psychiatric disorders

BACKGROUND AND AIM

Transcranial direct current stimulation (tDCS) is a non-invasive and well-tolerated brain stimulation technique with promising efficacy as an add-on treatment for schizophrenia and for several other psychiatric disorders. tDCS modulates neuroplasticity; psychiatric disorders are established to be associated with neuroplasticity abnormalities. This review presents the summary of research on potential genetic basis of neuroplasticity-modulation mechanism underlying tDCS and its implications for treating various psychiatric disorders.

METHOD

A systematic review highlighting the genes involved in neuroplasticity and their role in psychiatric disorders was carried out. The focus was on the established genetic findings of tDCS response relationship with BDNF and COMT gene polymorphisms.

RESULT

Synthesis of these preliminary observations suggests the potential influence of neuroplastic genes on tDCS treatment response. These include several animal models, pharmacological studies, mentally ill and healthy human subject trials.

CONCLUSION

Taking into account the rapidly unfolding understanding of tDCS and the role of synaptic plasticity disturbances in neuropsychiatric disorders, in-depth evaluation of the mechanism of action pertinent to neuroplasticity modulation with tDCS needs further systematic research. Genes such as NRG1, DISC1, as well as those linked with the glutamatergic receptor in the context of their direct role in the modulation of neuronal signalling related to neuroplasticity aberrations, are leading candidates for future research in this area. Such research studies might potentially unravel observations that might have potential translational implications in psychiatry.

Sex-dichotomous effects of functional COMT genetic variations on cognitive functions disappear after menopause in both health and schizophrenia

Different genetic variations in the catechol-O-methyltransferase (COMT) gene have been indicated to functionally regulate the encoded enzyme. Despite the vast literature on the single nucleotide COMT ValMet polymorphism, the impact of complex haplotypes on cognitive functions has been overlooked. Here we contrasted the effects of complex COMT haplotypes with the ValMet polymorphism on cognitive functions and their interaction with menopause, in healthy subjects and patients with schizophrenia. Healthy adults (N=229) as well as patients with schizophrenia (N=172) underwent a comprehensive cognitive assessment taking into account the menopausal state. Functional COMT variations selectively modulated working memory and executive functions. Strikingly, these effects were present only in adult men but not in women before menopause, in both healthy subjects and patients with schizophrenia. Importantly, the same pattern of COMT-dependent effects present in men reappeared in women after menopause. Thus, functional COMT mutations seem to modulate cognitive functions depending on the hormonal status. These data clarify the importance of taking into account the combined effect of sex, hormonal status and genetics.

Depression, Cytokine, and Cytokine by Treatment Interactions Modulate Gene Expression in Antipsychotic Naïve First Episode Psychosis

In schizophrenia, genetic and environmental factors affect neurodevelopment and neuroprogressive trajectory. Altered expression of neuro-immune genes and increased levels of cytokines are observed, especially in patients with comorbid depression. However, it remains unclear whether circulating levels of cytokines and expression of these genes are associated, and how antipsychotic treatments impact this association. Relationships between messenger RNA (mRNA) expression of 11 schizophrenia-related genes and circulating levels of cytokines (interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α) were analyzed in 174 antipsychotic naïve first episode psychosis (FEP) and in 77 healthy controls. A subgroup of 72 patients was reassessed after treatment with risperidone. FEP patients were divided into those with and without depression. FEP patients with depression showed increased COMT expression and decreased NDEL1 expression. Increased IL-6 was associated with lowered AKT1 and DROSHA expression, while increased IL-10 was associated with increased NDEL1, DISC1, and MBP expression. IL-6 levels significantly increased the risperidone-induced expression of AKT1, DICER1, DROSHA, and COMT mRNA. The differential mRNA gene expression in FEP is largely associated with increased cytokine levels. While increased IL-6 may downregulate AKT-mediated cellular functions and dysregulate genes involved in microRNA (miRNA) machinery, increased IL-10 has neuroprotective properties. Increased IL-6 levels may prime the expression of genes (AKT1, DICER1, DROSHA, and COMT) in response to risperidone, suggesting that cytokine × treatment × gene interactions may improve cell function profiles. FEP patients with depression show a different gene expression profile reinforcing the theory that depression in FEP is a different phenotype.

COMT genotype and response to cognitive remediation in schizophrenia

BACKGROUND

A functional polymorphism of the catechol-O-methyltransferase (COMT) gene (Val158Met) partially appears to influence cognitive performance in schizophrenia subjects and healthy controls by modulating prefrontal dopaminergic activity. This study evaluated the association of the COMT Val108/158 Met genotype with response to computerized neurocognitive remediation (CRT).

METHOD

145 subjects with DSM-IV-TR schizophrenia or schizoaffective disorder were genotyped via saliva sampling. Subjects were evaluated on neurocognitive assessments (MATRICS) and clinical symptoms (PANSS) at baseline and endpoint after 12weeks of CRT. "Improvement" was defined as ≥67% of cognitive domains (≥4) showing performance increases. If ≤67% (≤2) of domains improved, the change was defined as "minimal improvement." A general linear model was conducted for change of each cognitive domain.

RESULTS

Of 145 subjects, data from 138 subjects were usable. Distribution of COMT genotype: Met/Met: 28 (20.29%), Val/Met: 61 (44.20%), and Val/Val: 49 (35.51%). No significant differences were seen among genotype groups at baseline or across genotype group for "Improvement" vs. "Minimal Improvement." GLM analysis showed significant differences in Verbal Learning (p=0.003), Visual Learning (p=0.014) and Attention/Vigilance (p=0.011) favoring Met/Met and Val/Met groups.

CONCLUSIONS

The low activity Met allele (Met/Met; Val/Met) was associated with significantly greater improvements in the MATRICS domains of Verbal Learning, Visual Learning and Attention/Vigilance after CRT.

Look beyond Catechol-O-Methyltransferase genotype for cathecolamines derangement in migraine: the BioBIM rs4818 and rs4680 polymorphisms study

Background

The study of COMT gene polymorphisms in migraine could be of particular interest since impaired catecholaminergic neurotransmission, namely chronic dopaminergic and noradrenergic hypofunction, is a peculiar migraine trait. In this study, for the first time, we focused on the role of COMT rs4818 genetic variant, the polymorphism most strongly affecting COMT activity, in migraine. This study was conducted in a cohort of carefully clinical characterized Caucasian migraineurs recruited in a specifically dedicated migraine biobank, providing also a replication study on rs4680 polymorphism.

Findings

Genotyping of rs4680 and rs4818 Catechol-O-Methyltransferase gene polymorphisms was performed on 380 unrelated migraine patients, and 132 healthy subjects matched for age, gender and race-ethnicity, with no clinical evidence or family history of migraine or other neurological diseases. The rs4680 and rs4818 genotypic frequencies did not deviate from those expected for a population in Hardy-Weinberg equilibrium and did not correlate with demographics or clinical migraine features, even when considering migraine subtypes such as dopaminergic migraine, menstrual migraine, and menstrually related migraine.

Conclusions

COMT genotype does not influence migraine susceptibility or phenotype, even considering rs4818 polymorphism and peculiar clinical subtypes. This finding prompts to go over COMT to explain catecholamine derangement in migraine, exploring enzymes involved in catecholamines synthesis and catabolism, such as monoamine-oxidase, dopamine beta-hydroxylase, tyrosine-hydroxylase or tyrosine-decarboxylase, among others.