Comparison of visual evoked-related potentials in healthy young adults of different catechol-O-methyltransferase genotypes in a continuous 3-back task

Working memory dysfunction in fibromyalgia is associated with genotypes of the catechol- O-methyltransferase gene: an event-related potential study

Recent findings have associated different COMT genotypes with working memory capacity in patients with fibromyalgia. Although it is thought that the COMT gene may influence neural correlates (P2 and P3 ERP components) underlying working memory impairment in this chronic-pain syndrome, it has not yet been explored. Therefore, the aim of the present research was to investigate the potential effect of the COMT gene in fibromyalgia patients on ERP working memory indices (P2 and P3 components). For this purpose, 102 participants (51 patients and 51 healthy control participants) took part in the experiment. Event-related potentials and behavioral responses were recorded while participants performed a spatial n-back task. Participants had to decide if the stimulus coincided or not in the same location as the one presented one (1-back condition) or two (2-back condition) trials before. Genotypes of the COMT gene were determined through a saliva sample from all participants. Present results significantly showed lower working memory performance (p < 0.05) in patients with fibromyalgia as compared to control participants (higher rate of errors and slower reaction times). At neural level, we found that patients exhibited enhanced frontocentral and parieto-occipital P2 amplitudes compared to control participants (p < 0.05). Interestingly, we also observed that only fibromyalgia patients carrying the Val/Val genotype of the COMT gene showed higher frontocentral P2 amplitudes than control participants (p < 0.05). Current results (behavioral outcomes and P2 amplitudes) confirmed the presence of an alteration in working memory functioning in fibromyalgia. The enhancement of frontocentral P2 could be reflecting that these patients would manifest an inefficient way of activating executive attention processes, in carriers of the Val/Val genotype of COMT. To our knowledge, the present findings are the first linking neural indices of working memory dysfunctions and COMT genotypes in fibromyalgia. Applying a subgroup of patient's strategy based on this genetic marker could be useful to establish more tailored therapeutical approaches.

Influence of Concussion History and Genetics on Event-Related Potentials in Athletes: Potential Use in Concussion Management

Sports-related concussions are an increasing public health issue with much concern about the possible long-term decrements in cognitive function and quality of life that may occur in athletes. The measurement of cognitive function is a common component of concussion management protocols due to cognitive impairments that occur after sustaining a concussion; however, the tools that are often used may not be sensitive enough to expose long term problems with cognitive function. The current paper is a brief review, which suggests that measuring cognitive processing through the use of event related potentials (ERPs) may provide a more sensitive assessment of cognitive function, as shown through recent research showing concussion history to influence ERPs components. The potential influence of genetics on cognitive function and ERPs components will also be discussed in relation to future concussion management.

Association of catechol-O-methyltransferase Val(108/158) Met genetic polymorphism with schizophrenia, P50 sensory gating, and negative symptoms in a Chinese population

Catechol-O-methyltransferase (COMT), an enzyme involved in the degradation and inactivation of the neurotransmitter dopamine, is associated with the sensory gating phenomenon, protecting the cerebral cortex from information overload. The COMT Val(108/158)Met polymorphism is essential for prefrontal cortex processing capacity and efficiency. The current study was designed to investigate the role of COMT Val(108/158)Met polymorphism in development, sensory gating deficit, and symptoms of schizophrenia in Han Chinese population. P50 gating was determined in 139 schizophrenic patients and 165 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess the clinical symptomatology in 370 schizophrenic subjects. COMT Val(108/158)Met polymorphism was genotyped by PCR-restriction fragment length polymorphism (PCR-RFLP). No significant differences in COMT allele and genotype distributions were observed between schizophrenic patients and control groups. Although P50 deficits were present in patients, there was no evidence for an association between COMT Val(108/158)Met polymorphism and the P50 biomarker. Moreover, PANSS negative subscore was significantly higher in Val allele carriers than in Met/Met individuals. The present findings suggest that COMT Val(108/158)Met polymorphism may not contribute to the risk of schizophrenia and to the P50 deficits, but may contribute to the negative symptoms of schizophrenia among Han Chinese.

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

BACKGROUND

Endophenotypes in genetic psychiatry may increase our understanding of the molecular mechanisms underlying disease risk and its manifestations. We sought to investigate the link between neuropsychological impairments and brain structural abnormalities associated with the COMT Val(158)Met polymorphism in patients with schizophrenia to improve understanding of the pathophysiology of this disorder.

METHODS

We performed a systematic review using studies identified in PubMed and MEDLINE (from the date of the first available article to July 2012). Our review examined evidence of an association between the COMT Val(158)Met polymorphism and both neuropsychological performance and brain structure in patients with psychosis, in their relatives and in healthy individuals (step 1). The review also explored whether the neuropsychological tasks and brain structures identified in step 1 met the criteria for an endophenotype (step 2). Then we evaluated evidence that the neuropsychological endophenotypes identified in step 2 are associated with the brain structure endophenotypes identified in that step (step 3). Finally, we propose a neurobiological interpretation for this evidence.

RESULTS

A poorer performance on the n-back task and the Continuous Performance Test (CPT) and smaller temporal and frontal brain areas were associated with the COMT Val allele in patients with schizophrenia and their relatives and met most of the criteria for an endophenotype. It is possible that the COMT Val(158)Met polymorphism therefore contributes to the development of these neuropsychological and brain structural endophenotypes of schizophrenia, in which the prefrontal cortex may represent the neural substrate underlying both n-back and CPT performances.

LIMITATIONS

The association between a single genetic variant and an endophenotype does not necessarily imply a causal relationship between them.

CONCLUSION

This evidence and the proposed interpretation contribute to explain, at least in part, the biological substrate of 4 important endophenotypes that characterize schizophrenia.

DBH -1021C>T and COMT Val108/158Met genotype are not associated with the P300 ERP in an auditory oddball task

OBJECTIVE

The amplitude and latency of the P300 may be associated by variations in dopaminergic genes. The current study was conducted to determine whether functional variants of the catechol-O-methyltransferase (COMT) and dopamine beta-hydroxylase (DBH) gene were associated with P300 amplitude and latency in an auditory oddball task.

METHODS

The P300 ERP was assessed by a two-tone auditory oddball paradigm in a large sample of 320 healthy volunteers. The Val108/158Met polymorphism (rs4680) of the COMT gene and the -1021C>T polymorphism (rs1611115) of the DBH gene were genotyped. P300 amplitude and latency were compared across genotype groups using analysis of variance.

RESULTS

There were no differences in demographic characteristics in subjects for genotypic subgroups. No genotype associations were observed for the P300 amplitude and latency on frontal, central and parietal electrode positions.

CONCLUSIONS

COMT Val108/158Met and DBH -1021C>T polymorphisms do not show evidence of association with characteristics of the P300 ERP in an auditory oddball paradigm in healthy volunteers.

SIGNIFICANCE

We failed to find evidence for the association between dopaminergic enzymatic polymorphisms and the P300 ERP in healthy volunteers, in the largest study undertaken to date.

Electrophysiological markers of genetic risk for attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder with complex genetic aetiology. The identification of candidate intermediate phenotypes may facilitate the detection of susceptibility genes and neurobiological mechanisms underlying the disorder. Electroencephalography (EEG) is an ideal neuroscientific approach, providing a direct measurement of neural activity that demonstrates reliability, developmental stability and high heritability. This systematic review evaluates the utility of a subset of electrophysiological measures as potential intermediate phenotypes for ADHD: quantitative EEG indices of arousal and intraindividual variability, and functional investigations of attention, inhibition and performance monitoring using the event-related potential (ERP) technique. Each measure demonstrates consistent and meaningful associations with ADHD, a degree of genetic overlap with ADHD and potential links to specific genetic variants. Investigations of the genetic and environmental contributions to EEG/ERP and shared genetic overlap with ADHD might enhance molecular genetic studies and provide novel insights into aetiology. Such research will aid in the precise characterisation of the clinical deficits seen in ADHD and guide the development of novel intervention and prevention strategies for those at risk.

Do COMT, BDNF and NRG1 polymorphisms influence P50 sensory gating in psychosis?

BACKGROUND

Auditory P50 sensory gating deficits correlate with genetic risk for schizophrenia and constitute a plausible endophenotype for the disease. The well-supported role of catechol-O-methyltransferase (COMT), brain-derived neurotrophic factor (BDNF) and neuregulin 1 (NRG1) genes in neurodevelopment and cognition make a strong theoretical case for their influence on the P50 endophenotype.

METHOD

The possible role of NRG1, COMT Val158Met and BDNF Val66Met gene polymorphisms on the P50 endophenotype was examined in a large sample consisting of psychotic patients, their unaffected relatives and unrelated healthy controls using linear regression analyses.

RESULTS

Although P50 deficits were present in patients and their unaffected relatives, there was no evidence for an association between NRG1, COMT Val158Met or BDNF Val66Met genotypes and the P50 endophenotype.

CONCLUSIONS

The evidence from our large study suggests that any such association between P50 indices and NRG1, COMT Val158Met or BDNF Val66Met genotypes, if present, must be very subtle.

COMT gene polymorphism and corpus callosum morphometry in preterm born adults

INTRODUCTION

Preterm birth is associated with a range of neurodevelopmental deficits, including corpus callosum (CC) abnormalities, which persist into late adolescence and early adulthood. A common single-nucleotide polymorphism in the catechol-o-methyl transferase (COMT) gene (Val158Met) is associated with cognition and brain structure and may play a role in neurodevelopment. It is not known whether this polymorphism is associated with CC morphometry in individuals born preterm.

METHODS

Structural MRI scans were acquired in 33 adults born very preterm (before 33 weeks' gestation) and 29 healthy controls. DNA was collected and COMT Val158Met polymorphism status determined using standard available assays. The mid-sagittal area of four antero-posterior subdivisions of the CC was measured. The effect of COMT Val158Met polymorphism on cross-sectional CC areas was studied using multivariate analysis and generalised linear models, adjusted for the effects of the clinical sample group (preterm vs. control), age and sex.

RESULTS

The COMT Val/Val homozygous genotype was observed to be significantly associated with reduced size of the total corpus callosum, and this relationship was present for the anterior, midposterior and posterior quarters of the CC.

CONCLUSIONS

The COMT Val158Met polymorphism possibly influences the morphometry of the corpus callosum associated with very preterm births. Further studies with larger sample sizes are warranted to conclusively establish the effects of individual genotypes of the COMT gene on corpus callosum in preterm born adults.