COMT and BDNF interacted in bipolar II disorder not comorbid with anxiety disorder

Associations of BDNF/BDNF-AS SNPs with Depression, Schizophrenia, and Bipolar Disorder

Brain-Derived Neurotrophic Factor (BDNF) is crucial for various aspects of neuronal development and function, including synaptic plasticity, neurotransmitter release, and supporting neuronal differentiation, growth, and survival. It is involved in the formation and preservation of dopaminergic, serotonergic, GABAergic, and cholinergic neurons, facilitating efficient stimulus transmission within the synaptic system and contributing to learning, memory, and overall cognition. Furthermore, BDNF demonstrates involvement in neuroinflammation and showcases neuroprotective effects. In contrast, BDNF antisense RNA (BDNF-AS) is linked to the regulation and control of BDNF, facilitating its suppression and contributing to neurotoxicity, apoptosis, and decreased cell viability. This review article aims to comprehensively overview the significance of single nucleotide polymorphisms (SNPs) in BDNF/BDNF-AS genes within psychiatric conditions, with a specific focus on their associations with depression, schizophrenia, and bipolar disorder. The independent influence of each BDNF/BDNF-AS gene variation, as well as the interplay between SNPs and their linkage disequilibrium, environmental factors, including early-life experiences, and interactions with other genes, lead to alterations in brain architecture and function, shaping vulnerability to mental health disorders. The potential translational applications of BDNF/BDNF-AS polymorphism knowledge can revolutionize personalized medicine, predict disease susceptibility, treatment outcomes, and guide the selection of interventions tailored to individual patients.

Association between BDNF Val66Met polymorphism and generalized anxiety disorder and clinical characteristics in a Mexican population: A case-control study

The aim of the present case-control study was to explore the association between BDNF Val66Met (rs6265) polymorphism and generalized anxiety disorder in Mexican individuals, and whether this polymorphism plays a role in the symptomatology of anxiety.A total of 212 subjects were included in the study. Around 75 patients with generalized anxiety disorder were diagnosed by psychiatrists based on the DSM-IV instrument and 137 unrelated subjects psychiatrically healthy were used as comparison group. The subclinical symptomatology in patients was assessed with the State-Trait Anxiety Inventory. BDNF rs6265 genotypes were analyzed using the polymerase chain reaction end-point method.The association between BDNF Val66Met with the risk for generalized anxiety disorder was evaluated using 4 inheritance models. The present study showed that carrying the Met allele confers increased risk for the presence of generalized anxiety disorder (χ = 4.7, P = .03; OR (95%) 1.96 (1.05-3.56)) when patients with generalized anxiety disorder were compared with the comparison group.Our results provide evidence of an association between the Val66Met polymorphism of the BDNF gene and generalized anxiety disorder in a Mexican population. However, no association was observed between this polymorphism and the symptomatology of anxiety.

Regulation of gene transcription in bipolar disorders: Role of DNA methylation in the relationship between prodynorphin and brain derived neurotrophic factor

Bipolar Disorder (BD) is a prevalent and disabling condition, determined by gene-environment interactions, possibly mediated by epigenetic mechanisms. The present study aimed at investigating the transcriptional regulation of BD selected target genes by DNA methylation in peripheral blood mononuclear cells of patients with a DSM-5 diagnosis of type I (BD-I) and type II (BD-II) Bipolar Disorders (n=99), as well as of healthy controls (CT, n=42). The analysis of gene expression revealed prodynorphin (PDYN) mRNA levels significantly reduced in subjects with BD-II but not in those with BD-I, when compared to CT. Other target genes (i.e. catechol-O-methyltransferase (COMT), glutamate decarboxylase (GAD67), serotonin transporter (SERT) mRNA levels remained unaltered. Consistently, an increase in DNA methylation at PDYN gene promoter was observed in BD-II patients vs CT. After stratifying data on the basis of pharmacotherapy, patients on mood-stabilizers (i.e., lithium and anticonvulsants) were found to have lower DNA methylation at PDYN gene promoter. A significantly positive correlation in promoter DNA methylation was observed in all subjects between PDYN and brain derived neurotrophic factor (BDNF), whose methylation status had been previously found altered in BD. Moreover, among key genes relevant for DNA methylation establishment here analysed, an up-regulation of DNA Methyl Transferases 3b (DNMT3b) and of the methyl binding protein MeCP2 (methyl CpG binding protein 2) mRNA levels was also observed again just in BD-II subjects. A clear selective role of DNA methylation involvement in BD-II is shown here, further supporting a role for BDNF and its possible interaction with PDYN. These data might be relevant in the pathophysiology of BD, both in relation to BDNF and for the improvement of available treatments and development of novel ones that modulate epigenetic signatures.

Prevalence and Associated Features of Anxiety Disorder Comorbidity in Bipolar Disorder: A Meta-Analysis and Meta-Regression Study

Objective: Bipolar disorder is highly comorbid with anxiety disorders, however current and lifetime comorbidity patterns of each anxiety disorder and their associated features are not well studied. Here, we aimed to conduct a meta-analysis and meta-regression study of current evidence. Method: We searched PubMed to access relevant articles published until September 2015, using the keywords "Bipolar disorder" or "Affective Psychosis" or "manic depressive" separately with "generalized anxiety," "panic disorder," "social phobia," "obsessive compulsive," and "anxiety." Variables for associated features and prevalence of anxiety disorders were carefully extracted. Results: Lifetime any anxiety disorder comorbidity in BD was 40.5%; panic disorder (PD) 18.1%, generalized anxiety disorder (GAD) 13.3%, social anxiety disorder (SAD) 13.5% and obsessive compulsive disorder (OCD) 9.7%. Current any anxiety disorder comorbidity in BD is 38.2%; GAD is 15.2%, PD 13.3%, SAD 11.7%, and OCD 9.9%. When studies reporting data about comorbidities in BDI or BDII were analyzed separately, lifetime any anxiety disorder comorbidity in BDI and BDII were 38% and 34%, PD was 15% and 15%, GAD was 14% and 16.6%, SAD was 8% and 13%, OCD was 8% and 10%, respectively. Current any DSM anxiety disorder comorbidity in BDI or BDII were 31% and 37%, PD was 9% and 13%, GAD was 8% and 12%, SAD was 7% and 11%, and OCD was 8% and 7%, respectively. The percentage of manic patients and age of onset of BD tended to have a significant impact on anxiety disorders. Percentage of BD I patients significantly decreased the prevalence of panic disorder and social anxiety disorder. A higher rate of substance use disorder was associated with greater BD-SAD comorbidity. History of psychotic features significantly affected current PD and GAD. Conclusions: Anxiety disorder comorbidity is high in BD with somewhat lower rates in BDI vs BDII. Age of onset, substance use disorders, and percentage of patients in a manic episode or with psychotic features influences anxiety disorder comorbidity.

COMT and BDNF Gene Variants Help to Predict Alcohol Consumption in Alcohol-dependent Patients

BACKGROUND

The neurobiology of alcohol dependence (AD) involves alterations in neurotransmitters and the stress response. We hypothesized that an interaction between functional variants of dopaminergic and neurotrophic genes may influence drinking in AD.

METHODS

The relationship between alcohol consumption and single-nucleotide polymorphisms, Val66Met in the brain-derived neurotrophic factor (BDNF), and Val158Met in the catechol-O-methyltransferase (COMT), was analyzed among 281 alcohol-dependent individuals.

RESULTS

Individuals carrying both the COMT Met158Met genotype and the BDNF Val66Val genotype drank more than those with other variants of these genes (P = 0.039). Those who had a family history of AD also drank more than those without a family history (P = 0.048). Patients with both Met/Met genotype in the COMT Val158Met polymorphism and Val/Val genotype in the BDNF Val66Met polymorphism suffered from more health problems than those carrying other variants (P = 0.030) and had lower motivation to change drinking patterns (P = 0.031).

CONCLUSIONS

Patients carrying both the BDNF Val66Val and COMT Met158Met variants had higher alcohol consumption. These effects may be influenced by the effects of BDNF and COMT on dopamine responses to alcohol. Motivation-enhancing strategies might benefit the group of patients identified by genotyping in this study, and also treatment aimed at reducing alcohol consumption.

Evidence of an epistatic effect between Dysbindin-1 and Neuritin-1 genes on the risk for schizophrenia spectrum disorders

BACKGROUND

The interest in studying gene-gene interactions is increasing for psychiatric diseases such as schizophrenia-spectrum disorders (SSD), where multiple genes are involved. Dysbindin-1 (DTNBP1) and Neuritin-1 (NRN1) genes have been previously associated with SSD and both are involved in synaptic plasticity. We aimed to study whether these genes show an epistatic effect on the risk for SSD.

METHODS

The sample comprised 388 SSD patients and 397 healthy subjects. Interaction was tested between: (i) three DTNBP1 SNPs (rs2619537, rs2743864, rs1047631) related to changes in gene expression; and (ii) an haplotype in NRN1 previously associated with the risk for SSD (rs645649-rs582262: HAP-risk C-C).

RESULTS

An interaction between DTNBP1 rs2743864 and NRN1 HAP-risk was detected by using the model based multifactor dimensionality reduction (MB-MDR) approach (P=0.0049, after permutation procedure), meaning that the risk for SSD is significantly higher in those subjects carrying both the A allele of rs2743864 and the HAP-risk C-C. This interaction was confirmed by using a logistic regression model (P=0.033, OR (95%CI)=2.699 (1.08-6.71), R²=0.162).

DISCUSSION

Our results suggest that DTNBP1 and NRN1 genes show a joint effect on the risk for SSD. Although the precise mechanism underlying this effect is unclear, the fact that these genes have been involved in synaptic maturation, connectivity and glutamate signalling suggests that our findings could be of value as a link to the schizophrenia aetiology.

The T Allele of MTHFR c.C677T and Its Synergism with G (Val 158) Allele of COMT c.G472A Polymorphism Are Associated with the Risk of Bipolar I Disorder

AIMS

The aims of the present study were to investigate the association between methylenetetrahydrofolate reductase (MTHFR) c.C677T (p.A222V) and catechol-O-methyltransferase (COMT) c.G472A (p.V158M) polymorphisms and their synergism with respect to bipolar I disorder (BID).

METHODS

Within an ethnic Kurdish population from Western Iran the MTHFR c.C677T and COMT c.G472A polymorphisms were studied in 150 patients with BID and 149 gender- and age-matched healthy individuals using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In the presence of MTHFR 677T allele and MTHFR TT genotype, the risk of BID was 1.44 times (p = 0.046) and 1.81-fold (p = 0.029), respectively. The frequency of COMT 472G allele compared to the A allele in cases and controls was not significant (p = 0.078); however there was a synergism between the presence of MTHFR 677T and COMT 472G alleles that increased the risk of BID by 2.58-fold (p = 0.003).

CONCLUSIONS

Our findings indicate that the presence of the lower activity allele of MTHFR (677T) increased the risk of BID. In addition, the concomitant presence of the MTHFR 677T allele with the COMT 472G allele was associated with increased susceptibility to BID in our population.

Interaction of DRD2TaqI, COMT, and ALDH2 genes associated with bipolar II disorder comorbid with anxiety disorders in Han Chinese in Taiwan

It is hypothesized that dopaminergic genes-dopamine type-2 receptor (DRD2), aldehyde dehydrogenase 2 (ALDH2), and catechol-O-methyltransferase (COMT)-are associated with bipolar disorder (BP) and anxiety disorder (AD). Bipolar II (BP-II) is reported to be highly comorbid with AD. We examined whether interactions among these three genes are susceptibility factors in BP-II with AD (BP-II(+AD)) and without AD (BP-II(-AD)). In this study, we hypothesize that the interaction of the dopaminergic genes between BP-II(+AD) and BP-II(-AD) is significant different. We recruited 1260 participants: 495 with BP-II(-AD), 170 with BP-II(+AD), and 595 healthy controls without BP-II or AD. Genotyping was done using polymerase chain reactions plus restriction fragment length polymorphism analysis. Genotypic frequencies of the DRD2TaqIA, COMT, and ALDH2 polymorphisms between the two BP-II groups were nonsignificant. In logistic regression, the ALDH2 and DRD2TaqIA genes showed a main effect that was protective against BP-II(-AD) (odds ratio [OR] = 0.497, p = 0.010, and OR = 0.415, p = 0.017, respectively). The interaction of DRD2TaqIA A1/A1 and ALDH2*1/*1 had a significant risk effect on the BP-II(-AD) group (OR = 7.177, p < 0.001). However, the interaction of DRD2TaqIA A1/A1, ALDH2*1/*1, and COMTMet/Met&Val/Met become a weak protective factor against BP-II(-AD) (OR = 0.205, p = 0.047). All of the significant results described above are found only in BP-II(-AD). This study supports the hypothesis the interaction of the dopaminergic genes between BP-II(+AD) and BP-II(-AD) is significant different,, and provides additional evidence that the DRD2TaqIA A1/A1, ALDH2*1/*1 and COMT genes interact in BP-II(-AD) but not in BP-II(+AD).

A potential interaction between COMT and MTHFR genetic variants in Han Chinese patients with bipolar II disorder

Bipolar II disorder (BP-II), characterized by recurrent dysregulation of mood, is a serious and chronic psychiatric illness. However, BP-II is commonly under-recognized, even in psychiatric settings. Because dopaminergic disturbance is thought to be involved in the development of bipolar disorder (BPD), it seems essential to investigate dopamine-related genes like the catechol-O-methyltransferase (COMT) gene, which are involved in dopamine metabolism, and the methylenetetrahydrofolate reductase (MTHFR) gene, which may affect COMT methylation and COMT function. The current study examined the association and interaction of the COMT Val158Met and MTHFR C677T variants with BP-II. Nine hundred seventy-eight participants were recruited: 531 with BP-II and 447 healthy controls. The genotypes of the COMT and MTHFR polymorphisms were determined using a polymerase chain reaction-restriction fragment length polymorphism analysis. Logistic regression analysis showed a significant interaction effect of the COMT Val158Met Val/Val genotype and the MTHFR C677T C/T + T/T genotype (P = 0.039) for the protective effect on the odds of developing BP-II. Our findings support preliminary evidence that the COMT and MTHFR genes interact in BP-II, and they imply the connection of both dopaminergic pathways and methylation pathways in the pathogenesis of BP-II.

The role of brain-derived neurotrophic factor (BDNF) Val66Met genetic polymorphism in bipolar disorder: a case-control study, comorbidities, and meta-analysis of 16,786 subjects

OBJECTIVES

The aim of this study was to evaluate the association of Val66Met brain-derived neurotrophic factor (BDNF) polymorphism with bipolar disorder in (i) a meta-analysis and (ii) a case-control study in a Mexican population. We also investigated the possible association of this polymorphism with clinical features.

METHODS

We performed a keyword search of the PubMed and Web of Science databases. A total of 22 studies that have investigated the association of Val66Met (rs6265) with bipolar disorder were selected for inclusion and combined with random effects meta-analysis, using allelic, additive, dominant, and recessive models. Finally, the single nucleotide polymorphism (rs6265) Val66Met in the BDNF gene was genotyped and compared between 139 patients with bipolar disorder and 141 healthy volunteers in a Mexican population.

RESULTS

The pooled results from the meta-analysis (9,349 cases and 7,437 controls) did not show a significant association in any of the models. The same results were obtained in our case-control study when analyzing the distribution of the genotypic frequencies of the Val66Met polymorphism in patients with bipolar disorder. However, when we analyzed the association between rs6265 and lifetime history of suicidal behavior, we found an association between genotype Val-Val and suicide attempt (p = 0.02).

CONCLUSIONS

Although the present study has some limitations, the results indicate a lack of association between the Val66Met polymorphism and bipolar disorder. However, in our case-control study in a Mexican population, the Val66Met polymorphism was associated with suicidal behavior in patients with bipolar disorder. Nevertheless, it is important to consider potential interactions of the BDNF gene, the environment, and different inheritance patterns, when carrying out future genetic studies with larger samples.

Association between brain-derived neurotrophic factor genetic polymorphism Val66Met and susceptibility to bipolar disorder: a meta-analysis

BACKGROUND

In view of previous conflicting findings, this meta-analysis was performed to comprehensively determine the overall strength of associations between brain-derived neurotrophic factor (BDNF) genetic polymorphism Val66Met and susceptibility to bipolar disorders (BPD).

METHODS

Literatures published and cited in Pubmed and Wanfang Data was searched with terms of 'Val66Met', 'G196A', 'rs6265', 'BDNF', 'association', and 'bipolar disorder' up to March 2014. All original case-control association studies were meta-analyzed with a pooled OR to estimate the risk and 95% confidence interval (CI) to reflect the magnitude of variance.

RESULTS

Twenty-one case-control association studies met our criteria for the meta-analysis. Overall, there was no significant difference in allelic distribution of Val66Met polymorphism between patients and controls with a pooled OR = 1.03 (95% CI 0.98, 1.08) although there was a trend towards association between Val66Met polymorphism and BPD in Caucasians with an OR of 1.08 (95% CI 1.00, 1.16). However, subgroup analyses showed that there was a significant association of Val allele with decreased disease susceptibility for bipolar disorder type II with a pooled OR of 0.88 (95% CI 0.78, 0.99).

CONCLUSIONS

There is no compelling evidence to supportVal66Met polymorphism in BDNF gene playing an important role in the susceptibility to BPD across different ethnicities.

The neurobiology of bipolar disorder: identifying targets for specific agents and synergies for combination treatment

Bipolar disorder (BD) is a chronic psychiatric illness described by severe changes in mood. Extensive research has been carried out to understand the aetiology and pathophysiology of BD. Several hypotheses have been postulated, including alteration in genetic factors, protein expression, calcium signalling, neuropathological alteration, mitochondrial dysfunction and oxidative stress in BD. In the following paper, we will attempt to integrate these data in a manner which is to understand targets of treatment and how they may be, in particular, relevant to combination treatment. In summary, the data suggested that BD might be associated with neuronal and glial cellular impairment in specific brain areas, including the prefrontal cortex. From molecular and genetics: (1) alterations in dopaminergic system, through catechol-O-aminotransferase; (2) decreased expression and polymorphism on brain-derived neurotrophic factor; (3) alterations cyclic-AMP responsive element binding; (4) dysregulation of calcium signalling, including genome-wide finding for voltage-dependent calcium channel α-1 subunit are relevant findings in BD. Future studies are now necessary to understand how these molecular pathways interact and their connection to the complex clinical manifestations observed in BD.

Gene×gene×gender interaction of BDNF and COMT genotypes associated with panic disorder

Genetic and gender differences are among the factors that have a role in the etiology of panic disorder (PD). It is thought that PD is related to neurotransmitter pathways, such as brain-derived neurotrophic factor (BDNF) and catechol-O-methyltransferase (COMT), both of which are involved in the regulation of the monoamine mechanism. We examined the interactions of BDNF, COMT and gender differences in terms of personality characteristics in PD. The subjects were 470 patients (178 men, 292 women) with a DSM-IV diagnosis of PD, and 458 healthy controls (195 men, 263 women). The subjects were further clinically characterized using the Revised NEO Personality Inventory (NEO-PI-R) and State-Trait Anxiety Inventory (STAI). COMT Val158Met polymorphisms (rs4680) and BDNF Val66Met (rs6265) polymorphisms were genotyped using allelic discrimination by a real-time PCR assay. A multivariate analysis of covariance (MANCOVA) was performed with STAI and NEO-PI-R scores as the dependent factor, gender and genotyping groups (BDNF and COMT) as fixed factors, and the covariate of age in the PD and healthy control groups. Post hoc MANCOVA tests were conducted to evaluate COMT × BDNF interactions. An interaction of BDNF × COMT × gender was confirmed in the PD group by MANCOVA on STAI scores and NEO-PI-R Neuroticism and Extraversion scores, whereas no association of such interactions was observed in the healthy controls. The anxiety sensitivity of the COMT Met+BDNF Val/Val carriers was higher than that of the COMT Val/Val+BDNF Val/Val carriers by post hoc MANCOVA. A significant BDNF × COMT × gender interaction was observed in the PD patients but not in the controls. Our findings partly demonstrated the involvement of a gene × gene × gender interaction in the pathogenesis of PD.