Association analysis of the catechol-O-methyltransferase /methylenetetrahydrofolate reductase genes and cognition in late-onset depression

Association between variants of MTHFR genes and psychiatric disorders: A meta-analysis

Background

Psychiatric disorders have seriously affected human life, one of the risk genes related to psychosis is the methylenetetrahydrofolatereductase (MTHFR) gene. This gene has a potential role in psychiatric disorders. Therefore, a meta-analysis is conducted to investigate the correlations between two prevalent MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T, A1298C, severe psychological disorders (schizophrenia, major depression, bipolar disorder).

Methods

A total of 81 published studies were screened and selected by a search of electronic databases up to April 2022. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR polymorphism and psychiatric disorders susceptibility by using random effect models.

Results

We found that MTHFR C677T polymorphism is significantly related to schizophrenia and major depression in the overall population. MTHFR C677T has been linked to an increased risk of bipolar disorder in the recessive model (TT vs. CT + CC). Ethnic subgroup analysis shows that schizophrenia and major depression significantly correlate with MTHFR C677T and A1298C in Asian populations but not Caucasians. Besides, schizophrenia is correlated substantially with MTHFR C677T in the African population. However, the MTHFR A1298C polymorphism is only marginally linked to major depression.

Conclusion

Findings of the current study revealed that MTHFR may contribute to the common pathogenesis of psychiatric diseases and that its variants may be essential in controlling the expression of psychosis-related genes. This study could help the researchers and health specialists in the early diagnosis and treatment of psychiatric disorders.

A Systematic Review of Candidate Genes for Major Depression

Background and Objectives: The aim of this systematic review was to analyse which candidate genes were examined in genetic association studies and their association with major depressive disorder (MDD). Materials and Methods: We searched PUBMED for relevant studies published between 1 July 2012 and 31 March 2019, using combinations of keywords: “major depressive disorder” OR “major depression” AND “gene candidate”, “major depressive disorder” OR “major depression” AND “polymorphism”. Synthesis focused on assessing the likelihood of bias and investigating factors that may explain differences between the results of studies. For selected gene list after literature overview, functional enrichment analysis and gene ontology term enrichment analysis were conducted. Results: 141 studies were included in the qualitative review of gene association studies focusing on MDD. 86 studies declared significant results (p < 0.05) for 172 SNPs in 85 genes. The 13 SNPs associations were confirmed by at least two studies. The 18 genetic polymorphism associations were confirmed in both the previous and this systematic analysis by at least one study. The majority of the studies (68.79 %) did not use or describe power analysis, which may have had an impact over the significance of their results. Almost a third of studies (N = 54) were conducted in Chinese Han population. Conclusion: Unfortunately, there is still insufficient data on the links between genes and depression. Despite the reported genetic associations, most studies were lacking in statistical power analysis, research samples were small, and most gene polymorphisms have been confirmed in only one study. Further genetic research with larger research samples is needed to discern whether the relationship is random or causal. Summations: This systematic review had summarized all reported genetic associations and has highlighted the genetic associations that have been replicated. Limitations: Unfortunately, most gene polymorphisms have been confirmed only once, so further studies are warranted for replicating these genetic associations. In addition, most studies included a small number of MDD cases that could be indicative for false positive. Considering that polymorphism loci and associations with MDD is also vastly dependent on interpersonal variation, extensive studies of gene interaction pathways could provide more answers to the complexity of MDD.

Influence of COMT polymorphism in cognitive performance on dementia in community-dwelling elderly Mexican (SADEM study)

There is an inconsistent finding about the relationship of catechol-O-methyltransferase (COMT) with dementia susceptibility, as well as with cognitive impairment. To substantiate this, we examined COMT genotype effects in certain cognitive domains in dementia. To evaluate the effects of COMT Val158Met on cognitive performance, we used The Mini-Mental State Examination (MMSE), the cognitive subscale of the Alzheimer's Disease Assessment Scale-cognitive (ADAS-cog) and the Syndrome Kurz Test (SKT). The results show COMT Val/Met, Val/Val genotype polymorphisms had a significant effect on cognition performance (OR = 1.75 (95 %CI 1.22-2.54) and (OR = 2.76 (95 %CI 1.78-4.26), p < 0.001), and with adjustment for all cognitive test scores together, Val/Val (OR = 4.98 (95 % CI 1.47-16.86) and Val/Met (OR = 3.62 (95 % CI 1.37-9.56) had effect. Our study allows us to understand the role of COMT in cognitive performance in dementia, as well as interaction with other known risk factors for this pathology. This data might help in developing new therapeutic targets for cognitive impairment, main symptom of dementia. Other risk genotypes or haplotypes should be evaluated to determine the association with cognitive decline in dementia.

COMT val158met is not associated with Aβ-amyloid and APOE ε4 related cognitive decline in cognitively normal older adults

The non-synonymous single nucleotide polymorphism (SNP), Val158Met within the Catechol-O-methyltransferase (COMT) gene has been associated with altered levels of cognition and memory performance in cognitively normal adults. This study aimed to investigate the independent and interactional effects of COMT Val158Met on cognitive performance. In particular, it was hypothesised that COMT Val158Met would modify the effect of neocortical Aβ-amyloid (Aβ) accumulation and carriage of the apolipoprotein E (APOE) ε4 allele on cognition in preclinical Alzheimer's disease (AD). In 598 cognitively normal older adults with known neocortical Aβ levels, linear mixed modelling revealed no significant independent or interactional associations between COMT Val158Met and cognitive decline. These findings do not support previous associations between COMT Val158Met and cognitive performance and suggest this variant does not influence Aβ-amyloid or APOE ε4 driven cognitive decline in a well characterised cohort of cognitively normal older adults.

Systematic review and meta-analysis of genetic studies of late-life depression

Late-life depression (LLD) is thought to be multifactorial in etiology, including a significant genetic component. While a number of candidate gene studies have been carried out, results remain inconclusive. We undertook a systematic review of all genetic association studies of depression or depressive symptoms in late life published before February 2016, and performed meta-analyses on polymorphisms investigated in three or more independent studies. A total of 46 candidate gene studies examining 56 polymorphisms in 23 genes as well as a genome-wide association study (GWAS) were included. Meta-analyses were conducted for four polymorphisms using random effects models, of which three (APOE, BDNF, SLC6A4) were associated with LLD. These genes are implicated in hippocampal plasticity and stress reactivity, suggesting that dysregulation of these pathways may contribute to LLD. Despite using a large sample, the only GWAS published to date identified only one genome-wide significant locus in the 5q21 region. In the future, larger genetic studies specifically examining LLD, including non-hypothesis-driven GWAS, are required to further identify genetic determinants of LLD.

Meta-analysis of the COMT Val158Met polymorphism in major depressive disorder: the role of gender

OBJECTIVES

Many studies have reported an association of the COMT Val158Met polymorphism and major depressive disorder (MDD), although with conflicting results. The role of gender is a possible modulator. To overcome the problem of poor sample size detecting genes of small effect, we perform a meta-analysis of the current literature, investigating the influence of the COMT Val158Met polymorphism on the pathogenesis of MDD, with a major focus on the effect of gender.

METHODS

Out of 977 retrieved articles, 21 included case-control studies allowed the analysis of 9005 patients with MDD and 12,095 controls. Allelic and genotypic pooled odds ratios (OR) were calculated for the total sample and gender-subgroups.

RESULTS

In the absence of publication bias, allelic and genotypic analyses showed no significant association in the total sample, as well as in gender-specific subgroups. Sensitivity analysis did not alter the ORs.

CONCLUSIONS

The results imply a complex nature of the genotype × phenotype interaction. Further studies of the COMT gene or the locus remain to be justified given the important positional and functional relevance and the plethora of gender-specific findings. A possible way to further dissect this topic is shifting the focus to gene-based or genome-wide analyses of intermediate phenotypes.

Meta-Analysis of the COMT Val158Met Polymorphism in Major Depressive Disorder: Effect of Ethnicity

The COMT (catechol-O-methyltransferase) Val158Met polymorphism (rs4680) is a potential susceptibility variant for major depressive disorder (MDD). Although many genetic studies have examined the association between MDD and this polymorphism, the results were inconclusive. In the present study, we conducted a series of meta-analyses of samples consisting of 2905 MDD cases and 2403 controls with the goal of determining whether this variant indeed has any effect on MDD. We revealed a significant association in the comparison of Val/Val + Val/Met vs. Met/Met (OR =1.180; 95 % CI = 1.019, 1.367; P = 0.027), Val/Met vs. Val/Val (OR =1.18; 95 % CI = 1.038, 1.361; P = 0.013), and Val/Met vs. Met/Met (OR =1.229; 95 % CI = 1.053, 1.435; P = 0.009). Further meta-analyses of samples with European ancestry demonstrated a significant association of this SNP with MDD susceptibility in Val/Val + Val/Met vs. Met/Met (OR =1.231, 95 % CI = 1.046, 1.449; P = 0.013) and Val/Met vs. Met/Met (OR =1.284, 95 % CI = 1.050, 1.484; P = 0.012). For the samples with East Asian ancestry, we found a significant association in both allelic (Val vs. Met: OR =0.835; 95 % CI = 0.714, 0.975; P = 0.023) and genotypic (Met/Met + Val/Met vs. Val/Val: OR =1.431, 95 % CI = 1.143, 1.791; P = 0.002; Val/Met vs. Val/Val: OR =1.482, 95 % CI = 1.171, 1.871; P = 0.001) analyses. No evidence of heterogeneity among studies or publication bias was observed. Together, our results indicate that the COMT Val158Met polymorphism is a vulnerability factor for MDD with distinct effects in different ethnic populations.

Moderating Effects of Genetic Polymorphisms on Improvements in Cognitive Impairment in Breast Cancer Survivors Participating in a 6-Week Mindfulness-Based Stress Reduction Program

Breast cancer (BC) survivors often report cognitive impairment, which may be influenced by single-nucleotide polymorphisms (SNPs). The purpose of this study was to test whether particular SNPs were associated with changes in cognitive function in BC survivors and whether these polymorphisms moderated cognitive improvement resulting from the Mindfulness-Based Stress Reduction for Breast Cancer (MBSR[BC]) program. BC survivors recruited from Moffitt Cancer Center and the University of South Florida's Breast Health Program, who had completed adjuvant radiation and/or chemotherapy treatment, were randomized to either the 6-week MBSR(BC) program (n = 37) or usual care (UC; n = 35) group. Measures of cognitive function and demographic and clinical history data were attained at baseline and at 6 and 12 weeks. A total of 10 SNPs from eight genes known to be related to cognitive function were analyzed using blood samples. Results showed that SNPs in four genes (ankyrin repeat and kinase domain containing 1 [ANKK1], apolipoprotein E [APOE], methylenetetrahydrofolate reductase [MTHFR], and solute carrier family 6 member 4 [SLC6A4]) were associated with cognitive impairment. Further, rs1800497 in ANKK1 was significantly associated with improvements in cognitive impairment in response to MBSR(BC). These results may help to identify individuals who would be better served by MBSR(BC) or other interventions.

Gene-environment interaction in major depression: focus on experience-dependent biological systems

Major depressive disorder (MDD) is a multifactorial and polygenic disorder, where multiple and partially overlapping sets of susceptibility genes interact each other and with the environment, predisposing individuals to the development of the illness. Thus, MDD results from a complex interplay of vulnerability genes and environmental factors that act cumulatively throughout individual's lifetime. Among these environmental factors, stressful life experiences, especially those occurring early in life, have been suggested to exert a crucial impact on brain development, leading to permanent functional changes that may contribute to lifelong risk for mental health outcomes. In this review, we will discuss how genetic variants (polymorphisms, SNPs) within genes operating in neurobiological systems that mediate stress response and synaptic plasticity, can impact, by themselves, the vulnerability risk for MDD; we will also consider how this MDD risk can be further modulated when gene × environment interaction is taken into account. Finally, we will discuss the role of epigenetic mechanisms, and in particular of DNA methylation and miRNAs expression changes, in mediating the effect of the stress on the vulnerability risk to develop MDD. Taken together, we aim to underlie the role of genetic and epigenetic processes involved in stress- and neuroplasticity-related biological systems on the development of MDD after exposure to early life stress, thereby building the basis for future research and clinical interventions.