Epigenetics of major depressive disorder

Epigenetic modifications can alter gene expression through mechanisms that are heritable, but do not involve direct changes in the nucleotide sequence of the genome. Recent findings have suggested that epigenetic modifications are associated with several psychiatric disorders. As such, this chapter will introduce the general principles of epigenetics and molecular mechanisms, and discuss the implications they have on major depressive disorder. We first begin with DNA methylation, as it is the most widely studied epigenetic modification. The importance of DNA methylation is outlined by monozygotic twin studies of major depressive disorder, and the role it plays in each of the three theories of depression. Afterward, we present two additional epigenetic modifications-histone modifications and noncoding RNAs-and their role in depression. In each section, we will also briefly touch on the therapeutic impact on patient diagnosis and care

Meta-Analysis of Neuropsychological Studies in Panic Disorder Patients: Evidence of Impaired Performance during the Emotional Stroop Task

Background: Recent investigations have highlighted significant differences in verbal recall between patients with panic disorder (PD) and controls. These studies have highlighted that verbal memory and working memory could be impaired in PD. Objectives: The objective of the present meta-analysis is to confirm this hypothesis, reviewing the studies that have investigated neurocognitive testing in PD. Methods: We performed a systematic literature search for studies published between 1980 and 2015 that reported cognitive measurements in PD patients and controls. Effect size estimates were computed using the restricted maximum likelihood model. Only case-control studies were selected for this meta-analysis. We included studies that made a direct comparison between PD subjects and healthy controls. The diagnostic group consisted of adult patients aged over 18 years diagnosed with PD. We excluded the studies that did not employ a case-control design. All statistical analyses were carried out on R using the "metafor" package version 1.9-8. The effect size for each study neuropsychological test was calculated using the mean and SD of performance results, and p values < 0.05 were considered significant. Results: We identified few studies that tested verbal memory and executive functions in PD patients and controls, and this difference was not significant. On the other hand, there are several studies that have used the emotional Stroop task to assess cognitive functions in PD. There is no robust evidence of impairment of memory function in PD; however, when considering the emotional Stroop task, it was found that PD patients performed slower (p < 0.01) than healthy controls for all three types of stimuli (neutral, negative, positive). Conclusion: This meta-analysis included a small number of studies, which may have introduced bias into the analysis. However, there is some evidence of impairment of neurocognitive functions in PD when performing the emotional Stroop task. Furthermore, the paucity of studies evaluating neurocognition in PD suggests the need for further research in this field in order to draw meaningful conclusions

Candidate genes in panic disorder: Meta-analyses of 23 common variants in major anxiogenic pathways

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case–control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel–Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15–1.40, P=2.49 × 10−6), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53–0.79, P=1.81 × 10−5) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14–1.42, P=2.49 × 10−5) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07–1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14–1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07–1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07–1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate larger sample sizes and genome-wide approaches to further quantify the observed genetic variation among populations and subphenotypes of PD

The 2019 Schizophrenia International Research Society Conference, 10–14 April, Orlando, Florida: A summary of topics and trends

The Schizophrenia International Research Society (SIRS) recently held its first North American congress, which took place in Orlando, Florida from 10-14 April 2019. The overall theme of this year's congress was United in Progress – with the aim of cultivating a collaborative effort towards advancing the field of schizophrenia research. Student travel awardees provided reports of the oral sessions and concurrent symposia that took place during the congress. A collection of these reports is summarized and presented below and highlights the main themes and topics that emerged during the congress. In summary, the congress covered a broad range of topics relevant to the field of psychiatry today