Methylated spirits: epigenetic hypotheses of psychiatric disorders

Epigenetic Regulation in Psychosomatics and Psychotherapy

Epigenetic modifications play a pivotal role in the regulation of gene expression and cell function, offering potential markers of disease states and therapeutic outcomes. Recent advancements in neuroscience have spurred interest in studying the epigenetic underpinnings of psychosomatic medicine. This review presents a new perspective on the role of epigenetic regulation in the realms of psychosomatics and psychotherapy. The authors first highlight epigenetic patterns associated with prevalent psychosomatic disorders, including irritable bowel syndrome, fibromyalgia, psoriasis, and lichen planus. For these conditions, psychotherapy serves as a treatment modality and can be conceptualized as an epigenetic intervention that beneficially affects the epigenome as part of the therapeutic process. Focusing on cognitive-behavioral and mindfulness-based therapies, the authors highlight evidence on psychotherapy-associated epigenetic signatures occurring at genes that are involved in stress response, inflammation, neurotransmission, neuroplasticity, and aging. Educating patients about the potential of psychotherapy to affect the epigenome may enhance patient engagement with and adherence to treatment, and psychotherapy-induced epigenetic changes have the potential to promote transgenerational disease prevention, underscoring the far-reaching implications of this therapeutic approach. Challenges persist in epigenetic studies, and this review aimed to catalyze further research in this burgeoning field, with the goal of enhancing patient care.

Oxidative Stress in Cognitive and Epigenetic Aging: A Retrospective Glance

Brain aging is the critical and common factor among several neurodegenerative disorders and dementia. Cellular, biochemical and molecular studies have shown intimate links between oxidative stress and cognitive dysfunction during aging and age-associated neuronal diseases. Brain aging is accompanied by oxidative damage of nuclear as well as mitochondrial DNA, and diminished repair. Recent studies have reported epigenetic alterations during aging of the brain which involves reactive oxygen species (ROS) that regulates various systems through distinct mechanisms. However, there are studies which depict differing roles of reactive oxidant species as a major factor during aging. In this review, we describe the evidence to show how oxidative stress is intricately linked to age-associated cognitive decline. The review will primarily focus on implications of age-associated oxidative damage on learning and memory, and the cellular events, with special emphasis on associated epigenetic machinery. A comprehensive understanding of these mechanisms may provide a perspective on the development of potential therapeutic targets within the oxidative system.

Brain, behavior and the journey towards neuroepigenetic therapeutics

Epigenetics has brought about a major shift in our understanding of biological mechanisms and their associated health effects. Strong epigenetic components have been found to be involved in the progression of many diseases. In several human diseases, including debilitating psychiatric disorders, altered epigenetic status has been found as one of the main causes. With continuous progress on drug development, researchers are enthusiastic toward epigenetic therapeutics which could possibly reverse epigenetic modifications. In this article certain developments in epigenetic therapeutics are highlighted, the indiscriminate use of which could also be associated with potential risk. These risks may partly be due to our limited knowledge on genes and the mechanisms underlying epigenetic involvement in different diseases. Epigenetic changes are fundamentally important for a large number of bodily functions; nonspecific usage of therapeutics could be potentially harmful therefore there is a need to harness epigenetics positively.

Toxoplasma gondii - obsessive -compulsive disorder relationship: is it different in children?

BACKGROUND AND AIM

Obsessive-compulsive disorder (OCD) is a common neuropsychiatric illness. Although the etiology of OCD is still unknown, recent investigations have associated development of OCD with infectious illness. Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes infection of the central nervous system. In the last decade, a lot of researches have focused on the possible relationship between exposure to T. gondii and neuropsychiatric disorders such as schizophrenia. Therefore, in this study, it was aimed to investigate a possible association between Toxoplasma infection and OCD in children and adolescents.

METHODS

We selected 55 patients with OCD (aged between 7 and 16 years) and 59 healthy children and adolescents (aged between 7 and 16 years), and investigated the seropositivity rate for anti-Toxoplasma IgG antibodies by enzyme-linked immunosorbent assay.

RESULTS

The seropositivity rate for anti-T. gondii IgG antibodies among OCD patients (21.82%) was found to be higher than the rate in control group (15.25%). However, the difference between the OCD group and the control group was not statistically significant (p > .05).

CONCLUSION

In contrast to studies in adult patients, the results of this study do not support the relationship between T. gondii and OCD children and adolescents.

COMT Val158Met and MTHFR C677T moderate risk of schizophrenia in response to childhood adversity

OBJECTIVE

Mesolimbic dopamine sensitization has been hypothesized to be a mediating factor of childhood adversity (CA) on schizophrenia risk. Activity of catechol-O-methyltransferase (COMT) Val158Met increases mesolimbic dopamine signaling and may be further regulated by methylenetetrahydrofolate reductase (MTHFR) C677T. This study investigates the three-way interaction between CA, COMT, and MTHFR.

METHODS

We conducted a nested case-control study on individuals born after 1981, linking population-based registers to study the three-way interaction. We included 1699 schizophrenia cases and 1681 controls, and used conditional logistic regression to report incidence rate ratios (IRRs).

RESULTS

Childhood adversity was robustly associated with schizophrenia. No main genetic effects were observed. MTHFR C677T increased schizophrenia risk in a dose-dependent manner per MTHFR T allele (P = 0.005) consequent upon CA exposure. After inclusion of the significant (P = 0.03) COMT × MTHFR × CA interaction, the risk was further increased per high-activity COMT Val allele. Hence, exposed COMT Val/Val and MTHFR T/T carriers had an IRR of 2.76 (95% CI, 1.66-4.61). Additional adjustments for ancestry and parental history of mental illness attenuated the results with the interaction being only marginally significant.

CONCLUSION

MTHFR C677T and COMT Val158Met interact with CA to increase risk of schizophrenia.

Epigenetics in Alzheimer's Disease: Perspective of DNA Methylation

Research over the years has shown that causes of Alzheimer's disease are not well understood, but over the past years, the involvement of epigenetic mechanisms in the developing memory formation either under pathological or physiological conditions has become clear. The term epigenetics represents the heredity of changes in phenotype that are independent of altered DNA sequences. Different studies validated that cytosine methylation of genomic DNA decreases with age in different tissues of mammals, and therefore, the role of epigenetic factors in developing neurological disorders in aging has been under focus. In this review, we summarized and reviewed the involvement of different epigenetic mechanisms especially the DNA methylation in Alzheimer's disease (AD), late-onset Alzheimer's disease (LOAD), familial Alzheimer's disease (FAD), and autosomal dominant Alzheimer's disease (ADAD). Down to the minutest of details, we tried to discuss the methylation patterns like mitochondrial DNA methylation and ribosomal DNA (rDNA) methylation. Additionally, we mentioned some therapeutic approaches related to epigenetics, which could provide a potential cure for AD. Moreover, we reviewed some recent studies that validate DNA methylation as a potential biomarker and its role in AD. We hope that this review will provide new insights into the understanding of AD pathogenesis from the epigenetic perspective especially from the perspective of DNA methylation.

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.

MTHFR gene polymorphism and age of onset of schizophrenia and bipolar disorder

Objective. Several studies with contradictory results from different cultures about association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in schizophrenia and bipolar disorders. Little is known about this association in Arab culture and Egypt. So the present study aimed to assess the association of MTHFR C677T polymorphism in bipolar disorder (BD) and schizophrenia in comparison to control group. The association between MTHFR C677T polymorphism and the age at onset in schizophrenia or BD was also studied. Methods. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to examine the genotype and allele frequencies of MTHFR C677T polymorphism in 149 healthy subjects and 134 bipolar and 103 schizophrenia patients. Results. In BD and schizophrenia, there was a higher prevalence of MTHFR C677T polymorphism than healthy subjects. Earlier age at onset was found in patients with BD, carrying one copy of the T allele or CT genotypes but not in patients with schizophrenia. Conclusion. The present findings suggest that the MTHFR C677T polymorphisms are likely to be associated with the risk of developing BD and schizophrenia and influence the age at onset of BD but not the age at onset of schizophrenia.

COMT and MTHFR polymorphisms interaction on cognition in schizophrenia: an exploratory study

The investigation of the catechol-O-methyltransferase (COMT-[rs4680]) and methylenetetrahydrofolate reductase (MTHFR-[rs1801133]) polymorphisms' interaction might shed light into the pathogenetic mechanisms of the cognitive dysfunction in schizophrenia. In an exploratory study, we hypothesized that the MTHFR 677T allele which has been related to a hypoactive MTHFR enzyme would augment the unfavorable effects of COMT Val158 homozygosity which has been associated with COMT enzyme hyperfunction. 90 schizophrenia patients and 55 healthy volunteers were assessed on psychomotor speed, pattern and spatial recognition memory (SRM), spatial working memory (SWM), attentional flexibility and planning (Stockings of Cambridge-SOC). IQ scores in a random subgroup of patients were also measured. A significant COMT×MTHFR interaction on SWM (p=0.048) and planning (p=0.026) was revealed in both groups. Among COMT-Val/Val participants, MTHFR-C/C made more SWM errors (p=0.033) and solved fewer SOC problems (p=0.025) than MTHFR-T carriers. In patients, there was a significant COMT×MTHFR interaction on full scale IQ (p=0.035): among COMT-Met carriers, MTHFR-T carriers performed significantly worse than MTHFR-C/C (p=0.021), which was driven by a COMT×MTHFR interaction involving performance IQ (p=0.047). In conclusion, COMT and MTHFR polymorphisms interacted on cognition, suggesting that the MTHFR enzyme activity might moderate the effects of the COMT enzyme. In contrast to our initial hypothesis, the MTHFR T-allele attenuated the cognitive effects of COMT Val homozygosity. In this preliminary study, we propose that dopaminergic and intracellular methylation mechanisms could interact on cognitive deficits in schizophrenia.

Perinatal conditions and parental age at birth as risk markers for subsequent suicide attempt and suicide: a population based case-control study

Restricted fetal growth and young maternal age have been associated with increased risk of suicidal behaviour later in life. Research investigating the independent and interacting effects of these risk factors with parental mental health and socio-economic status is scarce. A case-control study was effected through record linkage between Swedish registers. Individuals born 1973-1983 who were hospitalized due to a suicide attempt (n = 17,159) or committed suicide (n = 1,407) were matched to ≤10 controls by sex, month and county of birth. Controlling for parental conditions, significantly increased odds ratios (OR) for suicide attempt were found for low birth weight (OR = 1.12, 95 % CI 1.01-1.25), short birth length (OR = 1.15, 95 % CI 1.08-1.22), short and light for gestational age (OR = 1.23, 95 % CI: 1.10-1.38), short but not light for gestational age (OR = 1.18, 95 % CI: 1.09, 1.29), teenage motherhood (OR = 1.66, 95 % CI 1.53-1.80), young fatherhood (OR = 1.33, 95 % CI 1.27-1.39) and multiparity (OR = 1.40, 95 % CI 1.31-1.50). For completed suicide, increased odds ratios were found for low birth weight (OR = 1.65, 95 % CI 1.16-2.35), teenage motherhood (OR = 1.44, 95 % CI 1.09-1.90) and young fatherhood (OR = 1.20, 95 % CI 1.02-1.41). There was a synergy effect between teenage motherhood and parental psychiatric inpatient care with regard to suicide attempt in offspring [synergy index = 1.53 (95 % CI 1.27-1.84)]. Low birth weight and length, and short and light for gestational age may increase the risk of subsequent suicidal behaviour, and more research is needed to investigate underlying mechanisms. Public health implications from this study include measures to improve pre- and perinatal parental mental health, particularly in teenage pregnancies.

Meta-analysis of MTHFR gene variants in schizophrenia, bipolar disorder and unipolar depressive disorder: evidence for a common genetic vulnerability?

Past analyses examining the relationship between genetic variation in the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene and psychiatric disorders have provided mixed and largely inconclusive findings. MTHFR is involved in the one-carbon metabolic pathway which is essential for DNA biosynthesis and the epigenetic process of DNA methylation. We conducted a meta-analysis of all published case-control studies investigating associations between two common MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T (sample size 29,502) and A1298C (sample size 7934), and the major psychiatric disorders (i) schizophrenia (SZ), (ii) bipolar disorder (BPD), and (iii) unipolar depressive disorder (UDD). In order to examine possible shared genetic vulnerability, we also tested for associations between MTHFR and all of these major psychiatric disorders (SZ, BPD and UDD) combined. MTHFR C677T was significantly associated with all of the combined psychiatric disorders (SZ, BPD and UDD); random effects odds ratio (OR)=1.26 for TT versus CC genotype carriers; confidence interval (CI) 1.09-1.46); meta-regression did not suggest moderating effects of psychiatric diagnosis, sex, ethnic group or year of publication. Although MTHFR A1298C was not significantly associated with the combination of major psychiatric disorders, nor with SZ, there was evidence for diagnostic moderation indicating a significant association with BPD (random effects OR=2.03 for AA versus CC genotype carriers, CI: 1.07-3.86). Meta-analysis on UDD was not possible due to the small number of studies available. This study provides evidence for shared genetic vulnerability for SZ, BPD and UDD mediated by MTHFR 677TT genotype, which is in line with epigenetic involvement in the pathophysiology of these psychiatric disorders.

Genetics in psychiatry: are the promises met?

OBJECTIVES

Psychiatric disorders are among the most heritable common disorders, and for more than 20 years researchers have tried to unravel genetic susceptibility genes. This review briefly outlines the pros and cons of genetic approaches, important advances and possible future directions for readers not familiar with genetic studies.

METHODS

In this article the results of 20 years molecular genetics in psychiatry are shortly and critically summarized on the basis of important reviews and meta-analyses of the last decade, without describing and enumerating the different findings (see special reviews).

RESULTS

Conventional linkage and candidate association studies revealed numerous, but also inconsistent and sometimes contradictory results. The reasons are assumed to include the complexity of the disorder with interaction of several genes of small effects, lack of a valid phenotype, and invalid statistical and methodological issues. Recent systematic genome-wide association studies (GWAS) have reported association of some common variants for schizophrenia and bipolar disorder. However, the risk conferred by these variants is small and genome-wide significance is rare. Also structural variations might be important, and interesting data are arising from copy-number-variations (CNVs).

CONCLUSIONS

Although the new data from GWAS are promising, they still do not meet our initial expectations, identifying a "susceptibility gene". However, they opened new aspects concerning aetiology of psychoses, and the incorporation of new approaches, as epigenetics, or gene-environment interaction, is needed in future study designs.

Fooling mother nature: epigenetics and novel treatments for psychiatric disorders

Modern formulations of psychiatric disorders hypothesize that mother nature goes awry, causing both genetic and epigenetic disease actions. Genetic disease actions are the consequences of naturally inherited risk genes that have an altered sequence of DNA. This altered DNA sequence theoretically leads to the production of altered gene products in neurons, causing inefficient information processing in various brain circuits, and biasing those circuits towards developing symptoms of a mental illness. Epigenetic disease actions are theorized either to activate risk genes to make an altered gene product or to activate normal genes to make normal gene products but at the wrong time. Epigenetic disease mechanisms theoretically turn normal genes into risk genes by causing normal genes to be expressed in neurons when these genes should be silenced or by causing normal genes to be silenced when they should be expressed.