PTSD risk associated with a functional DRD2 polymorphism in heroin-dependent cases and controls is limited to amphetamine-dependent individuals

Genomic risk for post-traumatic stress disorder in families densely affected with alcohol use disorders

Recent genome-wide association studies (GWAS) have identified genetic markers of post-traumatic stress disorder (PTSD) in civilian and military populations. However, studies have yet to examine the genetics of PTSD while factoring in risk for alcohol dependence, which commonly co-occur. We examined genome-wide associations for DSM-IV PTSD among 4,978 trauma-exposed participants (31% with alcohol dependence, 50% female, 30% African ancestry) from the Collaborative Study on the Genetics of Alcoholism (COGA). We also examined associations of polygenic risk scores (PRS) derived from the Psychiatric Genomics Consortium (PGC)-PTSD Freeze 2 (N = 3533) and Million Veterans Program GWAS of PTSD (N = 5200) with PTSD and substance dependence in COGA, and moderating effects of sex and alcohol dependence. 7.3% of COGA participants met criteria for PTSD, with higher rates in females (10.1%) and those with alcohol dependence (12.3%). No independent loci met genome-wide significance in the PTSD meta-analysis of European (EA) and African ancestry (AA) participants. The PGC-PTSD PRS was associated with increased risk for PTSD (B = 0.126, p < 0.001), alcohol dependence (B = 0.231, p < 0.001), and cocaine dependence (B = 0.086, p < 0.01) in EA individuals. A significant interaction was observed, such that EA individuals with alcohol dependence and higher polygenic risk for PTSD were more likely to have PTSD (B = 0.090, p < 0.01) than those without alcohol dependence. These results further support the importance of examining substance dependence, specifically alcohol dependence, and PTSD together when investigating genetic influence on these disorders.

Genetic Markers as Risk Factors for the Development of Impulsive-Compulsive Behaviors in Patients with Parkinson's Disease Receiving Dopaminergic Therapy

Impulsive–compulsive and related behavioral disorders (ICD) are drug-induced non-motor symptoms of Parkinson’s disease (PD). Recently research has focused on evaluating whether ICD could be predicted and managed using a pharmacogenetic approach based on dopaminergic therapies, which are the main risk factors. The aim of our study was to evaluate the role of candidate genes such as DBH, DRD2, MAOA, BDNF, COMT, SLC6A4, SLC6A3, ACE, DRD1 gene polymorphisms in the pathogenesis of ICD in PD. We compared patients with PD and ICD (n = 49), patients with PD without ICD (n = 36) and a healthy control group (n = 365). ICD was diagnosed using the QUIP questionnaires and specific diagnostic criteria for subtypes of ICD. Genotyping was conducted using a number of PCR techniques and SNaPshot. Statistical analysis was performed using WinPepi and APSampler v3.6 software. PCA testing was conducted using RStudio software v1.4.1106-5. The following substitutions showed statistically significant correlations with PD and ICD: DBH (rs2097629, rs1611115), DRD2 (rs6275, rs12364283, rs1076560), ACE (rs4646994), DRD1 (rs686), BDNF (rs6265), these associations are novel in Russian PD patients. Our findings suggest that polymorphisms in DBH, BDNF, DRD2, ACE genes in Russian subjects are associated with an increased risk of ICD development.

Ventral Tegmental Area Dysfunction and Disruption of Dopaminergic Homeostasis: Implications for Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition characterized by intrusive recollections of the traumatic event, avoidance behaviors, hyper-arousal to event-related cues, cognitive disruption, and mood dysregulation. Accumulating preclinical and clinical evidence implicates dysfunction of the ventral tegmental area (VTA) dopaminergic system in PTSD pathogenesis. This article reviews recent advances in our knowledge of the relationship between dopaminergic dyshomeostasis and PTSD, including the contributions of specific dopaminergic gene variants to disease susceptibility, alterations in VTA dopamine neuron activity, dysregulation of dopaminergic transmission, and potential pharmacological and psychological interventions for PTSD targeting the dopaminergic system. An in-depth understanding of PTSD etiology is crucial for the development of innovative risk assessment, diagnostic, and treatment strategies following traumatic events.

Genetic and Neuroimaging Approaches to Understanding Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a highly disabling condition, increasingly recognized as both a disorder of mental health and social burden, but also as an anxiety disorder characterized by fear, stress, and negative alterations in mood. PTSD is associated with structural, metabolic, and molecular changes in several brain regions and the neural circuitry. Brain areas implicated in the traumatic stress response include the amygdala, hippocampus, and prefrontal cortex, which play an essential role in memory function. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders. Conventional methods of studying PTSD have proven to be insufficient for diagnosis, measurement of treatment efficacy, and monitoring disease progression, and currently, there is no diagnostic biomarker available for PTSD. A deep understanding of cutting-edge neuroimaging genetic approaches is necessary for the development of novel therapeutics and biomarkers to better diagnose and treat the disorder. A current goal is to understand the gene pathways that are associated with PTSD, and how those genes act on the fear/stress circuitry to mediate risk vs. resilience for PTSD. This review article explains the rationale and practical utility of neuroimaging genetics in PTSD and how the resulting information can aid the diagnosis and clinical management of patients with PTSD.

Association of DRD2, 5-HTTLPR, and 5-HTTVNTR Gene Polymorphisms With Posttraumatic Stress Disorder in Tibetan Adolescents: A Case-Control Study

BACKGROUND

Earthquake exposure is a source of stress, yet only a minority of survivors experience clinically meaningful disturbance in psychological function. Genetic epidemiological research has found that posttraumatic stress disorder (PTSD) symptoms are associated with genetic factors. Further research to reveal which genetic loci relate to the development of PTSD is warranted.

METHOD

We investigated the relationships between PTSD and the dopamine D2 receptor ( DRD2) gene Taq I polymorphism and the serotonin transporter gene ( SCL6A4) polymorphisms 5-hydroxytryptamine transporter gene-linked polymorphic region (5-HTTLPR) and 5-HTTVNTR in 565 adolescent earthquake survivors. PTSD-positive adolescents were identified using the PTSD Checklist-Civilian Version and the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders 4. Genotypes were analyzed using the polymerase chain reaction-restriction fragment length polymorphism analysis. The Pearson χ² test was used to investigate the differences in genotype and allele frequencies between case and control groups. Binary logistic regression analysis was performed to identify possible influencing factors for PTSD.

RESULTS

The DRD2 Taq I and 5-HTTVNTR polymorphisms had statistically significant effects on PTSD, while 5-HTTLPR did not. Specifically, the DRD2 Taq I A1 allele was highly positively correlated with PTSD, whereas the 10 allele of 5-HTTVNTR was negatively correlated.

CONCLUSIONS

These data suggest that the DRD2 Taq I and 5-HTTVNTR genotypes moderate sensitivity to stress and the expression of emotional disturbance involving PTSD symptoms. These findings have important implications for PTSD etiology as well as for both primary prevention and treatment strategies.

Understanding the Scientific Basis of Post-traumatic Stress Disorder (PTSD): Precision Behavioral Management Overrides Stigmatization

Post-traumatic stress disorder (PTSD) is a severe polygenic disorder triggered by environmental factors. Many polymorphic genes, particularly the genetic determinants of hypodopaminergia (low dopamine function), associate with a predisposition to PTSD as well as substance use disorder. Support from the National Institutes of Health for neuroimaging research and molecular, genetic applied technologies has improved understanding of brain reward circuitry functions that have inspired the development of new innovative approaches to their early diagnosis and treatment of some PTSD symptomatology and addiction. This review presents psychosocial and genetic evidence that vulnerability or resilience to PTSD can theoretically be impacted by dopamine regulation. From a neuroscience perspective, dopamine is widely accepted as a major neurotransmitter. Questions about how to modulate dopamine clinically in order to treat and prevent PTSD and other types of reward deficiency disorders remain. Identification of genetic variations associated with the relevant genotype-phenotype relationships can be characterized using the Genetic Addiction Risk Score (GARS®) and psychosocial tools. Development of an advanced genetic panel is under study and will be based on a new array of genes linked to PTSD. However, for now, the recommendation is that enlistees for military duty be given the opportunity to voluntarily pre-test for risk of PTSD with GARS, before exposure to environmental triggers or upon return from deployment as part of PTSD management. Dopamine homeostasis may be achieved via customization of neuronutrient supplementation "Precision Behavioral Management" (PBM™) based on GARS test values and other pro-dopamine regulation interventions like exercise, mindfulness, biosensor tracking, and meditation.

Significant association of DRD2 enhancer variant rs12364283 with heroin addiction in a Pakistani population

The dopamine D2 receptor encoded by DRD2 has been implicated in multiple psychiatric disorders, mediated at least in part by two intronic variants affecting mRNA splicing, rs1076560 and rs2283265, and a less frequent enhancer variant, rs12364283, which increases DRD2 mRNA expression. This study tests whether these functionally validated variants confer susceptibility toward heroin addiction in a Pakistani population. A total of 540 heroin addicts and 467 healthy controls were genotyped, basic allele and genotype tests were performed. Neither rs1076560 nor rs2283265 significantly associated with heroin addiction. The enhancer rs12364283 occurs more frequently in heroin-dependent cases than controls (MAF 13% vs. 7%, respectively), revealing significant association with heroin addiction (p = 3.0E-06, OR 2.1). This study identifies rs12364283 of DRD2 as a potential risk factor for heroin addiction in the Pakistani study population. This enhancer variant had been shown to increase DRD2 mRNA expression, a possible factor in increased vulnerability to heroin addiction. Further studies are needed to validate this association of rs12364283.

Biological underpinnings of trauma and post-traumatic stress disorder: focusing on genetics and epigenetics

Certain individuals are more susceptible to stress and trauma, as well as the physical and mental health consequences following such exposure, including risk for post-traumatic stress disorder (PTSD). This differing vulnerability is likely to be influenced by genetic predisposition and specific characteristics of the stress itself (nature, intensity and duration), as well as epigenetic mechanisms. In this review we provide an overview of research findings in this field. We highlight some of the key genetic risk factors identified for PTSD, and the evidence that epigenetic processes might play a role in the biological response to trauma, as well as being potential biomarkers of PTSD risk. We also discuss important considerations for future research in this area.

H4K5 histone acetylation of BRG1 is associated with heroin administration rather than addiction

Diacetylmorphine hydrochloride (heroin) addiction is a chronic relapsing brain disorder that is a heavy public health burden worldwide. Brm/SWI2-related gene-1 (BRG1) is a tumor suppressor gene that can influence embryogenesis and the development of the cerebellum. The current study aimed to investigate the effect of histone H4 lysine 5 (H4K5) modifications on the BRG1 gene in brain tissue of the ventral tegmental area (VTA) of heroin-addicted rats. A total of 21 male Sprague Dawley rats were raised in a standard manner and underwent heroin self-administration training. Rats were randomly divided into three equal groups: Group A, self-administered delivery of heroin; group B, yoked delivery of heroin; and group C, yoked delivery of saline. The VTA was harvested and subjected to chromatin immunoprecipitation (ChIP) analysis. Gene expression was evaluated by quantitative polymerase chain reaction. We calculated the recovery rate, which indicated the percentage of the total input BRG1 recovered by ChIP. Our results showed that BRG1 was less associated with H4K5 histone modification in the group of rats that underwent heroin self-administration than in the other two groups (A vs. B, P=0.031; A vs. C, P=0.067). The recovery fold changes of the self-administration group and the passive-administration group were significantly different from those of the group with yoked saline (A vs. C, P=0.013; B vs. C, P=0.009; A vs. B, P=0.731). The results of the current study demonstrated that H4K5 histone acetylation of BRG1 in the VTA may be associated with heroin administration, but not addiction.

The Association Between Genetic Variants in the Dopaminergic System and Posttraumatic Stress Disorder: A Meta-Analysis

Posttraumatic stress disorder (PTSD) is a complex mental disorder and can severely interfere with the normal life of the affected people. Previous studies have examined the association of PTSD with genetic variants in multiple dopaminergic genes with inconsistent results. To perform a systematic literature search and conduct meta-analysis to examine whether genetic variants in the dopaminergic system is associated with PTSD. Data Sources: PubMed, Cochrane Library, Embase, Google Scholar, and HuGE. Study eligibility criteria and participants: The studies included subjects who had been screened for the presence of PTSD; the studies provided data for genetic variants of genes involved in the dopaminergic system; the outcomes of interest included diagnosis status of PTSD; and the studies were case-control studies. Study appraisal and synthesis methods: Odds ratio was used as a measure of association. We used random-effects model in all the meta-analyses. Between-study heterogeneity was assessed using I², and publication bias was evaluated using Egger test. Findings from meta-analyses were confirmed using random-effects meta-analyses under the framework of generalized linear model (GLM). A total of 19 studies met the eligibility criteria and were included in our analyses. We found that rs1800497 in DRD2 was significantly associated with PTSD (OR = 1.96, 95% CI: 1.15-3.33; P = 0.014). The 3'-UTR variable number tandem repeat (VNTR) in SLC6A3 also showed significant association with PTSD (OR = 1.62, 95% CI: 1.12-2.35; P = 0.010), but there was no association of rs4680 in COMT with PTSD (P = 0.595). Sample size is limited for some studies; type and severity of traumatic events varied across studies; we could not control for potential confounding factors, such as age at traumatic events and gender; and we could not examine gene-environment interaction due to lack of data. We found that rs1800497 in DRD2 and the VNTR in SLC6A3 showed significant association with PTSD. Future studies controlling for confounding factors, with large sample sizes and more homogeneous traumatic exposure, are needed to validate the findings from this study.

Progress towards understanding the genetics of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a complex syndrome that occurs following exposure to a potentially life threatening traumatic event. This review summarises the literature on the genetics of PTSD including gene-environment interactions (GxE), epigenetics and genetics of treatment response. Numerous genes have been shown to be associated with PTSD using candidate gene approaches. Genome-wide association studies have been limited due to the large sample size required to reach statistical power. Studies have shown that GxE interactions are important for PTSD susceptibility. Epigenetics plays an important role in PTSD susceptibility and some of the most promising studies show stress and child abuse trigger epigenetic changes. Much of the molecular genetics of PTSD remains to be elucidated. However, it is clear that identifying genetic markers and environmental triggers has the potential to advance early PTSD diagnosis and therapeutic interventions and ultimately ease the personal and financial burden of this debilitating disorder.