D2 dopamine receptor gene polymorphism: paroxetine and social functioning in posttraumatic stress disorder

Prominent genetic variants and epigenetic changes in post-traumatic stress disorder among combat veterans

Post-traumatic stress disorder (PTSD) is one of the most widespread and disabling psychiatric disorders among combat veterans. Substantial interindividual variability in susceptibility to PTSD suggests the presence of different risk factors for this disorder. Twin and family studies confirm genetic factors as important risk factors for PTSD. In addition to genetic factors, epigenetic factors, especially DNA methylation, can be considered as a potential mechanism in changing the risk of PTSD. So far, many genetic and epigenetic association studies have been conducted in relation to PTSD. In genetic studies, many single nucleotide polymorphisms have been identified as PTSD risk factors. Meanwhile, the variations in catecholamines-related genes, serotonin transporter and receptors, brain-derived neurotrophic factor, inflammatory factors, and apolipoprotein E are the most prominent candidates. CpG methylation in the upstream regions of many genes is also considered a PTSD risk factor. Accurate identification of genetic and epigenetic changes associated with PTSD can lead to the presentation of suitable biomarkers for susceptible individuals to this disorder. This study aimed to delineate prominent genetic variations and epigenetic changes associated with post-traumatic stress disorder in military veterans who have experienced combat, focusing on genetic and epigenetic association studies.

Insights into the Involvement and Therapeutic Target Potential of the Dopamine System in the Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a neuropsychiatric disease closely related to life-threatening events and psychological stress. Re-experiencing, hyperarousal, avoidance, and numbness are the hallmark symptoms of PTSD, but their underlying neurological processes have not been clearly elucidated. Therefore, the identification and development of drugs for PTSD that targets brain neuronal activities have stalled. Considering that the persistent fear memory induced by traumatic stimulation causes high alertness, high arousal, and cognitive impairment of PTSD symptoms. While the midbrain dopamine system can affect physiological processes such as aversive fear memory learning, consolidation, persistence, and extinction, by altering the functions of the dopaminergic neurons, our viewpoint is that the dopamine system plays a considerable role in the PTSD occurrence and acts as a potential therapeutic target of the disorder. This paper reviews recent findings on the structural and functional connections between ventral tegmental area neurons and the core synaptic circuits involved in PTSD, gene polymorphisms related to the dopamine system that confer susceptibility to clinical PTSD. Moreover, the progress of research on medications that target the dopamine system as PTSD therapies is also discussed. Our goal is to offer some hints for early detection and assist in identifying novel, efficient approaches for treating PTSD.

Valeriana jatamansi Jones ex Roxb. Against Post-Traumatic Stress Disorder, Network Pharmacological Analysis, and In Vivo Evaluation

Zhi zhu xiang (ZZX) is the root and rhizome of Valeriana jatamansi Jones ex Roxb. Recent studies have shown that ZZX can exert antianxiety, antidepressant, and sedative effects. Because post-traumatic stress disorder (PTSD) is similar to depression and anxiety in terms of its etiology, pathogenesis, and clinical manifestations, it is possible that ZZX may also be useful for the prevention and treatment of PTSD. In this study, a mouse model of PTSD was established and used to study the pharmacological action of a 95% ethanol extract of ZZX on PTSD via a series of classic behavioral tests. We found that a 95% ethanol extract of ZZX was indeed effective for relieving the symptoms of PTSD in mice. Moreover, network pharmacology analysis was used to predict the potential active ingredients, targets, and possible pathways of ZZX in the treatment of PTSD. The neurotransmitter system, the hypothalamic-pituitary-adrenal (HPA) axis, and the endocannabinoid (eCB) system were identified to be the most likely pathways for anti-PTSD action in ZZX. Due to the lack of a falsification mechanism in network pharmacology, in vivo tests were carried out in mice, and the expression levels of neurotransmitters, hormones, and genes of key targets were detected by enzyme-linked immunosorbent assay and real-time PCR to further verify this inference. Analysis showed that the levels of norepinephrine, 5-hydroxytryptamine, and glutamic acid were increased in the hippocampus, prefrontal cortex, and amygdala of PTSD mice, while the levels of dopamine and γ-aminobutyric acid were decreased in these brain regions; furthermore, ZZX could restore the expression of these factors, at least to a certain extent. The levels of adrenocorticotropic hormone, corticosterone, and corticotropin-releasing hormone were increased in these different brain regions and the serum of PTSD mice; these effects could be reversed by ZZX to a certain extent. The expression levels of cannabinoid receptor 1 and diacylglycerol lipase α mRNA were decreased in PTSD mice, while the levels of fatty acid amide hydrolase and monoacylglycerol lipase mRNA were increased; these effects were restored by ZZX to a certain extent. In conclusion, our findings suggest that ZZX may provide new therapeutic pathways for treating PTSD by the regulation of neurotransmitters, the HPA, and expression levels of eCB-related genes in the brain.

Dopamine, endocannabinoids and their interaction in fear extinction and negative affect in PTSD

There currently exist few frameworks for common neurobiology between reexperiencing and negative cognitions and mood symptoms of PTSD. Adopting a dopaminergic framework for PTSD unites many aspects of unique symptom clusters, and this approach also links PTSD symptomology to common comorbidities with a common neurobiological deficiency. Here we review the dopamine literature and incorporate it with a growing field of research that describes both the contribution of endocannabinoids to fear extinction and PTSD, as well as the interactions between dopaminergic and endocannabinoid systems underlying this disorder. Based on current evidence, we outline an early, preliminary model that links re-experiencing and negative cognitions and mood in PTSD by invoking the interaction between endocannabinoid and dopaminergic signalling in the brain. These interactions between PTSD, dopamine and endocannabinoids may have implications for future therapies for treatment-resistant and comorbid PTSD patients.

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.

Rethinking post-traumatic stress disorder - A predictive processing perspective

Predictive processing has become a popular framework in neuroscience and computational psychiatry, where it has provided a new understanding of various mental disorders. Here, we apply the predictive processing account to post-traumatic stress disorder (PTSD). We argue that the experience of a traumatic event in Bayesian terms can be understood as a perceptual hypothesis that is subsequently given a very high a-priori likelihood due to its (life-) threatening significance; thus, this hypothesis is re-selected although it does not fit the actual sensory input. Based on this account, we re-conceptualise the symptom clusters of PTSD through the lens of a predictive processing model. We particularly focus on re-experiencing symptoms as the hallmark symptoms of PTSD, and discuss the occurrence of flashbacks in terms of perceptual and interoceptive inference. This account provides not only a new understanding of the clinical profile of PTSD, but also a unifying framework for the corresponding pathologies at the neurobiological level. Finally, we derive directions for future research and discuss implications for psychological and pharmacological interventions.

The D2 dopamine receptor (DRD2) gene is associated with co-morbid depression, anxiety and social dysfunction in untreated veterans with post-traumatic stress disorder

Objective.

To identify clusters of patients with post-traumatic stress disorder (PTSD) according to symptom profile and to examine the association of the A1 allele of the D2 dopamine receptor (DRD2) gene with these clusters.

Method.

Fifty-seven untreated Caucasian Vietnam veterans with PTSD were administered the General Health Questionnaire-28 (GHQ) and the Mississippi Scale for combat-related PTSD. DRD2 allelic status was determined by PCR.

Results.

Subjects with the DRD2 Al allele compared to those without this allele had significantly higher scores on GHQ 2 (anxiety/insomnia), GHQ 3 (social dysfunction) and GHQ 4 (depression). Cluster analysis of the GHQ data identified two primary groups. A high psychopathology cluster (cluster 3), featured by high co-morbid levels of somatic concerns, anxiety/insomnia, social dysfunction and depression, and a low psychopathology cluster (cluster 1), manifested by the reverse pattern. Scores in each of the four GHQ groups were significantly higher in cluster 3 than cluster 1, as was Mississippi Scale PTSD score. DRD2 A1 allele veterans compared to those without this allele were significantly more likely to be found in the high than the low psychopathology cluster group.

Conclusions.

DRD2 variants are associated with severe co-morbid psychopathology in PTSD subjects.

Impact of orthognathic surgery on quality of life: Predisposing clinical and genetic factors

INTRODUCTION

Dentofacial deformities have an impact on quality of life (QOL). Many factors can influence this perception, including genetic aspects. ANKK1 and DRD2 genes are associated with dopaminergic system and could modulate behavioral dysfunction.

PURPOSE

The impact of orthognathic surgery and associated factors on QOL of adults was evaluated.

MATERIAL AND METHODS

The abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-BREF) was applied to patients from two surgery services one week before (T0) and six months after surgery (T1). The independent variables were age, sex, race, facial pattern, presence of jaw asymmetry and vertical deformities, and polymorphisms associated with ANKK1 and DRD2 genes. Descriptive and bivariate analyses were performed.

RESULTS

There was improvement in the perception of QOL from T0 to T1 in the general score, in the physical and psychological domains, and in the quality of life and general health perception (QOLGHP) (p < 0.001). In this interval, individuals aged ≥30 years reported positive impacts on all outcomes (p < 0.05), whereas in women this improvement did not occur only for the physical domain (p = 0.136). There was an association between the polymorphisms associated with the ANKK1 gene (rs1800497) and the perception of QOL in the social relationship's domain (p = 0.021) and QOLGHP (p = 0.042). The other clinical conditions were not associated with outcomes (p > 0.05).

CONCLUSION

Perception of QOL of patients improved following orthognathic surgery in physical, psychological, and QOLGHP domains. Aged ≥30 years, being women and polymorphisms associated with the ANKK1 gene were related to positive impacts.

Pharmacogenetics and Pharmacotherapy of Military Personnel Suffering from Post-traumatic Stress Disorder

Background:

Posttraumatic stress disorder (PTSD) is a severe problem among soldiers with combating experience difficult to treat. The pathogenesis is still not fully understood at the psychological level. Therefore, genetic research became a focus of interest. The identification of single nucleotide polymorphisms (SNPs) may help to predict, which persons are at high risk to develop PTSD as a starting point to develop novel targeted drugs for treatment.

Methods:

We conducted a systematic review on SNPs in genes related to PTSD pathology and development of targeted pharmacological treatment options based on PubMed database searches. We focused on clinical trials with military personnel.

Results:

SNPs in 22 human genes have been linked to PTSD. These genes encode proteins acting as neurotransmitters and receptors, downstream signal transducers and metabolizing enzymes. Pharmacological inhibitors may serve as drug candidates for PTSD treatment, e.g. β2 adrenoreceptor antagonists, dopamine antagonists, partial dopamine D2 receptor agonists, dopamine β hydroxylase inhibitors, fatty acid amid hydrolase antagonists, glucocorticoid receptor agonists, tropomyosin receptor kinase B agonists, selective serotonin reuptake inhibitors, catechol-O-methyltransferase inhibitors, gamma-amino butyric acid receptor agonists, glutamate receptor inhibitors, monoaminoxidase B inhibitors, N-methyl-d-aspartate receptor antagonists.

Conclusion:

The combination of genetic and pharmacological research may lead to novel target-based drug developments with improved specificity and efficacy to treat PTSD. Specific SNPs may be identified as reliable biomarkers to assess individual disease risk. Focusing on soldiers suffering from PTSD will not only help to improve treatment options for this specific group, but for all PTSD patients and the general population.

Efficacy and Tolerability of High-Dose Escitalopram in Posttraumatic Stress Disorder

BACKGROUND

Open-label trials suggest that escitalopram (up to 20 mg/d) is an effective treatment for some, but not all posttraumatic stress disorder (PTSD) patients. Higher doses of escitalopram effectively reduced major depression symptoms in patients who had not responded to regular doses. The current study examines the efficacy, tolerability, and adherence to high-dose escitalopram in PTSD.

METHODS

Forty-five PTSD patients received 12 weeks of gradually increasing doses of escitalopram reaching 40 mg daily at 4 weeks. Among those, 12 participants received regular doses of antidepressants at study onset including escitalopram (n = 7). The Clinician-Administered PTSD Scale (CAPS) evaluated PTSD symptoms severity before treatment, at 3 months (upon treatment termination), and at 6 months (maintenance effect). A 20% reduction in CAPS scores was deemed clinically significant.

RESULTS

Adverse events and medication adherence were monitored at each clinical session. Linear mixed-models analysis showed a significant reduction of mean CAPS scores (11.5 ± 18.1 points) at 3 months and maintenance of gains by 6 months (F2,34.56 = 8.15, P = 0.001). Eleven participants (34.3%) showed clinically significant improvement at 3 months. Only 9 participants (20%) left the study. There were no serious adverse events and few mild ones with only 2 adverse events (diarrhea, 11.1%; drowsiness, 11.1%) reported by more than 10% of participants.

CONCLUSION

High doses of escitalopram are tolerable and well adhered to in PTSD. Their beneficial effect at a group level is due to a particularly good response in a subset of patients.Variability in prior pharmacological treatment precludes a definite attribution of the results to high doses of escitalopram.

Genome to Phenome: A Systems Biology Approach to PTSD Using an Animal Model

Post-traumatic stress disorder (PTSD) is a debilitating illness that imposes significant emotional and financial burdens on military families. The understanding of PTSD etiology remains elusive; nonetheless, it is clear that PTSD is manifested by a cluster of symptoms including hyperarousal, reexperiencing of traumatic events, and avoidance of trauma reminders. With these characteristics in mind, several rodent models have been developed eliciting PTSD-like features. Animal models with social dimensions are of particular interest, since the social context plays a major role in the development and manifestation of PTSD.For civilians, a core trauma that elicits PTSD might be characterized by a singular life-threatening event such as a car accident. In contrast, among war veterans, PTSD might be triggered by repeated threats and a cumulative psychological burden that coalesced in the combat zone. In capturing this fundamental difference, the aggressor-exposed social stress (Agg-E SS) model imposes highly threatening conspecific trauma on naïve mice repeatedly and randomly.There is abundant evidence that suggests the potential role of genetic contributions to risk factors for PTSD. Specific observations include putatively heritable attributes of the disorder, the cited cases of atypical brain morphology, and the observed neuroendocrine shifts away from normative. Taken together, these features underscore the importance of multi-omics investigations to develop a comprehensive picture. More daunting will be the task of downstream analysis with integration of these heterogeneous genotypic and phenotypic data types to deliver putative clinical biomarkers. Researchers are advocating for a systems biology approach, which has demonstrated an increasingly robust potential for integrating multidisciplinary data. By applying a systems biology approach here, we have connected the tissue-specific molecular perturbations to the behaviors displayed by mice subjected to Agg-E SS. A molecular pattern that links the atypical fear plasticity to energy deficiency was thereby identified to be causally associated with many behavioral shifts and transformations.PTSD is a multifactorial illness sensitive to environmental influence. Accordingly, it is essential to employ the optimal animal model approximating the environmental condition that elicits PTSD-like symptoms. Integration of an optimal animal model with a systems biology approach can contribute to a more knowledge-driven and efficient next-generation care management system and, potentially, prevention of PTSD.

Altered spontaneous neuronal activity in chronic posttraumatic stress disorder patients before and after a 12-week paroxetine treatment

BACKGROUND

Abnormal functional brain activity has been revealed in patients with Posttraumatic Stress Disorder (PTSD) in recent years, while the recovery neuromechanism of PTSD has not yet been elucidated. The aim of this study was to investigate the altered spontaneous brain activity in treatment-naïve chronic PTSD patients before and after 12 weeks׳ treatment with paroxetine.

METHODS

Twenty-one earthquake-related PTSD patients and seventeen traumatized controls underwent a resting functional magnetic resonance imaging (Rs-fMRI) scan at baseline. Amplitude of low-frequency fluctuation (ALFF) was calculated and compared between PTSD patients and controls. Then, the PTSD group completed 12 weeks of treatment with paroxetine, and Rs-fMRI was repeated to compare with the baseline. Lastly, correlation analyses of ALFF values within altered brain areas were conducted.

RESULTS

Hyperactive function of visual cortex was observed in PTSD patients before and after treatment. After treatment, significantly increased ALFF values were observed in the left orbitofrontal cortex (OFC), while decreased ALFF values were found in the precuneus. Interestingly, a negative correlation between the mean ALFF values of OFC and those of precuneus and visual cortex was only observed in controls, but not in PTSD patients pre- or post-treatment.

LIMITATIONS

A corresponding control condition was absent in this study.

CONCLUSION

The findings showed that manipulating regional spontaneous activity of precuneus and OFC could be a potential prognostic indicator of PTSD. However, hyperactive function of visual cortex and disrupted connections between OFC, precuneus and visual cortex did not reverse after treatment, which could be a potential target for further treatment.

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.

Lack of influence of DAT1 and DRD2 gene variants on antidepressant response in generalized anxiety disorder

OBJECTIVE

Although antidepressant drugs are used as first-line intervention to treat patients with generalized anxiety disorder (GAD), only one-third of patients respond positively to treatment. In our study, we investigated whether functional genetic polymorphisms in the dopamine active transporter 1 (DAT1) and dopamine receptor D2 (DRD2) may play a role in antidepressant treatment response in GAD.

METHODS

We examined 156 patients diagnosed with GAD who received venlafaxine Extended-Release (XR) treatment as part of an 18-month relapse-prevention study to determine whether variation in these genes had an effect on treatment response after 6 months of open-label treatment. Genotypes were obtained for rs1076560 (DRD2), rs1800497 (DRD2), rs2550948 (DAT1), and a variable number tandem repeat in the 3' untranslated region of the DAT1 gene using standard methods.

RESULTS

Results show that none of the tested variants were associated with treatment response to venlafaxine XR in GAD. Genotype and allele frequencies did not differ statistically significantly between responders and non-responders using either the Hamilton Anxiety or Clinical Global Impressions of Improvement Scale at 6 months.

CONCLUSIONS

Although we detected no association in our sample, future studies using larger samples and more comprehensive gene coverage are needed to evaluate potential effects of dopaminergic variants on antidepressant treatment response in anxiety disorders.

Pharmacogenetics of antidepressant drugs: current clinical practice and future directions

While antidepressants are widely used to treat mood and anxiety disorders, only half of the patients will respond to antidepressant treatment and only one-third of patients experience a full remission of symptoms. The identification of genetic biomarkers that predict antidepressant-treatment response can improve current clinical practice. This is an emerging field known as pharmacogenetics, which comprises of genetic studies on both the pharmacokinetics and pharmacodynamics of treatment response. Recent studies on antidepressant-treatment response have focused on both aspects of pharmacogenetics research, identifying new candidate genes that may predict better treatment response for patients. This paper reviews recent findings on the pharmacogenetics of antidepressant drugs and future clinical applications. Ultimately, these studies should lead to the use of genetic testing to guide the use of antidepressants in clinical practice.

Alcohol Use Disorders Identification Test (AUDIT) scores are elevated in antipsychotic-induced hyperprolactinaemia

Hyperprolactinaemia in antipsychotic treated patients with schizophrenia is a consequence of D2 receptor (DRD2) blockade. Alcohol use disorder is commonly comorbid with schizophrenia and low availability of striatal DRD2 may predispose individuals to alcohol use. In this pilot study we investigated whether hyperprolactinaemia secondary to pharmacological DRD2 blockade was associated with alcohol use disorder in 219 (178 males and 41 females) patients with schizophrenia. Serum prolactin determinations were made in patients diagnosed with schizophrenia and maintained on antipsychotic agents. Clinical assessment included demographics, family history and administration of the AUDIT (Alcohol Use Disorders Identification Test). Higher AUDIT scores were associated with prolactin-raising antipsychotic medication (n=106) compared with prolactin-sparing medication (n=113). Risperidone (n=63) treated patients had higher AUDIT scores and prolactin levels than those on other atypical antipsychotics (n = 113). Across the entire sample, patients with a prolactin greater than 800 mIU/L had higher AUDIT scores and were more likely to exceed the cut-off score for harmful and hazardous alcohol use. These differences were not explained by potential confounds related to clinical features and demographics, comorbidity or medication side-effects. These data suggest that by lowering dosage, or switching to another antipsychotic agent, the risk for alcohol use disorder in those with schizophrenia may be reduced. This hypothesis requires testing using a prospective methodology.

Genetics and outcomes after traumatic brain injury (TBI): what do we know about pediatric TBI?

Human genetic association studies in individuals with traumatic brain injury (TBI) have increased rapidly over the past few years. Recently, several review articles evaluated the association of genetics with outcomes after TBI. However, almost all of the articles discussed in these reviews focused on adult TBI. The primary objective of this review is to gain a better understanding of which genes and/or genetic polymorphisms have been evaluated in pediatric TBI. Our initial search identified 113 articles. After review of these articles only 5 genetic association studies specific to pediatric TBI were identified. All five of these studies evaluated the apolipoprotein (APOE) gene. The study design and methods of these identified papers will be discussed. An additional search was then performed to evaluate genes beyond APOE that have been evaluated in adult TBI; findings from these studies are highlighted. Larger genetic studies will need to be performed in the future to better elucidate the association of APOE and other genes with outcomes after TBI in children. There is great potential to utilized genetic information to inform prognosis and management after TBI in children; however, we have much work ahead of us to reach the goal of individualized management.

Generational association studies of dopaminergic genes in reward deficiency syndrome (RDS) subjects: selecting appropriate phenotypes for reward dependence behaviors

Abnormal behaviors involving dopaminergic gene polymorphisms often reflect an insufficiency of usual feelings of satisfaction, or Reward Deficiency Syndrome (RDS). RDS results from a dysfunction in the "brain reward cascade," a complex interaction among neurotransmitters (primarily dopaminergic and opioidergic). Individuals with a family history of alcoholism or other addictions may be born with a deficiency in the ability to produce or use these neurotransmitters. Exposure to prolonged periods of stress and alcohol or other substances also can lead to a corruption of the brain reward cascade function. We evaluated the potential association of four variants of dopaminergic candidate genes in RDS (dopamine D1 receptor gene [DRD1]; dopamine D2 receptor gene [DRD2]; dopamine transporter gene [DAT1]; dopamine beta-hydroxylase gene [DBH]).

METHODOLOGY

We genotyped an experimental group of 55 subjects derived from up to five generations of two independent multiple-affected families compared to rigorously screened control subjects (e.g., N = 30 super controls for DRD2 gene polymorphisms). Data related to RDS behaviors were collected on these subjects plus 13 deceased family members.

RESULTS

Among the genotyped family members, the DRD2 Taq1 and the DAT1 10/10 alleles were significantly (at least p < 0.015) more often found in the RDS families vs. controls. The TaqA1 allele occurred in 100% of Family A individuals (N = 32) and 47.8% of Family B subjects (11 of 23). No significant differences were found between the experimental and control positive rates for the other variants.

CONCLUSIONS

Although our sample size was limited, and linkage analysis is necessary, the results support the putative role of dopaminergic polymorphisms in RDS behaviors. This study shows the importance of a nonspecific RDS phenotype and informs an understanding of how evaluating single subset behaviors of RDS may lead to spurious results. Utilization of a nonspecific "reward" phenotype may be a paradigm shift in future association and linkage studies involving dopaminergic polymorphisms and other neurotransmitter gene candidates.

Neuro-psychopharmacogenetics and Neurological Antecedents of Posttraumatic Stress Disorder: Unlocking the Mysteries of Resilience and Vulnerability

BACKGROUND AND HYPOTHESIS

Although the biological underpinnings of immediate and protracted trauma-related responses are extremely complex, 40 years of research on humans and other mammals have demonstrated that trauma (particularly trauma early in the life cycle) has long-term effects on neurochemical responses to stressful events. These effects include the magnitude of the catecholamine response and the duration and extent of the cortisol response. In addition, a number of other biological systems are involved, including mesolimbic brain structures and various neurotransmitters. An understanding of the many genetic and environmental interactions contributing to stress-related responses will provide a diagnostic and treatment map, which will illuminate the vulnerability and resilience of individuals to Posttraumatic Stress Disorder (PTSD).

PROPOSAL AND CONCLUSIONS

We propose that successful treatment of PTSD will involve preliminary genetic testing for specific polymorphisms. Early detection is especially important, because early treatment can improve outcome. When genetic testing reveals deficiencies, vulnerable individuals can be recommended for treatment with "body friendly" pharmacologic substances and/or nutrients. Results of our research suggest the following genes should be tested: serotoninergic, dopaminergic (DRD2, DAT, DBH), glucocorticoid, GABAergic (GABRB), apolipoprotein systems (APOE2), brain-derived neurotrophic factor, Monamine B, CNR1, Myo6, CRF-1 and CRF-2 receptors, and neuropeptide Y (NPY). Treatment in part should be developed that would up-regulate the expression of these genes to bring about a feeling of well being as well as a reduction in the frequency and intensity of the symptoms of PTSD.

PTSD and dopaminergic genes, DRD2 and DAT, in multigenerational families exposed to the Spitak earthquake

The objective of this study was to assess the generality of the association of DRD2 and DAT genes and Post-Traumatic Stress Disorder (PTSD) diagnosis/symptom severity. Two hundred ethnic Armenians from 12 multigenerational families exposed to the catastrophic 1988 Spitak earthquake were studied. Common polymorphisms A1/A2 alleles of the DRD2 and '9' repeat allele of DAT gene were genotyped. Heritability, association and linkage were assessed using variance component genetic analyses. After adjusting for the covariates, the heritabilities of PTSD diagnosis and B and C category symptoms were: 0.37, 0.75 and 0.39 respectively. Category D symptoms were not heritable. Neither the DRD2 nor the DAT polymorphisms explained the variation seen in PTSD diagnosis, total PTSD symptom severity, and categories B and C symptom severities. These findings contradict prior reports of positive associations between both DRD2 and DAT, and PTSD.

Sexual behavior modulates contextual fear memory through dopamine D1/D5 receptors

Traumatic events always lead to aversive emotional memory, i.e., fear memory. In contrast, positive events in daily life such as sex experiences seem to reduce aversive memory after aversive events. Thus, we hypothesized that post-traumatic pleasurable experiences, especially instinctive behaviors such as sex, might modulate traumatic memory through a memory competition mechanism. Here, we first report that male rats persistently expressed much lower fear responses when exposed to females, but not when exposed to males, for 24 h immediately after contextual fear conditioning. Remarkably, this effect of sexual behavior was blocked by either systemic or intrahippocampal injection of the dopamine D1/D5 receptor antagonist R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390) and was mimicked by systemic but not intrahippocampal injection of the D1/D5 receptor agonist R(+)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol hydrochloride (SKF39393). Furthermore, as a candidate mechanism underlying contextual fear memory, the impaired induction of hippocampal long-term potentiation (LTP) elicited by conditioned fear was rescued in male rats immediately exposed to female but not male rats for 24 h. Systemic injection of the dopamine D1/D5 receptor antagonist SCH23390 or agonist SKF38393 prevented or mimicked the effect of sexual behavior on the impaired induction of hippocampal LTP. Thus, our finding suggests that dopaminergic functions may, at least partially, govern competition between contextual fear and enjoyable memories through the modulation of hippocampal LTP.

Pharmacotherapy of PTSD: premises, principles, and priorities

Post-traumatic stress disorder (PTSD) is a prevalent anxiety disorder that results in multiple disabling symptoms. Research into the underlying neurobiology has implicated dysregulation in multiple neurotransmitter systems including norepinephrine, serotonin, and glutamate as well as the hypothalamic-pituitary axis. Understanding how these biological systems interact with each other and how they may affect key neural structures, such as the amygdala, hippocampus, and prefrontal cortex, to produce post-traumatic symptoms is critical for the development of effective pharmacological treatments. We briefly discuss the proposed biological dysfunctions underlying PTSD and how agents that target these dysfunctions may be utilized in PTSD. We then provide a review of the different pharmacological agents that have been investigated in PTSD. These drugs include: antidepressants, anti-adrenergic agents, anticonvulsants, benzodiazepines, atypical antipsychotics, and novel agents.

Pharmacogenetic testing in schizophrenia and posttraumatic stress disorder

Genotyping patients prior to beginning psychiatric pharmacological therapy can serve to inform practitioners as to each patient's likelihood of therapeutic response and their relative risk of experiencing toxicity and other adverse side effects from certain drugs. Such information could arm physicians with the knowledge they need to make appropriate drug and dosing decisions and avoid the lengthy trial-and-error process with which they are faced today. This article describes the current state of pharmacogenetic testing in schizophrenia and posttraumatic stress disorder.

Common genetic, clinical, demographic and psychosocial predictors of response to pharmacotherapy in mood and anxiety disorders

The aim of this study is to summarize available knowledge about common genetic, clinical, demographic and psychosocial predictors of response to pharmacotherapy in mood and anxiety disorders. A literature search was carried out by using MEDLINE and references of selected articles. The search included articles published up to March 2008. The main genetic finding concerns the serotonin transporter gene promoter polymorphisms, the long variant of which seems to be related to a positive response to therapy in mood disorders and could also have a role in the treatment of anxiety disorders. Among other predictors, the main factors common to both classes of disorder are comorbid axis II disorders and early onset of illness, which are related to a worse response to therapy and concomitant good physical conditions, absence of earlier treatments, early administration and response to therapies, and higher self- directedness, which is related to a better outcome. Many common predictors have been identified and these seem to be related to features covering the totality of patients that go beyond specific characteristics of single disorders. Possible limitations and suggestions for future research based on a more integrated vision of human complexity are discussed.

Gene-environment interaction in posttraumatic stress disorder: review, strategy and new directions for future research

The purpose of this article is to encourage research investigating the role of measured gene-environment interaction (G x E) in the etiology of posttraumatic stress disorder (PTSD). PTSD is uniquely suited to the study of G x E as the diagnosis requires exposure to a potentially-traumatic life event. PTSD is also moderately heritable; however, the role of genetic factors in PTSD etiology has been largely neglected both by trauma researchers and psychiatric geneticists. First, we summarize evidence for genetic influences on PTSD from family, twin, and molecular genetic studies. Second, we discuss the key challenges in G x E studies of PTSD and offer practical strategies for addressing these challenges and for discovering replicable G x E for PTSD. Finally, we propose some promising new directions for PTSD G x E research. We suggest that G x E research in PTSD is essential to understanding vulnerability and resilience following exposure to a traumatic event.

Comorbidity of fibromyalgia and psychiatric disorders

There are mounting data supporting comorbidity of fibromyalgia syndrome (FMS) and psychiatric conditions. These include depression, panic disorders, anxiety, and post-traumatic stress disorder (PTSD). The nature of the relationship between depression and FMS is not fully understood, and it was hypothesized that chronic pain causes depression, or vice versa, and that chronic pain syndromes are variants of depression. A link between PTSD symptoms and FMS has been reported, and both conditions share similar symptomatology and pathogenetic mechanisms. Assessment of comorbid psychiatric disorders in FMS patients has clinical implications because treatment in these patients should focus both on physical and emotional dimensions of dysfunction.

Genetics of posttraumatic stress disorder: Review and recommendations for future studies

Posttraumatic stress disorder (PTSD) is common and debilitating. Posttraumatic stress disorder is moderately heritable; however, the role of genetic factors in PTSD etiology has been largely neglected by trauma researchers. The goal of this study is to motivate trauma researchers to reflect on the role genetic variation may play in vulnerability and resilience following trauma exposure. Evidence from family, twin, and molecular genetic studies for genetic influences on PTSD is reviewed. Recommendations for future studies are presented with emphasis on study design and assessment issues particular to the field of trauma and PTSD. Clinical implications of PTSD genetic studies are discussed.

Genetics of chronic pain states

Chronic pain states are common in the general population. Genetic factors can explain a significant amount of the variability in the perception of pain. Fibromyalgia syndrome (FMS) and related conditions are syndromes characterized by generalized pain sensitivity as well as a constellation of other symptoms. Family studies show a strong familial aggregation of FMS and related conditions, suggesting the importance of genetic factors in the development of these conditions. Recent evidence suggests a role for polymorphisms of genes in the serotoninergic, dopaminergic and catecholaminergic systems in the pathogenesis of FMS and related conditions. Environmental factors may trigger the development of these disorders in genetically predisposed individuals. Future large well-designed studies are needed to further clarify the role of genetic factors in FMS and related conditions. The knowledge of these gene polymorphisms may help with better subgrouping of FMS patients and in designing a more specific pharmacologic treatment approach.

Genetic variants in the DRD2 gene moderate the relationship between stressful life events and depressive symptoms in adults: cardiovascular risk in young Finns study

OBJECTIVE

To examine the potential moderating role of DRD2 polymorphism (rs1800497) in the association between stressful life events and depressive symptoms among young adults. Although stressful life events, such as divorce, unemployment, and serious illness in the family, are generally associated with negative health outcomes, including depressive symptoms, there are large individual differences in coping with such events. A number of studies suggest that variants in dopamine receptor genes, such as DRD2, are associated with depression but it is unclear if such variants also modify the association between life events and depression.

METHODS

We analyzed the prospective data on life events and depressive symptoms in 1992 and 2001 related to 1611 young adults (672 men and 939 women, aged 15-30 years at baseline) who participated in the ongoing population-based cardiovascular risk in young Finns study.

RESULTS

Occurrence of stressful life events was associated with increased risk of subsequent depressive symptoms in men and women. However, this association was seen only among those who carried A2/A2 (n = 872) genotype. No such association was detected in participants carrying A1/A1 or A1/A2 (n = 486) genotype.

CONCLUSION

DRD2 polymorphism moderates the effect of stressful life events on depressive symptoms and those who carry A2/A2 DRD2 genotypes may be more vulnerable than others.

Biology and therapy of fibromyalgia. Genetic aspects of fibromyalgia syndrome

Genetic and environmental factors may play a role in the etiopathology of fibromyalgia syndrome (FMS) and other related syndromes. There is a high aggregation of FMS in families of FMS patients. The mode of inheritance is unknown but it is most probably polygenic. There is evidence that polymorphisms of genes in the serotoninergic, dopaminergic and catecholaminergic systems play a role in the etiology of FMS. These polymorphisms are not specific for FMS and are associated with other functional somatic disorders and depression. Future genetic studies in the field of FMS and related conditions should be conducted in larger cohorts of patients and ethnically matched control groups.

Mechanisms of Disease: genetics of fibromyalgia

Fibromyalgia is characterized by widespread pain and tenderness, and has a significant familial component. The etiology of fibromyalgia remains unclear, but genetic factors seem to have a significant role, and are influenced by environmental factors. Research over the past two decades has demonstrated that genetic polymorphisms in the serotoninergic, dopaminergic and catecholaminergic systems of pain transmission and processing are involved in the etiology of fibromyalgia, but additional candidates continue to emerge. Fibromyalgia is thought to belong to the group of affective spectrum disorders, which include related psychiatric and medical disorders. As the concept of affective spectrum disorders continues to evolve, progress in the understanding of the genetic basis of related functional disorders, such as irritable bowel syndrome and post-traumatic-stress disorder, is aiding our understanding of the genetic basis of fibromyalgia.

Dopamine and monogamy

Social attachments play a central role in human society. In fact, such attachments are so important that deficits in the ability to form meaningful social bonds are associated with a variety of psychological disorders. Although mother-infant bonding has been studied for many years, we only recently have begun to examine the processes that underlie social bonds between adults. Over the past decade, central dopamine has become a focus of such research, especially its role in pair bonding between mates in species that display monogamous life strategies. Neuroanatomical and pharmacological studies in rodents have firmly established central dopamine systems, especially the mesocorticolimbic dopamine circuitry, in the formation, expression, and maintenance of monogamous pair bonds. As this research has progressed, it has become apparent that there is considerable overlap between the processes that underlie pair bonding and those that mediate responses to abused substances. This suggests that social bonding and substance abuse each may affect the other. Herein we review the current state of knowledge of central dopamine involvement in pair bond formation, expression, and maintenance. We first describe the neuroanatomical substrate within which dopamine exerts its effects on social bonding. We then describe dopamine receptor subtype-specific influences on pair bonding and how dopamine receptor activation may interact with activation of other neurochemical systems. Finally, we describe possible interactions between social bonding and substance abuse.

The genetic background to PTSD

Although extensive research has already been done on the genetic bases of psychiatric disorders, little is known about polygenetic influences in posttraumatic stress disorder (PTSD). This article reviews molecular genetic studies relating to PTSD that were found in a literature search in Medline, Embase and Web of Science. Association studies have investigated 8 major genotypes in connection with PTSD. They have tested hypotheses involving key candidate genes in the serotonin (5-HTT), dopamine (DRD2, DAT), glucocorticoid (GR), GABA (GABRB), apolipoprotein systems (APOE2), brain-derived neurotrophic factor (BDNF) and neuropeptide Y (NPY). The studies have produced inconsistent results, many of which may be attributable to methodological shortcomings and insufficient statistical power. The complex aetiology of PTSD, for which experiencing a traumatic event forms a necessary condition, makes it difficult to identify specific genes that substantially contribute to the disorder. Gene-finding strategies are difficult to apply. Interactions between different genes and between them and the environment probably make certain people vulnerable to developing PTSD. Gene-environmental studies are needed that focus more narrowly on specific, distinct endophenotypes and on influences from environmental factors.

Psychiatric and physical health ramifications of traumatic events in women

All individuals are at some risk of experiencing a traumatic event and developing posttraumatic stress disorder (PTSD); however some individuals are at higher risk due to individual and environmental factors. This critical literature review focuses on women, as they are twice as likely as men to develop PTSD in their lifetimes. Should a woman develop PTSD, she is then at risk of developing psychiatric and physical health comorbidities that can further impact her quality of life. The strengths and limitations of current studies regarding this topic are discussed as are directions for future research and issues for nurses treating traumatized individuals.

Genetics of fibromyalgia

The pathogenesis of fibromyalgia (FM) and related conditions is not entirely understood. Recent evidence suggests that these syndromes may share heritable pathophysiologic features. Familial studies suggest that genetic and familial factors may play a role in the etiopathogenesis of these conditions. There is evidence that polymorphisms of genes in the serotoninergic and catecholaminergic systems are linked to the pathophysiology of FM and related conditions and are associated with personality traits. The precise role of genetic factors in the etiopathology of FM remains unknown, but it is likely that several genes are operating together to initiate this syndrome. Larger longitudinal studies are needed to better clarify the role of genetics in the development of FM.

Predictors of pharmacotherapy response in anxiety disorders

Although treatment with different compounds such as tricyclic antidepressants, selective serotonin reuptake inhibitors, high-potency benzodiazepines, and monoamine oxidase inhibitors has been proven effective in anxiety disorders, 20% to 40% of patients are nonresponders. Given the limited efficacy, the delayed onset of response (it takes several weeks before a clinical effect can be seen for most of these drugs), and the occurrence of side effects associated with pharmacotherapy, predicting response in anxiety disorders would be immensely valuable. This review surveys the literature over the past years on predictors of response to pharmacotherapy in obsessive-compulsive disorder, social anxiety disorder, panic disorder, and posttraumatic stress disorder. Prediction of treatment response may be founded on demographic and clinical variables, neurochemical and electrophysiologic parameters, imaging studies, and genetic markers.

Negative symptoms of schizophrenia are improved by the addition of paroxetine to neuroleptics: a double-blind placebo-controlled study

Despite the availability of atypical antipsychotics, the treatment of negative symptoms in schizophrenia remains a challenge. This study was designed to confirm the positive effect observed in our pilot study with paroxetine as augmentation to antipsychotics in the treatment of negative symptoms in chronic schizophrenia. Twenty-nine patients with chronic schizophrenia, as defined by DSM-IV, who scored at least 20 points on the negative subscale of the Positive and Negative Syndrome Scale (PANSS) were randomized for treatment with 30 mg paroxetine or placebo in a double-blind, placebo-controlled study for 12 weeks. Ratings included the PANSS, the Hamilton Rating Scale for Depression (HAM-D) and scales for extrapyramidal side-effects. An intention-to-treat analysis was based on the 25 patients who were available for at least one follow-up assessment. The last observation carried forward principle was applied. The mean score of the negative subscale of the PANSS decreased in both groups. Using an analysis of covariance, there was a significant treatment effect with paroxetine compared to placebo with respect to negative symptoms (-4.53; 95% confidence interval -9.054 to -0.015). The mean HAM-D scores remained almost constant. The study suggests the efficacy of paroxetine with respect to the treatment of negative symptoms in chronic schizophrenia.

Advances in molecular genetics and the prevention and treatment of substance misuse: Implications of association studies of the A1 allele of the D2 dopamine receptor gene

Substance misuse is influenced by multiple genetic and environmental factors. Recent research has identified a number of potential genetic markers of risk and those associated with drug reward substrates show particular promise. The current study reexamines the extant published data of the association between the D2 dopamine receptor (DRD2) gene minor Taq 1A (A1) allele and substance misuse risk. A series of meta-analyses was performed on 64 studies examining DRD2 A1+ allelic status and substance misuse. In addition, personality was examined as a possible endophenotype. Significant association was found between the A1 allele and severe substance dependence in both Caucasian and non-Caucasian groups. The data did not support a significant association between the A1 allele and personality features. While the specific mechanism underlying these associations requires further elucidation, this genetic marker shows promise as a marker of brain reinforcement processes. Possible ways of utilising the A1 allele to inform prevention and treatment initiatives are discussed.

Genetics of anxiety disorders

There is considerable evidence that genetic determinants play a major role in the etiology of anxiety. Investigations into susceptibility genes for anxiety are well underway, particularly for panic disorder and obsessive-compulsive disorder and more broadly defined anxiety-related traits, such as neuroticism and harm avoidance. This review will discuss some of the core issues related to diagnosis and molecular genetic methodology, followed by a review of recent molecular genetic findings for anxiety. The authors will attempt to highlight the numerous convergent and exciting findings. Given the rapid acceleration in knowledge of the human genome, a more definitive understanding of the genetic roots of these complex conditions may be anticipated in the relatively near future.