Association analysis between the A118G polymorphism in the OPRM1 gene and treatment response to venlafaxine XR in generalized anxiety disorder

A systems omics-based approach to decode substance use disorders and neuroadaptations

Substance use disorders (SUDs) are a group of neuropsychiatric conditions manifesting due to excessive dependence on potential drugs of abuse such as psychostimulants, opioids including prescription opioids, alcohol, inhalants, etc. Experimental studies have generated enormous data in the area of SUDs, but outcomes from such data have remained largely fragmented. In this review, we attempt to coalesce these data points providing an important first step towards our understanding of the etiology of SUDs. We propose and describe a 'core addictome' pathway that behaves central to all SUDs. Besides, we also have made some notable observations paving way for several hypotheses; MECP2 behaves as a master switch during substance use; five distinct gene clusters were identified based on respective substance addiction; a central cluster of genes serves as a hub of the addiction pathway connecting all other substance addiction clusters. In addition to describing these findings, we have emphasized the importance of some candidate genes that are of substantial interest for further investigation and serve as high-value targets for translational efforts.

The role of pharmacogenetics in the treatment of anxiety disorders and the future potential for targeted therapeutics

INTRODUCTION

Anxiety disorders (AD) are among the most common mental disorders worldwide. Pharmacotherapy, including benzodiazepines, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and tricyclic antidepressants is currently based on 'trial-and-error,' and is effective in a subset of patients or produces partial response only. Recent research proposes that treatment response and tolerability of the drugs are associated with genetic factors.

AREAS COVERED

In the present review, we provide information on pharmacogenetics (PGx) in AD, including pharmacokinetic and pharmacodynamic genes. Moreover, we discuss the future potential of PGx for personalized treatment.

EXPERT OPINION

In psychiatry, PGx testing is still in its infancy, especially in the treatment of AD. As of today, implementation in clinical routine is recommended only for CYP2D6 and CYP2C19, mainly in terms of safety of treatment and potentially of treatment outcome in general. However, the evidence for PGx testing addressing pharmacodynamics for specific AD is limited to date. Nevertheless, PGx may develop into a valuable and promising tool to improve therapy in AD, but there is a need for more research to fully exploit its possibilities. Future perspectives include research into single genes, polygenic risk scores, and pharmacoepigenetics to provide targeted therapy.

Towards precision medicine in generalized anxiety disorder: Review of genetics and pharmaco(epi)genetics

Generalized anxiety disorder (GAD) is a prevalent and chronic mental disorder that elicits widespread functional impairment. Given the high degree of non-response/partial response among patients with GAD to available pharmacological treatments, there is a strong need for novel approaches that can optimize outcomes, and lead to medications that are safer and more effective. Although investigations have identified interesting targets predicting treatment response through pharmacogenetics (PGx), pharmaco-epigenetics, and neuroimaging methods, these studies are often solitary, not replicated, and carry several limitations. This review provides an overview of the current status of GAD genetics and PGx and presents potential strategies to improve treatment response by combining better phenotyping with PGx and improved analytical methods. These strategies carry the dual benefit of delivering data on biomarkers of treatment response as well as pointing to disease mechanisms through the biology of the markers associated with response. Overall, these efforts can serve to identify clinical, genetic, and epigenetic factors that can be incorporated into a pharmaco(epi)genetic test that may ultimately improve treatment response and reduce the socioeconomic burden of GAD.

Venlafaxine pharmacogenetics: a comprehensive review

Antidepressant response could be from 42 to 50% genetically determined. Venlafaxine (VEN) was the sixth most-prescribed antidepressant in the USA in 2017. Therefore, we reviewed studies which focused on the pharmacogenetics of VEN and found that there is a lack of guidelines for pharmacogenetic testing for VEN. Within investigated genetic polymorphisms, few of them can be indicated as potential predictors of VEN efficacy and tolerance. However, additional pharmacogenetic studies of VEN should be performed to reproduce already obtained results or explain contradictory ones. The individualization of pharmacotherapy is a key issue in providing patients with the highest possible quality of treatment, therefore pharmacogenetic studies should be one of the components of therapy optimization.

Predictors of Pharmacotherapy Response in Generalized Anxiety Disorder: A Systematic Review

BACKGROUND

Pharmacotherapy for generalized anxiety disorder (GAD) may be effective in reducing symptoms in the majority of patients. The study of moderators and predictors of treatment response may help clinicians both to select appropriate interventions to maximize the probability of response and to inform the general prognosis.

METHODS

A systematic literature search of electronic databases, selected authors, and reference lists was used to identify articles that reported trials of drug monotherapy in GAD. Data on predictors and moderators were extracted. Quality of evidence was determined by the presence of a priori hypotheses, number of variables investigated, adequate quality of the measurement, and use of interaction-effects testing.

RESULTS

From the 98 articles meeting inclusion criteria, 24 reported a total of 22 factors associated with treatment response. The reported results were heterogeneous, ranging over sociodemographic, clinical, comorbidity, genetic, and functional-imaging studies. Major depressive symptoms were found to moderate treatment outcome in favor of antidepressants versus benzodiazepines. Neuroticism, previous treatment, genetic polymorphisms (including serotonin receptor gene 2A), and functional activation of the anterior cingulate cortex and amygdala were identified as potential predictors of treatment response.

CONCLUSIONS

Correlates of poor emotion regulation predicted poor treatment response, but subclinical depression was the only variable capable of informing treatment selection in this review. Future research should focus on further exploring the value of depression as a moderator and on a narrower list of potential genetic, brain-imaging, and temperament predictors of response to pharmacotherapy in GAD.

Biological markers of generalized anxiety disorder

Generalized anxiety disorder (GAD) is a prevalent and highly disabling mental health condition; however, there is still much to learn with regard to pertinent biomarkers, as well as diagnosis, made more difficult by the marked and common overlap of GAD with affective and anxiety disorders. Recently, intensive research efforts have focused on GAD, applying neuroimaging, genetic, and blood-based approaches toward discovery of pathogenetic and treatment-related biomarkers. In this paper, we review the large amount of available data, and we focus in particular on evidence from neuroimaging, genetic, and neurochemical measurements in GAD in order to better understand potential biomarkers involved in its etiology and treatment. Overall, the majority of these studies have produced results that are solitary findings, sometimes inconsistent and not clearly replicable. For these reasons, they have not yet been translated into clinical practice. Therefore, further research efforts are needed to distinguish GAD from other mental disorders and to provide new biological insights into its pathogenesis and treatment.

Biological markers for anxiety disorders, OCD and PTSD - a consensus statement. Part I: Neuroimaging and genetics

OBJECTIVES

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part I) summarises findings on potential biomarkers in neuroimaging studies, including structural brain morphology, functional magnetic resonance imaging and techniques for measuring metabolic changes, including positron emission tomography and others. Furthermore, this review reports on the clinical and molecular genetic findings of family, twin, linkage, association and genome-wide association studies. Part II of the review focuses on neurochemistry, neurophysiology and neurocognition.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high-quality research has accumulated that will improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Biological predictors of pharmacological therapy in anxiety disorders

At least one third of patients with anxiety disorders do not adequately respond to available pharmacological treatment. The reason that some patients with anxiety disorders respond well, but others not, to the same classes of medication is not yet fully understood. It is suggested that several biological factors may influence treatment mechanisms in anxiety and therefore could be identified as possible biomarkers predicting treatment response. In this review, we look at current evidence exploring different types of treatment predictors, including neuroimaging, genetic factors, and blood-related measures, which could open up novel perspectives in clinical management of patients with anxiety disorders.

Long-Term Pharmacological Treatments of Anxiety Disorders: An Updated Systematic Review

Many aspects of long-term pharmacological treatments for anxiety disorders (AnxDs) are still debated. We undertook an updated systematic review of long-term pharmacological studies on panic disorder (PD), generalized anxiety disorder (GAD), and social anxiety disorder (SAD). Relevant studies dating from January 1, 2012 to August 31, 2015 were identified using the PubMed database and a review of bibliographies. Of 372 records identified in the search, five studies on PD and 15 on GAD were included in the review. No studies on SAD were found. Our review confirms the usefulness of long-term pharmacological treatments for PD and GAD and suggests that they can provide further improvement over that obtained during short-term therapy. Paroxetine, escitalopram, and clonazepam can be effective for long-term treatment of PD. However, further studies are needed to draw conclusions about the long-term benzodiazepine use in PD, particularly for the possible cognitive side-effects over time. Pregabalin and quetiapine can be effective for long-term treatment of GAD, while preliminary suggestions emerged for agomelatine and vortioxetine. We did not find any evidence for determining the optimal length and/or dosage of medications to minimize the relapse risk. Few investigations have attempted to identify potential predictors of long-term treatment response. Personalized treatments for AnxDs can be implemented using predictive tools to explore those factors affecting treatment response/tolerability heterogeneity, including neurobiological functions/clinical profiles, comorbidity, biomarkers, and genetic features, and to tailor medications according to each patient's unique features.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Understanding the pharmacogenetics of selective serotonin reuptake inhibitors

INTRODUCTION

The genetic background of antidepressant response represents a unique opportunity to identify biological markers of treatment outcome. Encouraging results alternating with inconsistent findings made antidepressant pharmacogenetics a stimulating but often discouraging field that requires careful discussion about cumulative evidence and methodological issues.

AREAS COVERED

The present review discusses both known and less replicated genes that have been implicated in selective serotonin reuptake inhibitors (SSRIs) efficacy and side effects. Candidate genes studies and genome-wide association studies (GWAS) were collected through MEDLINE database search (articles published till January 2014). Further, GWAS signals localized in promising genetic regions according to candidate gene studies are reported in order to assess the general comparability of results obtained through these two types of pharmacogenetic studies. Finally, a pathway enrichment approach is applied to the top genes (those harboring SNPs with p < 0.0001) outlined by previous GWAS in order to identify possible molecular mechanisms involved in SSRI effect.

EXPERT OPINION

In order to improve the understanding of SSRI pharmacogenetics, the present review discusses the proposal of moving from the analysis of individual polymorphisms to genes and molecular pathways, and from the separation across different methodological approaches to their combination. Efforts in this direction are justified by the recent evidence of a favorable cost-utility of gene-guided antidepressant treatment.

Propensity for social interaction predicts nicotine-reinforced behaviors in outbred rats

Social and genetic factors can influence smoking behavior. Using olfactogustatory stimuli as the sensory cue for intravenous nicotine self-administration (SA), we previously showed that social learning of nicotine contingent odor cue prevented rats from developing conditioned taste aversion and allowed them to instead establish stable nicotine SA. We hypothesized that genetic factors influenced socially acquired nicotine SA. A heterogeneous stock (HS; N/NIH) of outbred rats was trained to self-administer nicotine using the social learning protocol. Both male and female HS rats acquired nicotine SA, but females self-administered more nicotine than males. After extinction, the context previously paired with nicotine SA, in conjunction with socially transmitted drug cues, was sufficient to cause reinstatement of drug-seeking behavior. Wide variation in both nicotine intake and reinstatement was observed. Using multiple regression analysis, we found that measures of social interaction were significant predictors of nicotine intake and reinstatement of drug seeking in both males and females. Furthermore, measures of depression were predictors of nicotine intake in both males and females, anxiety was a predictor only in males and response to novelty was a predictor only in females. In males, measures of both depression and anxiety predicted nicotine reinstatement. Together, these data supported the ideas that genetically determined propensities for emotional and social phenotypes are significant determinants for nicotine-reinforced behavior, and that the HS rat is a suitable tool for dissecting genetic mechanisms that may underlie the interaction between social behavior, anxiety, depression and smoking.