Genome-wide association analyses identify 95 risk loci and provide insights into the neurobiology of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) genetics are characterized by lower discoverability than most other psychiatric disorders. The contribution to biological understanding from previous genetic studies has thus been limited. We performed a multi-ancestry meta-analysis of genome-wide association studies across 1,222,882 individuals of European ancestry (137,136 cases) and 58,051 admixed individuals with African and Native American ancestry (13,624 cases). We identified 95 genome-wide significant loci (80 new). Convergent multi-omic approaches identified 43 potential causal genes, broadly classified as neurotransmitter and ion channel synaptic modulators (for example, GRIA1, GRM8 and CACNA1E), developmental, axon guidance and transcription factors (for example, FOXP2, EFNA5 and DCC), synaptic structure and function genes (for example, PCLO, NCAM1 and PDE4B) and endocrine or immune regulators (for example, ESR1, TRAF3 and TANK). Additional top genes influence stress, immune, fear and threat-related processes, previously hypothesized to underlie PTSD neurobiology. These findings strengthen our understanding of neurobiological systems relevant to PTSD pathophysiology, while also opening new areas for investigation.

Discovery of 95 PTSD loci provides insight into genetic architecture and neurobiology of trauma and stress-related disorders

Posttraumatic stress disorder (PTSD) genetics are characterized by lower discoverability than most other psychiatric disorders. The contribution to biological understanding from previous genetic studies has thus been limited. We performed a multi-ancestry meta-analysis of genome-wide association studies across 1,222,882 individuals of European ancestry (137,136 cases) and 58,051 admixed individuals with African and Native American ancestry (13,624 cases). We identified 95 genome-wide significant loci (80 novel). Convergent multi-omic approaches identified 43 potential causal genes, broadly classified as neurotransmitter and ion channel synaptic modulators (e.g., GRIA1, GRM8, CACNA1E ), developmental, axon guidance, and transcription factors (e.g., FOXP2, EFNA5, DCC ), synaptic structure and function genes (e.g., PCLO, NCAM1, PDE4B ), and endocrine or immune regulators (e.g., ESR1, TRAF3, TANK ). Additional top genes influence stress, immune, fear, and threat-related processes, previously hypothesized to underlie PTSD neurobiology. These findings strengthen our understanding of neurobiological systems relevant to PTSD pathophysiology, while also opening new areas for investigation.

Associations Between Cannabis Use, Polygenic Liability for Schizophrenia, and Cannabis-related Experiences in a Sample of Cannabis Users

BACKGROUND AND HYPOTHESIS

Risk for cannabis use and schizophrenia is influenced in part by genetic factors, and there is evidence that genetic risk for schizophrenia is associated with subclinical psychotic-like experiences (PLEs). Few studies to date have examined whether genetic risk for schizophrenia is associated with cannabis-related PLEs.

STUDY DESIGN

We tested whether measures of cannabis involvement and polygenic risk scores (PRS) for schizophrenia were associated with self-reported cannabis-related experiences in a sample ascertained for alcohol use disorders (AUDs), the Collaborative Study on the Genetics of Alcoholism (COGA). We analyzed 4832 subjects (3128 of European ancestry and 1704 of African ancestry; 42% female; 74% meeting lifetime criteria for an AUD).

STUDY RESULTS

Cannabis use disorder (CUD) was prevalent in this analytic sample (70%), with 40% classified as mild, 25% as moderate, and 35% as severe. Polygenic risk for schizophrenia was positively associated with cannabis-related paranoia, feeling depressed or anhedonia, social withdrawal, and cognitive difficulties, even when controlling for duration of daily cannabis use, CUD, and age at first cannabis use. The schizophrenia PRS was most robustly associated with cannabis-related cognitive difficulties (β = 0.22, SE = 0.04, P = 5.2e-7). In an independent replication sample (N = 1446), associations between the schizophrenia PRS and cannabis-related experiences were in the expected direction and not statistically different in magnitude from those in the COGA sample.

CONCLUSIONS

Among individuals who regularly use cannabis, genetic liability for schizophrenia-even in those without clinical features-may increase the likelihood of reporting unusual experiences related to cannabis use.

Cnih3 Deletion Dysregulates Dorsal Hippocampal Transcription across the Estrous Cycle

In females, the hippocampus, a critical brain region for coordination of learning, memory, and behavior, displays altered physiology and behavioral output across the estrous or menstrual cycle. However, the molecular effectors and cell types underlying these observed cyclic changes have only been partially characterized to date. Recently, profiling of mice null for the AMPA receptor trafficking gene Cnih3 have demonstrated estrous-dependent phenotypes in dorsal hippocampal synaptic plasticity, composition, and learning/memory. We therefore profiled dorsal hippocampal transcriptomes from female mice in each estrous cycle stage, and contrasted it with that of males, across wild-type (WT) and Cnih3 mutants. In wild types, we identified only subtle differences in gene expression between the sexes, while comparing estrous stages to one another revealed up to >1000 differentially expressed genes (DEGs). These estrous-responsive genes are especially enriched in gene markers of oligodendrocytes and the dentate gyrus, and in functional gene sets relating to estrogen response, potassium channels, and synaptic gene splicing. Surprisingly, Cnih3 knock-outs (KOs) showed far broader transcriptomic differences between estrous cycle stages and males. Moreover, Cnih3 knock-out drove subtle but extensive expression changes accentuating sex differential expression at diestrus and estrus. Altogether, our profiling highlights cell types and molecular systems potentially impacted by estrous-specific gene expression patterns in the adult dorsal hippocampus, enabling mechanistic hypothesis generation for future studies of sex-differential neuropsychiatric function and dysfunction. Moreover, these findings suggest an unrecognized role of Cnih3 in buffering against transcriptional effects of estrous, providing a candidate molecular mechanism to explain estrous-dependent phenotypes observed with Cnih3 loss.

Multi-trait genome-wide association study of opioid addiction: OPRM1 and beyond

Opioid addiction (OA) is moderately heritable, yet only rs1799971, the A118G variant in OPRM1, has been identified as a genome-wide significant association with OA and independently replicated. We applied genomic structural equation modeling to conduct a GWAS of the new Genetics of Opioid Addiction Consortium (GENOA) data together with published studies (Psychiatric Genomics Consortium, Million Veteran Program, and Partners Health), comprising 23,367 cases and effective sample size of 88,114 individuals of European ancestry. Genetic correlations among the various OA phenotypes were uniformly high (rg > 0.9). We observed the strongest evidence to date for OPRM1: lead SNP rs9478500 (p = 2.56 × 10-9). Gene-based analyses identified novel genome-wide significant associations with PPP6C and FURIN. Variants within these loci appear to be pleiotropic for addiction and related traits.

Enhancing Discovery of Genetic Variants for Posttraumatic Stress Disorder Through Integration of Quantitative Phenotypes and Trauma Exposure Information

BACKGROUND

Posttraumatic stress disorder (PTSD) is heritable and a potential consequence of exposure to traumatic stress. Evidence suggests that a quantitative approach to PTSD phenotype measurement and incorporation of lifetime trauma exposure (LTE) information could enhance the discovery power of PTSD genome-wide association studies (GWASs).

METHODS

A GWAS on PTSD symptoms was performed in 51 cohorts followed by a fixed-effects meta-analysis (N = 182,199 European ancestry participants). A GWAS of LTE burden was performed in the UK Biobank cohort (N = 132,988). Genetic correlations were evaluated with linkage disequilibrium score regression. Multivariate analysis was performed using Multi-Trait Analysis of GWAS. Functional mapping and annotation of leading loci was performed with FUMA. Replication was evaluated using the Million Veteran Program GWAS of PTSD total symptoms.

RESULTS

GWASs of PTSD symptoms and LTE burden identified 5 and 6 independent genome-wide significant loci, respectively. There was a 72% genetic correlation between PTSD and LTE. PTSD and LTE showed largely similar patterns of genetic correlation with other traits, albeit with some distinctions. Adjusting PTSD for LTE reduced PTSD heritability by 31%. Multivariate analysis of PTSD and LTE increased the effective sample size of the PTSD GWAS by 20% and identified 4 additional loci. Four of these 9 PTSD loci were independently replicated in the Million Veteran Program.

CONCLUSIONS

Through using a quantitative trait measure of PTSD, we identified novel risk loci not previously identified using prior case-control analyses. PTSD and LTE have a high genetic overlap that can be leveraged to increase discovery power through multivariate methods.

Exploring the genetic overlap of suicide-related behaviors and substance use disorders

Suicide-related behaviors are heterogeneous and transdiagnostic, and may demonstrate varying levels of genetic overlap with different substance use disorders (SUDs). We used linkage disequilibrium score regression, genomic structural equation models, and Mendelian randomization to examine the genetic relationships between several SUDs and suicide-related behaviors. Our analyses incorporated summary statistics from the largest genome-wide association studies (GWAS) of problematic alcohol use, the Fagerström test for nicotine dependence, cannabis use disorder, and opioid use disorder (Ns ranging from 46,213-435,563) and GWAS of ever self-harmed, suicide attempt, and suicide death (Ns ranging from 18,223-117,733). We also accounted for genetic liability to depression (N = 500,199) and risk tolerance (N = 315,894). Suicide-related behaviors were significantly genetically correlated with each other and each SUD, but there was little evidence of causal relationships between the traits. Simultaneously correlating a common SUD factor with each specific suicide indicator while controlling for depression and risk tolerance revealed significant, positive genetic correlations between the SUD factor and suicide-related behaviors (rg  = 0.26-0.45, SE = 0.08-0.09). In the model, depression's association with suicide death (β = 0.42, SE = 0.06) was weaker compared to ever-self harmed and suicide attempt (β = 0.58, SE = 0.05 and β = 0.50, SE = 0.06, respectively). We identify a general level of genetic overlap between SUDs and suicide-related behaviors, which is independent of depression and risk tolerance. Additionally, our findings suggest that genetic and behavioral contributions to suicide death may somewhat differ from nonlethal suicide-related behaviors.

Sex Differences in the Role of CNIH3 on Spatial Memory and Synaptic Plasticity

BACKGROUND

CNIH3 is an AMPA receptor (AMPAR) auxiliary protein prominently expressed in the dorsal hippocampus (dHPC), a region that plays a critical role in spatial memory and synaptic plasticity. However, the effects of CNIH3 on AMPAR-dependent synaptic function and behavior have not been investigated.

METHODS

We assessed a gain-of-function model of Cnih3 overexpression in the dHPC and generated and characterized a line of Cnih3-/- C57BL/6 mice. We assessed spatial memory through behavioral assays, protein levels of AMPAR subunits and synaptic proteins by immunoblotting, and long-term potentiation in electrophysiological recordings. We also utilized a super-resolution imaging workflow, SEQUIN (Synaptic Evaluation and Quantification by Imaging of Nanostructure), for analysis of nanoscale synaptic connectivity in the dHPC.

RESULTS

Overexpression of Cnih3 in the dHPC improved short-term spatial memory in female mice but not in male mice. Cnih3-/- female mice exhibited weakened short-term spatial memory, reduced dHPC synapse density, enhanced expression of calcium-impermeable AMPAR (GluA2-containing) subunits in synaptosomes, and attenuated long-term potentiation maintenance compared with Cnih3+/+ control mice; Cnih3-/- males were unaffected. Further investigation revealed that deficiencies in spatial memory and changes in AMPAR composition and synaptic plasticity were most pronounced during the metestrus phase of the estrous cycle in female Cnih3-/- mice.

CONCLUSIONS

This study identified a novel effect of sex and estrous on CNIH3's role in spatial memory and synaptic plasticity. Manipulation of CNIH3 unmasked sexually dimorphic effects on spatial memory, synaptic function, AMPAR composition, and hippocampal plasticity. These findings reinforce the importance of considering sex as a biological variable in studies of memory and hippocampal synaptic function.

Using Monozygotic Twins to Dissect Common Genes in Posttraumatic Stress Disorder and Migraine

Epigenetic mechanisms have been associated with genes involved in Posttraumatic stress disorder (PTSD). PTSD often co-occurs with other health conditions such as depression, cardiovascular disorder and respiratory illnesses. PTSD and migraine have previously been reported to be symptomatically positively correlated with each other, but little is known about the genes involved. The aim of this study was to understand the comorbidity between PTSD and migraine using a monozygotic twin disease discordant study design in six pairs of monozygotic twins discordant for PTSD and 15 pairs of monozygotic twins discordant for migraine. DNA from peripheral blood was run on Illumina EPIC arrays and analyzed. Multiple testing correction was performed using the Bonferroni method and 10% false discovery rate (FDR). We validated 11 candidate genes previously associated with PTSD including DOCK2, DICER1, and ADCYAP1. In the epigenome-wide scan, seven novel CpGs were significantly associated with PTSD within/near IL37, WNT3, ADNP2, HTT, SLFN11, and NQO2, with all CpGs except the IL37 CpG hypermethylated in PTSD. These results were significantly enriched for genes whose DNA methylation was previously associated with migraine (p-value = 0.036). At 10% FDR, 132 CpGs in 99 genes associated with PTSD were also associated with migraine in the migraine twin samples. Genes associated with PTSD were overrepresented in vascular smooth muscle, axon guidance and oxytocin signaling pathways, while genes associated with both PTSD and migraine were enriched for AMPK signaling and longevity regulating pathways. In conclusion, these results suggest that common genes and pathways are likely involved in PTSD and migraine, explaining at least in part the co-morbidity between the two disorders.

A large-scale genome-wide association study meta-analysis of cannabis use disorder

BACKGROUND

Variation in liability to cannabis use disorder has a strong genetic component (estimated twin and family heritability about 50-70%) and is associated with negative outcomes, including increased risk of psychopathology. The aim of the study was to conduct a large genome-wide association study (GWAS) to identify novel genetic variants associated with cannabis use disorder.

METHODS

To conduct this GWAS meta-analysis of cannabis use disorder and identify associations with genetic loci, we used samples from the Psychiatric Genomics Consortium Substance Use Disorders working group, iPSYCH, and deCODE (20 916 case samples, 363 116 control samples in total), contrasting cannabis use disorder cases with controls. To examine the genetic overlap between cannabis use disorder and 22 traits of interest (chosen because of previously published phenotypic correlations [eg, psychiatric disorders] or hypothesised associations [eg, chronotype] with cannabis use disorder), we used linkage disequilibrium score regression to calculate genetic correlations.

FINDINGS

We identified two genome-wide significant loci: a novel chromosome 7 locus (FOXP2, lead single-nucleotide polymorphism [SNP] rs7783012; odds ratio [OR] 1·11, 95% CI 1·07-1·15, p=1·84 × 10-9) and the previously identified chromosome 8 locus (near CHRNA2 and EPHX2, lead SNP rs4732724; OR 0·89, 95% CI 0·86-0·93, p=6·46 × 10-9). Cannabis use disorder and cannabis use were genetically correlated (rg 0·50, p=1·50 × 10-21), but they showed significantly different genetic correlations with 12 of the 22 traits we tested, suggesting at least partially different genetic underpinnings of cannabis use and cannabis use disorder. Cannabis use disorder was positively genetically correlated with other psychopathology, including ADHD, major depression, and schizophrenia.

INTERPRETATION

These findings support the theory that cannabis use disorder has shared genetic liability with other psychopathology, and there is a distinction between genetic liability to cannabis use and cannabis use disorder.

FUNDING

National Institute of Mental Health; National Institute on Alcohol Abuse and Alcoholism; National Institute on Drug Abuse; Center for Genomics and Personalized Medicine and the Centre for Integrative Sequencing; The European Commission, Horizon 2020; National Institute of Child Health and Human Development; Health Research Council of New Zealand; National Institute on Aging; Wellcome Trust Case Control Consortium; UK Research and Innovation Medical Research Council (UKRI MRC); The Brain & Behavior Research Foundation; National Institute on Deafness and Other Communication Disorders; Substance Abuse and Mental Health Services Administration (SAMHSA); National Institute of Biomedical Imaging and Bioengineering; National Health and Medical Research Council (NHMRC) Australia; Tobacco-Related Disease Research Program of the University of California; Families for Borderline Personality Disorder Research (Beth and Rob Elliott) 2018 NARSAD Young Investigator Grant; The National Child Health Research Foundation (Cure Kids); The Canterbury Medical Research Foundation; The New Zealand Lottery Grants Board; The University of Otago; The Carney Centre for Pharmacogenomics; The James Hume Bequest Fund; National Institutes of Health: Genes, Environment and Health Initiative; National Institutes of Health; National Cancer Institute; The William T Grant Foundation; Australian Research Council; The Virginia Tobacco Settlement Foundation; The VISN 1 and VISN 4 Mental Illness Research, Education, and Clinical Centers of the US Department of Veterans Affairs; The 5th Framework Programme (FP-5) GenomEUtwin Project; The Lundbeck Foundation; NIH-funded Shared Instrumentation Grant S10RR025141; Clinical Translational Sciences Award grants; National Institute of Neurological Disorders and Stroke; National Heart, Lung, and Blood Institute; National Institute of General Medical Sciences.

Leveraging genome-wide data to investigate differences between opioid use vs. opioid dependence in 41,176 individuals from the Psychiatric Genomics Consortium

To provide insights into the biology of opioid dependence (OD) and opioid use (i.e., exposure, OE), we completed a genome-wide analysis comparing 4503 OD cases, 4173 opioid-exposed controls, and 32,500 opioid-unexposed controls, including participants of European and African descent (EUR and AFR, respectively). Among the variants identified, rs9291211 was associated with OE (exposed vs. unexposed controls; EUR z = -5.39, p = 7.2 × 10-8). This variant regulates the transcriptomic profiles of SLC30A9 and BEND4 in multiple brain tissues and was previously associated with depression, alcohol consumption, and neuroticism. A phenome-wide scan of rs9291211 in the UK Biobank (N > 360,000) found association of this variant with propensity to use dietary supplements (p = 1.68 × 10-8). With respect to the same OE phenotype in the gene-based analysis, we identified SDCCAG8 (EUR + AFR z = 4.69, p = 10-6), which was previously associated with educational attainment, risk-taking behaviors, and schizophrenia. In addition, rs201123820 showed a genome-wide significant difference between OD cases and unexposed controls (AFR z = 5.55, p = 2.9 × 10-8) and a significant association with musculoskeletal disorders in the UK Biobank (p = 4.88 × 10-7). A polygenic risk score (PRS) based on a GWAS of risk-tolerance (n = 466,571) was positively associated with OD (OD vs. unexposed controls, p = 8.1 × 10-5; OD cases vs. exposed controls, p = 0.054) and OE (exposed vs. unexposed controls, p = 3.6 × 10-5). A PRS based on a GWAS of neuroticism (n = 390,278) was positively associated with OD (OD vs. unexposed controls, p = 3.2 × 10-5; OD vs. exposed controls, p = 0.002) but not with OE (p = 0.67). Our analyses highlight the difference between dependence and exposure and the importance of considering the definition of controls in studies of addiction.

Retrospectively assessed subjective effects of initial opioid use differ between opioid misusers with opioid use disorder (OUD) and those who never progressed to OUD: Data from a pilot and a replication sample

Attempts to identify opioid users with increased risk of escalating to opioid use disorder (OUD) have had limited success. Retrospectively assessed subjective effects of initial opioid misuse were compared in a pilot sample of opioid misusers (nonmedical use ≤60 times lifetime) who had never met criteria for OUD (N = 14) and heroin-addicted individuals in treatment for OUD (N = 15). Relative to opioid misusers without a lifetime OUD diagnosis, individuals with OUD reported greater euphoria and other positive emotions, activation, pruritus, and internalizing symptoms. Consistent with these findings, proxy Addiction Research Center Inventory (ARCI) Amphetamine Group, and Morphine Benzedrine Group scale mean item scores were significantly higher in those with OUD. Replication was attempted in opioid misusers with (N = 25) and without OUD (N = 25) who were assessed as part of an ongoing genetic study. We observed similar significant between-group differences in individual subjective effect items and ARCI scale mean item scores in the replication sample. We, thus confirm findings from prior reports that retrospectively assessed subjective responses to initial opioid exposure differ significantly between opioid users who do, and do not, progress to OUD. Our report extends these findings in comparisons limited to opioid misusers. Additional research will be necessary to examine prospectively whether the assessment of subjective effects after initial use has predictive utility in the identification of individuals more likely to progress to OUD.

Single cell transcriptomics reveals opioid usage evokes widespread suppression of antiviral gene program

Chronic opioid usage not only causes addiction behavior through the central nervous system, but also modulates the peripheral immune system. However, how opioid impacts the immune system is still barely characterized systematically. In order to understand the immune modulatory effect of opioids in an unbiased way, here we perform single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells from opioid-dependent individuals and controls to show that chronic opioid usage evokes widespread suppression of antiviral gene program in naive monocytes, as well as in multiple immune cell types upon stimulation with the pathogen component lipopolysaccharide. Furthermore, scRNA-seq reveals the same phenomenon after a short in vitro morphine treatment. These findings indicate that both acute and chronic opioid exposure may be harmful to our immune system by suppressing the antiviral gene program. Our results suggest that further characterization of the immune modulatory effects of opioid is critical to ensure the safety of clinical opioids.

Over 100 million of opioid prescriptions are issued yearly in the USA alone, but the impact of opioid use on the immune system is barely characterized. Here the authors report antiviral immune response is blunted in several types of blood cells from opioid-dependent individuals, and when healthy donor cells are exposed to morphine in a dish.

International meta-analysis of PTSD genome-wide association studies identifies sex- and ancestry-specific genetic risk loci

The risk of posttraumatic stress disorder (PTSD) following trauma is heritable, but robust common variants have yet to be identified. In a multi-ethnic cohort including over 30,000 PTSD cases and 170,000 controls we conduct a genome-wide association study of PTSD. We demonstrate SNP-based heritability estimates of 5-20%, varying by sex. Three genome-wide significant loci are identified, 2 in European and 1 in African-ancestry analyses. Analyses stratified by sex implicate 3 additional loci in men. Along with other novel genes and non-coding RNAs, a Parkinson's disease gene involved in dopamine regulation, PARK2, is associated with PTSD. Finally, we demonstrate that polygenic risk for PTSD is significantly predictive of re-experiencing symptoms in the Million Veteran Program dataset, although specific loci did not replicate. These results demonstrate the role of genetic variation in the biology of risk for PTSD and highlight the necessity of conducting sex-stratified analyses and expanding GWAS beyond European ancestry populations.

Childhood Trauma and Two Stages of Alcohol Use in African American and European American Women: Findings from a Female Twin Sample

The current investigation assessed for moderating effects of childhood trauma on genetic and environmental contributions to timing of alcohol use initiation and alcohol use disorder in African American (AA) and European American (EA) women. Data were drawn from diagnostic telephone interviews conducted with 3786 participants (14.6% AA) in a longitudinal female twin study. Childhood trauma was defined alternately as child maltreatment and more broadly to include other events (e.g., witnessing violence). Phenotypic associations between childhood trauma and alcohol outcomes were estimated using logistic regression analyses. Twin modeling was conducted to test for moderating effects of childhood trauma on the contributions of genetic and environmental factors to timing of initiation and alcohol use disorder. Under both definitions, childhood trauma was associated with early initiation (relative risk ratios: 1.90, 1.72) and alcohol use disorder (odds ratios: 1.92, 1.76). Yet gene by environment effects were observed only for child maltreatment and timing of initiation in EA women, with heritable influences less prominent in those who had experienced child maltreatment (0.35, 95% CI: 0.05-0.66 vs. 0.52, 95% CI: 0.30-0.73). We found more similarities than differences in the association of childhood trauma with alcohol outcomes across racial/ethnic groups, trauma type, and stages of alcohol use. However, findings suggest that the relative contribution of genetic factors to alcohol outcomes differs by childhood maltreatment history in EA women specifically in the earliest stage of alcohol use.

Common genetic contributions to high-risk trauma exposure and self-injurious thoughts and behaviors

BACKGROUND

Prior research has documented shared heritable contributions to non-suicidal self-injury (NSSI) and suicidal ideation (SI) as well as NSSI and suicide attempt (SA). In addition, trauma exposure has been implicated in risk for NSSI and suicide. Genetically informative studies are needed to determine common sources of liability to all three self-injurious thoughts and behaviors, and to clarify the nature of their associations with traumatic experiences.

METHODS

Multivariate biometric modeling was conducted using data from 9526 twins [59% female, mean age = 31.7 years (range 24-42)] from two cohorts of the Australian Twin Registry, some of whom also participated in the Childhood Trauma Study and the Nicotine Addiction Genetics Project.

RESULTS

The prevalences of high-risk trauma exposure (HRT), NSSI, SI, and SA were 24.4, 5.6, 27.1, and 4.6%, respectively. All phenotypes were moderately to highly correlated. Genetic influences on self-injurious thoughts and behaviors and HRT were significant and highly correlated among men [rG = 0.59, 95% confidence interval (CI) (0.37-0.81)] and women [rG = 0.56 (0.49-0.63)]. Unique environmental influences were modestly correlated in women [rE = 0.23 (0.01-0.45)], suggesting that high-risk trauma may confer some direct risk for self-injurious thoughts and behaviors among females.

CONCLUSIONS

Individuals engaging in NSSI are at increased risk for suicide, and common heritable factors contribute to these associations. Preventing trauma exposure may help to mitigate risk for self-harm and suicide, either directly or indirectly via reductions in liability to psychopathology more broadly. In addition, targeting pre-existing vulnerability factors could significantly reduce risk for life-threatening behaviors among those who have experienced trauma.

Publisher Correction: Novel pleiotropic risk loci for melanoma and nevus density implicate multiple biological pathways

The original version of this Article contained errors in the spelling of the authors Fan Liu and M. Arfan Ikram, which were incorrectly given as Fan Lui and Arfan M. Ikram. In addition, the original version of this Article also contained errors in the author affiliations which are detailed in the associated Publisher Correction.

Overlap of heritable influences between cannabis use disorder, frequency of use and opportunity to use cannabis: trivariate twin modelling and implications for genetic design

BACKGROUND

The genetic component of Cannabis Use Disorder may overlap with influences acting more generally on early stages of cannabis use. This paper aims to determine the extent to which genetic influences on the development of cannabis abuse/dependence are correlated with those acting on the opportunity to use cannabis and frequency of use.

METHODS

A cross-sectional study of 3303 Australian twins, measuring age of onset of cannabis use opportunity, lifetime frequency of cannabis use, and lifetime DSM-IV cannabis abuse/dependence. A trivariate Cholesky decomposition estimated additive genetic (A), shared environment (C) and unique environment (E) contributions to the opportunity to use cannabis, the frequency of cannabis use, cannabis abuse/dependence, and the extent of overlap between genetic and environmental factors associated with each phenotype.

RESULTS

Variance components estimates were A = 0.64 [95% confidence interval (CI) 0.58-0.70] and E = 0.36 (95% CI 0.29-0.42) for age of opportunity to use cannabis, A = 0.74 (95% CI 0.66-0.80) and E = 0.26 (95% CI 0.20-0.34) for cannabis use frequency, and A = 0.78 (95% CI 0.65-0.88) and E = 0.22 (95% CI 0.12-0.35) for cannabis abuse/dependence. Opportunity shares 45% of genetic influences with the frequency of use, and only 17% of additive genetic influences are unique to abuse/dependence from those acting on opportunity and frequency.

CONCLUSIONS

There are significant genetic contributions to lifetime cannabis abuse/dependence, but a large proportion of this overlaps with influences acting on opportunity and frequency of use. Individuals without drug use opportunity are uninformative, and studies of drug use disorders must incorporate individual exposure to accurately identify aetiology.

Transancestral GWAS of alcohol dependence reveals common genetic underpinnings with psychiatric disorders

Liability to alcohol dependence (AD) is heritable, but little is known about its complex polygenic architecture or its genetic relationship with other disorders. To discover loci associated with AD and characterize the relationship between AD and other psychiatric and behavioral outcomes, we carried out the largest genome-wide association study to date of DSM-IV-diagnosed AD. Genome-wide data on 14,904 individuals with AD and 37,944 controls from 28 case-control and family-based studies were meta-analyzed, stratified by genetic ancestry (European, n = 46,568; African, n = 6,280). Independent, genome-wide significant effects of different ADH1B variants were identified in European (rs1229984; P = 9.8 × 10-13) and African ancestries (rs2066702; P = 2.2 × 10-9). Significant genetic correlations were observed with 17 phenotypes, including schizophrenia, attention deficit-hyperactivity disorder, depression, and use of cigarettes and cannabis. The genetic underpinnings of AD only partially overlap with those for alcohol consumption, underscoring the genetic distinction between pathological and nonpathological drinking behaviors.

Novel pleiotropic risk loci for melanoma and nevus density implicate multiple biological pathways

The total number of acquired melanocytic nevi on the skin is strongly correlated with melanoma risk. Here we report a meta-analysis of 11 nevus GWAS from Australia, Netherlands, UK, and USA comprising 52,506 individuals. We confirm known loci including MTAP, PLA2G6, and IRF4, and detect novel SNPs in KITLG and a region of 9q32. In a bivariate analysis combining the nevus results with a recent melanoma GWAS meta-analysis (12,874 cases, 23,203 controls), SNPs near GPRC5A, CYP1B1, PPARGC1B, HDAC4, FAM208B, DOCK8, and SYNE2 reached global significance, and other loci, including MIR146A and OBFC1, reached a suggestive level. Overall, we conclude that most nevus genes affect melanoma risk (KITLG an exception), while many melanoma risk loci do not alter nevus count. For example, variants in TERC and OBFC1 affect both traits, but other telomere length maintenance genes seem to affect melanoma risk only. Our findings implicate multiple pathways in nevogenesis.

Predictors of transitions across stages of heroin use and dependence prior to treatment-seeking among people in treatment for opioid dependence

BACKGROUND AND AIMS

Little is known about transition pathways among heroin users prior to treatment. This study examined the demographic and clinical predictors of transition speed from heroin use, to dependence, to first treatment episode.

METHODS

1149 heroin-dependent participants recruited from opioid agonist treatment clinics in Sydney, Australia, underwent a structured interview. Age of onset (AOO) was collected for heroin use, dependence and treatment-seeking, childhood maltreatment, psychiatric history and other substance dependence. Discrete-time survival analyses modelled years from onset of use to dependence, and from dependence to treatment-seeking, including demographic and clinical covariates.

FINDINGS

Median AOO for first heroin use, dependence and treatment-seeking was 18 years (inter-quartile range, or IQR = 6), 21 years (IQR = 7), and 24 years (IQR = 10) respectively. In adjusted models, younger birth cohorts (vs. born <1960), greater childhood maltreatment and later AAO of first heroin use were associated with more rapid transitions from heroin use to dependence. Living independently, parental violence, and alcohol dependence were associated with slower transitions. Earlier treatment-seeking was associated with younger birth cohorts, having dependent children and later AOO of dependence. Delayed treatment-seeking was associated with <10 years school education, living independently, depression and alcohol dependence.

CONCLUSIONS

In this treatment sample, onset of heroin use occurred during late adolescence, suggesting the need for targeted interventions in mid-adolescence. Transitions to heroin dependence, then treatment-seeking, occurred during early adulthood. Rapid transitions from use to dependence were associated with younger birth cohorts, greater exposure to childhood maltreatment, and later onset of use.

Phenotypic and familial associations between childhood maltreatment and cannabis initiation and problems in young adult European-American and African-American women

BACKGROUND

Childhood maltreatment is a known risk factor for cannabis initiation and problem use, but the extent to which this association is attributable to shared familial influences is unknown. We estimate the magnitude of associations between childhood maltreatment, timing of cannabis initiation, and cannabis-related problems, in European-American (EA) and African-American (AA) women, and parse the relative influence of additive genetic (A), shared environmental (C), and individual-specific environmental (E) factors on these constructs and their covariation.

METHODS

Data were from diagnostic telephone interviews conducted with 3786 participants (14.6% AA) in a population-based study of female twins. Logistic regression analyses and twin modeling were used to test for associations, and estimate the relative contributions of genetic and environmental influences to childhood maltreatment and cannabis outcomes and their covariation.

RESULTS

Maltreatment was significantly associated with increased likelihood of cannabis initiation before age 15 among EAs (OR=6.33) and AAs (OR=3.93), but with increased likelihood of later initiation among EAs only (OR=1.68). Maltreatment was associated with cannabis problems among both groups (EA OR=2.32; AA OR=2.03). Among EA women, the covariation between maltreatment and cannabis outcomes was primarily attributable to familial environment (rC=0.67-0.70); among AAs, only individual-specific environment contributed (rE=0.37-0.40).

CONCLUSION

Childhood maltreatment is a major contributor to early initiation of cannabis as well as progression to cannabis problems in both AA and EA women. Distinctions by race/ethnicity are not in the relative contribution of genetic factors, but rather in the type of environmental influences that contribute to stages of cannabis involvement.

Major depressive disorder, suicidal thoughts and behaviours, and cannabis involvement in discordant twins: a retrospective cohort study

BACKGROUND

Early and frequent cannabis use are associated with an increased likelihood of major depressive disorder (MDD) as well as suicidal thoughts and behaviours. We identify associations between aspects of cannabis use, MDD, and suicidal thoughts and behaviours and examine whether such associations persist after accounting for those predisposing factors, including genetic liability and early family environment, that are shared by identical twins who are discordant for cannabis exposure. Any residual association in such identical pairs might be indicative of individual-specific pathways that might be of a causal nature.

METHODS

We did a logistic regression analysis of cannabis use from retrospective data on same-sex male and female twin pairs drawn from 3 studies that had recruited twins from the Australian Twin Registry, 1992-93 (sample 1), 1996-2000 (sample 2), and 2005-09 (sample 3). We studied associations between early use and frequent use of cannabis and MDD, suicidal ideation (ever and persistent), and suicide plan and attempt in the full sample as well as in pairs of monozygotic and dizygotic twins that were discordant for each measure of cannabis involvement at a single timepoint. Significant monozygotic associations were further adjusted for covariates, such as early alcohol or nicotine use, early dysphoric or anhedonic mood, conduct disorder, and childhood sexual abuse. Interactions between each cannabis measure and sex, sample or study effects, and birth year category were also examined as covariates.

FINDINGS

In 13 986 twins (6181 monozygotic and 7805 dizygotic), cannabis use ranged from 1345 (30·4%) of 4432 people in sample 1 to 2275 (69·0%) of 3299 in sample 3. Mean age of first cannabis use ranged from 17·9 years (SD 3·3) in sample 3 to 21·1 years (5·2) in sample 1, and frequent use (≥100 times) was reported by 214 (15·9%) of 1345 users in sample 1 and 499 (21·9%) of 2275 in sample 3. The prevalence of suicidal ideation ranged from 1102 (24·9%) of 4432 people in sample 1 to 1644 (26·3%) of 6255 people in sample 2 and 865 (26·2%) of 3299 people in sample 3. Prevalence of MDD ranged from 901 (20·3%) people in sample 1 to 1773 (28·3%) in sample 2. The monozygotic twin who used cannabis frequently was more likely to report MDD (odds ratio 1·98, 95% CI 1·11-3·53) and suicidal ideation (2·47, 1·19-5·10) compared with their identical twin who had used cannabis less frequently, even after adjustment for covariates. For early cannabis use, the monozygotic point estimate was not significant but could be equated to the significant dizygotic estimate, suggesting a possible association with suicidal ideation.

INTERPRETATION

The increased likelihood of MDD and suicidal ideation in frequent cannabis users cannot be solely attributed to common predisposing factors.

FUNDING

National Institute on Drug Abuse, National Institutes of Health, Australian National Health and Medical Research Council.

Cannabis Involvement and Nonsuicidal Self-Injury: A Discordant Twin Approach

OBJECTIVE

Cannabis use, particularly at an early age, has been linked to suicidal thoughts and behavior, but minimal work has examined the association between cannabis use and lifetime nonsuicidal self-injury (NSSI). The current study aims to characterize the overlap between lifetime and early cannabis use and NSSI and to examine genetic and environmental mechanisms of this association.

METHOD

Adult male and female twins from the Australian Twin Registry (N = 9,583) were used to examine the odds of NSSI associated with lifetime cannabis use and early cannabis use (i.e., <17 years of age). These associations were also examined within monozygotic (MZ) twins discordant for cannabis use and MZ twins discordant for early cannabis use. Analyses were replicated in an independent sample of female twins (n = 3,787) accounting for the age at onset of cannabis use and NSSI.

RESULTS

Lifetime cannabis use (odds ratio [OR] = 2.84, 95% CI [2.23, 3.61]) and early cannabis use were associated with increased odds of NSSI (OR = 2.15, 95% CI [1.75, 2.65]), and this association remained when accounting for covariates. The association was only significant, however, in MZ twin pairs discordant for early cannabis use (OR = 3.20, 95% CI [1.17, 8.73]). Replication analyses accounting for the temporal ordering of cannabis use and NSSI yielded similar findings of nominal significance.

CONCLUSIONS

Results suggest that NSSI is associated with cannabis involvement via differing mechanisms. For lifetime cannabis use, the lack of association in discordant pairs suggests the role of shared genes and family environment. However, in addition to such shared familial influences, person-specific and putatively causal factors contribute to the relationship between early cannabis use and NSSI. Therefore, delaying the onset of cannabis use may reduce exposure to influences that exacerbate vulnerabilities to NSSI.

Reciprocal relationships between substance use and disorders and suicidal ideation and suicide attempts in the Collaborative Study of the Genetics of Alcoholism

BACKGROUND

Substance use and misuse and suicidal thoughts and behaviors tend to co-occur. The purpose of this study was to examine whether (a) suicidal ideation and attempt are related to onset of alcohol, nicotine and cannabis use and dependence; (b) early use of alcohol, nicotine and cannabis is associated with onset of suicidal ideation and attempt; and (c) whether these associations persist while controlling for covariates, such as family history of alcohol problems, major depression and other internalizing and externalizing disorders.

METHODS

The prospective cohort of the Collaborative Study of the Genetics of Alcoholism (COGA; N=3277) was used. Cross-sectional and discrete time logistic regression (i.e. survival) analyses examined associations between suicidal ideation and attempt and onset of alcohol, nicotine and cannabis use and dependence. Survival models also examined whether individual early substance use was related to onset of ideation and attempt.

RESULTS

Ideation was related to 0.71-0.77 odds of onset of subsequent alcohol, nicotine and cannabis use. Attempt was associated with 1.44-1.61 odds of later alcohol, nicotine and cannabis dependence, even after accounting for covariates. Evidence for early substance use being related to subsequent onset of ideation or attempt was limited. Several sex and race differences emerged.

LIMITATIONS

The sample was ascertained for family history of alcoholism; not all participants had been followed up allowing for censored observations; reporting bias.

CONCLUSION

Suicide attempts are associated with increased likelihood of onset of substance dependence.

A polymorphism in the OPRM1 3'-untranslated region is associated with methadone efficacy in treating opioid dependence

The mu-opioid receptor (MOR) is the primary target of methadone and buprenorphine. The primary neuronal transcript of the OPRM1 gene, MOR-1, contains a ~13kb 3′ untranslated region with five common haplotypes in European-Americans. We analyzed the effects of these haplotypes on the percentage of opioid positive urine tests in European-Americans (n = 582) during a 24-week, randomized, open-label trial of methadone or buprenorphine/naloxone (Suboxone) for the treatment of opioid dependence. A single haplotype, tagged by rs10485058, was significantly associated with patient urinalysis data in the methadone treatment group. Methadone patients with the A/A genotype at rs10485058 were less likely to have opioid-positive urine drug screens than those in the combined A/G and G/G genotypes group (Relative Risk = 0.76, 95% confidence intervals = 0.73–0.80, p = 0.0064). Genotype at rs10485058 also predicted self-reported relapse rates in an independent population of Australian patients of European descent (n = 1215) who were receiving opioid substitution therapy (p = 0.003). In silico analysis predicted that miR-95-3p would interact with the G, but not the A allele of rs10485058. Luciferase assays indicated miR-95-3p decreased reporter activity of constructs containing the G, but not the A allele of rs10485058, suggesting a potential mechanism for the observed pharmacogenetic effect. These findings suggest that selection of a medication for opioid dependence based on rs10485058 genotype might improve outcomes in this ethnic group.

Adolescent cannabis use and repeated voluntary unprotected sex in women

BACKGROUND AND AIMS

Substance use has been implicated in the onset and maintenance of risky sexual behaviors, which have particularly devastating consequences in young women. This study examined whether (i) adolescent onset of cannabis use is associated with repeated voluntary unprotected sex in women and (ii) whether this association persists after accounting for correlated familial influences.

DESIGN

General population sample of female twins.

SETTING

Midwestern United States.

PARTICIPANTS

A total of 2784 sexually active twin women (15.5% African American) aged 18-27 years (assessed 2002-05), including 119 dizygotic (DZ) and 115 monozygotic (MZ) discordant pairs.

MEASUREMENTS

Self-report interview data on cannabis use that first occurred prior to age 17 (27.1%) and repeated voluntary unprotected sex (27.2%). Key covariates included early onset of regular drinking, regular smoking, sexual debut and menstruation as well as conduct disorder symptoms and childhood sexual abuse.

FINDINGS

Compared with never users and those who started using cannabis at a later age, adolescent cannabis users were more likely to report repeated voluntary unprotected sex [odds ratio (OR) = 2.69; 95% confidence interval (CI) = 2.24-3.22]. Genetic (r_g  = 0.57, 95% CI = 0.38-0.87) and non-shared environmental (r_e  = 0.21, 95% CI = 0.02-0.38) factors contributed to the association. After accounting for correlated familial factors, there was a consistent elevation in the likelihood of repeated voluntary unprotected sex in the exposed twin relative to her genetically identical never/late-onset user co-twin (unadjusted OR = 2.25, 95% CI = 1.14-4.44), even after adjustment for covariates (adjusted OR = 2.27, 95% CI = 1.08-4.80).

CONCLUSIONS

Women who start using cannabis during adolescence appear to be more likely to report voluntary engagement in repeated unprotected sex than women who never use cannabis or who initiate cannabis use after adolescence. The results appear to be independent of shared genetic influences.

Association of Specific Traumatic Experiences With Alcohol Initiation and Transitions to Problem Use in European American and African American Women

BACKGROUND

The aims of this study were to (i) characterize racial differences in alcohol involvement and (ii) examine the risk conferred by specific trauma exposures and posttraumatic stress disorder (PTSD) for different stages of alcohol involvement in European American (EA) and African American (AA) women.

METHODS

Data are from the Missouri Adolescent Female Twins Study (N = 3,787, 14.6% AA; mean age at most recent interview = 24.5 [SD 2.8]). Trauma exposures (e.g., sexual abuse [SA], physical abuse [PA], witnessing another person being killed or injured, experiencing an accident, and experiencing a disaster) were modeled as time-varying predictors of alcohol initiation, transition to first alcohol use disorder (AUD) symptom, and transition to AUD diagnosis using Cox proportional hazards regression while taking into account other substance involvement, parental characteristics, and commonly co-occurring psychiatric disorders.

RESULTS

In EA women only, SA was associated with alcohol initiation prior to the age of 14, PA predicted transition from initiation to first AUD symptom, and PA, witnessing injury or death, and SA predicted transition to AUD diagnosis. No association was discovered between trauma exposures or PTSD for any stage of alcohol involvement in AA women.

CONCLUSIONS

Results reveal trauma experiences as important contributors to all stages of alcohol involvement in EA women only, with different trauma types conferring risk for each stage of alcohol involvement. PTSD was not revealed as a significant predictor of AUD in EA or AA women, suggesting trauma, independent of PTSD, directly contributes to alcohol involvement. Findings highlight the importance of considering racial differences when developing etiologic models of the association of traumatic experiences with alcohol involvement.

Childhood sexual abuse and two stages of cigarette smoking in African-American and European-American young women

OBJECTIVE

The aim of the current study was to determine whether the higher rates of childhood sexual abuse (CSA) but lower rates of cigarette smoking in African-American vs. European-American women can be explained in part by a lower magnitude of association between CSA and smoking in African-American women.

METHODS

Data were drawn from a same-sex female twin study of substance use (n=3521; 14.3% African-American). Cox proportional hazards regression analyses using CSA to predict smoking initiation and progression to regular smoking were conducted separately by race/ethnicity. Co-twin status on the smoking outcome was used to adjust for familial influences on smoking (which may overlap with family-level influences on CSA exposure).

RESULTS

After adjusting for co-twin status, CSA was associated with smoking initiation in European Americans (hazard ratio (HR)=1.43, 95% confidence intervals (CI): 1.26-1.62) and with smoking initiation ≤16 in African Americans (HR=1.70, CI: 1.26-2.29). CSA was associated with regular smoking onset ≤15 in European Americans (HR=1.63, CI: 1.21-2.18), with no change in HR after adjusting for co-twin status. In the African-American subsample, the HR for CSA was reduced to non-significance after adjusting for co-twin status (from HR=3.30, CI: 1.23-8.89 to HR=1.16, CI: 0.71-1.92 for regular smoking ≤15).

CONCLUSIONS

CSA is associated with moderate elevation in risk for initiating smoking among African-American and European-American women. By contrast, CSA is associated with elevated risk for (adolescent onset) regular smoking only in European-American women. Furthermore, there is significant overlap between risk conferred by CSA and familial influences on regular smoking in African-American but not European-American women.

Associations between Polygenic Risk for Psychiatric Disorders and Substance Involvement

Despite evidence of substantial comorbidity between psychiatric disorders and substance involvement, the extent to which common genetic factors contribute to their co-occurrence remains understudied. In the current study, we tested for associations between polygenic risk for psychiatric disorders and substance involvement (i.e., ranging from ever-use to severe dependence) among 2573 non-Hispanic European–American participants from the Study of Addiction: Genetics and Environment. Polygenic risk scores (PRS) for cross-disorder psychopathology (CROSS) were generated based on the Psychiatric Genomics Consortium’s Cross-Disorder meta-analysis and then tested for associations with a factor representing general liability to alcohol, cannabis, cocaine, nicotine, and opioid involvement (GENSUB). Follow-up analyses evaluated specific associations between each of the five psychiatric disorders which comprised CROSS—attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (AUT), bipolar disorder (BIP), major depressive disorder (MDD), and schizophrenia (SCZ)—and involvement with each component substance included in GENSUB. CROSS PRS explained 1.10% of variance in GENSUB in our sample (p < 0.001). After correction for multiple testing in our follow-up analyses of polygenic risk for each individual disorder predicting involvement with each component substance, associations remained between: (A) MDD PRS and non-problem cannabis use, (B) MDD PRS and severe cocaine dependence, (C) SCZ PRS and non-problem cannabis use and severe cannabis dependence, and (D) SCZ PRS and severe cocaine dependence. These results suggest that shared covariance from common genetic variation contributes to psychiatric and substance involvement comorbidity.

Outcome Trends after US Military Concussive Traumatic Brain Injury

Care for US military personnel with combat-related concussive traumatic brain injury (TBI) has substantially changed in recent years, yet trends in clinical outcomes remain largely unknown. Our prospective longitudinal studies of US military personnel with concussive TBI from 2008-2013 at Landstuhl Regional Medical Center in Germany and twp sites in Afghanistan provided an opportunity to assess for changes in outcomes over time and analyze correlates of overall disability. We enrolled 321 active-duty US military personnel who sustained concussive TBI in theater and 254 military controls. We prospectively assessed clinical outcomes 6-12 months later in 199 with concussive TBI and 148 controls. Global disability, neurobehavioral impairment, depression severity, and post-traumatic stress disorder (PTSD) severity were worse in concussive TBI groups in comparison with controls in all cohorts. Global disability primarily reflected a combination of work-related and nonwork-related disability. There was a modest but statistically significant trend toward less PTSD in later cohorts. Specifically, there was a decrease of 5.9 points of 136 possible on the Clinician Administered PTSD Scale (-4.3%) per year (95% confidence interval, 2.8-9.0 points, p = 0.0037 linear regression, p = 0.03 including covariates in generalized linear model). No other significant trends in outcomes were found. Global disability was more common in those with TBI, those evacuated from theater, and those with more severe depression and PTSD. Disability was not significantly related to neuropsychological performance, age, education, self-reported sleep deprivation, injury mechanism, or date of enrollment. Thus, across multiple cohorts of US military personnel with combat-related concussion, 6-12 month outcomes have improved only modestly and are often poor. Future focus on early depression and PTSD after concussive TBI appears warranted. Adverse outcomes are incompletely explained, however, and additional studies with prospective collection of data on acute injury severity and polytrauma, as well as reduced attrition before follow-up will be required to fully address the root causes of persistent disability after wartime injury.

The association of specific traumatic experiences with cannabis initiation and transition to problem use: Differences between African-American and European-American women

INTRODUCTION

To examine the contribution of trauma exposure to cannabis initiation and transition to first cannabis use disorder (CUD) symptom in African-American (AA) and European-American (EA) emerging adults.

METHODS

Data are from the Missouri Adolescent Female Twins Study [(N=3787); 14.6% AA; mean age=21.7 (SD 3.8)]. Trauma exposures (e.g. sexual abuse, physical abuse, witnessing another person being killed or injured, experiencing an accident, and experiencing a disaster) were modeled as time-varying predictors of cannabis initiation and transition to CUD symptom using Cox proportional hazards regression. Other substance involvement and psychiatric disorders were considered as time-varying covariates.

RESULTS

Analyses revealed different trauma-related and psychiatric predictors for cannabis use supporting racially distinct etiologic models of cannabis involvement. For AA women, history of witnessing injury/death or experiencing a life-threatening accident was associated with cannabis initiation across the complete emerging adult risk period while sexual abuse predicted cannabis initiation only before 15 years old. For EA women, history of sexual or physical abuse and major depressive disorder (MDD) predicted cannabis initiation and physical abuse and MDD predicted transition from initiation to first CUD symptom. No association was discovered between trauma exposures and transition to first CUD symptom in AA women.

CONCLUSIONS

Results reveal trauma exposures as important contributors to cannabis initiation and to a lesser extent transition to CUD symptom, with different trauma types conferring risk for cannabis involvement in AA and EA women. Findings suggest the importance of considering racial/ethnic differences when developing etiologic models of cannabis involvement.

The variance shared across forms of childhood trauma is strongly associated with liability for psychiatric and substance use disorders

INTRODUCTION

Forms of childhood trauma tend to co-occur and are associated with increased risk for psychiatric and substance use disorders. Commonly used binary measures of trauma exposure have substantial limitations.

METHODS

We performed multigroup confirmatory factor analysis (CFA), separately by sex, using data from the Childhood Trauma (CT) Study's sample of twins and siblings (N = 2594) to derive three first-order factors (childhood physical abuse, childhood sexual abuse, and parental partner abuse) and, as hypothesized, one higher order, childhood trauma factor (CTF) representing a measure of their common variance.

RESULTS

CFA produced a good-fitting model in the CT Study; we replicated the model in the Comorbidity and Trauma (CAT) Study's sample (N = 1981) of opioid-dependent cases and controls. In both samples, first-order factors are moderately correlated (indicating they measure largely unique, but related constructs) and their loadings on the CTF suggest it provides a reasonable measure of their common variance. We examined the association of CTF score with risk for psychiatric and substance use disorders in these samples and the OZ-ALC GWAS sample (N = 1538) in which CT Study factor loadings were applied. We found that CTF scores are strongly associated with liability for psychiatric and substance use disorders in all three samples; estimates of risk are extremely consistent across samples.

CONCLUSIONS

The CTF is a continuous, robust measure that captures the common variance across forms of childhood trauma and provides a means to estimate shared liability while avoiding multicollinearity.

The role of conduct disorder in the relationship between alcohol, nicotine and cannabis use disorders

BACKGROUND

Genetic influences contribute significantly to co-morbidity between conduct disorder and substance use disorders. Estimating the extent of overlap can assist in the development of phenotypes for genomic analyses.

METHOD

Multivariate quantitative genetic analyses were conducted using data from 9577 individuals, including 3982 complete twin pairs and 1613 individuals whose co-twin was not interviewed (aged 24-37 years) from two Australian twin samples. Analyses examined the genetic correlation between alcohol dependence, nicotine dependence and cannabis abuse/dependence and the extent to which the correlations were attributable to genetic influences shared with conduct disorder.

RESULTS

Additive genetic (a(2) = 0.48-0.65) and non-shared environmental factors explained variance in substance use disorders. Familial effects on conduct disorder were due to additive genetic (a(2) = 0.39) and shared environmental (c(2) = 0.15) factors. All substance use disorders were influenced by shared genetic factors (rg = 0.38-0.56), with all genetic overlap between substances attributable to genetic influences shared with conduct disorder. Genes influencing individual substance use disorders were also significant, explaining 40-73% of the genetic variance per substance.

CONCLUSIONS

Among substance users in this sample, the well-documented clinical co-morbidity between conduct disorder and substance use disorders is primarily attributable to shared genetic liability. Interventions targeted at generally reducing deviant behaviors may address the risk posed by this shared genetic liability. However, there is also evidence for genetic and environmental influences specific to each substance. The identification of these substance-specific risk factors (as well as potential protective factors) is critical to the future development of targeted treatment protocols.

Hepatitis C testing and status among opioid substitution treatment clients in New South Wales

BACKGROUND

In Australia about half of the people who inject drugs (PWID) are hepatitis C (HCV) antibody positive (anti-HCV+). The prevalence among opioid substitution treatment (OST) clients specifically is unclear, despite OST clinics being a potential setting for HCV care. This study aimed to report the prevalence of HCV among a large sample of NSW OST clients, understand whether HCV testing is translating into knowledge of status, and identify the correlates of inaccurate self-reporting of HCV status.

METHODS

Participants completed an interview that included self-reported HCV status. Participants also provided a blood sample that was tested for HCV IgG antibodies, and for viral load using a quantitative real-time reverse-transcriptase polymerase chain reaction. Valid interviews and viable blood sample were provided by 1,484 participants. Logistic regression modelling was used to identify independent predictors of knowledge of HCV antibody status.

RESULTS

Overall, 84% of participants were anti-HCV+. Of these, 65% were RNA+. Four per cent of anti-HCV negative participants were RNA+. One-quarter of anti-HCV+ participants did not know their status or reported it incorrectly, compared with 14.5% of anti-HCV negative participants.

CONCLUSION

The prevalence of HCV in this sample was higher than that found among other samples of people who inject drugs, suggesting the need for greater prevention efforts with OST clients. Anti-HCV+ individuals are less accurate at reporting their HCV status than those who are anti-HCV-. Inaccurate knowledge is associated with different variables for anti-HCV+ vs. anti-HCV- individuals. There are opportunities to improve knowledge of HCV status and to therefore improve health outcomes and reduce transmission among this at-risk population.

Monoacylglycerol lipase (MGLL) polymorphism rs604300 interacts with childhood adversity to predict cannabis dependence symptoms and amygdala habituation: Evidence from an endocannabinoid system-level analysis

Despite evidence for heritable variation in cannabis involvement and the discovery of cannabinoid receptors and their endogenous ligands, no consistent patterns have emerged from candidate endocannabinoid (eCB) genetic association studies of cannabis involvement. Given interactions between eCB and stress systems and associations between childhood stress and cannabis involvement, it may be important to consider childhood adversity in the context of eCB-related genetic variation. We employed a system-level gene-based analysis of data from the Comorbidity and Trauma Study (N = 1,558) to examine whether genetic variation in six eCB genes (anabolism: DAGLA, DAGLB, NAPEPLD; catabolism: MGLL, FAAH; binding: CNR1; SNPs N = 65) and childhood sexual abuse (CSA) predict cannabis dependence symptoms. Significant interactions with CSA emerged for MGLL at the gene level (p = .009), and for rs604300 within MGLL (ΔR2 = .007, p < .001), the latter of which survived SNP-level Bonferroni correction and was significant in an additional sample with similar directional effects (N = 859; ΔR2 = .005, p = .026). Furthermore, in a third sample (N = 312), there was evidence that rs604300 genotype interacts with early life adversity to predict threat-related basolateral amygdala habituation, a neural phenotype linked to the eCB system and addiction (ΔR2 = .013, p = .047). Rs604300 may be related to epigenetic modulation of MGLL expression. These results are consistent with rodent models implicating 2-arachidonoylglycerol (2-AG), an endogenous cannabinoid metabolized by the enzyme encoded by MGLL, in the etiology of stress adaptation related to cannabis dependence, but require further replication.

Early onset alcohol use and self-harm: a discordant twin analysis

BACKGROUND

Self-harm has considerable societal and economic costs and has been extensively studied in relation to alcohol involvement. Although early onset alcohol use (EAU) has been causally linked to maladaptive clinical outcomes, its association with self-harm is less well characterized. This study aimed to further examine the link between EAU and both nonsuicidal self-injury (NSSI) and suicide attempt (SA), and elucidate shared familial and causal/individual-specific pathways that explain this co-occurrence.

METHODS

Using data from 6,082 Australian same-sex twin pairs (1,732 monozygotic [MZ] and 1,309 dizygotic [DZ]), ages 23 to 40, we examined prevalence rates of NSSI and SA among twin pairs concordant and discordant for EAU. Conditional logistic regression, controlling for early clinical covariates and the influence of zygosity on EAU, was used to examine the odds ratio (OR) of self-harm within twin pairs discordant for EAU.

RESULTS

Prevalence rates of both NSSI and SA were highest among twin pairs concordant for EAU and for twins who reported EAU within discordant twin pairs. Results from discordant twin analyses revealed nearly 4-fold increased odds of SA for the twin who endorsed EAU, and this OR was equal across MZ and DZ twins. EAU also was associated with elevated odds of NSSI (OR = 7.62), although this was only the case for DZ twins in discordant pairs.

CONCLUSIONS

The equivalent increase in odds of SA for both MZ and DZ twins suggests that causal or individual-specific influences explain the link between EAU and SA. For NSSI, elevated odds for DZ twins and nonsignificant findings for MZ twins implicate correlated genetic factors in the association between EAU and NSSI. Future studies should test mechanisms through which EAU may causally influence SA, as well as examine whether genetic risk for third variables (e.g., negative urgency, stress reactivity) may explain the genetic overlap between EAU and NSSI.

Cis-Expression Quantitative Trait Loci Mapping Reveals Replicable Associations with Heroin Addiction in OPRM1

BACKGROUND

No opioid receptor, mu 1 (OPRM1) gene polymorphisms, including the functional single nucleotide polymorphism (SNP) rs1799971, have been conclusively associated with heroin/other opioid addiction, despite their biological plausibility. We used evidence of polymorphisms altering OPRM1 expression in normal human brain tissue to nominate and then test associations with heroin addiction.

METHODS

We tested 103 OPRM1 SNPs for association with OPRM1 messenger RNA expression in prefrontal cortex from 224 European Americans and African Americans of the BrainCloud cohort. We then tested the 16 putative cis-expression quantitative trait loci (cis-eQTL) SNPs for association with heroin addiction in the Urban Health Study and two replication cohorts, totaling 16,729 European Americans, African Americans, and Australians of European ancestry.

RESULTS

Four putative cis-eQTL SNPs were significantly associated with heroin addiction in the Urban Health Study (smallest p = 8.9 × 10(-5)): rs9478495, rs3778150, rs9384169, and rs562859. Rs3778150, located in OPRM1 intron 1, was significantly replicated (p = 6.3 × 10(-5)). Meta-analysis across all case-control cohorts resulted in p = 4.3 × 10(-8): the rs3778150-C allele (frequency = 16%-19%) being associated with increased heroin addiction risk. Importantly, the functional SNP allele rs1799971-A was associated with heroin addiction only in the presence of rs3778150-C (p = 1.48 × 10(-6) for rs1799971-A/rs3778150-C and p = .79 for rs1799971-A/rs3778150-T haplotypes). Lastly, replication was observed for six other intron 1 SNPs that had prior suggestive associations with heroin addiction (smallest p = 2.7 × 10(-8) for rs3823010).

CONCLUSIONS

Our findings show that common OPRM1 intron 1 SNPs have replicable associations with heroin addiction. The haplotype structure of rs3778150 and nearby SNPs may underlie the inconsistent associations between rs1799971 and heroin addiction.

The association between speed of transition from initiation to subsequent use of cannabis and later problematic cannabis use, abuse and dependence

AIMS

To test whether speed of transition from initiation use to subsequent use of cannabis is associated with likelihood of later cannabis dependence and other outcomes, and whether transition speed is attributable to genetic or environmental factors.

DESIGN

Cross-sectional interview study.

SETTING

Australia.

PARTICIPANTS

A total of 2239 twins and siblings who reported using cannabis at least twice [mean age at time of survey = 32.0, 95% confidence interval (CI) = 31.9 - 32.1, range = 22-45].

MEASUREMENTS

Time between initiation and subsequent cannabis use (within 1 week; within 3 months; between 3 and 12 months; more than 1 year later), later use of cannabis and symptoms of DSM-IV cannabis abuse/dependence. Multinomial regression analyses (comparison group: more than 1 year later) adjusted the association between speed of transition and the outcomes of cannabis daily use, abuse/dependence and treatment-seeking after controlling for socio-demographic, childhood, mental health, peer and licit drug factors. Twin modelling estimated the proportion of variance in transition speed attributable to genetic (A), common environment (C) and unique environmental (E) factors.

FINDINGS

Subsequent use of cannabis within 1 week of initiation was associated with daily use [odds ratio (OR) = 2.64, 95% CI = 1.75-3.99], abuse and/or dependence (OR = 3.25, 95% CI = 2.31-4.56) and treatment-seeking for cannabis problems (OR = 1.89, 95% CI = 1.03-3.46). Subsequent use within 3 months was associated with abuse and/or dependence (OR = 1.61, 95% CI = 1.18-2.19). The majority of the variation of the speed of transition was accounted for by unique environment factors (0.75).

CONCLUSIONS

Rapid transition from initiation to subsequent use of cannabis is associated with increased likelihood of subsequent daily cannabis use and abuse/dependence.

Associations between body mass index, post-traumatic stress disorder, and child maltreatment in young women

The objective of this study was to examine interrelationships between child maltreatment, post-traumatic stress disorder (PTSD) and body mass index (BMI) in young women. We used multinomial logistic regression models to explore the possibility that PTSD statistically mediates or moderates the association between BMI category and self-reported childhood sexual abuse (CSA), physical abuse (CPA), or neglect among 3,699 young women participating in a population-based twin study. Obese women had the highest prevalence of CSA, CPA, neglect, and PTSD (p<.001 for all). Although all three forms of child maltreatment were significantly, positively associated with overweight and obesity in unadjusted models, only CSA was significantly associated with obesity after adjusting for other forms of maltreatment and covariates (OR=2.21, 95% CI: 1.63, 3.00). CSA and neglect, but not CPA, were associated with underweight in unadjusted models; however, after adjusting for other forms of maltreatment and covariates, the associations were no longer statistically significant (OR=1.43, 95% CI: 0.90-2.28 and OR=2.16, 95% CI: 0.90-5.16 for CSA and neglect, respectively). Further adjustment for PTSD generally resulted in modest attenuation of effects across associations of child maltreatment forms with BMI categories, suggesting that PTSD may, at most, be only a weak partial mediator of these associations. Future longitudinal studies are needed to elucidate the mechanisms linking CSA and obesity and to further evaluate the role of PTSD in associations between child maltreatment and obesity.

Trait-based assessment of borderline personality disorder using the NEO Five-Factor Inventory: Phenotypic and genetic support

[Correction Notice: An Erratum for this article was reported in Vol 28(1) of Psychological Assessment (see record 2015-54029-001). The FFI-BPD values for Sample 3 in Table 2 should read 1.42 (0.44), 0.83.] The aim of the current study was to examine the reliability and validity of a trait-based assessment of borderline personality disorder (BPD) using the NEO Five-Factor Inventory. Correlations between the Five-Factor Inventory-BPD composite (FFI-BPD) and explicit measures of BPD were examined across 6 samples, including undergraduate, community, and clinical samples. The median correlation was .60, which was nearly identical to the correlation between measures of BPD and a BPD composite generated from the full Revised NEO Personality Inventory (i.e., NEO-BPD; r = .61). Correlations between FFI-BPD and relevant measures of psychiatric symptomatology and etiology (e.g., childhood abuse, drug use, depression, and personality disorders) were also examined and compared to those generated using explicit measures of BPD and NEO-BPD. As expected, the FFI-BPD composite correlated most strongly with measures associated with high levels of Neuroticism, such as depression, anxiety, and emotion dysregulation, and the pattern of correlations generated using the FFI-BPD was highly similar to those generated using explicit measures of BPD and NEO-BPD. Finally, genetic analyses estimated that FFI-BPD is 44% heritable, which is comparable to meta-analytic research examining genetics associated with BPD, and revealed that 71% of the genetic influences are shared between FFI-BPD and a self-report measure assessing BPD (Personality Assessment Inventory-Borderline subscale; Morey, 1991). Generally, these results support the use of FFI-BPD as a reasonable proxy for BPD, which has considerable implications, particularly for potential gene-finding efforts in large, epidemiological datasets that include the NEO FFI.

Acute post-traumatic stress symptoms and age predict outcome in military blast concussion

High rates of adverse outcomes have been reported following blast-related concussive traumatic brain injury in US military personnel, but the extent to which such adverse outcomes can be predicted acutely after injury is unknown. We performed a prospective, observational study of US military personnel with blast-related concussive traumatic brain injury (n = 38) and controls (n = 34) enrolled between March and September 2012. Importantly all subjects returned to duty and did not require evacuation. Subjects were evaluated acutely 0-7 days after injury at two sites in Afghanistan and again 6-12 months later in the United States. Acute assessments revealed heightened post-concussive, post-traumatic stress, and depressive symptoms along with worse cognitive performance in subjects with traumatic brain injury. At 6-12 months follow-up, 63% of subjects with traumatic brain injury and 20% of controls had moderate overall disability. Subjects with traumatic brain injury showed more severe neurobehavioural, post-traumatic stress and depression symptoms along with more frequent cognitive performance deficits and more substantial headache impairment than control subjects. Logistic regression modelling using only acute measures identified that a diagnosis of traumatic brain injury, older age, and more severe post-traumatic stress symptoms provided a good prediction of later adverse global outcomes (area under the receiver-operating characteristic curve = 0.84). Thus, US military personnel with concussive blast-related traumatic brain injury in Afghanistan who returned to duty still fared quite poorly on many clinical outcome measures 6-12 months after injury. Poor global outcome seems to be largely driven by psychological health measures, age, and traumatic brain injury status. The effects of early interventions and longer term implications of these findings are unknown.

Seasonality shows evidence for polygenic architecture and genetic correlation with schizophrenia and bipolar disorder

OBJECTIVE

To test common genetic variants for association with seasonality (seasonal changes in mood and behavior) and to investigate whether there are shared genetic risk factors between psychiatric disorders and seasonality.

METHOD

Genome-wide association studies (GWASs) were conducted in Australian (between 1988 and 1990 and between 2010 and 2013) and Amish (between May 2010 and December 2011) samples in whom the Seasonal Pattern Assessment Questionnaire (SPAQ) had been administered, and the results were meta-analyzed in a total sample of 4,156 individuals. Genetic risk scores based on results from prior large GWAS studies of bipolar disorder, major depressive disorder (MDD), and schizophrenia were calculated to test for overlap in risk between psychiatric disorders and seasonality.

RESULTS

The most significant association was with rs11825064 (P = 1.7 × 10⁻⁶, β = 0.64, standard error = 0.13), an intergenic single nucleotide polymorphism (SNP) found on chromosome 11. The evidence for overlap in risk factors was strongest for schizophrenia and seasonality, with the schizophrenia genetic profile scores explaining 3% of the variance in log-transformed global seasonality scores. Bipolar disorder genetic profile scores were also associated with seasonality, although at much weaker levels (minimum P value = 3.4 × 10⁻³), and no evidence for overlap in risk was detected between MDD and seasonality.

CONCLUSIONS

Common SNPs of large effect most likely do not exist for seasonality in the populations examined. As expected, there were overlapping genetic risk factors for bipolar disorder (but not MDD) with seasonality. Unexpectedly, the risk for schizophrenia and seasonality had the largest overlap, an unprecedented finding that requires replication in other populations and has potential clinical implications considering overlapping cognitive deficits in seasonal affective disorders and schizophrenia.

Prospectively assessed clinical outcomes in concussive blast vs nonblast traumatic brain injury among evacuated US military personnel

IMPORTANCE

Blast injury has been identified as the signature injury in the conflicts in Iraq and Afghanistan. However it remains to be determined whether fundamental differences may exist between blast-related traumatic brain injury (TBI) and TBI due to other mechanisms.

OBJECTIVES

To determine similarities and differences between clinical outcomes in US military personnel with blast-related vs. non-blast-related concussive TBI and to identify the specific domains of impairment that best correlate with overall disability.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study involving active duty US Military personnel evacuated from Iraq or Afghanistan to Landstuhl Regional Medical Center, in Landstuhl, Germany. Four groups of participants were enrolled from 2010 to 2013: (1) blast plus impact complex TBI (n=53), (2) non-blast related TBI with injury due to other mechanisms (n=29), (3) blast-exposed controls evacuated for other medical reasons (n=27) (4) non-blast-exposed controls evacuated for other medical reasons (n=69). All patients with TBI met Department of Defense criteria for concussive (mild) TBI. The study participants were evaluated 6-12 months after injury at Washington University in St Louis. In total, 255 subjects were enrolled in the study, and 183 participated in follow-up evaluations, 5 of whom were disqualified.

MAIN OUTCOMES AND MEASURES

In-person clinical examinations included evaluation for overall disability, a standardized neurological exam, headache questionnaires, neuropsychological test battery, combat exposure and alcohol use surveys, and structured interview evaluations for post-traumatic stress disorder (PTSD) and depression.

RESULTS

Global outcomes, headache severity, neuropsychological performance, and surprisingly even PTSD severity and depression were indistinguishable between the two TBI groups, independent of mechanism of injury. Both TBI groups had higher rates of moderate to severe overall disability than the respective control groups: 41/53 (77%) of blast plus impact TBI and 23/29 (79%) of nonblast TBI vs. 16/27 (59%) of blast-exposed controls and 28/69 (41%) of non-blast-exposed controls. In addition, blast-exposed controls had worse headaches and more severe PTSD than non-blast-exposed controls. Self-reported combat exposure intensity was higher in the blast plus impact TBI group than in nonblast TBI group and was higher in blast-exposed controls than in non-blast-exposed controls. However, combat exposure intensity did not correlate with PTSD severity in the TBI groups, but a modest positive correlation was observed in the controls. Overall outcomes were most strongly correlated with depression, headache severity, and number of abnormalities on neuropsychological testing. However a substantial fraction of the variance in overall outcome was not explained by any of the assessed measures.

CONCLUSIONS AND RELEVANCE

One potential interpretation of these results is that TBI itself, independent of injury mechanism and combat exposure intensity, is a primary driver of adverse outcomes. Many other important factors may be as yet unmeasured, and adverse outcomes following war-time injuries are difficult to fully explain.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01313130.

Human mate selection and addiction: a conceptual critique

The authors review past work on modeling human mate selection, and suggest, using illustrations from existing literature on the impact of alcoholism on relationship formation and dissolution and reproduction, that the challenges of adequately characterizing human mate selection have not yet been overcome. Some paths forwards are suggested.

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

Posttraumatic stress disorder (PTSD), a pathologic response to severe stress, is a common co-morbid disorder in substance-dependent individuals. Evidence from twin studies suggests that PTSD is moderately heritable. Genetic association studies to date have reported a limited number of replicated findings. We conducted a candidate gene association study in trauma-exposed individuals within the Comorbidity and Trauma Study's sample (1343 heroin-dependent cases and 406 controls from economically disadvantaged neighborhoods). After data cleaning, the 1430 single nucleotide polymorphisms (SNPs) retained for analyses provided coverage of 72 candidate genes and included additional SNPs for which association was previously reported as well as 30 ancestry-informative markers. We found a functional DRD2 promoter polymorphism (rs12364283) to be most highly associated with PTSD liability [odds ratio (OR) 1.65 (1.27-2.15); P = 1.58 × 10(-4) ]; however, this association was not significant, with a stringent Bonferroni correction for multiple comparisons. The top hits include SNPs from other dopaminergic system genes: DRD2 DRD3, TH and DBH. Additional analyses revealed that the association involving rs12364283 is largely limited to amphetamine-dependent individuals. Substantial risk is observed in amphetamine-dependent individuals, with at least one copy of this SNP [OR 2.86 (1.92-4.27); P = 2.6 × 10(-7) ]. Further analyses do not support extensive mediation of PTSD risk via self-reported impulsivity (BIS total score). These findings suggest roles for impairment in inhibitory control in the pathophysiology of PTSD and raise questions about stimulant use in certain populations (e.g. those in combat).

Functional status after blast-plus-impact complex concussive traumatic brain injury in evacuated United States military personnel

Fundamental questions remain unanswered about the longitudinal impact of blast-plus-impact complex traumatic brain injuries (TBI) from wars in Iraq and Afghanistan. This prospective, observational study investigated measures of clinical outcome in US military personnel evacuated to Landstuhl Regional Medical Center (LRMC) in Germany after such "blast-plus" concussive TBIs. Glasgow Outcome Scale-Extended assessments completed 6-12 months after injury indicated a moderate overall disability in 41/47 (87%) blast-plus TBI subjects and a substantial but smaller number (11/18, 61%, p=0.018) of demographically similar US military controls without TBI evacuated for other medical reasons. Cognitive function assessed with a neuropsychological test battery was not different between blast-plus TBI subjects and controls; performance of both groups was generally in the normal range. No subject was found to have focal neurological deficits. However, 29/47 (57%) of blast-plus subjects with TBI met all criteria for post-traumatic stress disorder (PTSD) versus 5/18 (28%) of controls (p=0.014). PTSD was highly associated with overall disability; 31/34 patients with PTSD versus 19/31 patients who did not meet full PTSD criteria had moderate to severe disability (p=0.0003). Symptoms of depression were also more severe in the TBI group (p=0.05), and highly correlated with PTSD severity (r=0.86, p<0.0001). Thus, in summary, high rates of PTSD and depression but not cognitive impairment or focal neurological deficits were observed 6-12 months after concussive blast-plus-impact complex TBI. Overall disability was substantially greater than typically reported in civilian non-blast concussive ("mild") patients with TBI, even with polytrauma. The relationship between these clinical outcomes and specific blast-related aspects of brain injuries versus other combat-related factors remains unknown.

Association of OPRD1 polymorphisms with heroin dependence in a large case-control series

Genes encoding the opioid receptors (OPRM1, OPRD1 and OPRK1) are obvious candidates for involvement in risk for heroin dependence. Prior association studies commonly had samples of modest size, included limited single nucleotide polymorphism (SNP) coverage of these genes and yielded inconsistent results. Participants for the current investigation included 1459 heroin-dependent cases ascertained from maintenance clinics in New South Wales, Australia, 1495 unrelated individuals selected from an Australian sample of twins and siblings as not meeting DSM-IV criteria for lifetime alcohol or illicit drug dependence (non-dependent controls) and 531 controls ascertained from economically disadvantaged neighborhoods in proximity to the maintenance clinics. A total of 136 OPRM1, OPRD1 and OPRK1 SNPs were genotyped in this sample. After controlling for admixture with principal components analysis, our comparison of cases to non-dependent controls found four OPRD1 SNPs in fairly high linkage disequilibrium for which adjusted P values remained significant (e.g. rs2236857; OR 1.25; P=2.95×10(-4) ) replicating a previously reported association. A post hoc analysis revealed that the two SNP (rs2236857 and rs581111) GA haplotype in OPRD1 is associated with greater risk (OR 1.68; P=1.41×10(-5) ). No OPRM1 or OPRK1 SNPs reached more than nominal significance. Comparisons of cases to neighborhood controls reached only nominal significance. Our results replicate a prior report providing strong evidence implicating OPRD1 SNPs and, in particular, the two SNP (rs2236857 and rs581111) GA haplotype in liability for heroin dependence. Support was not found for similar association involving either OPRM1 or OPRK1 SNPs.