Inhibitory control in siblings discordant for exposure to maternal smoking during pregnancy

Maternal smoking during pregnancy (SDP) has been linked to poorer offspring executive function across development, but SDP does not occur independent of other familial risk factors. As such, poor and inconsistent control for potential confounds, notably shared familial (i.e., genetic and environmental) confounds, preclude concluding causal effects of SDP on child outcomes. We examined the within-family association between SDP and one component of executive function, inhibitory control, in a sample of families (N = 173) specifically selected for sibling pairs discordant for exposure to SDP. Thus, the present study examines if the SDP-inhibitory control association withstands rigorous control for potential child and familial confounds. 79% of the variation in child inhibitory control was attributable to within-family differences and 21% was attributable to differences between families, indicating that the variability in inhibitory control was primarily a function of differences between siblings rather than differences across families. Further, the association between SDP and inhibitory control was fully attenuated when confounds were considered. These findings suggest that co-occurring vulnerabilities act as more salient risk factors for poorer child inhibitory control than SDP and may serve as effective targets of interventions seeking to improve children's inhibitory control in families with nicotine dependent mothers. (PsycINFO Database Record

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.

An Analysis of Two Genome-wide Association Meta-analyses Identifies a New Locus for Broad Depression Phenotype

BACKGROUND

The genetics of depression has been explored in genome-wide association studies that focused on either major depressive disorder or depressive symptoms with mostly negative findings. A broad depression phenotype including both phenotypes has not been tested previously using a genome-wide association approach. We aimed to identify genetic polymorphisms significantly associated with a broad phenotype from depressive symptoms to major depressive disorder.

METHODS

We analyzed two prior studies of 70,017 participants of European ancestry from general and clinical populations in the discovery stage. We performed a replication meta-analysis of 28,328 participants. Single nucleotide polymorphism (SNP)-based heritability and genetic correlations were calculated using linkage disequilibrium score regression. Discovery and replication analyses were performed using a p-value-based meta-analysis. Lifetime major depressive disorder and depressive symptom scores were used as the outcome measures.

RESULTS

The SNP-based heritability of major depressive disorder was 0.21 (SE = 0.02), the SNP-based heritability of depressive symptoms was 0.04 (SE = 0.01), and their genetic correlation was 1.001 (SE = 0.2). We found one genome-wide significant locus related to the broad depression phenotype (rs9825823, chromosome 3: 61,082,153, p = 8.2 × 10^-9) located in an intron of the FHIT gene. We replicated this SNP in independent samples (p = .02) and the overall meta-analysis of the discovery and replication cohorts (1.0 × 10^-9).

CONCLUSIONS

This large study identified a new locus for depression. Our results support a continuum between depressive symptoms and major depressive disorder. A phenotypically more inclusive approach may help to achieve the large sample sizes needed to detect susceptibility loci for depression.

Single Motherhood, Alcohol Dependence, and Smoking During Pregnancy: A Propensity Score Analysis

OBJECTIVE

Few studies linking single motherhood and maternal smoking during pregnancy consider correlated risk from problem substance use beyond history of smoking and concurrent use of alcohol. In the present study, we used propensity score methods to examine whether the risk of smoking during pregnancy associated with single motherhood is the result of potential confounders, including alcohol dependence.

METHOD

Data were drawn from mothers participating in a birth cohort study of their female like-sex twin offspring (n = 257 African ancestry; n = 1,711 European or other ancestry). We conducted standard logistic regression models predicting smoking during pregnancy from single motherhood at twins' birth, followed by propensity score analyses comparing single-mother and two-parent families stratified by predicted probability of single motherhood.

RESULTS

In standard models, single motherhood predicted increased risk of smoking during pregnancy in European ancestry but not African ancestry families. In propensity score analyses, rates of smoking during pregnancy were elevated in single-mother relative to two-parent European ancestry families across much of the spectrum a priori risk of single motherhood. Among African ancestry families, within-strata comparisons of smoking during pregnancy by single-mother status were nonsignificant.

CONCLUSIONS

These findings highlight single motherhood as a unique risk factor for smoking during pregnancy in European ancestry mothers, over and above alcohol dependence. Additional research is needed to identify risks, beyond single motherhood, associated with smoking during pregnancy in African ancestry mothers.

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.

The Influence of Paternal Separation, Paternal History of Alcohol Use Disorder Risk, and Early Substance Use on Offspring Educational Attainment by Young Adulthood

OBJECTIVE

This study aimed to determine the associations among paternal alcohol problems, separation, and educational attainment in European American and African American offspring and whether offspring early alcohol/tobacco/marijuana use influenced these associations.

METHOD

Families with offspring ages 13-19 years at intake were selected from state birth records and screened by telephone to determine high-risk or low-risk status (with/without paternal heavy drinking). Families of men with two or more driving-under-the-influence offenses were added as a very-high-risk group. Data from 340 African American and 288 European American offspring who were not enrolled in school at their last interview were analyzed. Educational attainment was modeled as less than high school, high school only (reference category), and some college or higher. Separation was defined as offspring report of not having lived continuously in the same household with their biological father from birth to age 14. Analyses were stratified by race.

RESULTS

In European Americans, neither family risk status nor early alcohol/tobacco/marijuana use was associated with educational outcomes. However, paternal separation significantly elevated the likelihood of not completing high school in all models (relative risk ratios [RRRs] = 6.0-8.1, p <.001). For African American offspring, likelihoods of high school noncompletion were elevated marginally for paternal separation in only one model, but significantly for early marijuana use (RRRs = 2.8-3.2, p < .05). Very-high-risk status significantly reduced the likelihood of post-high school education in an adjusted model (RRR = 0.4, p < .05).

CONCLUSIONS

High school noncompletion was significantly associated with paternal separation in European Americans and with early marijuana use in African American offspring. In addition, very-high-risk status reduced the likelihood of post-high school education in African American offspring only, suggesting that research with ethnically diverse samples yields important differences when examining outcomes of both separation and substance use on offspring education.

Genomewide Association Study of Alcohol Dependence Identifies Risk Loci Altering Ethanol-Response Behaviors in Model Organisms

BACKGROUND

Alcohol dependence (AD) shows evidence for genetic liability, but genes influencing risk remain largely unidentified.

METHODS

We conducted a genomewide association study in 706 related AD cases and 1,748 unscreened population controls from Ireland. We sought replication in 15,496 samples of European descent. We used model organisms (MOs) to assess the role of orthologous genes in ethanol (EtOH)-response behaviors. We tested 1 primate-specific gene for expression differences in case/control postmortem brain tissue.

RESULTS

We detected significant association in COL6A3 and suggestive association in 2 previously implicated loci, KLF12 and RYR3. None of these signals are significant in replication. A suggestive signal in the long noncoding RNA LOC339975 is significant in case:control meta-analysis, but not in a population sample. Knockdown of a COL6A3 ortholog in Caenorhabditis elegans reduced EtOH sensitivity. Col6a3 expression correlated with handling-induced convulsions in mice. Loss of function of the KLF12 ortholog in C. elegans impaired development of acute functional tolerance (AFT). Klf12 expression correlated with locomotor activation following EtOH injection in mice. Loss of function of the RYR3 ortholog reduced EtOH sensitivity in C. elegans and rapid tolerance in Drosophila. The ryanodine receptor antagonist dantrolene reduced motivation to self-administer EtOH in rats. Expression of LOC339975 does not differ between cases and controls but is reduced in carriers of the associated rs11726136 allele in nucleus accumbens (NAc).

CONCLUSIONS

We detect association between AD and COL6A3, KLF12, RYR3, and LOC339975. Despite nonreplication of COL6A3, KLF12, and RYR3 signals, orthologs of these genes influence behavioral response to EtOH in MOs, suggesting potential involvement in human EtOH response and AD liability. The associated LOC339975 allele may influence gene expression in human NAc. Although the functions of long noncoding RNAs are poorly understood, there is mounting evidence implicating these genes in multiple brain functions and disorders.

Heritability of brain activity related to response inhibition: A longitudinal genetic study in adolescent twins

The ability to inhibit prepotent but context- or goal-inappropriate responses is essential for adaptive self-regulation of behavior. Deficits in response inhibition, a key component of impulsivity, have been implicated as a core dysfunction in a range of neuropsychiatric disorders such as ADHD and addictions. Identification of genetically transmitted variation in the neural underpinnings of response inhibition can help to elucidate etiological pathways to these disorders and establish the links between genes, brain, and behavior. However, little is known about genetic influences on the neural mechanisms of response inhibition during adolescence, a developmental period characterized by weak self-regulation of behavior. Here we investigated heritability of ERPs elicited in a Go/No-Go task in a large sample of adolescent twins assessed longitudinally at ages 12, 14, and 16. Genetic analyses showed significant heritability of inhibition-related frontal N2 and P3 components at all three ages, with 50 to 60% of inter-individual variability being attributable to genetic factors. These genetic influences included both common genetic factors active at different ages and novel genetic influences emerging during development. Finally, individual differences in the rate of developmental changes from age 12 to age 16 were significantly influenced by genetic factors. In conclusion, the present study provides the first evidence for genetic influences on neural correlates of response inhibition during adolescence and suggests that ERPs elicited in the Go/No-Go task can serve as intermediate neurophysiological phenotypes (endophenotypes) for the study of disinhibition and impulse control disorders.

Genome-wide meta-analysis of 241,258 adults accounting for smoking behaviour identifies novel loci for obesity traits

Few genome-wide association studies (GWAS) account for environmental exposures, like smoking, potentially impacting the overall trait variance when investigating the genetic contribution to obesity-related traits. Here, we use GWAS data from 51,080 current smokers and 190,178 nonsmokers (87% European descent) to identify loci influencing BMI and central adiposity, measured as waist circumference and waist-to-hip ratio both adjusted for BMI. We identify 23 novel genetic loci, and 9 loci with convincing evidence of gene-smoking interaction (GxSMK) on obesity-related traits. We show consistent direction of effect for all identified loci and significance for 18 novel and for 5 interaction loci in an independent study sample. These loci highlight novel biological functions, including response to oxidative stress, addictive behaviour, and regulatory functions emphasizing the importance of accounting for environment in genetic analyses. Our results suggest that tobacco smoking may alter the genetic susceptibility to overall adiposity and body fat distribution.

Genetic effects influencing risk for major depressive disorder in China and Europe

Major depressive disorder (MDD) is a common, complex psychiatric disorder and a leading cause of disability worldwide. Despite twin studies indicating its modest heritability (~30-40%), extensive heterogeneity and a complex genetic architecture have complicated efforts to detect associated genetic risk variants. We combined single-nucleotide polymorphism (SNP) summary statistics from the CONVERGE and PGC studies of MDD, representing 10 502 Chinese (5282 cases and 5220 controls) and 18 663 European (9447 cases and 9215 controls) subjects. We determined the fraction of SNPs displaying consistent directions of effect, assessed the significance of polygenic risk scores and estimated the genetic correlation of MDD across ancestries. Subsequent trans-ancestry meta-analyses combined SNP-level evidence of association. Sign tests and polygenic score profiling weakly support an overlap of SNP effects between East Asian and European populations. We estimated the trans-ancestry genetic correlation of lifetime MDD as 0.33; female-only and recurrent MDD yielded estimates of 0.40 and 0.41, respectively. Common variants downstream of GPHN achieved genome-wide significance by Bayesian trans-ancestry meta-analysis (rs9323497; log10 Bayes Factor=8.08) but failed to replicate in an independent European sample (P=0.911). Gene-set enrichment analyses indicate enrichment of genes involved in neuronal development and axonal trafficking. We successfully demonstrate a partially shared polygenic basis of MDD in East Asian and European populations. Taken together, these findings support a complex etiology for MDD and possible population differences in predisposing genetic factors, with important implications for future genetic studies.

Differences in childhood physical abuse reporting and the association between CPA and alcohol use disorder in European American and African American women

The goal of the current study was to examine whether the magnitude of the association between childhood physical abuse (CPA) and alcohol use disorder (AUD) varies by type of CPA assessment and race of the respondents. Data are from the Missouri adolescent female twins study and the Missouri family study (N = 4508) where 21.2% identified as African American (AA) and 78.8% as European American (EA); mean age = 23.8. Data were collected using a structured comprehensive interview which assessed CPA experiences using behavioral questions about specific abusive behaviors and trauma checklist items. Cox proportional hazards regression analyses were conducted, adjusting for additional risk factors associated with AUD, including co-occurring psychiatric disorders (defined as time-varying) and parental alcohol misuse. Overall, CPA reporting patterns were highly correlated (tetrachoric ρ = 0.73); although, only 25.8% of women who endorsed behaviorally defined CPA also endorsed checklist items whereas 72.2% of women who endorsed checklist items also endorsed behavioral questions. Racial disparities were evident, with behaviorally defined CPA increasing the hazard for AUD in EA but not AA women. Additional racial disparities in the risk for AUD were observed: increased hazard for AUD were associated with major depressive disorder in AA, and cannabis dependence and paternal alcohol problems in EA, women. Results demonstrate the relevance of the type of CPA measure in assessing CPA in studies of alcohol-related problems-behavioral items may be more inclusive of CPA exposure and more predictive of AUD- and highlight racial distinctions of AUD etiology in women. (PsycINFO Database Record

Smoking as an early risk factor for problematic parenting practices

Parenting among those who use non-illicit and more common drugs such as cigarettes remains an understudied area for investigation. Secondary data analyses were performed in 2015 on a prospective study with parent and twin data available on n=3,009 individual members of female twin pairs born between July 1975 and June 1985 identified from Missouri-state birth records. Maternal smoking when the twins were 3+ years of age remained a significant predictor of offspring report of childhood sexual abuse (OR, 1.40; 95% CI, 1.02-1.92) after controlling for key covariates. Given limited public health resources, mothers who smoke during child’s preschool years may be targeted for tailored parenting intervention.

Prior Dietary Practices and Connections to a Human Gut Microbial Metacommunity Alter Responses to Diet Interventions

Ensuring that gut microbiota respond consistently to prescribed dietary interventions, irrespective of prior dietary practices (DPs), is critical for effective nutritional therapy. To address this, we identified DP-associated gut bacterial taxa in individuals either practicing chronic calorie restriction with adequate nutrition (CRON) or without dietary restrictions (AMER). When transplanted into gnotobiotic mice, AMER and CRON microbiota responded predictably to CRON and AMER diets but with variable response strengths. An individual's microbiota is connected to other individuals' communities ("metacommunity") by microbial exchange. Sequentially cohousing AMER-colonized mice with two different groups of CRON-colonized mice simulated metacommunity effects, resulting in enhanced responses to a CRON diet intervention and changes in several metabolic features in AMER animals. This response was driven by an influx of CRON DP-associated taxa. Certain DPs may impair responses to dietary interventions, necessitating the introduction of diet-responsive bacterial lineages present in other individuals and identified using the strategies described.

Progression in substance use initiation: A multilevel discordant monozygotic twin design

Considerable attention has been paid to the "gateway" pattern of drug use initiation in which individuals progress from tobacco and alcohol use to cannabis and other illicit drugs. The extent to which this sequence reflects a causal impact of licit substance use on illicit substance involvement remains unclear. Clarifying the mechanisms underlying substance use initiation may help inform our understanding of risk for psychopathology, as increasing research is demonstrating associations between initiation patterns and heavier involvement. This study examined patterns of substance use initiation using a discordant twin design. Participants were 3,476 monozygotic twins (37% male) from the Australian Twin Registry who reported on their ages of tobacco, alcohol, and cannabis initiation. Multilevel proportional hazard regression models were used to (a) estimate within-twin-pair and between-twin-pair contributions to associations between the ages of onset of different drugs; and (b) examine whether the magnitude of effects differed as a function of the order of substance use initiation. Finding significant effects within twin pairs would support the hypothesis that the age of initiation of a substance causally influences the age of initiation of a subsequent substance. Finding significant effects between twin pairs would support the operation of familial influences that explain variation in the ages of initiation of multiple drugs. Within-twin-pair effects for typical patterns were modest. When initiation was atypical, however, larger within-twin-pair effects were observed and causal influences were more strongly implicated. Results support the utility of examining the timing and ordering of substance use initiation within sophisticated, genetically informative designs.

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.

Differences between White and Black young women in the relationship between religious service attendance and alcohol involvement

BACKGROUND AND OBJECTIVES

We examined the associations of religious attendance during childhood (C-RA) and adulthood (A-RA) with alcohol involvement (ever drinking, timing of first alcohol use, and alcohol use disorder [AUD]) in White and Black female twins. As genetic and environmental factors influence religious attendance and alcohol involvement, we examined the extent to which they contribute to their association.

METHODS

Data on 3,234 White and 553 Black female twins (18-29 years) from the Missouri Adolescent Female twin Study. Significant correlations between C-RA or A-RA and alcohol involvement were parsed into their additive genetic, shared environmental, and individual-specific environmental sources.

RESULTS

C-RA was associated with ever drinking and timing of first alcohol use in Whites. A-RA was associated with ever drinking and AUD in both Whites and Blacks. Shared environmental influences did not contribute to alcohol or religiosity phenotypes in Blacks. In Whites, the association between C-RA and alcohol was due to shared environmental influences, whereas the association between A-RA and alcohol was attributable to additive genetic, shared environmental, and individual-specific environmental sources. Individual-specific environment and genetics contributed to associations between A-RA and ever drinking and AUD, respectively, in Blacks.

CONCLUSIONS

Factors other than C-RA contribute to lower rates of alcohol involvement in Blacks. Shared environment does not contribute to links between A-RA and alcohol involvement in Blacks.

SCIENTIFIC SIGNIFICANCE

The protective impact of childhood religiosity on alcohol use and misuse is important in Whites and is due to familial factors shared by religiosity and alcohol involvement. (Am J Addict 2017;26:437-445).

Smoking during pregnancy and ADHD risk: A genetically informed, multiple-rater approach

Maternal smoking during pregnancy (SDP) is a significant public health concern with adverse consequences to the health and well-being of the developing child, including behavioral outcomes such as Attention-Deficit Hyperactivity Disorder (ADHD). There is substantial interest in understanding the nature of this reported association, particularly in light of more recent genetically informed studies that suggest that the SDP-ADHD link is less clear than once thought. In a sample of families (N = 173) specifically selected for sibling pairs discordant for prenatal smoking exposure, we use a sibling-comparison approach that controls for shared genetic and familial influences to assess the effects of SDP on ADHD symptom dimensions. ADHD was measured by both parent and teacher report on the Conners report forms and the Child Behavior Checklist/Teacher Report Form (CBCL/TRF). Results for the CBCL/TRF Total ADHD score are consistent with prior genetically informed approaches and suggest that previously reported associations between SDP and ADHD are largely due to familial confounding rather than causal teratogenic effects. However, results from the Conners parent report suggest a potentially causal effect of SDP on hyperactive/impulsive and, to a lesser extent, total ADHD symptoms; SDP results in increased parent-reported hyperactive/impulsive and total ADHD symptoms even after accounting for genetic and familial confounding factors. This suggests that the Conners assessment (parent-report) may provide a sensitive measure for use in studies examining child specific SDP effects on continuous and dimensional aspects of ADHD. © 2016 Wiley Periodicals, Inc.

Genetic variants in RBFOX3 are associated with sleep latency

Time to fall asleep (sleep latency) is a major determinant of sleep quality. Chronic, long sleep latency is a major characteristic of sleep-onset insomnia and/or delayed sleep phase syndrome. In this study we aimed to discover common polymorphisms that contribute to the genetics of sleep latency. We performed a meta-analysis of genome-wide association studies (GWAS) including 2 572 737 single nucleotide polymorphisms (SNPs) established in seven European cohorts including 4242 individuals. We found a cluster of three highly correlated variants (rs9900428, rs9907432 and rs7211029) in the RNA-binding protein fox-1 homolog 3 gene (RBFOX3) associated with sleep latency (P-values=5.77 × 10(-08), 6.59 × 10(-)(08) and 9.17 × 10(-)(08)). These SNPs were replicated in up to 12 independent populations including 30 377 individuals (P-values=1.5 × 10(-)(02), 7.0 × 10(-)(03) and 2.5 × 10(-)(03); combined meta-analysis P-values=5.5 × 10(-07), 5.4 × 10(-07) and 1.0 × 10(-07)). A functional prediction of RBFOX3 based on co-expression with other genes shows that this gene is predominantly expressed in brain (P-value=1.4 × 10(-316)) and the central nervous system (P-value=7.5 × 10(-)(321)). The predicted function of RBFOX3 based on co-expression analysis with other genes shows that this gene is significantly involved in the release cycle of neurotransmitters including gamma-aminobutyric acid and various monoamines (P-values<2.9 × 10(-11)) that are crucial in triggering the onset of sleep. To conclude, in this first large-scale GWAS of sleep latency we report a novel association of variants in RBFOX3 gene. Further, a functional prediction of RBFOX3 supports the involvement of RBFOX3 with sleep latency.

Meta-analysis of genome-wide association studies of anxiety disorders

Anxiety disorders (ADs), namely generalized AD, panic disorder and phobias, are common, etiologically complex conditions with a partially genetic basis. Despite differing on diagnostic definitions based on clinical presentation, ADs likely represent various expressions of an underlying common diathesis of abnormal regulation of basic threat-response systems. We conducted genome-wide association analyses in nine samples of European ancestry from seven large, independent studies. To identify genetic variants contributing to genetic susceptibility shared across interview-generated DSM-based ADs, we applied two phenotypic approaches: (1) comparisons between categorical AD cases and supernormal controls, and (2) quantitative phenotypic factor scores (FS) derived from a multivariate analysis combining information across the clinical phenotypes. We used logistic and linear regression, respectively, to analyze the association between these phenotypes and genome-wide single nucleotide polymorphisms. Meta-analysis for each phenotype combined results across the nine samples for over 18 000 unrelated individuals. Each meta-analysis identified a different genome-wide significant region, with the following markers showing the strongest association: for case-control contrasts, rs1709393 located in an uncharacterized non-coding RNA locus on chromosomal band 3q12.3 (P=1.65 × 10(-8)); for FS, rs1067327 within CAMKMT encoding the calmodulin-lysine N-methyltransferase on chromosomal band 2p21 (P=2.86 × 10(-9)). Independent replication and further exploration of these findings are needed to more fully understand the role of these variants in risk and expression of ADs.

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.

The Role of Genes and Environment in Degree of Partner Self-Similarity

Choice of romantic partner is an enormously important component of human life, impacting almost every facet of day-to-day existence, however; the processes underlying this choice are remarkably complex and have so far been largely resistant to scientific explanation. One consistent finding is that, on average, members of romantic dyads tend to be more alike than would be expected by chance. Selecting for self-similarity is at least partially driven by phenotypic matching wherein couples share similar phenotypes, and preferences for a number of these traits are partly genetically influenced (e.g., education, height, social attitudes and religiosity). This suggests that genetically influenced preferences for self-similarity might contribute to phenotypic matching (and thus assortative mating), but it has never been studied in actual couples. In the present study, we use a large sample of twins to model sources of variation in self-similarity between partners. Biometrical modelling revealed that very little of the variation in the tendency to assortatively mate across 14 traits was due to genetic effects (7 %) or the shared environment of twins (0 %).

The Association of Genetic Predisposition to Depressive Symptoms with Non-suicidal and Suicidal Self-Injuries

Non-suicidal and suicidal self-injury are very destructive, yet surprisingly common behaviours. Depressed mood is a major risk factor for non-suicidal self-injury (NSSI), suicidal ideation and suicide attempts. We conducted a genetic risk prediction study to examine the polygenic overlap of depressive symptoms with lifetime NSSI, suicidal ideation, and suicide attempts in a sample of 6237 Australian adult twins and their family members (3740 females, mean age = 42.4 years). Polygenic risk scores for depressive symptoms significantly predicted suicidal ideation, and some predictive ability was found for suicide attempts; the polygenic risk scores explained a significant amount of variance in suicidal ideation (lowest p = 0.008, explained variance ranging from 0.10 to 0.16 %) and, less consistently, in suicide attempts (lowest p = 0.04, explained variance ranging from 0.12 to 0.23 %). Polygenic risk scores did not significantly predict NSSI. Results highlight that individuals genetically predisposed to depression are also more likely to experience suicidal ideation/behaviour, whereas we found no evidence that this is also the case for NSSI.