Genome-wide Association Studies in Ancestrally Diverse Populations: Opportunities, Methods, Pitfalls, and Recommendations.

Genome-wide association studies (GWASs) have focused primarily on populations of European descent, but it is essential that diverse populations become better represented. Increasing diversity among study participants will advance our understanding of genetic architecture in all populations and ensure that genetic research is broadly applicable. To facilitate and promote research in multi-ancestry and admixed cohorts, we outline key methodological considerations and highlight opportunities, challenges, solutions, and areas in need of development. Despite the perception that analyzing genetic data from diverse populations is difficult, it is scientifically and ethically imperative, and there is an expanding analytical toolbox to do it well.

Socioeconomic position indicators and risk of alcohol-related medical conditions: A national cohort study from Sweden.

BACKGROUND: Alcohol consumption contributes to excess morbidity and mortality in part through the development of alcohol-related medical conditions (AMCs, including alcoholic cardiomyopathy, hepatitis, cirrhosis, etc.). The current study aimed to clarify the extent to which risk for these outcomes differs as a function of socioeconomic position (SEP), as discrepancies could lead to exacerbated health disparities. METHODS AND FINDINGS: We used longitudinal Swedish national registries to estimate the individual and joint associations between 2 SEP indicators, educational attainment and income level, and risk of AMC based on International Classification of Diseases codes, while controlling for other sociodemographic covariates and psychiatric illness. We conducted Cox proportional hazards models in sex-stratified analyses (N = 1,162,679 females and N = 1,196,659 males), beginning observation at age 40 with follow-up through December 2018, death, or emigration. By the end of follow-up, 4,253 (0.37%) females and 11,183 (0.93%) males had received an AMC registration, corresponding to overall AMC incidence rates among females and males of 2.01 and 5.20, respectively. In sex-stratified models adjusted for birth year, marital status, region of origin, internalizing and externalizing disorder registrations, and alcohol use disorder (AUD) registration, lower educational attainment was associated with higher risk of AMC in both females (hazard ratios [HRs] = 1.40 to 2.46 for low- and mid-level educational attainment across 0 to 15 years of observation) and males (HRs = 1.13 to 1.48). Likewise, risk of AMC was increased for those with lower income levels (females: HRs = 1.10 to 5.86; males: HRs = 1.07 to 6.41). In secondary analyses, we further adjusted for aggregate familial risk of AUD by including family genetic risk scores for AUD (FGRSAUD), estimated using medical, pharmacy, and criminal registries in extended families, as covariates. While FGRSAUD were associated with risk of AMC in adjusted models (HR = 1.17 for females and HR = 1.21 for males), estimates for education and income level remained largely unchanged. Furthermore, FGRSAUD interacted with income level, but not education level, such that those at higher familial liability to AUD were more susceptible to the adverse effect of low income. Limitations of these analyses include the possibility of false negatives for psychiatric illness registrations, changes in income after age 40 that were not accounted for due to modeling restrictions, restriction to residents of a high-income country, and the inability to account for individual-level alcohol consumption using registry data. CONCLUSIONS: Using comprehensive national registry data, these analyses demonstrate that individuals with lower levels of education and/or income are at higher risk of developing AMC. These associations persist even when accounting for a range of sociodemographic, psychiatric, and familial risk factors. Differences in risk could contribute to further health disparities, potentially warranting increased screening and prevention efforts in clinical and public health settings.

Clarifying the relationship between physical injuries and risk for suicide attempt in a Swedish national sample.

INTRODUCTION: The Interpersonal-Psychological Theory of Suicide proposes that capability for suicide is acquired through exposure to painful and provocative events (PPEs). Although there is robust evidence for a positive association between aggregate measures of PPEs and risk for suicidal behavior, little is known about the contributions of physical injuries. The present study investigated the relationship between injuries and risk of subsequent suicide attempt (SA). METHODS: Data were from Swedish population-based registers. All individuals born in Sweden between 1970 and 1990 were included (N = 1,011,725 females and 1,067,709 males). We used Cox regression models to test associations between 10 types of injuries (eye injury; fracture; dislocation/sprain/strain; injury to nerves and spinal cord; injury to blood vessels; intracranial injury; crushing injury; internal injury; traumatic amputation; and other or unspecified injuries) and risk for later SA. Analyses were stratified by sex and adjusted for year of birth and parental education. Additional models tested for differences in the pattern of associations based on age group and genetic liability for SA. In co-relative models, we tested the association between each injury type and risk for SA in relative pairs of varying genetic relatedness to control for unmeasured familial confounders. RESULTS: All 10 injury types were associated with elevated risk for SA (hazard ratios [HRs] = 1.2-7.0). Associations were stronger in the first year following an injury (HRs = 1.8-7.0), but HRs remained above 1 more than 1 year after injury exposure (HRs = 1.2-2.6). The strength of associations varied across injury type, sex, age, and genetic liability for SA. For example, the magnitude of the association between crushing injury and risk for SA was larger in females than males, whereas other injuries showed a similar pattern of associations across sex. Moreover, there was evidence to support positive additive interaction effects between several injury types and aggregate genetic liability for SA (relative excess risk due to interaction [RERI] = 0.1-0.3), but the majority of these interactions became non-significant or changed direction after accounting for comorbid psychiatric and substance use disorders. In co-relative models, the pattern of associations differed by injury type, such that there was evidence to support a potential causal effect of eye injury, fracture, dislocation/sprain/strain, intracranial injury, and other and unspecified injuries on risk for SA. For the remaining injury types, HRs were not significantly different from 1 in monozygotic twins, which is consistent with confounding by familial factors. CONCLUSIONS: Injuries are associated with increased risk for subsequent SA, particularly in the first year following an injury. While genetic and familial environmental factors may partly explain these associations, there is also evidence to support a potential causal effect of several injury types on future risk for SA.

Alcohol use disorder and risk of specific methods of suicide death in a national cohort.

INTRODUCTION: Alcohol use disorder (AUD) is among the strongest correlates of suicide death, but it is unclear whether AUD status is differentially associated with risk of suicide by particular methods. METHODS: The authors used competing risks models to evaluate the association between AUD status and risk of suicide by poisoning, suffocation, drowning, firearm, instruments, jumping, or other means in a large Swedish cohort born 1932-1995 (total N = 6,581,827; 48.8% female). Data were derived from Swedish national registers, including the Cause of Death Register and a range of medical registers. RESULTS: After adjusting for sociodemographic factors and familial liability to suicidal behavior, AUD was positively associated with risk of suicide for each method evaluated (cumulative incidence differences: 0.006-1.040 for females, 0.046-0.680 for males), except the association with firearm suicide in females. AUD was most strongly associated with risk of suicide by poisoning. Sex differences in the effects of AUD and family liability were observed for some, but not all, methods. Furthermore, high familial liability for suicidal behavior exacerbated AUD's impact on risk for suicide by poisoning (both sexes) and suffocation and jumping (males only), while the inverse interaction was observed for firearm suicide (males only). CONCLUSIONS: AUD increases risk of suicide by all methods examined and is particularly potent with respect to risk of suicide by poisoning. Differences in risk related to sex and familial liability to suicidal behavior underscore AUD's nuanced role in suicide risk. Future research should investigate targeted means restriction effectiveness among persons with AUD.

Mediational pathways between aggregate genetic liability and nonfatal suicide attempt: A Swedish population-based cohort.

Despite recent progress in the genetics of suicidal behavior, the pathway by which genetic liability increases suicide attempt risk is unclear. We investigated the mediational pathways from family/genetic risk for suicide attempt (FGRSSA) to suicide attempt by considering the roles of psychiatric illnesses. In a Swedish cohort, we evaluated time to suicide attempt as a function of FGRSSA and the mediational effects of alcohol use disorder, drug use disorder, attention-deficit/hyperactivity disorder, major depression, anxiety disorder, bipolar disorder, and non-affective psychosis. Analyses were conducted by sex in three age periods: 15-25 years (Nfemales = 850,278 and Nmales = 899,366), 26-35 years (Nfemales = 800,189 and Nmales = 861,774), and 36-45 years (Nfemales = 498,285 and Nmales = 535,831). The association between FGRSSA and suicide attempt was mediated via psychiatric disorders. The highest mediation effects were observed for alcohol use disorder in males (15-25 years, HRtotal = 1.60 [1.59; 1.62], mediation = 14.4%), drug use disorder in females (25-36 years, HRtotal = 1.46 [1.44; 1.49], mediation = 11.2%), and major depression (25-36 years) in females (HRtotal = 1.46 [1.44; 1.49], mediation = 7%) and males (HRtotal = 1.50 [1.47;1.52], mediation = 4.7%). While the direct effect of FGRSSA was higher at ages of 15-25, the mediation via psychiatric disorders was more prominent in later adulthood. Our study informs about the psychiatric illnesses via which genetic liability operates to impact suicide attempt risk, with distinct contributions according to age and sex.

Associations between polygenic liability to psychopathology and non-suicidal versus suicidal self-injury.

Little is known about how non-suicidal and suicidal self-injury are differentially genetically related to psychopathology and related measures. This research was conducted using the UK Biobank Resource, in participants of European ancestry (N = 2320 non-suicidal self-injury [NSSI] only; N = 2648 suicide attempt; 69.18% female). We compared polygenic scores (PGS) for psychopathology and other relevant measures within self-injuring individuals. Logistic regressions and likelihood ratio tests (LRT) were used to identify PGS that were differentially associated with these outcomes. In a multivariable model, PGS for anorexia nervosa (odds ratio [OR] = 1.07; 95% confidence intervals [CI] 1.01; 1.15) and suicidal behavior (OR = 1.06; 95% CI 1.00; 1.12) both differentiated between NSSI and suicide attempt, while the PGS for other phenotypes did not. The LRT between the multivariable and base models was significant (Chi square = 11.38, df = 2, p = 0.003), and the multivariable model explained a larger proportion of variance (Nagelkerke's pseudo-R2 = 0.028 vs. 0.025). While NSSI and suicidal behavior are similarly genetically related to a range of mental health and related outcomes, genetic liability to anorexia nervosa and suicidal behavior is higher among those reporting a suicide attempt than those reporting NSSI-only. Further elucidation of these distinctions is necessary, which will require a nuanced assessment of suicidal versus non-suicidal self-injury in large samples.

Genetic liability to suicide attempt, suicide death, and psychiatric and substance use disorders on the risk for suicide attempt and suicide death: a Swedish national study.

BACKGROUND: How does genetic liability to suicide attempt (SA), suicide death (SD), major depression (MD), bipolar disorder (BD), schizophrenia (SZ), alcohol use disorder (AUD), and drug use disorder (DUD) impact on risk for SA and SD? METHODS: In the Swedish general population born 1932-1995 and followed through 2017 (n = 7 661 519), we calculate family genetic risk scores (FGRS) for SA, SD, MD, BD, SZ, AUD, and DUD. Registration for SA and SD was assessed from Swedish national registers. RESULTS: In univariate and multivariate models predicting SA, FGRS were highest for SA, AUD, DUD, and MD. In univariate models predicting SD, the strongest FGRS were AUD, DUD, SA, and SD. In multivariate models, the FGRS for SA and AUD were higher in predicting SA while the FGRS for SD, BD, and SZ were higher in predicting SD. Higher FGRS for all disorders significantly predicted both younger age at first SA and frequency of attempts. For SD, higher FGRS for MD, AUD, and SD predicted later age at SD. Mediation of FGRS effects on SA and SD was more pronounced for SD than SA, strongest for AUD, DUD, and SZ FGRS and weakest for MD. CONCLUSIONS: FGRS for both SA and SD and for our five psychiatric disorders impact on risk for SA and SD in a complex manner. While some of the impact of genetic risk factors for psychiatric disorders on risk for SA and SD is mediated through developing the disorders, these risks also predispose directly to suicidal behaviors.

Divorce and risk of suicide attempt: a Swedish national study.

BACKGROUND: Prior research has reported an association between divorce and suicide attempt. We aimed to clarify this complex relationship, considering sex differences, temporal factors, and underlying etiologic pathways. METHODS: We used Swedish longitudinal national registry data for a cohort born 1960-1990 that was registered as married between 1978 and 2018 (N = 1 601 075). We used Cox proportional hazards models to estimate the association between divorce and suicide attempt. To assess whether observed associations were attributable to familial confounders or potentially causal in nature, we conducted co-relative analyses. RESULTS: In the overall sample and in sex-stratified analyses, divorce was associated with increased risk of suicide attempt (adjusted hazard ratios [HRs] 1.66-1.77). Risk was highest in the year immediately following divorce (HRs 2.20-2.91) and declined thereafter, but remained elevated 5 or more years later (HRs 1.41-1.51). Divorcees from shorter marriages were at higher risk for suicide attempt than those from longer marriages (HRs 3.33-3.40 and 1.20-1.36, respectively). In general, HRs were higher for divorced females than for divorced males. Co-relative analyses suggested that familial confounders and a causal pathway contribute to the observed associations. CONCLUSIONS: The association between divorce and risk of suicide attempt is complex, varying as a function of sex and time-related variables. Given evidence that the observed association is due in part to a causal pathway from divorce to suicide attempt, intervention or prevention efforts, such as behavioral therapy, could be most effective early in the divorce process, and in particular among females and those whose marriages were of short duration.

Shared genetic and environmental etiology between substance use disorders and suicidal behavior.

BACKGROUND: Previous studies have demonstrated substantial associations between substance use disorders (SUD) and suicidal behavior. The current study empirically assesses the extent to which shared genetic and/or environmental factors contribute to associations between alcohol use disorders (AUD) or drug use disorders (DUD) and suicidal behavior, including attempts and death. METHODS: The authors used Swedish national registry data, including medical, pharmacy, criminal, and death registrations, for a large cohort of twins, full siblings, and half siblings (N = 1 314 990) born 1960-1980 and followed through 2017. They conducted twin-sibling modeling of suicide attempt (SA) or suicide death (SD) with AUD and DUD to estimate genetic and environmental correlations between outcomes. Analyses were stratified by sex. RESULTS: Genetic correlations between SA and SUD ranged from rA = 0.60-0.88; corresponding shared environmental correlations were rC = 0.42-0.89 but accounted for little overall variance; and unique environmental correlations were rE = 0.42-0.57. When replacing attempt with SD, genetic and shared environmental correlations with AUD and DUD were comparable (rA = 0.48-0.72, rC = 0.92-1.00), but were attenuated for unique environmental factors (rE = -0.01 to 0.31). CONCLUSIONS: These findings indicate that shared genetic and unique environmental factors contribute to comorbidity of suicidal behavior and SUD, in conjunction with previously reported causal associations. Thus, each outcome should be considered an indicator of risk for the others. Opportunities for joint prevention and intervention, while limited by the polygenic nature of these outcomes, may be feasible considering moderate environmental correlations between SA and SUD.

Clinical, environmental, and genetic risk factors for substance use disorders: characterizing combined effects across multiple cohorts.

Substance use disorders (SUDs) incur serious social and personal costs. The risk for SUDs is complex, with risk factors ranging from social conditions to individual genetic variation. We examined whether models that include a clinical/environmental risk index (CERI) and polygenic scores (PGS) are able to identify individuals at increased risk of SUD in young adulthood across four longitudinal cohorts for a combined sample of N = 15,134. Our analyses included participants of European (NEUR = 12,659) and African (NAFR = 2475) ancestries. SUD outcomes included: (1) alcohol dependence, (2) nicotine dependence; (3) drug dependence, and (4) any substance dependence. In the models containing the PGS and CERI, the CERI was associated with all three outcomes (ORs = 01.37-1.67). PGS for problematic alcohol use, externalizing, and smoking quantity were associated with alcohol dependence, drug dependence, and nicotine dependence, respectively (OR = 1.11-1.33). PGS for problematic alcohol use and externalizing were also associated with any substance dependence (ORs = 1.09-1.18). The full model explained 6-13% of the variance in SUDs. Those in the top 10% of CERI and PGS had relative risk ratios of 3.86-8.04 for each SUD relative to the bottom 90%. Overall, the combined measures of clinical, environmental, and genetic risk demonstrated modest ability to distinguish between affected and unaffected individuals in young adulthood. PGS were significant but added little in addition to the clinical/environmental risk index. Results from our analysis demonstrate there is still considerable work to be done before tools such as these are ready for clinical applications.

Military service and risk of subsequent drug use disorders among Swedish men.

PURPOSE: Environmental factors contribute substantially to risk for drug use disorders (DUD). The current study applies multiple methods to empirically test whether military service is associated with subsequent DUD, as previous findings are inconsistent. METHODS: Longitudinal Swedish national registry data on a cohort of male conscripts born 1972-1987 (maximum N = 485,900) were used to test the association between military service and subsequent registration for DUD. Cox proportional hazard models were used in preliminary analyses, followed by three methods that enable causal inference: propensity score models, co-relative models, and instrumental variable analysis. RESULTS: Across all methods, military service was causally associated with lower risk of DUD. Hazard ratios ranged from HR = 0.43 (95% confidence intervals [CI] 0.37; 0.50) in the instrumental variable analysis to 0.77 (0.75; 0.79) in the multivariate propensity score matching analysis. This effect diminished across time. In the model including a propensity score, HRs remained below 1 across the observation period, while confidence intervals included 1 after ~ 11 years in the co-relative analysis and after ~ 21 years in the instrumental variable analysis. CONCLUSIONS: In this cohort of Swedish men, complementary methods indicate that military service conferred substantial but time-limited protection against subsequent DUD. The observed effect could be due to reduced opportunity for substance use during service, social cohesion experienced during and after service, and/or socioeconomic advantages among veterans. Additional research is necessary to clarify these protective mechanisms and determine how other environmental contexts can provide similar benefits.

The effect of parental alcohol use on alcohol use disorder in young adulthood: Exploring the mediating roles of adolescent alcohol expectancies and consumption.

INTRODUCTION: Parental alcohol use and problems are risk factors for alcohol use disorder (AUD), and these effects may be mediated by adolescent alcohol expectancies and consumption. In the present study, we tested the direct effects of mothers' and fathers' alcohol consumption on young adult AUD, as well as the indirect effects through adolescent maximum alcohol use, alcohol consumption, and alcohol expectancies. METHODS: Participants were 5160 individuals (49.1% female) and their biological parents from the Avon Longitudinal Study of Parents and Children, a cohort study of children born in southwestern England during 1991 and 1992. Structural equation modeling (SEM) was used to test associations of mothers' and fathers' alcohol use (assessed when children were 12 years old) with age 24 AUD. Potential mediator variables included the maximum number of alcoholic drinks consumed within a 24-h period by age 13.5 and alcohol expectancies and alcohol consumption at ages 17 and 20. RESULTS: Higher maternal and paternal alcohol use were associated with higher levels of alcohol consumption at age 17. Greater alcohol consumption, in turn, was related to a more severe presentation of AUD. The overall indirect effects of mothers' (b = 0.033, 95% confidence interval [CI] = 0.006, 0.059) and fathers' drinking (b = 0.041, 95% CI = 0.018, 0.064) on AUD were modest but significant, and were primarily comprised of adolescent alcohol consumption rather than alcohol expectancies. CONCLUSIONS: Our findings underscore the importance of both mothers' and fathers' drinking for the development of alcohol use and problems across adolescence and young adulthood.

The role of substance use disorders in the transition from suicide attempt to suicide death: a record linkage study of a Swedish cohort.

BACKGROUND: Suicidal behavior and substance use disorders (SUDs) are important public health concerns. Prior suicide attempts and SUDs are two of the most consistent predictors of suicide death, and clarifying the role of SUDs in the transition from suicide attempt to suicide death could inform prevention efforts. METHODS: We used national Swedish registry data to identify individuals born 1960-1985, with an index suicide attempt in 1997-2017 (N = 74 873; 46.7% female). We assessed risk of suicide death as a function of registration for a range of individual SUDs. We further examined whether the impact of SUDs varied as a function of (i) aggregate genetic liability to suicidal behavior, or (ii) age at index suicide attempt. RESULTS: In univariate models, risk of suicide death was higher among individuals with any SUD registration [hazard ratios (HRs) = 2.68-3.86]. In multivariate models, effects of specific SUDs were attenuated, but remained elevated for AUD (HR = 1.86 95% confidence intervals 1.68-2.05), opiates [HR = 1.58 (1.37-1.82)], sedatives [HR = 1.93 (1.70-2.18)], and multiple substances [HR = 2.09 (1.86-2.35)]. In secondary analyses, the effects of most, but not all, SUD were exacerbated by higher levels of genetic liability to suicide death, and among individuals who were younger at their index suicide attempt. CONCLUSIONS: In the presence of a strong predictor of suicide death - a prior attempt - substantial predictive power is still attributable to SUDs. Individuals with SUDs may warrant additional suicide screening and prevention efforts, particularly in the context of a family history of suicidal behavior or early onset of suicide attempt.

Oral contraceptive use and risk of suicidal behavior among young women.

BACKGROUND: Oral contraceptive use has been previously associated with an increased risk of suicidal behavior in some, but not all, samples. The use of large, representative, longitudinally-assessed samples may clarify the nature of this potential association. METHODS: We used Swedish national registries to identify women born between 1991 and 1995 (N = 216 702) and determine whether they retrieved prescriptions for oral contraceptives. We used Cox proportional hazards models to test the association between contraceptive use and first observed suicidal event (suicide attempt or death) from age 15 until the end of follow-up in 2014 (maximum age 22.4). We adjusted for covariates, including mental illness and parental history of suicide. RESULTS: In a crude model, use of combination or progestin-only oral contraceptives was positively associated with suicidal behavior, with hazard ratios (HRs) of 1.73-2.78 after 1 month of use, and 1.25-1.82 after 1 year of use. Accounting for sociodemographic, parental, and psychiatric variables attenuated these associations, and risks declined with increasing duration of use: adjusted HRs ranged from 1.56 to 2.13 1 month beyond the initiation of use, and from 1.19 to 1.48 1 year after initiation of use. HRs were higher among women who ceased use during the observation period. CONCLUSIONS: Young women using oral contraceptives may be at increased risk of suicidal behavior, but risk declines with increased duration of use. Analysis of former users suggests that women susceptible to depression/anxiety are more likely to cease hormonal contraceptive use. Additional studies are necessary to determine whether the observed association is attributable to a causal mechanism.

Suicidal ideation during adolescence: The roles of aggregate genetic liability for suicide attempts and negative life events in the past year.

BACKGROUND: Suicidal thoughts and behaviors (STB) constitute a central public health concern in adolescence. Previous studies emphasized the difficulty to cope with negative life events during adolescence as a risk factor for STB. Familial and genetic liability has also been documented to explain STB risk. Nevertheless, less is known about aggregate genetic liability and its possible interaction with negative life events. Moreover, information is needed to understand how these factors differently affect STB in boys and girls. METHODS: We evaluated suicidal ideation at 17 years old and examined the role of aggregate genetic liability, negative life events, and their interaction in a sample of 2,571 adolescents. Aggregate genetic liability was measured using a polygenic score (PGS) for suicide attempts. Negative life events were assessed in the past year and included parental divorce and hospitalizations, death of friends and relatives, bullying, failure-related events, and involvement with drugs. We conducted univariable and multivariable general linear models stratified by sex and evaluated the interactions between PGS and negative life events in subsequent models. RESULTS: Analyses showed that suicidal ideation in boys is associated with failure to achieve something important (estimate = 0.198), bullying (estimate = 0.285), drug use (estimate = 0.325), and parental death (estimate = 0.923). In girls, both aggregate genetic liability (estimate = 0.041) and negative life events (failure at school [estimate = 0.120], failure to achieve something important [estimate = 0.279], drug use [estimate = 0.395], and bullying [estimate = 0.472]) were associated with suicidal ideation. Interaction analyses suggested that PGS interacted with drug use and failures at school, though this would need additional support. CONCLUSIONS: These findings represent significant contributions to the fundamental understanding of STB in adolescence, suggesting to monitor the impact of negative life events during adolescence to better prevent suicide risk. Genetic liability is also of importance in girls and might influence the way they respond to environmental threats.

Patterns and Correlates of Polysubstance Use Among Individuals With Severe Alcohol Use Disorder.

AIM: The present study examined patterns and correlates of polysubstance use among individuals with severe alcohol use disorder (AUD). METHODS: Participants were 2785 individuals (63% female; mean age = 43 years, range = 18-78 years) from the Genes, Addiction and Personality Study. All participants met lifetime criteria for severe AUD (6+ symptoms). We used latent class analysis to identify patterns of frequency of lifetime use for cigarettes, marijuana, cocaine, stimulants, sedatives, opioids and hallucinogens. A variety of demographic and behavioral correlates of latent class membership were tested in univariable and multivariable models. RESULTS: A five-class solution was selected: extended range polysubstance use (24.5%); cigarette and marijuana use (18.8%); 'testers,' characterized by high probabilities of smoking 100 or more cigarettes, using marijuana 6+ times, and trying the remaining substances 1-5 times (12.3%); moderate range polysubstance use (17.1%) and minimal use (reference class; 27.3%). In univariable analyses, all potential correlates were related to latent class membership. In the multivariable model, associations with gender, race/ethnicity, age of onset for alcohol problems, dimensions of impulsivity, depressive symptoms, antisocial behavior and family history density of alcohol problems remained significant, though the pattern and strength of associations differed across classes. For instance, sensation-seeking, lack of premeditation and family history were uniquely associated with membership in the extended range polysubstance use class. CONCLUSION: Patterns of polysubstance use are differentially related to demographic and behavioral factors among individuals with severe AUD. Assessing use across multiple substances may inform the selection of targets for treatment and prevention.

The role of adolescent social relationships in promoting alcohol resistance: Interrupting the intergenerational transmission of alcohol misuse.

Genetic factors contribute to the intergenerational transmission of alcohol misuse, but not all individuals at high genetic risk develop problems. The present study examined adolescent relationships with parents, peers, and romantic partners as predictors of realized resistance, defined as high biological risk for disorder combined with a healthy outcome, to alcohol initiation, heavy episodic drinking, and alcohol use disorder (AUD). Data were from the Collaborative Study on the Genetics of Alcoholism (N = 1,858; 49.9% female; mean age at baseline = 13.91 years). Genetic risk, indexed using family history density and polygenic risk scores for alcohol problems and AUD, was used to define alcohol resistance. Adolescent predictors included parent-child relationship quality, parental monitoring, peer drinking, romantic partner drinking, and social competence. There was little support for the hypothesis that social relationship factors would promote alcohol resistance, with the exception that higher father-child relationship quality was associated with higher resistance to alcohol initiation ( ß ^ = - 0.19 , 95% CI = -0.35, -0.03). Unexpectedly, social competence was associated with lower resistance to heavy episodic drinking ( ß ^ = 0.10 , 95% CI = 0.01, 0.20). This pattern of largely null effects underscores how little is known about resistance processes among those at high genetic risk for AUD.

Coffee and energy drink use patterns in college freshmen: associations with adverse health behaviors and risk factors.

BACKGROUND: Public health concern over college students mixing caffeine-containing energy drinks (EDs) and alcohol has contributed to an array of ED-focused research studies. One review found consistent associations between ED use and heavy/problem drinking as well as other drug use and risky behaviors (Nutr Rev 72:87-97, 2014). The extent to which similar patterns exist for other sources of caffeine is not known. The present study examined associations between coffee and ED consumption and alcohol, tobacco and other drug use; alcohol use problems; and parental substance abuse and mental health problems in a sample of college freshmen. METHODS: Subjects were N = 1986 freshmen at an urban university who completed an on-line survey about demographics; caffeine; alcohol, tobacco and other drug use; and family history. The sample was 61% female and 53% White. Chi-square analyses and multivariable binary or ordinal logistic regression were used to compare substance use, problem alcohol behavior, and familial risk measures across 3 caffeine use groups: ED (with or without Coffee) (ED + Co; N = 350); Coffee but no ED (Co; N = 761); and neither coffee nor ED (NoCE; N = 875) use. RESULTS: After adjusting for gender and race, the 3 caffeine use groups differed on 8 of 9 symptoms for alcohol dependence. In all cases, the ED + Co group was most likely to endorse the symptom, followed by the Co group and finally the NoCE group (all p < .002). A similar pattern was found for: use 6+ times of 5 other classes of drugs (all p < .05); extent of personal and peer smoking (all p < .001); and paternal problems with alcohol, drugs and anxiety/depression as well as maternal alcohol problems and depression/anxiety (p < .04). CONCLUSIONS: The response pattern was ubiquitous, with ED + Co most likely, Co intermediate, and NoCE least likely to endorse a broad range of substance use, problem alcohol behaviors, and familial risk factors. The finding that the Co group differed from both the ED + Co and NoCE groups on 8 measures and from the NoCE group on one additional measure underscores the importance of looking at coffee in addition to EDs when considering associations between caffeine and other risky behaviors.

Polygenic contributions to alcohol use and alcohol use disorders across population-based and clinically ascertained samples.

BACKGROUND: Studies suggest that alcohol consumption and alcohol use disorders have distinct genetic backgrounds. METHODS: We examined whether polygenic risk scores (PRS) for consumption and problem subscales of the Alcohol Use Disorders Identification Test (AUDIT-C, AUDIT-P) in the UK Biobank (UKB; N = 121 630) correlate with alcohol outcomes in four independent samples: an ascertained cohort, the Collaborative Study on the Genetics of Alcoholism (COGA; N = 6850), and population-based cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC; N = 5911), Generation Scotland (GS; N = 17 461), and an independent subset of UKB (N = 245 947). Regression models and survival analyses tested whether the PRS were associated with the alcohol-related outcomes. RESULTS: In COGA, AUDIT-P PRS was associated with alcohol dependence, AUD symptom count, maximum drinks (R2 = 0.47-0.68%, p = 2.0 × 10-8-1.0 × 10-10), and increased likelihood of onset of alcohol dependence (hazard ratio = 1.15, p = 4.7 × 10-8); AUDIT-C PRS was not an independent predictor of any phenotype. In ALSPAC, the AUDIT-C PRS was associated with alcohol dependence (R2 = 0.96%, p = 4.8 × 10-6). In GS, AUDIT-C PRS was a better predictor of weekly alcohol use (R2 = 0.27%, p = 5.5 × 10-11), while AUDIT-P PRS was more associated with problem drinking (R2 = 0.40%, p = 9.0 × 10-7). Lastly, AUDIT-P PRS was associated with ICD-based alcohol-related disorders in the UKB subset (R2 = 0.18%, p < 2.0 × 10-16). CONCLUSIONS: AUDIT-P PRS was associated with a range of alcohol-related phenotypes across population-based and ascertained cohorts, while AUDIT-C PRS showed less utility in the ascertained cohort. We show that AUDIT-P is genetically correlated with both use and misuse and demonstrate the influence of ascertainment schemes on PRS analyses.

Genetic and environmental influences on the progression from alcohol use disorder to alcohol-related medical conditions.

BACKGROUND: Medical conditions related to alcohol use disorders (AUD) represent a substantial public health concern. However, only a subset of individuals with AUD develop these conditions and the extent to which genetic and environmental factors that are shared with AUD, versus those distinct from it, contribute to this progression has not yet been determined. METHODS: Using data from Swedish national registries for a cohort born from 1932 to 1970 (N = 1,319,214, 48.9% women), we conducted twin-sibling biometric model fitting to examine the genetic and environmental sources of variance that contribute to the liability to alcohol-related medical conditions (AMC). Progression to AMC, determined using medical registry data, was contingent on an AUD registration, which was determined using medical and criminal registry data. RESULTS: We identified AUD registrations in 3.2% of women and 9.2% of men. Among individuals with an AUD registration, 14.4% of women and 15.4% of men had an AMC registration. In the final models, we constrained the beta pathway from AUD to AMC and the genetic and unique environmental paths to be equal across sexes. The beta path was estimated at 0.59. AMC was modestly heritable in women (A = 0.32) and men (A = 0.30). The proportion of total heritability unique to AMC was 39.6% among women and 41.3% among men. A higher proportion of total environmental variance was unique to AMC: 76.7% for women and 77.2% for men. In a sensitivity analysis limited to liver-related AMC, we observed similar results, with a slightly lower beta path from AUD to AMC (0.46) and higher proportions of AMC-specific genetic (70.0% in women; 71.7% in men) and environmental (84.5% in both sexes) variance. CONCLUSIONS: A moderate-to-substantial proportion of genetic and environmental variance that contributes to AMC risk is not shared with AUD, underscoring the need for additional gene identification efforts for AMC. Furthermore, the prominent influence of environmental factors specific to AMC provides a promising area for the identification of prevention targets. We did not observe significant sex differences in the etiology of AMC, although follow-up is warranted in other well-powered studies.