Alcohol use disorder and non-fatal suicide attempt: findings from a Swedish National Cohort Study

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.

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.

Risk of suicidal behavior as a function of alcohol use disorder typologies: A Swedish population-based study

BACKGROUND AND AIMS

Alcohol use disorder (AUD) is one of the strongest predictors of suicidal behavior. Here, we measured risk of suicide attempt and death as a function of AUD typologies.

DESIGN

We used AUD typologies from previous latent class analysis: (i) externalizing subtype (characterized by externalizing symptomatology and early age of onset; individuals in this group have lower education and higher familial/social difficulties); (ii) subtype described by minimal psychopathology; and (iii) internalizing subtype (characterized by internalizing symptomatology and later age of onset; individuals in this group have higher education). We used class membership to predict distal outcomes (attempt and death) and performed regressions to evaluate whether differences in suicidal behavior were explained by the group characteristics (sex, age of onset, number and type of AUD registrations, familial/genetic risk for AUD, externalizing and internalizing behaviors, socio-economic indicators, marital status and childhood family status). We also evaluated the effect of suicide attempt prior to AUD.

SETTING AND PARTICIPANTS

Based on longitudinal Swedish registry data, we included 217 074 individuals with AUD born 1950-80.

MEASUREMENTS

Suicide attempts were identified using medical registers and deaths using the mortality register.

FINDINGS

Individuals with the externalizing subtype had higher risks of suicidal behavior than other groups [attempt: externalizing versus minimal psychopathology: odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.35, 1.35; externalizing versus internalizing: OR = 1.47, 95% CI = 1.46, 1.48; death: externalizing versus minimal psychopathology: OR = 1.57, 95% CI = 1.57, 1.58; externalizing versus internalizing: OR = 1.99, 95% CI = 1.93, 2.06]. Individuals with minimal psychopathology had higher risks than those with internalizing symptomatology (attempt: OR = 1.09, 95% CI = 1.08, 1.10, death: OR = 1.26, 95% CI = 1.23, 1.30). These differences were explained by age at registration and were related to the number of registrations, sex, education, family disruption and suicide attempt prior to AUD.

CONCLUSIONS

Among people in Sweden, considering alcohol use disorder (AUD) heterogeneity appears to be a meaningful way to evaluate suicide risk. The highest risk of suicide attempt and death occurs in the externalizing subtype of AUD, followed by the minimal psychopathology subtype, and then the internalizing subtype.

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.

Association between substance-induced psychosis and suicide attempt: A Danish nation-wide register-based study

BACKGROUND AND AIMS

Substance-induced psychosis has previously been linked to an excess risk of suicide; however, the association between substance-induced psychosis and suicide attempt has hitherto not been investigated. We investigated whether substance-induced psychosis was associated with a higher risk of subsequent suicide attempt.

DESIGN

Nation-wide prospective register-based cohort study.

SETTING

Denmark.

PARTICIPANTS

All people living in Denmark aged 13 years or more during 1995 to 2017.

MEASUREMENTS

Substance-induced psychosis and suicide attempts were identified through hospital records as ICD-10 codes.

FINDINGS

A total of 8900 (78.8% males) individuals were diagnosed with a substance-induced psychosis, and 740 of these had a suicide attempt during follow-up. People with a substance-induced psychosis had a higher risk of a subsequent suicide attempt [hazard ratio (HR) = 13.4, 95% confidence interval (CI) = 12.4-14.4] when compared with the general population. The highest hazard ratios were found for psychosis induced by opioids (HR = 26.4, 95% CI = 18.2-38.2); alcohol (HR = 17.7, 95% CI = 15.2-20.6); sedatives (HR = 17.2, 95% CI = 8.9-33.0); and cocaine (HR = 15.6, 95% CI = 10.7-22.8), while cannabis-induced psychosis was linked to an HR of 8.9 (95% CI = 7.7-10.3). Approximately 15% of patients with substance-induced psychosis had had a suicide attempt within 20 years of their substance-induced psychosis diagnosis.

CONCLUSIONS

In Denmark, substance-induced psychosis appears to be strongly associated with subsequent suicide attempt, underscoring the importance of attention and better follow-up for this patient group.

Exposure to alcohol outlets and risk of suicidal behavior in a Swedish cohort of young adults

BACKGROUND

Greater alcohol accessibility, for example in the form of a high density of alcohol outlets or low alcohol taxation rates, may be associated with increased risk of suicidal behavior. However, most studies have been conducted at the aggregate level, and some have not accounted for potential confounders such as socioeconomic position or neighborhood quality.

METHODS

In a Swedish cohort of young adults aged 18 to 25, we used logistic regressions to evaluate whether living in a neighborhood that included bars, nightclubs, and/or government alcohol outlets was associated with risk of suicide attempt (SA) or suicide death (SD) during four separate 2-year observation periods. Neighborhoods were defined using pre-established nationwide designations. We conducted combined-sex and sex-stratified analyses, and included as covariates indicators of socioeconomic position, neighborhood deprivation, and aggregate genetic liability to suicidal behavior.

RESULTS

Risk of SA was increased in some subsamples of individuals living in a neighborhood with a bar or government alcohol outlet (odds ratios [ORs] = 1.05 to 1.15). Risk of SD was also higher among certain subsamples living in a neighborhood with a government outlet (ORs = 1.47 to 1.56), but lower for those living near a bar (ORs = 0.89 to 0.91). Significant results were driven by, but not exclusive to, the male subsample. Individuals with higher aggregate genetic risk for SA were more sensitive to the effects of a neighborhood government alcohol outlet, pooled across observation periods, in analyses of the sexes combined (relative excess risk due to interaction [RERI] = 0.05; 95% confidence intervals [CI] 0.01; 0.09) and in the male subsample (RERI = 0.06; 95% CI 0.001; 0.12).

CONCLUSIONS

Although effect sizes are small, living in a neighborhood with bars and/or government alcohol outlets may increase suicidal behavior among young adults. Individuals with higher genetic liability for SA are slightly more susceptible to these exposures.

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.

Risk of non-fatal suicide attempt in individuals with substance use disorder: the roles of aggregate genetic liability and environmental exposures in a Swedish population-based cohort

BACKGROUND AND AIMS

Substance use disorder (SUD) is related to widespread adverse consequences, including higher suicidality. Shared genetic liability has been demonstrated between SUD and suicidality. Here, we measured the factors that contribute to increased risk of non-fatal suicide attempt among individuals with SUD by focusing upon aggregate genetic risks and both childhood and past-year environmental factors.

DESIGN

Longitudinal study. Family genetic risk scores and environmental factors (childhood, aged from 0 to 15 years, and the year preceding SUD registration) were used to predict the relative risk of non-fatal suicide attempt using Cox proportional hazards models. Additional analyses employed a co-relative design, accounting for genetic factors and shared familial environment, to test for potential causality.

SETTING AND PARTICIPANTS

Based on longitudinal Swedish registry data, 228 617 individuals with SUD registrations from 1991 to 2015 were included.

MEASUREMENTS

SUD and suicide attempts were identified using medical records (International Classification of Diseases codes). SUD was also identified using pharmacy and criminal registries.

FINDINGS

In multivariable analyses that jointly accounted for all the selected potential predictors, individuals with SUD were at higher risk for non-fatal suicide attempt if they had experienced a parental death [hazard ratio (HR) = 1.58; 95% confidence interval (CI) = 1.30, 1.93], were female (HR = 1.53, 95% CI = 1.49, 1.57), had low educational attainment (HR = 1.50, 95% CI = 1.46, 1.55), received social welfare (HR = 1.21, 95% CI = 1.17, 1.25) or had lived in a non-intact family (HR = 1.11, 95% CI = 1.08, 1.14). In co-relative analyses, low education was supported as a possible causal factor for suicide attempt. Aggregate genetic risks interacted with low education and being raised in a non-intact family, with increased prevalence of suicide attempt in people with high genetic risks and unfavorable environmental exposures.

CONCLUSIONS

Aggregate genetic liability, childhood environmental experiences and specific socio-economic indicators are important risk factors for non-fatal suicide attempt among individuals with substance use disorder.

Roles of alcohol use disorder and resilience in risk of suicide attempt in men: A Swedish population-based cohort

INTRODUCTION

Alcohol use disorder (AUD) has been identified as a strong risk factor for suicide attempt. However, few studies have considered protective factors that may moderate this association, such as resilience.

METHODS

We used longitudinal nationwide Swedish data of 903,333 males born 1960-1980 and 48,285 males born 1949-1951. We performed Cox proportional hazards models to test the role of AUD, resilience, and their interaction on risk for suicide attempt. We used co-relative models to account for familial factors.

RESULTS

Alcohol use disorder was strongly associated with increased risk of suicide attempt [hazard ratio (HR) = 12.22], while resilience was associated with reduced risk (HR = 0.73). Multiplicative interaction (HR = 1.21) showed that, in the context of AUD, the protective role of resilience on risk of suicide attempt was somewhat attenuated. Co-relative analyses supported both familial liability and a possible causal pathway between AUD, resilience, and suicide attempt. In the cohort born 1949-1951, resilience subcomponents-social maturity, interests, psychological energy, home conditions, and emotional control-were all associated with reduced suicide attempt risk (HRs between 0.63 and 0.74).

CONCLUSION

While resilience is associated with reduced risk of suicide attempt, this effect is less pronounced in the context of AUD. These associations are potentially causal.

Comparative risk of suicide by specific substance use disorders: A national cohort study

Substance use disorders (SUDs) are important risk factors for suicide, yet little is known about how suicide risks vary by specific SUDs. We examined these risks for the first time in a large general population to facilitate comparisons across SUDs. A national cohort study was conducted of all 6,947,191 adults in Sweden. SUDs (opioid, sedative/hypnotic, hallucinogen, cannabis, amphetamine, cocaine, and alcohol use disorders) were identified using inpatient, outpatient, and crime data, and suicide deaths using nationwide death data with follow-up during 2003-2016. Cox regression was used to compute hazard ratios (HRs) for suicide death while adjusting for sociodemographic factors and psychiatric, SUD, and somatic comorbidities. Co-sibling analyses assessed for confounding by unmeasured shared familial (genetic and/or environmental) factors. In 79.8 million person-years of follow-up, 15,616 (0.2%) suicide deaths were identified. All SUDs were associated with significantly increased risks, with HRs ranging from 12- to 26-fold and 2.5- to 6.4-fold before and after adjusting for covariates, respectively. After adjusting for all covariates, opioid use disorder was the strongest risk factor (HR, 6.39; 95% CI, 5.53-7.38) (P ≤ 0.002 compared with any other SUD), followed by sedative/hypnotic use disorder (4.62; 4.06-5.27) (P ≤ 0.009 compared with any other SUD except opioid or hallucinogen). Most associations persisted after controlling for shared familial factors, consistent with causal effects. In this large national cohort, all SUDs were associated with significantly increased risks of suicide death, especially opioid and sedative/hypnotic use disorders. These findings may improve risk stratification and inform interventions to prevent suicide in the highest-risk subgroups with SUDs.