Different Characteristics and Heritabilities of Alcohol Use Disorder Classes: A Population-Based Swedish Study

Generalized genetic liability to substance use disorders

Lifetime and temporal co-occurrence of substance use disorders (SUDs) is common and compared with individual SUDs is characterized by greater severity, additional psychiatric comorbidities, and worse outcomes. Here, we review evidence for the role of generalized genetic liability to various SUDs. Coaggregation of SUDs has familial contributions, with twin studies suggesting a strong contribution of additive genetic influences undergirding use disorders for a variety of substances (including alcohol, nicotine, cannabis, and others). GWAS have documented similarly large genetic correlations between alcohol, cannabis, and opioid use disorders. Extending these findings, recent studies have identified multiple genomic loci that contribute to common risk for these SUDs and problematic tobacco use, implicating dopaminergic regulatory and neuronal development mechanisms in the pathophysiology of generalized SUD genetic liability, with certain signals demonstrating cross-species and translational validity. Overlap with genetic signals for other externalizing behaviors, while substantial, does not explain the entirety of the generalized genetic signal for SUD. Polygenic scores (PGS) derived from the generalized genetic liability to SUDs outperform PGS for individual SUDs in prediction of serious mental health and medical comorbidities. Going forward, it will be important to further elucidate the etiology of generalized SUD genetic liability by incorporating additional SUDs, evaluating clinical presentation across the lifespan, and increasing the granularity of investigation (e.g., specific transdiagnostic criteria) to ultimately improve the nosology, prevention, and treatment of SUDs.

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.

Offspring hospitalization for substance use and changes in parental mental health: A Finnish register-based study

Prior research indicates that parental psychiatric disorders increase their offspring's risk of substance use problems. Though the association is likely bidirectional, the effects of an adult child's substance use on parental mental health remain understudied. We examined parents' psychotropic medication use trajectories by parental sex and educational attainment before and after a child's alcohol- or narcotics-attributable hospitalization. We identified Finnish residents, born 1979-1988, with a first hospitalization for substance use during emerging adulthood (ages 18-29, n = 12,851). Their biological mothers (n = 12,283) and/or fathers (n = 10,765) were followed for the two years before and after the hospitalization. Psychotropic medication use was measured in three-month periods centered around the time of child's hospitalization, and the probability of psychotropic medication use at each time point was assessed using generalized estimating equations logit models. Among mothers, the prevalence of psychotropic medication use increased during the year before, peaked during the 0-3 months after hospitalization, and remained at a similarly elevated level until the end of follow-up. The prevalence among fathers increased gradually and linearly across follow-up, with minimal changes evident either directly before or after the hospitalization. Parents' educational attainment did not modify these trajectories. Our results highlight the importance of considering linked lives when quantifying substance use-attributable harms and underscore the need for future research examining the intergenerational spillover effects of substance use in both directions, particularly in mother-child dyads.

The Typology of Alcohol Use Disorder: Latent Class Analyses of a Population-Based Swedish Sample

OBJECTIVE

The purpose of this study was to clarify the clinical heterogeneity of alcohol use disorder (AUD) in a national Swedish sample of affected individuals using latent class analysis.

METHOD

Using a Swedish population-based sample of AUD cases ascertained from medical, criminal, and pharmacy registries (n = 217,071), we applied latent class analysis to sex, externalizing and internalizing syndromes before first registration, and age at first registration. The resulting types were evaluated against 15 diverse validators and degree of resemblance in relative pairs concordant for AUD.

RESULTS

A three-class solution was preferred by fit indices. The three classes were as follows: type 1 (male preponderant, externalizing; 32%), type 2 (minimal prior psychopathology; 46%), and type 3 (mixed-sex internalizing; 23%). Repeated split-half analyses revealed the statistical stability of these solutions. Meaningful differences emerged between the classes on many validators. Type 1 had the greatest family disruption, lowest educational levels, most AUD registrations, highest rates of criminal registration, and highest genetic risk for externalizing disorders and AUD. Type 2 had the least social dysfunction. Type 3 had the highest educational attainment, genetic liability to internalizing disorders, and proportion of women. All types significantly aggregated in affected pairs of relatives.

CONCLUSIONS

Meaningful and reproducible subtypes of AUD, consistent with prior typological results, can be obtained from national registry-based samples. Using a range of external validators and patterns of familial aggregation, our results suggest that our three-class solution captured a meaningful proportion of the clinical heterogeneity of AUD.