The patterns of family genetic risk scores for eleven major psychiatric and substance use disorders in a Swedish national sample

Familial coaggregation of major psychiatric disorders and neurodevelopmental disorders among first-degree relatives of individuals with generalized anxiety disorder

BACKGROUND

Anxiety disorders, major psychiatric disorders (e.g., schizophrenia and major affective disorders), and neurodevelopmental disorders (e.g., autism and attention-deficit/hyperactivity disorder [ADHD]) may cluster together within families. However, whether the first-degree relatives (FDRs) of individuals with generalized anxiety disorder (GAD) are at an elevated risk of neurodevelopmental or major psychiatric disorders remains unknown.

METHODS

We identified 2,378,190 FDRs of patients with GAD and 9,512,760 birth year-matched and sex-matched controls from Taiwan's National Health Insurance Research Database. Neurodevelopmental disorders, including autism and ADHD, and major psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, and GAD, were identified.

RESULTS

The FDRs-parents, offspring, and siblings-of individuals with GAD were more likely to be diagnosed as having schizophrenia (relative risk: 1.22), bipolar disorder (1.36), major depressive disorder (1.29), autism (1.20), ADHD (1.52), obsessive-compulsive disorder (1.21), and GAD (1.61) than are the FDRs of individuals without GAD.

CONCLUSION

Our findings support the notion of a familial coaggregation between GAD, major psychiatric disorders, and neurodevelopmental disorders. Future studies should elucidate the definitive genetic etiology of this familial coaggregation.

The risks for major psychiatric disorders in the siblings of probands with major depressive disorder

Using a case-controlled study including siblings of major depression (MD) and control probands, born 1970-1990 and followed through 2018, we sought to clarify the degree to which the familial liability to MD is reflected in its clinical features, and the pattern of psychiatric disorders at elevated risk in the siblings of MD probands. The study population included full-siblings of 197,309 MD and matched 197,309 control probands. The proband-sibling tetrachoric correlation of for MD was +0.20. Both linear and quadratic effects of younger AAO and number of episodes significantly increased the risk of MD in siblings. Male sex, anxiety disorder, alcohol use disorder (AUD), inpatient treatment, psychotic symptoms, severity, and antidepressant prescription in MD probands increased the risk of MD in siblings. Cox proportional hazard models (hazard ratios, 95% CI) revealed a significantly increased risk of attention deficit hyperactivity disorder (1.82, 1.76-1.88), generalized anxiety disorder (1.79, 1.74-1.85), bipolar disorder (1.78, 1.70-1.85), MD (1.74, 1.72-1.76), obsessive-compulsive disorder (1.72, 1.65-1.80), phobic anxiety disorder (1.71, 1.65-1.76), and panic disorder (1.68, 1.64-1.72) in MD co-siblings. The HRs for AUD (1.64, 1.60-1.68), post-traumatic stress disorder (1.62, 1.59-1.66) were modestly lower, and the lowest was seen for schizophrenia (1.42, 1.30-1.54). The overall pattern of increased risk of these disorders was similar in reared-apart half-siblings and cousins of MD probands. Our findings suggest that MD is familial, and a range of important clinical factors predict its familial liability. The familial liability to MD, mostly due to genetic factors, is shared with a broad range of psychiatric disorders.

Assessment and ascertainment in psychiatric molecular genetics: challenges and opportunities for cross-disorder research

Psychiatric disorders are highly comorbid, heritable, and genetically correlated [1-4]. The primary objective of cross-disorder psychiatric genetics research is to identify and characterize both the shared genetic factors that contribute to convergent disease etiologies and the unique genetic factors that distinguish between disorders [4, 5]. This information can illuminate the biological mechanisms underlying comorbid presentations of psychopathology, improve nosology and prediction of illness risk and trajectories, and aid the development of more effective and targeted interventions. In this review we discuss how estimates of comorbidity and identification of shared genetic loci between disorders can be influenced by how disorders are measured (phenotypic assessment) and the inclusion or exclusion criteria in individual genetic studies (sample ascertainment). Specifically, the depth of measurement, source of diagnosis, and time frame of disease trajectory have major implications for the clinical validity of the assessed phenotypes. Further, biases introduced in the ascertainment of both cases and controls can inflate or reduce estimates of genetic correlations. The impact of these design choices may have important implications for large meta-analyses of cohorts from diverse populations that use different forms of assessment and inclusion criteria, and subsequent cross-disorder analyses thereof. We review how assessment and ascertainment affect genetic findings in both univariate and multivariate analyses and conclude with recommendations for addressing them in future research.

The impact of family-genetic risk scores on social functioning in individuals affected with six major psychiatric and substance use disorders in a Swedish National Sample

To examine whether the level of genetic risk in psychiatric disorders impacts the social functioning of affected individuals, we examine the relationship between genetic risk factors for major depression (MD), anxiety disorders (AD), bipolar disorder (BD), non-affective psychosis (NAP), alcohol use disorder (AUD), and drug use disorder (DUD) in disordered individuals and five adverse social outcomes: unemployment, residence in areas of social deprivation, social welfare, early retirement, and divorce. We examine all cases with registration for these disorders from 1995 to 2015 in individuals born in Sweden. Genetic risk was assessed by the family genetic risk score (FGRS) and statistical estimates by Cox proportional hazard models. High genetic risk was significantly and modestly associated with poorer social outcomes in 23 of 30 analyses. Overall, genetic risk for MD, AD, AUD, and DUD impacted social functioning more strongly in affected individuals than did genetic risk for BD and NAP. Social welfare had the strongest associations with genetic risk, and residence in areas of high deprivation had the weakest. In individuals suffering from psychiatric and substance use disorders, high levels of genetic risk impact not only clinical features but also diverse measures of social functioning.

Family Genetic-Risk Profiles Associated With Divorce

We used Swedish national register data (N = 2,828,777) to examine divorce and its associated patterns of family genetic risk scores (FGRS; personalized measures of genetic risk inferred from diagnoses in relatives) across ten psychiatric disorders: major depression, anxiety disorders, obsessive-compulsive disorder, bipolar disorder, schizophrenia, anorexia nervosa, alcohol use disorder, drug use disorder, ADHD, and autism-spectrum disorder. Individuals who divorced had elevated FGRS across all disorders compared to those who were stably married or never married. FGRS for all disorders were higher among divorced females compared to divorced males; among those who did not go on to have a stable second marriage compared to those who had a stable second marriage; and increased as the cumulative number of divorces increased. In summary, genetic predispositions for psychiatric disorders are associated with the propensity to divorce, and with several differences as a function of sex, remarriage, and the cumulative number of divorce transitions.

The number of episodes of major psychiatric and substance use disorders as an index of genetic risk and genetic heterogeneity

We investigate whether number of episodes (NoEs) meaningfully reflect genetic risk and genetic heterogeneity for five primary disorders-Drug Use Disorder (DUD), Alcohol Use Disorder (AUD), Major Depression (MD), Bipolar Disorder (BD), and Schizophrenia (SZ) ascertained from Swedish population registries. We utilize Genetic Risk Ratios (GRR)-defined as the ratio of the genetic risk for secondary disorders to the genetic risk for the primary disorder-derived from Family Genetic Risk Scores (FGRS). For all five primary disorders, genetic risk rose robustly with increasing NoEs. For both AUD and DUD, the GRR for all six secondary disorders-selected to have a likely genetic relationship with the particular primary disorder-declined with increasing NoEs so that cases of AUD and DUD with high versus low NoEs had both a higher genetic risk and a purer genetic signal. With MD, genetic risk maximized at an intermediate NoEs. While the GRRs for AUD and DUD in MD cases dropped sharply with increasing NoEs, GRR for BD increased. For BD, genetic risk rose sharply with increasing NoEs while for all secondary disorders the GRRs showed a mixture of modest increases and decreases. Like AUD and DUD, but even more markedly, selecting BD cases with high rates of recurrence would produce a sample with a high overall genetic risk and a relatively homogeneous genetic signal. For SZ, genetic risk rose moderately with increases in NoEs. GRRs for other non-affective psychoses (ONAP) and autism spectrum disorder (ASD) fell quite slowly with increasing NoEs, and more rapidly for other secondary disorders. Cases of SZ with high recurrence rates had a high genetic risk and a relatively pure signal, albeit with contributions from ONAP and ASD. In summary, NOEs are a robust index of genetic risk and genetic heterogeneity across our primary disorders with important inter-disorder differences.

Peer Social Genetic Effects and the Etiology of Substance Use Disorders, Major Depression, and Anxiety Disorder in a Swedish National Sample

OBJECTIVE

There is growing interest in how peers' genotypes may influence health (i.e., peer social genetic effects). The authors sought to clarify the nature of peer social genetic effects on risk for drug use disorder, alcohol use disorder (AUD), major depression, and anxiety disorder.

METHOD

Cox models were used with data from a population-based Swedish cohort (N=655,327). Outcomes were drug use disorder, AUD, major depression, and anxiety disorder registrations between ages 17 and 30 from medical, criminal, and pharmacy registries. The authors indexed peer social genetic effects with peers' family genetic risk scores (FGRSs) for the same disorders, which are personalized measures of genetic risk inferred from diagnoses in first- to fifth-degree relatives.

RESULTS

Across disorders, peer FGRSs predicted increased risks of proband registration (hazard ratio range, 1.01-1.59), with stronger effects for drug use disorder and AUD than for major depression and anxiety disorder. Peer social genetic effects were stronger for school classmates than for geographically proximal peers, and for peers from upper secondary school (ages 16-19) versus peers from lower secondary school (ages 7-16). Peer social genetic effects remained significant following statistical control for sociodemographic confounders, whether peers were affected, and peers' FGRS for educational attainment. Peer social genetic effects were more pronounced for probands at higher genetic risk.

CONCLUSIONS

The genetic makeup of adolescents' peers has long-reaching consequences on risks for drug use disorder, AUD, major depression, and anxiety disorder. Individuals at high genetic risk are more sensitive to social genetic effects. Alternative hypotheses such as sociodemographic stratification, exposure to affected peers, and genetic predispositions for educational attainment did not explain the risk associated with peer social genetic effects for substance use and psychiatric disorders.

The Prediction of Diagnostic Change From Bipolar Disorder to Schizophrenia and Schizophrenia to Bipolar Disorder in a Population-Based, Longitudinal, National Swedish Sample

BACKGROUND AND HYPOTHESIS

To clarify, in a large, representative, longitudinal sample, the rate and predictors of diagnostic conversion from Bipolar Disorder (BD) to Schizophrenia (SZ) and from SZ→BD.

DESIGN

From individuals born in Sweden 1950-1995 and living there in 1970 or later, we identified at least one initial diagnoses of SZ (n = 8449) and BD (n = 8438) followed for a minimum of 10 and a mean of 24 years. Diagnostic conversion required, respectively, at least two final diagnoses of BD and SZ 30 days apart with no intervening diagnosis of SZ or BD.

RESULTS

At follow-up, rates of BD→SZ and SZ→BD conversion were 10.1 and 4.5%, respectively. Conversions occurred slowly, with around 50% completed in the first decade. Using a diverse range of variables available at first onset including family genetic risk scores, BD→SZ conversion was predicted with greater accuracy (AUC = 0.78) than SZ→BD conversion (AUC = 0.65). The strongest predictors of BD→SZ conversion were earlier years of birth, younger age at BD onset, low BD genetic risk, and being unmarried at BD onset. SZ→BD conversion was most strongly predicted by high BD genetic risk, being married at SZ onset, female sex, early age at SZ onset, and an MD episode prior to SZ onset. Cases of BD and SZ in the highest decile for conversion risk had HRs for a diagnostic change of, respectively, 12.5 and 3.4.

CONCLUSIONS

Diagnostic conversion of BD→SZ and SZ→BD are not rare, are moderately predictable, and should likely be accounted for in many research designs.

Environmental risk factors for schizophrenia and bipolar disorder from childhood to diagnosis: a Swedish nested case-control study

BACKGROUND

Shared genetic risk between schizophrenia (SCZ) and bipolar disorder (BD) is well-established, yet the extent to which they share environmental risk factors remains unclear. We compare the associations between environmental exposures during childhood/prior to disorder onset with the risk of developing SCZ and BD.

METHODS

We conducted a Swedish register-based nested case-control study using 4184 SCZ cases and 18 681 BD cases diagnosed 1988-2013. Cases were matched to five controls by birth year, birth region, and sex. Conditional logistic regression was used to estimate incidence rate ratios (IRR) for SCZ and BD for each exposure (severe childhood infections, adverse childhood experiences (ACEs), substance use disorders (SUDs), urban birth/longest residence).

RESULTS

All SUD types were associated with very high risk (IRR 4.9-25.5), and all forms of ACEs with higher risk (IRR 1.5-4.3) for both disorders. In the mutually adjusted models, ACEs demonstrated slightly higher risk for BD (SCZ IRR 1.30, 1.19-1.42; BD IRR 1.49, 1.44-1.55), while for SUD, risk was higher for SCZ (SCZ IRR 9.43, 8.15-10.92; BD IRR 5.50, 5.15-5.88). Infections were associated with increased risk of BD (IRR 1.21, 1.17-1.26) but not SCZ. Urban birth and urban longest residence were associated with higher risk of SCZ (IRR 1.19, 1.03-1.37), while only the combination of urban birth and rural longest residence showed higher risk for BD (IRR 1.24, 1.13-1.35).

CONCLUSIONS

There were both shared and unique environmental risk factors: SUDs and ACEs were risk factors for both disorders, while infections were more strongly associated with BD and urbanicity with SCZ.

The genetic epidemiology of schizotypal personality disorder

BACKGROUND

The concept of schizotypal personality disorder (SPD) emerged from observations of personality characteristics common in relatives of schizophrenic patients. While often studied in family designs, few studies and none with genetic measures, have examined SPD in epidemiological samples.

METHODS

We studied individuals born in Sweden 1940-2000 with an ICD-10 diagnosis of SPD with no prior schizophrenia (SZ) diagnosis (n = 2292). Demographic features, patterns of comorbidity, and Family Genetic Risk Scores (FGRS) were assessed from multiple Swedish registries. Prediction of progression to SZ was assessed by Cox models.

RESULTS

SPD was rare, with a prevalence of 0.044%, and had high levels of comorbidity with autism spectrum disorder (ASD), OCD, ADHD, and major depression (MD), and increased rates of being single, unemployed and in receipt of welfare. Affected individuals had elevated levels of FGRS for SZ (+0.42), ASD (+0.30), MD (+0.29), and ADHD (+0.20). Compared to cases of schizophrenia, they had significantly lower rates of FGRSSZ, but significantly elevated rates of genetic risk for ASD, MD, and ADHD. Over a mean follow-up of 8.7 years, 14.6% of SPD cases received a first diagnosis of SZ, the risk for which was significantly increased by levels of FGRSSZ, male sex, young age at SPD diagnosis and an in-patient SPD diagnosis and significantly decreased by comorbidity with MD, ASD, and ADHD.

CONCLUSIONS

Our results not only support the designation of SPD as a schizophrenia spectrum disorder but also suggest potentially important etiologic links between SPD and ASD and, to a lesser extent, ADHD, OCD, and MD.

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.

The predictive effect of family genetic risk scores as an indirect measure of causal effects of one disorder on another

BACKGROUND

One potential cause of comorbidity is the direct causal effect of one disorder - A - on risk for subsequent onset of disorder B. Could genetic risk scores be utilized to test for such an effect? If disorder A causally impacts on risk for disorder B, then genetic risk for disorder A should be lower in cases of disorder A with v. without a prior onset of B.

METHODS

In all individuals (n = 905 736) born in Sweden from 1980 to 1990, from six psychiatric and drug use disorders (major depression, anxiety disorders, alcohol use disorder, drug use disorder, bipolar disorder, and schizophrenia), we formed 14 pairs of disorders A and B. In these pairs, we compared, using Cox proportional hazards models, the predictive effect of the familial-genetic risk score (FGRS) for disorder B in those who had v. had not had a prior onset of disorder A.

RESULTS

In all pairs, the impact of the FGRS for disorder B was significantly stronger in cases without v. with a prior history of disorder A. These effects were similar across sex, stable across levels of FGRS and not likely due to clinician bias. In many of our disorder pairs, previous clinical studies suggest a mechanism for a causal effect of disorder A on B.

CONCLUSIONS

Our findings provide indirect evidence that the occurrence of one psychiatric or substance use disorder often has a causal effect on risk for subsequent disorders. This mechanism may substantially contribute to the widespread comorbidity among psychiatric conditions.

The joint effects of genetic liability and the death of close relatives on risk for major depression and alcohol use disorder in a Swedish national sample

BACKGROUND

To determine whether genetic risk factors for major depression (MD) and alcohol use disorder (AUD) interact with a potent stressor - death of spouse, parent, and sibling - in predicting episodes of, respectively, MD and AUD.

METHODS

MD and AUD registrations were assessed from national Swedish registries. In individuals born in Sweden 1960-1970, we identified 7586, 388 459, and 34 370 with the loss of, respectively, a spouse, parent, and sibling. We started following subjects at age 18 or the year 2002 with end of follow-up in 2018. We examined time to event - a registration for MD within 6 months or AUD within a year - on an additive scale, using the Nelson-Aalen estimator. Genetic risk was assessed by the Family Genetic Risk Score (FGRS).

RESULTS

In separate models controlling for the main effects of death of spouse, parent, and sibling, FGRS, and sex, significant interactions were seen in all analyses between genetic risk for MD and death of relative in prediction of subsequent MD registration. A similar pattern of results, albeit with weaker interaction effects, was seen for genetic risk for AUD and risk for AUD registration. Genetic risk for bipolar disorder (BD) and anxiety disorders (AD) also interacted with event exposure in predicting MD.

CONCLUSIONS

Genetic risk for both MD and AUD act in part by increasing the sensitivity of individuals to the pathogenic effects of environmental stressors. For prediction of MD, similar effects are also seen for genetic risk for AD and BD.

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.

The ethics of polygenic scores in psychiatry: minefield or opportunity for patient-centered psychiatry?

Recent advancements in psychiatric genetics have sparked a lively debate on the opportunities and pitfalls of incorporating polygenic scores into clinical practice. Yet, several ethical concerns have been raised, casting doubt on whether further development and implementation of polygenic scores would be compatible with providing ethically responsible care. While these ethical issues warrant thoughtful consideration, it is equally important to recognize the unresolved need for guidance on heritability among patients and their families. Increasing the availability of genetic counseling services in psychiatry should be regarded as a first step toward meeting these needs. As a next step, future integration of novel genetic tools such as polygenic scores into genetic counseling may be a promising way to improve psychiatric counseling practice. By embedding the exploration of polygenic psychiatry into the supporting environment of genetic counseling, some of the previously identified ethical pitfalls may be prevented, and opportunities to bolster patient empowerment can be seized upon. To ensure an ethically responsible approach to psychiatric genetics, active collaboration with patients and their relatives is essential, accompanied by educational efforts to facilitate informed discussions between psychiatrists and patients.

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.

The relationship between familial-genetic risk and pharmacological treatment in a Swedish national sample of patients with major depression, bipolar disorder, and schizophrenia

Using Swedish registers, we examine whether the prescription of and the response to antidepressants (AD), mood stabilizers (MS), and antipsychotics (AP) in the treatment of, respectively, major depression (MD), bipolar disorder (BD), and schizophrenia (SZ), are influenced by familial-genetic risk. We examined individuals born in Sweden 1960-1995 with a first diagnosis of MD (n = 257,177), BD (n = 23,032), and SZ (n = 4248) from 2006 to 2018. Drug classes and Defined Daily Dose (DDD) were obtained from the Pharmacy register using the Anatomical Therapeutic Chemical system. We utilized the Familial Genetic Risk Scores (FGRS) calculated from morbidity risks in first- through fifth degree relatives. Treatment with antidepressants (AD) in MD, mood-stabilizers (MS) in BD, and antipsychotics (AP) in SZ were associated with significantly higher disorder-specific familial-genetic risks. Using dosage trajectory analysis of AD, MS, and AP treatment for MD, BD, and SZ, respectively, familial-genetic risk was positively associated with higher and/or increasing drug dosages over time. For MD and BD, examining cases started on the most common pharmacologic treatment class (SSRIs for MD and "other anti-epileptics" for BD), familial-genetic risks were significantly lower in those who did not versus did later receive treatment from other AD and MS classes, respectively. Higher familial-genetic risk for BD predicted switching AD medication in cases of MD. Among pharmacologically treated cases of BD, familial-genetic risk was significantly higher for those treated with lithium. In a large population-based patient cohort, we found evidence of a wide-spread association between higher familial-genetic risk and i) increased likelihood of receiving pharmacologic treatment but 2) responding more poorly to it-as indicated by a switching of medications -- and/or requiring higher doses. Further investigations into the clinical utility of genetic risk scores in the clinical managements of MD, BD, and SZ are warranted.

Recognition of others' interoceptive states in those with and without eating disorders

BACKGROUND

The ability to recognize one's own emotions is associated with one's ability to recognize others' emotions. Beyond the domain of emotion, however, the relationship between recognition of one's own internal states (interoception) and others' interoceptive states has not been investigated, either in the typical population or clinical groups with interoceptive difficulties (e.g. eating disorders; EDs).

METHOD

This study investigated recognition of one's own and others' internal states in adults with and without eating disorders, using a high frequency visual noise paradigm. Participants completed self-report measures of interoception, alexithymia (difficulties recognising one's own emotional internal states) and ED symptomatology, and the Heartbeat Counting Task measure of cardiac interoceptive accuracy.

RESULTS

Alexithymia was significantly negatively correlated with recognition of others' interoceptive states. EDs were not associated with difficulties recognising others' interoceptive states.

CONCLUSIONS

The ability to recognise one's own emotional internal states is associated with the recognition of others' interoceptive states, which may contribute to social skills and the ability to care for others.

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.

Predictors of diagnostic conversion from major depression to bipolar disorder: a Swedish national longitudinal study

BACKGROUND

It is clinically important to predict the conversion of major depression (MD) to bipolar disorder (BD). Therefore, we sought to identify related conversion rates and risk factors.

METHODS

This cohort study included the Swedish population born from 1941 onward. Data were collected from Swedish population-based registers. Potential risk factors, including family genetic risk scores (FGRS), which were calculated based on the phenotypes of relatives in the extended family and not molecular data, and demographic/clinical characteristics from these registers were retrieved. Those with first MD registrations from 2006 were followed up until 2018. The conversion rate to BD and related risk factors were analyzed using Cox proportional hazards models. Additional analyses were performed for late converters and with stratification by sex.

RESULTS

The cumulative incidence of conversion was 5.84% [95% confidence interval (95% CI) 5.72-5.96] for 13 years. In the multivariable analysis, the strongest risk factors for conversion were high FGRS of BD [hazard ratio (HR) = 2.73, 95% CI 2.43-3.08], inpatient treatment settings (HR = 2.64, 95% CI 2.44-2.84), and psychotic depression (HR = 2.58, 95% CI 2.14-3.11). For late converters, the first registration of MD during the teenage years was a stronger risk factor when compared with the baseline model. When the interactions between risk factors and sex were significant, stratification by sex revealed that they were more predictive in females.

CONCLUSIONS

Family history of BD, inpatient treatment, and psychotic symptoms were the strongest predictors of conversion from MD to BD.

Selecting cases of major psychiatric and substance use disorders in Swedish national registries on the basis of clinical features to maximize the strength or specificity of the genetic risk

We investigate how selection of psychiatric cases by phenotypic criteria can alter the strength and specificity of their genetic risk by examining samples from national Swedish registries for five disorders: major depression (MD, N = 158,557), drug use disorder (DUD, N = 69,841), bipolar disorder (BD, N = 13,530)) ADHD (N = 54,996) and schizophrenia (N = 11,227)). We maximized the family genetic risk score (FGRS) for each disorder and then the specificity of the FGRS in six disorder pairs by univariable and multivariable regression. We use split-half methods to divide our cases for each disorder into deciles for prediction of genetic risk magnitude and quintiles for prediction of specificity by FGRS differences between two disorders. We utilized seven predictor groups: demography/sex, # registrations, site of diagnosis, severity, comorbidity, treatment, and educational/social variables. The ratio of the FGRS in the upper vs two lower deciles from our multivariable prediction model was, in order, DUD - 12.6, MD - 4.9, BD - 4.5, ADHD - 3.3 and schizophrenia 1.4. From the lowest to highest quintile, our measures of genetic specificity increased more than five-fold for i) MD vs. Anxiety Disorders, ii) MD vs BD, iii) MD versus alcohol use disorder (AUD), iv) BD vs schizophrenia and v) DUD vs AUD. This increase was nearly two-fold for ADHD vs DUD. We conclude that the level of genetic liability for our psychiatric disorders could be substantially enriched by selection of cases with our predictors. Specificity of genetic risk could also be substantially impacted by these same predictors.

Cross-generational transmission of genetic risk for alcohol and drug use disorders: the impact of substance availability on the specificity of genetic risk

BACKGROUND

Among individuals with alcohol use disorder (AUD) and drug use disorder (DUD), is their genetic liability and its specificity moderated by substance availability?

METHODS

Offspring (born 1960-1995) and their biological parents from three family types [not-lived-with (NLW) biological father, mother and adoptive] and their AUD and DUD diagnoses were ascertained from Swedish national registers. Parent-offspring resemblance was calculated by tetrachoric correlation.

RESULTS

In Swedes born from 1960 to 1995, prevalence rates of AUD were stable while DUD rates increased substantially. Best-estimate tetrachoric correlations (±95% confidence intervals) between AUD in biological parents and AUD and DUD in their offspring were, respectively, +0.19 (0.18-0.20) and +0.18 (0.17-0.20). Parallel results from DUD in parents to AUD and DUD in children were +0.12 (0.10-0.13) and +0.27 (0.26-0.28). When divided into older and younger cohorts, the specificity of DUD transmission increased substantially over time, while the genetic correlation between AUD and DUD significantly decreased.

CONCLUSIONS

Raised when alcohol was the preferred substance of abuse and illicit drugs highly stigmatized, AUD in parents reflected a general liability to substance use disorders, as they transmitted similar genetic risk for AUD and DUD to their children raised when both substances were widely available and relatively acceptable. DUD in parents, by contrast, reflected a more specific liability to DUD and, when transmitted to offspring, produced a considerably stronger risk for DUD than for AUD that increased over time. The magnitude and specificity of the genetic liability to psychoactive substances can be influenced by the availability of that substance.

A distinctive profile of family genetic risk scores in a Swedish national sample of cases of fibromyalgia, irritable bowel syndrome, and chronic fatigue syndrome compared to rheumatoid arthritis and major depression

BACKGROUND

Functional somatic disorders (FSD) feature medical symptoms of unclear etiology. Attempts to clarify their origin have been hampered by a lack of rigorous research designs. We sought to clarify the etiology of the FSD by examining the genetic risk patterns for FSD and other related disorders.

METHODS

This study was performed in 5 829 186 individuals from Swedish national registers. We quantified familial genetic risk for FSD, internalizing disorders, and somatic disorders in cases of chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS), using a novel method based on aggregate risk in first to fifth degree relatives, adjusting for cohabitation. We compared these profiles with those of a prototypic internalizing psychiatric - major depression (MD) - and a somatic/autoimmune disorder: rheumatoid arthritis (RA).

RESULTS

Patients with FM carry substantial genetic risks not only for FM, but also for pain syndromes and internalizing, autoimmune and sleep disorders. The genetic risk profiles for IBS and CFS are also widely distributed although with lower average risks. By contrast, genetic risk profiles of MD and RA are much more restricted to related conditions.

CONCLUSION

Patients with FM have a relatively unique family genetic risk score profile with elevated genetic risk across a range of disorders that differs markedly from the profiles of a classic autoimmune disorder (RA) and internalizing disorder (MD). A similar less marked pattern of genetic risks was seen for IBS and CFS. FSD arise from a distinctive pattern of genetic liability for a diversity of psychiatric, autoimmune, pain, sleep, and functional somatic disorders.

Is an elevated family-genetic risk for major psychiatric disorders specific to creative occupations?

BACKGROUND

Despite a large descriptive literature linking creativity and risk for psychiatric illness, the magnitude and specificity of this relationship remain controversial.

METHODS

We examined, in 1 137 354 native Swedes with one of 59 3-digit official and objective occupational codes in managerial and educated classes, their familial genetic risk score (FGRS) for ten major disorders, calculated from 1st through 5th degree relatives. Mean FGRS across disorders were calculated, in 3- and 4-digit occupational groups, and then controlled for those whose disorder onset preceded occupational choice. Using sequential analyses, p values were evaluated using Bonferroni correction.

RESULTS

3-digit professions considered to reflect creativity (e.g. 'artists' and 'authors') were among those with statistically significant elevations of FGRS. Among more specific 4-digit codes, visual artists, actors, and authors stood out with elevated genetic risks, highest for major depression (MD), anxiety disorders (AD) and OCD, more modest for bipolar disorders (BD) and schizophrenia and, for authors, for drug and alcohol use disorders. However, equal or greater elevations in FGRS across disorders were seen for religious (e.g. ministers), helping (e.g. psychologists, social workers), and teaching/academic occupations (e.g. professors). The potential pathway from FGRS → Disorder → Occupation accounts for a modest proportion of the signal, largely for MD and AD risk.

CONCLUSIONS

While traditional creative occupations were associated with elevated genetic risk for a range of psychiatric disorders, this association was not unique, as similar, or greater elevations were seen for religious, helping and teaching professions and was stronger for internalizing than psychotic disorders.

Sickness absence transitions among Swedish twins with back, neck or shoulder pain and common mental disorders applying a multi-state approach

We aimed to investigate transitions to and from sickness absence, or disability pension among individuals with back, neck, or shoulder pain and/or with common mental disorders (CMDs), and the role of familial (genetics and shared environment) influences on the transitions. Swedish twins born 1935-1985 who responded to pain and CMDs survey items (N = 41,516) were followed on average 8.7 years for sickness absence states in national registers. Multi-state Cox regression models were applied for three exposure groups: pain, CMDs, and presence of both, compared to unexposed. Exposure discordant twin pairs, stratified by zygosity, were analysed to assess the role of familial factors. Hazard Ratios (HR) with 95% confidence intervals and transition intensities were calculated. HRs were similar for transitions between states among those with pain or CMDs. The highest HRs were for transitions from entry to sickness absence and sickness absence to disability pension among those with both pain and CMDs (HRs: 1.61 and 1.43, respectively). Higher HRs for dizygotic compared to monozygotic twins for the first transition to sickness absence and for altering back to not being sickness absent indicate familial confounding. Back, neck, or shoulder pain and/or CMDs indicate a higher risk to become sickness absent and for repeated sickness absence episodes over time compared to unaffected.

Impact of Early-Life Factors on Risk for Schizophrenia and Bipolar Disorder

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) and bipolar disorder (BD) have shared genetic risk and clinical symptoms, yet the extent to which environmental risk factors are shared is not well known. We aimed to examine the associations of early-life environmental exposures with the risk of SCZ and BD.

STUDY DESIGN

We conducted a Swedish register-based nested case-control study using 4184 SCZ and 18 681 BD cases diagnosed 1988-2013, individually matched to 5 population-based controls by birth year, sex and birthplace. Conditional logistic regression was used to evaluate the risk of SCZ and BD by seasonality, severe prenatal infections, and perinatal factors.

STUDY RESULTS

Seasonality had similar patterns of risk for both disorders: Higher risk for births November-December; lower risk April-June. Experiencing any perinatal factor was associated with a significantly higher risk of SCZ (incidence rate ratio [IRR] 1.19, 95%CI 1.11-1.63) and to a lesser extent BD (IRR 1.08, 95%CI 1.05-1.12). Prenatal infections were only associated with a greater risk of SCZ (IRR 1.30, 95%CI 1.04-1.63). In the mutually adjusted model, only perinatal factors were associated with outcomes. Several perinatal factors were associated with both disorders, but estimates were significantly higher for SCZ for low birth weight, low APGAR, and high parity. Congenital malformations were only associated with risk of SCZ, and jaundice with BD.

CONCLUSIONS

Adverse perinatal factors and winter birth were the risk factors for both disorders, while severe prenatal infections were only risk a factor for SCZ. Early-life exposures were associated with a higher risk of both disorders, but may play a larger role in the development of SCZ than BD.

The Interrelationship of the Genetic Risks for Different Forms of Substance Use Disorder in a Swedish National Sample: A Top-Down Genetic Analysis

OBJECTIVE

The purpose of this study was to determine, using a top-down genetic analysis, the degree of specificity of the genetic risk factors for individual forms of substance use disorders (SUD).

METHOD

We examined and followed to December 31, 2018, all individuals born in Sweden between 1960 and 1990 (N = 2,772,752) diagnosed with any of the following six SUDs: alcohol use disorder (AUD), drug use disorder (DUD), or one of four specific forms of DUD involving cannabis (CUD), cocaine and other stimulants (CSUD), opioids (OUD), or sedatives (SeUD). We examined population subsamples at high versus median genetic liability to each of these SUDs. In those samples, we then examined the prevalence of our SUDs in the high versus median liability groups, expressed as a tetrachoric correlation. Genetic liability was assessed by a family genetic risk score.

RESULTS

All SUDs were concentrated in those at high versus median risk for all six groups. DUD, CUD, and CSUD showed modest genetic specificity in that they were more concentrated in samples with high genetic liability to each of them than were other SUDs. The differences, however, were modest. No evidence for genetic specificity was seen for AUD, OUD, and SeUD, as other disorders were equally or more concentrated in those at high versus median genetic risk for that form of SUD.

CONCLUSIONS

Individuals at high genetic risk for particular forms of SUD typically had elevated rates for all forms of SUDs, consistent with the nonspecificity of much of SUD genetic liability. Evidence of specificity of genetic risk for particular forms of SUD was noted but was quantitatively modest.

Obsessive-compulsive symptoms in the schizophrenia-spectrum: current developments in psychopathology research

PURPOSE OF REVIEW

Schizophrenia-spectrum disorders (SSD) frequently involve symptoms that usually are ascribed to nonpsychotic disorder spectra, such as obsessive-compulsive symptoms (OCS). These symptoms can cause differential diagnostic challenges, particularly in early illness stages, and must be considered in treatment planning. In this review, we provide an overview of recent literature within the field of OCS in SSD, with a focus on psychopathology research.

RECENT FINDINGS

OCS are seen in approximately a quarter of patients with SSD or at-risk mental state of psychosis. They are associated with more severe clinical features and specific temporal patterns of OCS may be linked with different clinical trajectories. However, the current definitions of OCS have been criticized for their overinclusive nature, which is a limiting step for differential diagnosis and more precise prognostic stratification. Specific phenomenological features, including a link with experiential anomalies (disorders of basic self), have been suggested to provide clinically relevant distinctions.

SUMMARY

The presence of OCS in SSD is associated with more severe clinical features and invites a higher clinical attention and perspectival monitoring. Some findings suggest that more fine-grained psychopathological distinctions might be a viable clinical and research strategy to advance the field in the direction of precision psychiatry.

The moderation of the genetic risk for alcohol and drug use disorders in a Swedish national sample by the genetic aptitude for educational attainment

BACKGROUND

Does the genetic aptitude for educational attainment (GAEA) moderate the genetic risk for alcohol use disorder (AUD) and drug use disorder (DUD)?

METHODS

In the native Swedish population, born 1960-1980 and followed through 2017 (n = 1 862 435), the family genetic risk score (FGRS) for AUD and DUD and GAEA were calculated from, respectively, the educational attainment and risk for AUD and DUD, of 1st through 5th degree relatives from Swedish national registers. Analyses utilized Aalen's linear hazards models.

RESULTS

Risk for AUD was robustly predicted by the main effects of FGRSAUD [b = 6.32 (95% CI 6.21-6.43), z = 64.9, p < 0.001) and GAEA [b = -2.90 (2.83-2.97), z = 44.1, p < 0.001] and their interaction [b = -1.93 (1.83-2.03), z = 32.9, p < 0.001]. Results were similar for the prediction of DUD by the main effects of FGRSDUD [b = 4.65 (CI 4.56-4.74), z = 59.4, p < 0.001] and GAEA [-2.08 (2.03-2.13), z = 46.4, p < 0.001] and their interaction [b = -1.58 (1.50-1.66)), z = 30.2, p < 0.001]. The magnitude of the interactions between GAEA and FGRSAUD and FGRSDUD in the prediction of, respectively, AUD and DUD was attenuated only slightly by the addition of educational attainment to the model.

CONCLUSIONS AND RELEVANCE

The genetic propensity to high educational attainment robustly moderates the genetic risk for both AUD and DUD such that the impact of the genetic liability to AUD and DUD on the risk of illness is substantially attenuated in those with high v. low GAEA. This effect is not appreciably mediated by the actual level of educational attainment. These naturalistic findings could form the basis of prevention efforts in high-risk youth.

Impact of comorbidity on family genetic risk profiles for psychiatric and substance use disorders: a descriptive analysis

BACKGROUND

- Comorbidity between psychiatric disorders is extensive but, from a genetic perspective, still poorly understood. Modern molecular genetic approaches to this problem are limited by a reliance on case-control designs.

METHODS

- In 5 828 760 individuals born in Sweden from 1932-1995 with a mean (s.d.) age at follow-up of 54.4 (18.1), we examined family genetic risk score (FGRS) profiles including internalizing, psychotic, substance use and developmental disorders in 10 pairs of psychiatric and substance use disorders diagnosed from population registries. We examined these profiles in three groups of patients: disorder A only, disorder B only and comorbid cases with both disorders.

RESULTS

- The most common pattern of findings, seen in five pairings, was simple and quantitative. Comorbid cases had higher FGRS than both non-comorbid cases for all (or nearly all) disorders. However, the pattern was more complex in the remaining five pairings and included qualitative changes where the comorbid cases showed no increases in FGRS for certain disorders and in a few cases significant decreases. Several comparisons showed an asymmetric pattern of findings with increases, in comorbidity compared to single disorder cases, of the FGRS for only one of the two disorders.

CONCLUSIONS

- The examination of FGRS profiles in general population samples where all disorders are assessed in all subjects provides a fruitful line of inquiry to understand the origins of psychiatric comorbidity. Further work will be needed, with an expansion of analytic approaches, to gain deeper insights into the complex mechanisms likely involved.

The impact of sex, age at onset, recurrence, mode of ascertainment and medical complications on the family genetic risk score profiles for alcohol use disorder

BACKGROUND

Alcohol use disorder (AUD) is clinically heterogeneous. We examine its potential genetic heterogeneity as a function of sex, age, clinical features and mode of ascertainment.

METHODS

In the Swedish population born 1932-1995 (n = 5 829 952), we examined the genetic risk profiles for AUD, major depression (MD), anxiety disorders, bipolar disorder, drug use disorder (DUD), attention deficit-hyperactivity disorder (ADHD) and criminal behavior (CB) in 361 124 cases of AUD subdivided by sex, age at onset (AAO), recurrence, mode of ascertainment and medical complications. Family genetic risk scores (FGRS), calculated from 1st to 5th-degree relatives controlling of cohabitation, assesses genetic risk from phenotypes in the family, not from DNA variants.

RESULTS

FGRS profiles differed modestly across sex with all scores higher in females. Differences were more pronounced for AAO and recurrence with the FGRS for AUD, DUD, ADHD and CB substantially higher in cases with early AAO or high recurrence rates. Genetic profiles differed considerably by mode of ascertainment, with higher FGRS for AUD and most other disorders in patients seen in hospital v. primary care settings. Cases of AUD with medical complications had higher FGRS for AUD. AUD cases comorbid with MD and DUD had higher FGRS risk for AUD, but this genetic may be less specific given increases in FGRS for multiple other disorders.

CONCLUSIONS

From a genetic perspective, AUD differs substantially as a function of AAO, recurrence, mode of ascertainment and patterns of comorbidity, suggesting caution in cross-sample comparisons of AUD cohorts that differ in these features.

Preventing eating disorders and disordered eating in genetically vulnerable, high-risk families

OBJECTIVE

To close the chasm between theory about families containing a parent with an eating disorders (EDs) history and lack of selective or indicated prevention programming for such families with an older child or adolescent who is, genetically, at high risk.

METHOD

A search of four major databases for January 2000 through September 2022 yielded no publications that (a) identified genetically high-risk families with offspring ages 10 through 18; (b) devised a prevention program for the family; and (c) evaluated program effects on risk/protective factors. To rectify this gap, research on three lines of family-based prevention is reviewed: (1) programs for adolescents at genetic risk for depression or anxiety; (2) the Stanford-Dresden project for adolescents at high risk for anorexia nervosa; and (3) Sadeh-Sharvit et al.'s work concerning the Parent-Based Prevention program for mothers with an EDs history and a child under age 5.

RESULTS

The significant challenges for innovative prevention programming should be addressed by experts in effective EDs, depression, and anxiety prevention, and in family-based treatment (FBT) for EDs, collaborating with people from genetically vulnerable families. Innovative programming should focus on robust risk factors for EDs, adaptive expression of non-specific risk factors (e.g., temperament), and strengthening family functioning.

DISCUSSION

The field is overdue for development of prevention programs designed for older children or adolescents who are at risk because a parent has an ED. Evidence-based prevention programs for EDs and for depression and anxiety, as well as parent-based prevention informed by FBT, provide a springboard for addressing this gap.

PUBLIC SIGNIFICANCE

The foundation of theory and research is available for stakeholders to develop prevention programming that closes the huge gap between theory and research about families that are genetically vulnerable for eating disorders versus the complete lack of prevention programming for such families that have an older child or adolescent at high risk.

Relationship of Family Genetic Risk Score With Diagnostic Trajectory in a Swedish National Sample of Incident Cases of Major Depression, Bipolar Disorder, Other Nonaffective Psychosis, and Schizophrenia

Importance

Since its inception under Kraepelin in the modern era, diagnostic stability and familial/genetic risk have been among the most important psychiatric nosologic validators.

Objective

To assess the interrelationships of family genetic risk score (FGRS) with diagnostic stability or diagnostic change in major depression (MD), bipolar disorder (BD), other nonaffective psychosis (ONAP), and schizophrenia.

Design, Setting, and Participants

This longitudinal population-based cohort (N = 4 171 120) included individuals with incident cases of MD (n = 235 095), BD (n = 11 681), ONAP (n = 16 009), and schizophrenia (n = 6312) who had at least 1 further diagnosis of the 4 disorders during follow-up, as assessed from Swedish national medical registries, observed over a mean (SD) of 13.1 (5.9) years until a mean (SD) age of 48.4 (12.3) years. Data were collected from January 1973 to December 2018, and data were analyzed from August to September 2022.

Exposures

FGRS for MD, BD, ONAP, and schizophrenia, calculated from morbidity risks for disorders in first-degree through fifth-degree relatives, controlling for cohabitation effects.

Main Outcomes and Measures

Final diagnostic outcome of MD, BD, ONAP, or schizophrenia.

Results

Of 269 097 included individuals, 173 061 (64.3%) were female, and the mean (SD) age at first registration was 35.1 (11.9) years. Diagnostic stability was highest for MD (214 794 [91.4%]), followed by schizophrenia (4621 [73.2%]), BD (7428 [63.6%]), and ONAP (6738 [42.1%]). The second most common final diagnosis for each of these MD, schizophrenia, BD, and ONAP were BD (15 506 [6.6%]), ONAP (1110 [17.6%]), MD (2681 [23.0%]), and schizophrenia (4401 [27.5%]), respectively. A high FGRS for the incident diagnosis was consistently associated with diagnostic stability, while a high FGRS for the final diagnosis and a low FGRS for the incident diagnosis was associated with diagnostic change. In multivariate models, those in the upper 5% of genetic risk had an odds ratio (OR) of 1.75 or greater for the following diagnostic transition: for MD FGRS, ONAP to MD (OR, 1.91; 95% CI, 1.59-2.29) and schizophrenia to MD (OR, 2.45; 95% CI, 1.64-3.68); for BD FGRS, MD to BD (OR, 2.60; 95% CI, 2.47-2.73), ONAP to BD (OR, 2.16; 95% CI, 1.85-2.52), and schizophrenia to BD (OR, 2.20; 95% CI, 1.39-3.49); for ONAP FGRS, MD to ONAP (OR, 1.80; 95% CI, 1.62-2.02), MD to schizophrenia (OR, 1.95; 95% CI, 1.58-2.41), and BD to schizophrenia (OR, 1.89; 95% CI, 1.39-2.56); and for schizophrenia FGRS, MD to schizophrenia (OR, 1.80; 95% CI, 1.46-2.23), and BD to schizophrenia (OR, 1.75; 95% CI, 1.25-2.45). FGRS profiles for incident cases confirmed at final diagnosis were more homogenous than genetic profiles for those who changed diagnoses.

Conclusions and Relevance

In a large population-based longitudinal cohort, the genetic risk factors for MD, BD, ONAP, and schizophrenia were meaningfully and systematically associated with the diagnostic trajectories of these 4 disorders. Over time, clinical diagnosis and genetic risk profiles became increasingly consilient, thereby providing genetic validation of these diagnostic constructs. Diagnostically unstable incident cases were more genetically heterogeneous than those who were diagnostically stable over time.

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.

Social genetic effects for drug use disorder among spouses

AIMS

Preclinical and human studies suggest that a social partner's genotype may be associated with addiction-related outcomes. This study measured whether spousal genetic makeup is associated with risk of developing drug use disorder (DUD) during marriage and whether the risk associated with a spouse's genotype could be disentangled from potentially confounding rearing environmental effects.

DESIGN

Univariable and multivariable logistic regression analyses.

SETTING

Sweden.

PARTICIPANTS

Men and women born between 1960 and 1990 and in opposite-sex first marriages before age 35 (n = 294 748 couples).

MEASUREMENTS

Outcome was DUD diagnosis (inclusive of opioids, sedatives/hypnotics/anxiolytics, cocaine, cannabis, amphetamine and other psychostimulants, hallucinogens, other drugs of abuse and combinations thereof) obtained from legal, medical and pharmacy registries. The focal predictor was family genetic risk scores for DUD (FGRS-DUD), which were inferred from diagnoses in first- through fifth-degree relatives and weighted by degree of genetic sharing. FGRS-DUD were calculated separately for each partner in a couple.

FINDINGS

Marriage to a spouse with a high FGRS-DUD was associated with increased risk of developing DUD during marriage, OR_males  = 1.68 (95% CI = 1.50, 1.88) and OR_females  = 1.35 (1.16, 1.56), above and beyond the risk associated with one's own FGRS-DUD. The risk associated with a spouse's FGRS-DUD remained statistically significant after covarying for parental education. As indicated by a series of null interaction effects, there was no evidence that the risk associated with a spouse's FGRS-DUD differed depending on whether the spouse was DUD-affected, probands' probable contact with in-laws and whether the spouse was raised by his/her biological parents or in another home.

CONCLUSIONS

There is relatively robust evidence that a person's risk for developing drug use disorder is associated with the genetic makeup of the person's spouse.

Risk for Mood, Anxiety, and Psychotic Disorders in Individuals at High and Low Genetic Liability for Bipolar Disorder and Major Depression

Importance

The nature of the genetic relationship between major depression and bipolar disorder remains unclear and might be clarified by considering disorders outside of the mood spectrum.

Objective

To better understand the relationship between genetic liabilities for major depression (MD) and bipolar disorder (BD).

Design, Setting, and Participants

A cohort study was conducted with data for individuals born in Sweden to Swedish parents from 1960 to 1990, with follow-up through December 31, 2018. The data included family genetic risk scores for MD and BD and International Classification of Diseases codes for a range of disorders as reported in primary care, specialist, and hospital registries. Data analysis was conducted from April 2022 to July 2022.

Exposures

High and low genetic liability were defined as being in the upper and lower 2 risk deciles. Risk was compared in individuals at high genetic liability to (1) MD only, (2) BD only, and (3) both MD and BD and those at (4) high genetic liability to BD and low genetic liability to MD and (5) high genetic liability to MD and low genetic liability to BD.

Main Outcomes and Measures

Risk for nonpsychotic MD and BD, psychotic MD and BD, anxiety disorders, obsessive-compulsive disorder, schizoaffective disorder (SAD), schizophrenia, and other nonaffective psychosis.

Results

Data were included for 2 736 950 individuals with a mean (SD) age at follow-up of 43.9 (9.1) years. High genetic liability to only BD increased risk for nonpsychotic BD, psychotic BD, and SAD. High genetic liability to only MD augmented risk for nonpsychotic MD, anxiety disorders, and nonpsychotic BD. High genetic liability to both BD and MD had the strongest association with risk for nonpsychotic BD, anxiety disorders, and nonpsychotic MD. High genetic liability to BD and low genetic liability to MD increased risk for psychotic BD, nonpsychotic BD, and SAD with no increased risk for nonpsychotic MD or anxiety disorders. High genetic liability to MD and low genetic liability to BD increased risk for nonpsychotic MD, nonpsychotic BD, and anxiety disorders with no increased risk for psychotic BD.

Conclusions and Relevance

In this study, hypotheses that BD and MD are either genetically distinct or genetically closely interrelated were not supported. Both BD and MD were associated with a genetic vulnerability to mood disorders, but even that liability was partially selective. However, compared with individuals at high liability to MD, those at elevated genetic liability for BD had a substantially increased risk for psychosis. Compared with individuals at elevated genetic liability to BD, those at high genetic risk for MD had a considerably augmented risk for anxiety disorders. Clarifying genetic relationships between psychiatric syndromes can be substantially aided by the consideration of profiles of risk for a range of disorders.

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.

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.

The actions and interactions of family genetic risk scores for alcohol use disorder and major depression on the risk for these two disorders

We know little about how genetic risk factors for two disorders jointly act and interact in predisposing to illness. Therefore, in the Swedish population, born 1970-1990 (n = 2,116,082) and followed through 2015, we examine, using additive Cox models, the impact of the family genetic risk scores (FGRS) for alcohol use disorder (AUD) and major depression (MD), their interaction with each other and with the relevant comorbid disorder on risk for AUD and MD. FGRS scores are constructed using rates of illness in first-fourth degree relatives. FGRS for AUD and MD interacted in predicting of both disorders and one FRGS (e.g., for AUD) interacted with the phenotype of MD to predict that disorder (e.g., AUD). These FGRS interactions were not substantially attenuated by adding interactions with the disorders. These results replicated across sexes. In predicting risk for a given disorder, we rarely consider genetic liabilities for other disorders. But such effects were here significant and interactive. Furthermore, the primary disorder genetic risk interacts with comorbid disorders. The pathways to risk for disorders from their and other disorders' genetic liability may be more complex than commonly considered.

Attention-Deficit/Hyperactivity Disorder and Alcohol and Other Substance Use Disorders in Young Adulthood: Findings from a Canadian Nationally Representative Survey

AIM

(a) To document the prevalence and odds of (i) alcohol use disorders, (ii) cannabis use disorders, (iii) other drug use disorders and (iv) any substance use disorder (SUD), among young adults with and without ADHD, and (b) to investigate the degree to which the association between ADHD and SUDs is attenuated by socio-demographics, early adversities and mental health.

METHOD

Secondary analysis of the nationally representative Canadian Community Health Survey-Mental Health (CCHS-MH). The sample included 6872 respondents aged 20-39, of whom 270 had ADHD. The survey response rate was 68.9%.

MEASUREMENTS

Substance Use Disorder: World Health Organization's Composite International Diagnostic Interview criteria, SUDs, were derived from lifetime algorithms for alcohol, cannabis and other substance abuse or dependence. ADHD was based on self-report of a health professional's diagnosis.

FINDINGS

One in three young adults with ADHD had a lifetime alcohol use disorder (36%) compared to 19% of those without ADHD (P < 0.001). After adjusting for all control variables, those with ADHD had higher odds of developing alcohol use disorders (OR = 1.38, 95% CI: 1.05, 1.81), cannabis use disorders (OR = 1.46, 95% CI: 1.06, 2.00), other drug use disorders (OR = 2.07, 95% CI: 1.46, 2.95) and any SUD (OR = 1.69, 95% CI: 1.28, 2.23). History of depression and anxiety led to the largest attenuation of the ADHD-SUD relationship, followed by childhood adversities and socioeconomic status.

CONCLUSIONS

Young adults with ADHD have a high prevalence of alcohol and other SUDs. Targeted outreach and interventions for this extremely vulnerable population are warranted.