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Background Nonrandom mating has been shown for psychiatric diagnoses, with hypothesized—but not quantified—implications for offspring liability. This national cohort study enumerated the incidence of major psychiatric disorders among the offspring of parent pairs affected with schizophrenia (SCZ) and/or bipolar disorder (BIP) (i.e., dual-affected pairs). Methods Participants were all Swedish residents alive or born between 1968 and 2013 (n = 4,255,196 unique pairs and 8,343,951 offspring). Offspring with dual-affected, single-affected, and unaffected parents were followed (1973–2013) for incidence of broad psychiatric disorders. Primary outcomes included hazard ratio (HR) and cumulative incidence for SCZ and BIP in the offspring. Additional outcomes included any neuropsychiatric, anxiety, depressive, personality, or substance use disorders. Cumulative incidences of SCZ and BIP were used to inform heritability models for these disorders. Results Hazards were highest within disorder (e.g., offspring of dual-SCZ pairs had sharply raised hazards for SCZ [HR = 55.3]); however, they were significantly raised for all diagnoses (HR range = 2.89–11.84). Incidences were significantly higher for the majority of outcomes, with 43.4% to 48.5% diagnosed with “any” disorder over follow-up. Risks were retained, with modest attenuations, for the offspring of heterotypic pairs. The estimated heritability of liability for SCZ (h2 = 0.62, 95% confidence interval = 0.55–0.70) and BIP (h2 = 0.52, 95% confidence interval = 0.46–0.58) did not differ significantly from estimates derived from single-affected parents. Conclusions Risks for a broad spectrum of psychiatric diagnoses are significantly raised in the offspring of dual-affected parents, in line with expectations from a polygenic model of liability to disease risk. How these risks may contribute to population maintenance of these disorders is considered.

In the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), obsessive-compulsive disorder (OCD) included a new “tic-related” specifier. However, strong evidence supporting tic-related OCD as a distinct subtype of OCD is lacking. This study investigated whether, at the population level, tic-related OCD has a stronger familial load than non-tic-related OCD. From a cohort of individuals born in Sweden between 1967 and 2007 (n = 4,085,367; 1257 with tic-related OCD and 20,975 with non-tic-related OCD), we identified all twins, full siblings, maternal and paternal half siblings, and cousins. Sex- and birth year-adjusted hazard ratios (aHR) were calculated to estimate the risk of OCD in relatives of individuals with OCD with and without comorbid tics, compared with relatives of unaffected individuals. We found that OCD is a familial disorder, regardless of comorbid tic disorder status. However, the risk of OCD in relatives of individuals with tic-related OCD was considerably greater than the risk of OCD in relatives of individuals with non-tic-related OCD (e.g., risk for full siblings: aHR = 10.63 [95% CI, 7.92–14.27] and aHR = 4.52 [95% CI, 4.06–5.02], respectively; p value for the difference

Background It remains unclear if individuals with Tourette syndrome (TS) or chronic tic disorder (CTD) have an elevated risk of subsequent substance misuse. Methods In this population-based cohort study, we investigated the association between ICD diagnoses of TS/CTD and substance misuse outcomes, accounting for psychiatric comorbidity and familial factors. The cohort included all individuals living in Sweden at any time between January 1, 1973, and December 31, 2013. Substance misuse outcomes were defined as an ICD code of substance use–related disorder or cause of death, or as a substance use–related criminal conviction in the nationwide registers. Results The cohort included 14,277,199 individuals, of whom 7832 had a TS/CTD diagnosis (76.3% men). TS/CTD was associated with an increased risk of any subsequent substance misuse outcomes (adjusted hazard ratio [aHR], 3.11; 95% confidence interval [CI], 2.94–3.29), including alcohol-related disorder (aHR, 3.45; 95% CI, 3.19–3.72), drug-related disorder (aHR, 6.84; 95% CI, 6.32–7.40), substance-related criminal convictions (aHR, 2.56; 95% CI, 2.36–2.77), and substance-related death (aHR, 2.54; 95% CI, 1.83–3.52). Excluding psychiatric comorbidities had little effect on the magnitude of the associations, with the exception of attention-deficit/hyperactivity disorder, which attenuated the risk of any substance misuse outcomes (aHR, 2.00; 95% CI, 1.82–2.19). The risk of any substance misuse outcomes in individuals with TS/CTD was substantially attenuated but remained significant when compared with their unaffected siblings (aHR, 1.74; 95% CI, 1.53–1.97). Conclusions TS/CTD were associated with various types of subsequent substance misuse outcomes, independently of psychiatric comorbidity and familial factors shared between siblings. Screening for drug and alcohol use should become part of the standard clinical routines, particularly in patients with comorbid attention-deficit/hyperactivity disorder.

Background It is unknown whether individuals with tic disorders are at increased risk for serious transport accidents. Objectives The aim of this study was to investigate the risk for injuries or death caused by transport and motor vehicle accidents in individuals with Tourette syndrome or chronic tic disorder. Methods This population‐based, sibling‐controlled cohort study included all individuals aged ≥18 years living in Sweden between 1997 and 2013 (N = 6,127,290). A total of 3449 individuals had a registered diagnosis of Tourette syndrome or chronic tic disorder in the Swedish National Patient Register. We also identified 2191 families with full siblings discordant for tic disorders. Cox proportional hazards regression modeling was used to estimate the risk for injuries or deaths as a result of transport accidents in individuals with a lifetime diagnosis of Tourette syndrome or chronic tic disorder compared with unexposed individuals and siblings. Results Individuals with tic disorders had a higher risk for transport injuries or death compared with the general population (adjusted hazard ratio, 1.50 [95% confidence interval: 1.33–1.69]) and their unaffected siblings (adjusted hazard ratio, 1.41 [95% confidence interval: 1.18–1.68]). The risks were similar across sexes. The exclusion of most psychiatric comorbidities did not alter the magnitude of the estimates. However, the risks were no longer significant after exclusion of individuals with comorbid attention deficit hyperactivity disorder. Conclusions The marginally increased risk for serious transport accidents in tic disorders is mainly driven by attention deficit hyperactivity disorder comorbidity. Improved detection and management of attention deficit hyperactivity disorder symptoms in this patient group are warranted. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Individuals with obsessive-compulsive disorder (OCD) may have an increased risk of cardiovascular disease (CVD), but evidence for specific types of CVD is limited. This population-based, sibling-controlled cohort study investigated the risk of specific CVD in individuals with OCD. Linking data from various Swedish population-based registers, we explored the risk of a range of CVD in a cohort of individuals diagnosed with OCD between 1973 and 2013 (n = 33,561), compared to matched (1:10) unaffected individuals (n = 335,610). Hazard ratios (HR) with 95% confidence intervals (CI) were calculated using conditional Cox proportional hazards regression models, adjusting for history of somatic diseases. To control for familial confounders, we analyzed 23,263 clusters of full siblings discordant for OCD. Individuals with psychiatric comorbidities were systematically excluded to assess the impact of these comorbidities. Over an average follow-up time of 27 years, OCD was associated with an increased risk of a broad range of CVD (adjusted HR [aHR] for any CVD = 1.25 [95% confidence interval [CI], 1.22–1.29]). These associations were strongest for the subtypes venous thrombo-embolism (aHR = 1.48 [95% CI, 1.38–1.58]) and heart failure (aHR = 1.37 [95% CI, 1.28–1.46]). When comparing OCD-exposed individuals with their non-exposed full siblings, results were largely similar. Exclusion of several groups of psychiatric comorbidities resulted in comparable results, albeit attenuated. Individuals with OCD have a moderately increased risk of CVD-related morbidity, independent from history of somatic diseases, familial confounders, and psychiatric comorbidities. The time may be ripe for the development and evaluation of lifestyle interventions to help reduce the risk of cardiovascular morbidity in OCD.

Background Psychiatric comorbidities are common and major determinants of quality of life in idiopathic dystonia. Their prevalence estimates from service-based studies are heterogeneous. Objective We explored the association between idiopathic dystonia and depressive disorders, anxiety disorders, suicide attempts, and death by suicide using Swedish population-based registers. Methods Diagnoses of idiopathic dystonia and psychiatric outcomes from inpatient and outpatient specialist services (1997-2013) were collected from the National Patient Register and the Cause of Death Register. Familial associations were explored using the Multi-Generation Register. Adjusted logistic regression analyses measured associations with psychiatric disorders in individuals with dystonia compared with general population individuals and their unaffected siblings, as well as in full siblings of individuals with dystonia compared with full siblings of unaffected individuals. Results Individuals with dystonia were more likely than those without to have a diagnosis of depressive disorder (adjusted odds ratio = 2.00, 95% confidence interval: 1.77-2.26), anxiety disorder (adjusted odds ratio = 2.13, 95% confidence interval: 1.90-2.39), and suicide attempts/death by suicide combined (adjusted odds ratio = 1.80, 95% confidence interval: 1.50-2.17), with odds higher in most idiopathic dystonia forms. In the full sibling comparison, estimates followed the same pattern, with overall attenuated magnitude. Full siblings of individuals with dystonia had higher likelihood of depressive or anxiety disorders and suicide attempts/death by suicide combined compared with siblings of individuals without dystonia. Conclusions Different forms of idiopathic dystonia confirm its association with increased risk for depressive and anxiety disorders and suicide attempts. Familial coaggregation of dystonia and these psychiatric comorbidities supports shared genetic and extragenetic factors. © 2020 International Parkinson and Movement Disorder Society.

Background Persons with neuropsychiatric disorders are at increased risk of suicide, but there is little data concerning Tourette’s and chronic tic disorders (TD/CTD). We aimed to quantify the risk of suicidal behavior in a large nationwide cohort of patients with TD/CTD, establish the contribution of psychiatric comorbidity to this risk, and identify predictors of suicide. Methods Using a validated algorithm, we identified 7736 TD/CTD cases in the Swedish National Patient Register during a 44-year period (1969–2013). Using a matched case-cohort design, patients were compared with general population control subjects (1:10 ratio). Risk of suicidal behavior was estimated using conditional logistic regressions. Predictors of suicidal behavior in the TD/CTD cohort were studied using Cox regression models. Results In unadjusted models, TD/CTD patients, compared with control subjects, had an increased risk of both dying by suicide (odds ratio: 4.39; 95% confidence interval [CI]: 2.89–6.67) and attempting suicide (odds ratio: 3.86; 95% CI: 3.50–4.26). After adjusting for psychiatric comorbidities, the risk was reduced but remained substantial. Persistence of tics beyond young adulthood and a previous suicide attempt were the strongest predictors of death by suicide in TD/CTD patients (hazard ratio: 11.39; 95% CI: 3.71–35.02, and hazard ratio: 5.65; 95% CI: 2.21–14.42, respectively). Conclusions TD/CTD are associated with substantial risk of suicide. Suicidal behavior should be monitored in these patients, particularly in those with persistent tics, history of suicide attempts, and psychiatric comorbidities. Preventive and intervention strategies aimed to reduce the suicidal risk in this group are warranted.

Adverse perinatal events may increase the risk of Tourette’s and chronic tic disorders (TD/CTD), but previous studies have been unable to control for unmeasured environmental and genetic confounding. We aimed to prospectively investigate potential perinatal risk factors for TD/CTD, taking unmeasured factors shared between full siblings into account. A population-based birth cohort, consisting of all singletons born in Sweden in 1973–2003, was followed until December 2013. A total of 3 026 861 individuals were identified, 5597 of which had a registered TD/CTD diagnosis. We then studied differentially exposed full siblings from 947 942 families; of these, 3563 families included siblings that were discordant for TD/CTD. Perinatal data were collected from the Medical Birth Register and TD/CTD diagnoses were collected from the National Patient Register, using a previously validated algorithm. In the fully adjusted models, impaired fetal growth, preterm birth, breech presentation and cesarean section were associated with a higher risk of TD/CTD, largely independent from shared family confounders and measured covariates. Maternal smoking during pregnancy was associated with risk of TD/CTD in a dose–response manner but the association was no longer statistically significant in the sibling comparison models or after the exclusion of comorbid attention-deficit/hyperactivity disorder. A dose–response relationship between the number of adverse perinatal events and increased risk for TD/CTD was also observed, with hazard ratios ranging from 1.41 (95% confidence interval (CI): 1.33–1.50) for one event to 2.42 (95% CI: 1.65–3.53) for five or more events. These results pave the way for future gene by environment interaction and epigenetic studies in TD/CTD.

The risk of death by suicide in individuals with obsessive–compulsive disorder (OCD) is largely unknown. Previous studies have been small and methodologically flawed. We analyzed data from the Swedish national registers to estimate the risk of suicide in OCD and identify the risk and protective factors associated with suicidal behavior in this group. We used a matched case–cohort design to estimate the risk of deaths by suicide and attempted suicide in individuals diagnosed with OCD, compared with matched general population controls (1:10). Cox regression models were used to study predictors of suicidal behavior. We identified 36 788 OCD patients in the Swedish National Patient Register between 1969 and 2013. Of these, 545 had died by suicide and 4297 had attempted suicide. In unadjusted models, individuals with OCD had an increased risk of both dying by suicide (odds ratio (OR)=9.83 (95% confidence interval (CI), 8.72–11.08)) and attempting suicide (OR=5.45 (95% CI, 5.24–5.67)), compared with matched controls. After adjusting for psychiatric comorbidities, the risk was reduced but remained substantial for both death by suicide and attempted suicide. Within the OCD cohort, a previous suicide attempt was the strongest predictor of death by suicide. Having a comorbid personality or substance use disorder also increased the risk of suicide. Being a woman, higher parental education and having a comorbid anxiety disorder were protective factors. We conclude that patients with OCD are at a substantial risk of suicide. Importantly, this risk remains substantial after adjusting for psychiatric comorbidities. Suicide risk should be carefully monitored in patients with OCD.

Objective To synthesize the current knowledge on possible environmental risk factors for Obsessive-Compulsive Disorder (OCD). Method We conducted a systematic review following PRISMA guidelines. The Embase, PubMed and Scopus databases were searched up until October 6, 2015, employing relevant keywords and MeSH terms. Results 128 studies met inclusion criteria. Potential environmental risk factors for OCD have been identified in the broad areas of perinatal complications, reproductive cycle, and stressful life events. There is limited evidence regarding other potential risk factors, such as parental age, season of birth, socioeconomic status, parental rearing practices, infections, traumatic brain injury, substance use or vitamin deficiency. In general, studies were of limited methodological quality. Conclusions At present, no environmental risk factors have convincingly been associated with OCD. We propose a roadmap for future studies, consisting of longitudinal, population-based research, employing quasi-experimental family and twin designs to identify risk factors that are not only associated with the disorder but also contribute to its causation either directly or moderating the effect of genes.

Background Obsessive-compulsive disorder (OCD) is associated with increased mortality, but the causes of this increase are poorly understood. This study examined whether OCD is associated with an increased risk of metabolic and cardiovascular complications. Methods Individuals diagnosed with OCD (n = 25,415) were identified from a cohort of 12,497,002 individuals living in Sweden between 1973 and 2013. Cox proportional hazard regression analyses were used to investigate the risk of metabolic and cardiovascular complications in OCD patients compared with the general population and unaffected full siblings of OCD individuals. Exploratory analyses were used to examine the effect of treatment with serotonin reuptake inhibitors, with or without antipsychotics, on the outcomes of interest. Results Individuals with OCD had a higher risk of any metabolic or cardiovascular complications compared with the general population (adjusted hazard ratio = 1.45; 95% confidence interval = 1.42–1.49) and their unaffected full siblings (adjusted hazard ratio = 1.47; 95% confidence interval = 1.40–1.54). In the fully adjusted sibling comparison models, patients had higher risks of obesity, type 2 diabetes mellitus, and circulatory system diseases. The risks were already evident from the beginning of the follow-up period and remained largely unchanged when excluding different groups of psychiatric comorbidities. Compared with patients who were not taking serotonin reuptake inhibitors, patients taking higher doses of serotonin reuptake inhibitors and who had a longer duration of treatment had significantly lower risks of metabolic and cardiovascular complications, regardless of whether they were also taking antipsychotics. Conclusions OCD is associated with an increased risk of metabolic and cardiovascular complications. Our results underscore the importance of carefully monitoring metabolic and cardiovascular health in patients with OCD early in the course of the disorder.

Importance There are limited data concerning the risk of metabolic and cardiovascular disorders among individuals with Tourette syndrome (TS) or chronic tic disorder (CTD). Objective To investigate the risk of metabolic and cardiovascular disorders among individuals with TS or CTD over a period of 40 years. Design, Settings, and Participants This longitudinal population-based cohort study included all individuals living in Sweden between January 1, 1973, and December 31, 2013. Families with clusters of full siblings discordant for TS or CTD were further identified. Data analyses were conducted from August 1, 2017, to October 11, 2018. Exposures Previously validatedInternational Classification of Diseasesdiagnoses of TS or CTD in the Swedish National Patient Register. Main Outcomes and Measures Registered diagnoses of obesity, dyslipidemia, hypertension, type 2 diabetes, and cardiovascular diseases (including ischemic heart diseases, arrhythmia, cerebrovascular diseases and transient ischemic attack, and arteriosclerosis). Results Of the 14 045 026 individuals in the cohort, 7804 individuals (5964 males [76.4%]; median age at first diagnosis, 13.3 years [interquartile range, 9.9-21.3 years]) had a registered diagnosis of TS or CTD in specialist care. Of 2 675 482 families with at least 2 singleton full siblings, 5141 families included siblings who were discordant for these disorders. Individuals with TS or CTD had a higher risk of any metabolic or cardiovascular disorders compared with the general population (hazard ratio adjusted by sex and birth year [aHR], 1.99; 95% CI, 1.90-2.09) and sibling controls (aHR for any disorder, 1.37; 95% CI, 1.24-1.51). Specifically, individuals with TS or CTD had higher risks for obesity (aHR, 2.76; 95% CI, 2.47-3.09), type 2 diabetes (aHR, 1.67; 95% CI, 1.42-1.96), and circulatory system diseases (aHR, 1.76; 95% CI, 1.67-1.86). The risk of any cardiometabolic disorder was significantly greater in males than in females (aHR, 2.13; 95% CI, 2.01-2.26 vs aHR, 1.79; 95% CI, 1.64-1.96), as was the risk of obesity (aHR, 3.24; 95% CI, 2.83-3.70 vs aHR, 1.97; 95% CI, 1.59-2.44). The risks were already evident from childhood (the groups were significantly different by age 8 years) and were significantly reduced with the exclusion of individuals with comorbid attention-deficit/hyperactivity disorder (aHR, 1.52; 95% CI, 1.42-1.62), while excluding other comorbidities did not significantly affect the results. Compared with patients with TS or CTD who were not taking antipsychotics, patients with a longer duration of antipsychotic treatment (>1 year) had significantly lower risks of metabolic and cardiovascular disorders. Conclusions and Relevance The findings of this study suggest that TS and CTD are associated with a substantial risk of metabolic and cardiovascular disorders. The results highlight the importance of carefully monitoring cardiometabolic health in patients with TS or CTD across the lifespan, particularly in those with comorbid attention-deficit/hyperactivity disorder.

Importance The influence of Tourette syndrome and chronic tic disorders on academic performance has not been objectively quantified. Objective To investigate the association of Tourette syndrome and chronic tic disorders with objectively measured educational outcomes, adjusting for measured covariates and unmeasured factors shared between siblings and taking common psychiatric comorbidities into account. Design, Setting, and Participants A population-based birth cohort consisting of all individuals born in Sweden from 1976 to 1998 was followed up until December 2013. Individuals with organic brain disorders, mental retardation, and 2 foreign-born parents were excluded. We further identified families with at least 2 singleton full siblings and families with siblings discordant for Tourette syndrome or chronic tic disorders. Exposures Previously validated International Classification of Diseases diagnoses of Tourette syndrome or chronic tic disorders in the Swedish National Patient Register. Main Outcomes and Measures Eligibility to access upper secondary school after compulsory education, finishing upper secondary school, starting a university degree, and finishing a university degree. Results Of the 2 115 554 individuals in the cohort, 3590 had registered a diagnosis of Tourette syndrome or a chronic tic disorder in specialist care (of whom 2822 [78.6%] were male; median [interquartile] age at first diagnosis, 14.0 [11-18] years). Of 726 198 families with at least 2 singleton full siblings, 2697 included siblings discordant for these disorders. Compared with unexposed individuals, people with Tourette syndrome or chronic tic disorders were significantly less likely to pass all core and additional courses at the end of compulsory school (odds ratios ranging from 0.23 [95% CI, 0.20-0.26] for the handcraft textile/wood course to 0.36 [95% CI, 0.31-0.41] for the English language course) and to access a vocational program (adjusted OR [aOR], 0.31; 95% CI, 0.28-0.34) or academic program (aOR, 0.43; 95% CI, 0.39-0.47) in upper secondary education. Individuals with the disorders were also less likely to finish upper secondary education (aOR, 0.35; 95% CI, 0.32-0.37), start a university degree (aOR, 0.41; 95% CI, 0.37-0.46), and finish a university degree (aOR, 0.39; 95% CI, 0.32-0.48). The results were only marginally attenuated in the fully adjusted sibling comparison models. Exclusion of patients with neuropsychiatric comorbidities, particularly attention-deficit/hyperactivity disorder and pervasive developmental disorders, resulted in attenuated estimates, but patients with Tourette syndrome or chronic tic disorders were still significantly impaired across all outcomes. Conclusions and Relevance Help-seeking individuals with Tourette syndrome or chronic tic disorders seen in specialist settings experience substantial academic underachievement across all educational levels, spanning from compulsory school to university, even after accounting for multiple confounding factors and psychiatric comorbidities.

Importance Perinatal complications may increase the risk of obsessive-compulsive disorder (OCD). Previous reports were based on small, retrospective, specialist clinic–based studies that were unable to rigorously control for unmeasured environmental and genetic confounding. Objective To prospectively investigate a wide range of potential perinatal risk factors for OCD, controlling for unmeasured factors shared between siblings in the analyses. Design, Setting, and Participants This population-based birth cohort study included all 2 421 284 children from singleton births in Sweden from January 1, 1973, to December 31, 1996, who were followed up through December 31, 2013. From the 1 403 651 families in the cohort, differentially exposed siblings from the 743 885 families with siblings were evaluated; of these, 11 592 families included clusters of full siblings that were discordant for OCD. Analysis of the data was conducted from January, 26, 2015, to September, 5, 2016. Exposures Perinatal data were collected from the Swedish Medical Birth Register and included maternal smoking during pregnancy, labor presentation, obstetric delivery, gestational age (for preterm birth), birth weight, birth weight in relation to gestational age, 5-minute Apgar score, and head circumference. Main Outcomes and Measures Previously validated OCD codes ( International Statistical Classification of Diseases and Health Related Problems, Tenth Revision , code F42) in the Swedish National Patient Register. Results Of 2 421 284 individuals included in the cohort, 17 305 persons were diagnosed with OCD. Of these, 7111 were men (41.1%). The mean (SD) age of individuals at first diagnosis of OCD was 23.4 (6.5) years. An increased risk for OCD remained after controlling for shared familial confounders and measured covariates (including sex, year of birth, maternal and paternal age at birth, and parity), for smoking 10 or more cigarettes per day during pregnancy (hazard ratio [HR], 1.27; 95% CI, 1.02-1.58), breech presentation (HR, 1.35; 95% CI, 1.06-1.71), delivery by cesarean section (HR, 1.17; 95% CI, 1.01-1.34), preterm birth (HR, 1.24; 95% CI, 1.07-1.43), birth weight 1501 to 2500 g (HR, 1.30; 95% CI, 1.05-1.62) and 2501 to 3500 g (HR, 1.08; 95% CI, 1.01-1.16), being large for gestational age (HR, 1.23; 95% CI, 1.05-1.45), and Apgar distress scores at 5 minutes (HR, 1.50; 95% CI, 1.07-2.09). Gestational age and birth weight followed inverse dose-response associations, whereby an increasingly higher risk for OCD was noted in children with a shorter gestational age and lower birth weight. We also observed a dose-response association between the number of perinatal events and increased OCD risk, with HRs ranging from 1.11 (95% CI, 1.07-1.15) for 1 event to 1.51 (95% CI, 1.18-1.94) for 5 or more events. Conclusions and Relevance A range of perinatal risk factors is associated with a higher risk for OCD independent of shared familial confounders, suggesting that perinatal risk factors may be in the causal pathway to OCD.