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Tic disorders are associated with multiple social adversities, but little is known about the experience of violent assault (including sexual assault) and criminality in this group.To establish if Tourette syndrome (TS) and chronic tic disorder (CTD) are associated with an increased risk of experiencing violent assault and criminal convictions.In this cohort study, all individuals living in Sweden at any time between January 1, 1973, and December 31, 2013, were identified from Swedish nationwide health and administrative registers. Cox proportional hazards regression models were used to estimate the risk of violent assault and criminal convictions among people with TS or CTD, compared with the general population and unaffected full siblings. Data analyses were conducted between September 1 and October 22, 2021.The Swedish version of the International Classification of Diseases, Eighth Revision (ICD-8), ICD-9, and ICD-10 diagnoses of TS or CTD in the Swedish National Patient Register.Records of sexual and nonsexual violent assault and death due to violent assaults were obtained from the National Patient Register and the Cause of Death Register, respectively. Convictions for violent and nonviolent criminal offenses were obtained from the Crime Register. Covariates included sex and birth year.The study cohort included 13 819 284 individuals living in Sweden between 1973 and 2013. A total of 7791 individuals with TS or CTD were identified (median [IQR] age at first diagnosis, 13.4 [10.0-21.8] years; 5944 [76%] male). Compared with unaffected individuals from the general population, people with TS or CTD had a 2-fold increased risk of experiencing any violent assault (sexual and nonsexual) (adjusted hazard ratio [aHR], 2.21; 95% CI, 2.00-2.43), a 3-fold increased risk of violent convictions (aHR, 3.13; 95% CI, 2.92-3.36), and a 1.6-fold increased risk of nonviolent crime convictions (aHR, 1.62; 95% CI, 1.54-1.71). Among people with TS or CTD, 37.0% (114 of 308; 95% CI, 31.6%-42.4%) of individuals who had experienced violent assault also had a violent crime conviction, compared with 17.9% (16 067 of 89 920; 95% CI, 17.6%-18.1%) in the general population. Exclusion of individuals with attention-deficit/hyperactivity disorder and substance use disorders partially attenuated the associations. Similarly, within-sibling models attenuated but did not eliminate the associations (any violent assault: aHR, 1.32; 95% CI, 1.08-1.61; violent crime: aHR, 2.23; 95% CI, 1.86-2.67; nonviolent crime: aHR, 1.34; 95% CI, 1.20-1.50).Results of this cohort study suggest that most individuals with TS or CTD are not assaulted nor are perpetrators of crime. However, individuals with TS or CTD diagnosed in specialist settings were more likely to both experience violent assault and be perpetrators of violence compared with the general population. The risk was highest in individuals with comorbid attention-deficit/hyperactivity disorder and substance use disorders. The increased risk found in specialty clinics will need to be better understood in the general population.

Background Insomnia is common in Tourette syndrome (TS) and chronic tic disorder (CTD), but precise prevalence estimates are lacking. Objective In this Swedish register-based cohort study, we estimated the prevalence of insomnia in TS/CTD and quantified the magnitude of this association, accounting for familial confounders and relevant somatic and psychiatric comorbidities. Methods Of 10,444,702 individuals living in Sweden during the period from 1997 to 2013, 5877 had a diagnosis of TS/CTD and were compared to unexposed individuals from the general population on the presence of insomnia using logistic regression models. Results Individuals with TS/CTD had a period prevalence of insomnia of 32.16%, compared to 13.70% of the unexposed population. This translated into a 6.7-fold increased likelihood of insomnia in TS/CTD (odds ratio adjusted [aOR] for sex, birth year, birth country, and somatic disorders = 6.74; 95% confidence interval [CI], 6.37-7.15). A full sibling comparison, designed to adjust for shared familial factors, attenuated the estimates (aOR = 5.41; 95% CI, 4.65-6.30). When individuals with attention-deficit/hyperactivity disorder (ADHD) and pervasive developmental disorders were excluded, the association was also attenuated, whereas exclusion of other psychiatric comorbidities had minimal impact. Having persistent TS/CTD, comorbid ADHD, and taking ADHD medication greatly increased the likelihood of insomnia. Conclusions Insomnia is significantly associated with TS/CTD, independently from somatic disorders, familial factors or psychiatric comorbidities, although familial factors, neurodevelopmental comorbidities, and ADHD/ADHD medication may explain part of the association. Insomnia should be routinely assessed and managed in TS/CTD, particularly in chronic patients and in those with comorbid ADHD. Other sleep disorders require further study. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

BackgroundSocial anxiety disorder (SAD) has been linked to academic underachievement, but previous studies had methodological limitations. We investigated the association between SAD and objective indicators of educational performance, controlling for a number of covariates and unmeasured confounders shared between siblings.MethodsThis population-based birth cohort study included 2 238 837 individuals born in Sweden between 1973 and 1997, followed-up until 2013. Within the cohort, 15 755 individuals had a recorded ICD-10 diagnosis of SAD in the Swedish National Patient Register. Logistic regression models tested the association between SAD and educational performance. We also identified 6488 families with full siblings discordant for SAD.ResultsCompared to unexposed individuals, individuals diagnosed with SAD were less likely to pass all subjects in the last year of compulsory education [adjusted odds ratios (aOR) ranging from 0.19 to 0.44] and less likely to be eligible for a vocational or academic programme in upper secondary education [aOR = 0.31 (95% confidence interval [CI] 0.30–0.33) and aOR = 0.52 (95% CI 0.50–0.55), respectively], finish upper secondary education [aOR = 0.19 (95% CI 0.19–0.20)], start a university degree [aOR = 0.47 (95% CI 0.45–0.49)], obtain a university degree [aOR = 0.35 (95% CI 0.33–0.37)], and finish postgraduate education [aOR = 0.58 (95% CI 0.43–0.80)]. Results were attenuated but remained statistically significant in adjusted sibling comparison models. When psychiatric comorbidities were taken into account, the results were largely unchanged.ConclusionsTreatment-seeking individuals with SAD have substantially impaired academic performance throughout the formative years. Early detection and intervention are warranted to minimise the long-term socioeconomic impact of the disorder.

Immune dysregulation due to chronic inflammation is a hypothesized risk factor underlying psychiatric disorders and suicidal behavior. Whether tonsillectomy and acute appendicitis used, respectively, as proxies for chronic and acute inflammation within the mucosa-associated lymphoid tissue (MALT) are associated with psychiatric disorders and suicidal behavior is currently unknown. A birth cohort study was conducted including 3,052,875 individuals born in Sweden between 1973 and 2003. We identified 210,686 individuals ever exposed to tonsillectomy and 86,928 individuals ever exposed to acute appendicitis, as well as 317,214 clusters of siblings discordant for tonsillectomy, and 160,079 sibling clusters discordant for acute appendicitis. Outcomes were an aggregate risk of ‘any psychiatric disorder’, ‘any suicidal behavior’, 12 individual psychiatric disorders, suicide attempts and deaths by suicide. Tonsillectomy was associated with increased odds of ‘any psychiatric disorder’ (adjusted odds ratio [aOR] = 1.39; 95% confidence interval (CI) = 1.38–1.41) and ‘any suicidal behavior’ (aOR = 1.41; 95% CI = 1.37–1.44), and most individual disorders. Acute appendicitis also increased the odds of ‘any psychiatric disorder’ and ‘any suicidal behavior’ (aOR = 1.23; 95% CI = 1.20–1.25, and aOR = 1.32; 95% CI = 1.28–1.37, respectively). Exposure to both tonsillectomy and appendicitis was associated with the highest odds of ‘any psychiatric disorder’ (aOR = 1.70; 95% CI = 1.59–1.82) and ‘any suicidal behavior’ (aOR = 1.90; 95% CI = 1.70–2.12). In sibling comparisons, the associations were attenuated but remained significant. We conclude that inflammation within the MALT, particularly when chronic, is robustly associated with a broad range of psychiatric disorders and suicidal behavior.

Aim: In 2006-2014, the rate of drug-related deaths, typically opioid poisonings, more than doubled in Sweden. Opioid prescriptions for pain control or opioid agonist therapy also increased. In this retrospective study, we compared death rates between individuals whose first recorded contact with prescribed opioids was for pain control and individuals that had received substance use disorder (SUD) treatment before their first recorded opioid prescription. Methods: We included 2834 forensically examined individuals (ages 15-64 years) that died of poisoning in Sweden in 2006-2014. For each death we acquired data on previous opioid prescriptions and SUD treatments. We compared three study groups: pain control (n = 788); a SUD treatment group (n = 1629); and a group with no prescription for pain control or SUD treatment (n = 417). Results: Overall fatal poisonings increased from 2.77 to 7.79 (per 100,000 individuals) from 2006 to 2014 (relative 181% increase). Fatal poisoning increased from 2006 to 2014 by 269% in the pain control group (0.64 to 2.36 per 100,000) and by 238% in the SUD treatment group (1.35 to 4.57 per 100,000). Heroin-related deaths remained constant; consequently, the increase was likely attributable to prescription opioids. Conclusion: A rapid increase in deaths attributable mainly to prescription opioids for pain control, was reported previously in the United States. Our study indicated that increased access to prescription opioids might contribute to higher death rates also in Sweden among patients seeking pain control and individuals with an established SUD; however, deaths related to prescription opioids mainly occurred among those with SUDs.

Obsessive−compulsive disorder (OCD) is associated with high risk of suicide. It is yet unknown whether OCD and suicidal behaviors coaggregate in families and, if so, what are the mechanisms underlying this coaggregation. In a population-based birth cohort and family study, we linked individuals born in Sweden in 1967–2003 (n = 3,594,181) to their parents, siblings, and cousins, and collected register-based diagnoses of OCD, suicide attempts, and deaths by suicide and followed them until December 31, 2013. We also applied quantitative genetic modeling to estimate the contribution of genetic and environmental factors to the familial coaggregation of OCD and suicidal behavior. An elevated risk of suicide attempts was observed across all relatives of individuals with OCD, increasing proportionally to the degree of genetic relatedness, with odds ratios (OR) ranging from 1.56 (95% confidence interval (CI) 1.49–1.63) in parents to 1.11 (95% CI 1.07–1.16) in cousins. The risk of death by suicide also increased alongside narrowing genetic distance, but was only significant in parents (OR 1.55; 95% CI 1.40–1.72) and full siblings (OR 1.80; 95% CI 1.43–2.26) of individuals with OCD. Familial coaggregation of OCD and suicide attempts was explained by additive genetic factors (60.7%) and non-shared environment (40.4%), with negligible contribution of shared environment. Similarly, familial coaggregation with death by suicide was attributed to additive genetics (65.8%) and nonshared environment (34.2%). Collectively, these observations indicate that OCD and suicidal behaviors coaggregate in families largely due to genetic factors. The contribution of unique environment is also considerable, providing opportunities to target high-risk groups for prevention and treatment.

ObjectivesThere is concern that the COVID-19 pandemic will be associated with an increase in suicides, but evidence supporting a link between pandemics and suicide is limited. Using data from the three influenza pandemics of the 20th century, we aimed to investigate whether an association exists between influenza deaths and suicide deaths.DesignTime series analysis.SettingSweden.ParticipantsDeaths from influenza and suicides extracted from the Statistical Yearbook of Sweden for 1910–1978, covering three pandemics (the Spanish influenza, the Asian influenza and the Hong Kong influenza).Main outcome measuresAnnual suicide rates in Sweden among the whole population, men and women. Non-linear autoregressive distributed lag models was implemented to explore if there is a short-term and/or long-term relationship of increases and decreases in influenza death rates with suicide rates during 1910–1978.ResultsBetween 1910 and 1978, there was no evidence of either short-term or long-term significant associations between influenza death rates and changes in suicides (β coefficients of 0.00002, p=0.931 and β=0.00103, p=0.764 for short-term relationship of increases and decreases in influenza death rates, respectively, with suicide rates, and β=−0.0002, p=0.998 and β=0.00211, p=0.962 for long-term relationship of increases and decreases in influenza death rates, respectively, with suicide rates). The same pattern emerged in separate analyses for men and women.ConclusionsWe found no evidence of short-term or long-term association between influenza death rates and suicide death rates across three 20th century pandemics.

IMPORTANCE Neurobiological models have postulated shared neural mechanisms between obsessive-compulsive disorder (OCD) and substance use disorders, but results from clinical and epidemiological studies are conflicting or even suggest that OCD may be protective against substance misuse.OBJECTIVE To investigate whether OCD and obsessive-compulsive symptoms are associated with substance misuse and the extent to which shared genetic and/or environmental factors account for this association.DESIGN, SETTING, AND PARTICIPANTS In this cohort study, individuals in the general population of Sweden born between January 1, 1932, and December 31, 1997 (population cohort), were followed up through Swedish nationwide registers from January 1,1997. to December 31. 2013. The second cohort included twin participants in the Child and Adolescent Twin Study in Sweden (CATSS) followed up from ages 18 to 24 years. Data were analyzed from March 1, 2021, to March 31, 2022.EXPOSURES Lifetime International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, diagnosis of OCD in the National Patient Register (population cohort 1), and self-reported obsessive-compulsive symptoms at 18 years of age (CATSS cohort).MAIN OUTCOMES AND MEASURES Substance misuse was defined as registered substance use-related disorder, criminal conviction, or death (population cohort), and self-reported alcohol and drug dependence symptoms at 18 and 24 years of age (CATSS cohort).RESULTS The general population cohort included 6 304188 individuals (48.9% women and 51.1% men; median baseline age, 30.5 [IQR, 15.0-46.4] years), of whom 27 342 had an OCD diagnosis. Obsessive-compulsive disorder was associated with an elevated risk of substance misuse (hazard ratio, 3.68 [95% CI, 3.52-3.85]). In the 9230 individuals in the CATSS cohort (5551 women [60.1%] and 3679 men [39.9%]), obsessive-compulsive symptoms at 18 years of age were associated with increased symptoms of alcohol dependence (concurrent [n = 9219], beta = 0.18 [95% CI, 0.16-0.20]; longitudinal [n = 3381], beta = 0.10 [95% CI, 0.06-0.14]) and drug dependence (concurrent [n = 749], beta = 0.19 [95% CI, 0.11-0.27]; longitudinal [n = 452]. beta = 0.15 [95% CI, 0.04-0.25]). Comorbid anxiety and depression did not entirely explain the associations in either cohort. Using data from full siblings and maternal half-siblings (population cohort) and monozygotic and dizygotic twins (CATSS cohort) provided estimates of the relative contribution of genetic and environmental influences to the covariance between OCD and obsessive-compulsive symptoms and substance misuse or dependence. The associations were explained by genetic (56%-68%) and nonshared environmental (32%-44%) factors.CONCLUSIONS AND RELEVANCE The findings of this Swedish population-based cohort study challenge the notion that OCD is protective against developing substance misuse. The association of OCD and obsessive-compulsive symptoms with substance misuse was largely explained by shared genetics but was also compatible with partial environmental mediation.

When used during pregnancy, benzodiazepines (BZDs) and related z-drugs could pass readily through the placenta and the foetal blood-brain barrier, where they can bind to γ-amino butyric acid (GABA) receptors in the developing foetal brain. Yet, data on long-term safety of prenatal BZD and z-drug use and its impact on offspring neurodevelopment are inconclusive. In this systematic review, we qualitatively synthetize the existing evidence on maternal exposure to various BZDs and z-drugs during pregnancy and offspring cognitive, emotional, behavioural, and motor skills developmental outcomes. Nineteen studies were included. We used harvest plots to visualize the directions of reported associations. Despite several associations between distinct types of BZDs and z-drugs and an increased risk of outcomes within different neurodevelopmental domains were observed, a remarkable scarcity of overall research on the topic and considerable discrepancies in methodology, particularly towards controlling for confounding by indication, precluded drawing conclusions with a reasonable degree of certainty. We outline various research strategies to mitigate methodological limitations and provide directions for future empirical studies on the topic.

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.

Purpose Individuals with obsessive–compulsive disorder (OCD) often report driving-related obsessions, such as fears of causing accidents, but the risk of transport accidents in OCD is unknown. We investigated whether individuals with OCD have an increased risk of serious transport accidents and convictions due to traffic offenses and explored the role of psychiatric comorbidities. Methods We included all individuals ≥ 18 years living in Sweden between 1997 and 2013 (N = 5,760,734). A total of 23,126 individuals had a diagnosis of OCD in the National Patient Register. We also identified 16,607 families with full siblings discordant for OCD. Cox proportional hazards regression models estimated hazard ratios (HRs) with 95% confidence intervals (CIs) for the risk of three outcomes in individuals with OCD, compared to unexposed individuals and their unexposed full siblings: injuries or deaths due to transport accidents, injuries or deaths due to motor vehicle accidents, and convictions related to traffic offenses. Psychiatric comorbidities were systematically adjusted for. Results Women, but not men, with OCD had a marginally increased risk of serious transport accidents (adjusted HR = 1.20 [95% CI 1.13–1.28]) and motor vehicle accidents (adjusted HR = 1.20 [95% CI 1.09–1.31]), compared to unaffected individuals. Neither women nor men with OCD had a significantly increased risk of convictions. The sibling comparisons showed no significant associations. When psychiatric comorbidities were adjusted for, several observed associations became non-significant or inversed (HRs and 95% CIs below one). Conclusion The risks of serious transport accidents and driving-related criminal convictions in OCD are negligible and heavily influenced by psychiatric comorbidity.

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.

This systematic review and meta-analysis examines the association between birth by cesarean delivery and risk of neurodevelopmental and psychiatric disorders in the offspring compared with birth by vaginal delivery., Key Points Question Is birth by cesarean delivery associated with an increased risk of neurodevelopmental and psychiatric disorders in the offspring compared with birth by vaginal delivery? Findings In this systematic review and meta-analysis of 61 studies comprising more than 20 million deliveries, birth by cesarean delivery was significantly associated with autism spectrum disorder and attention-deficit/hyperactivity disorder. Meaning The findings suggest that understanding the potential mechanisms behind these associations is important, especially given the increase in cesarean delivery rates for nonmedical reasons., Importance Birth by cesarean delivery is increasing globally, particularly cesarean deliveries without medical indication. Children born via cesarean delivery may have an increased risk of negative health outcomes, but the evidence for psychiatric disorders is incomplete. Objective To evaluate the association between cesarean delivery and risk of neurodevelopmental and psychiatric disorders in the offspring. Data Sources Ovid MEDLINE, Embase, Web of Science, and PsycINFO were searched from inception to December 19, 2018. Search terms included all main mental disorders in the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition). Study Selection Two researchers independently selected observational studies that examined the association between cesarean delivery and neurodevelopmental and psychiatric disorders in the offspring. Data Extraction and Synthesis Two researchers independently extracted data according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines and assessed study quality using the Newcastle-Ottawa Scale. Random-effects meta-analyses were used to pool odds ratios (ORs) with 95% CIs for each outcome. Sensitivity and influence analyses tested the robustness of the results. Main Outcomes and Measures The ORs for the offspring with any neurodevelopmental or psychiatric disorder who were born via cesarean delivery compared with those were born via vaginal delivery. Results A total of 6953 articles were identified, of which 61 studies comprising 67 independent samples were included, totaling 20 607 935 deliveries. Compared with offspring born by vaginal delivery, offspring born via cesarean delivery had increased odds of autism spectrum disorders (OR, 1.33; 95% CI, 1.25-1.41; I2 = 69.5%) and attention-deficit/hyperactivity disorder (OR, 1.17; 95% CI, 1.07-1.26; I2 = 79.2%). Estimates were less precise for intellectual disabilities (OR, 1.83; 95% CI, 0.90-3.70; I2 = 88.2%), obsessive-compulsive disorder (OR, 1.49; 95% CI, 0.87-2.56; I2 = 67.3%), tic disorders (OR, 1.31; 95% CI, 0.98-1.76; I2 = 75.6%), and eating disorders (OR, 1.18; 95% CI, 0.96-1.47; I2 = 92.7%). No significant associations were found with depression/affective psychoses or nonaffective psychoses. Estimates were comparable for emergency and elective cesarean delivery. Study quality was high for 82% of the cohort studies and 50% of the case-control studies. Conclusions and Relevance The findings suggest that cesarean delivery births are associated with an increased risk of autism spectrum disorder and attention-deficit/hyperactivity disorder, irrespective of cesarean delivery modality, compared with vaginal delivery. Future studies on the mechanisms behind these associations appear to be warranted.

Background Pharmacoepidemiological studies have long raised concerns on widespread use of benzodiazepines and benzodiazepine-related drugs (BZDs), in particular long-term use, among adults and the elderly. In contrast, evidence pertaining to the rates of BZD use at younger ages is still scarce, and the factors that influence BZD utilisation and shape the different prescribing patterns in youths remain largely unexplored. We examined the prevalence rates, relative changes in rates over time, and prescribing patterns for BZD dispensation in young people aged 0–24 years in Sweden during the period January 1, 2006–December 31, 2013, and explored demographic, clinical, pharmacological, and prescriber-related attributes of BZD prescribing in this group. Methods and findings Through the linkage of 3 nationwide Swedish health and administrative registers, we collected data on 17,500 children (0–11 years), 15,039 adolescents (12–17 years), and 85,200 young adults (18–24 years) with at least 1 dispensed prescription for a BZD during 2006–2013, out of 3,726,818 Swedish inhabitants aged 0–24 years. Age-specific annual prevalence rates of BZD dispensations were adjusted for population growth, and relative changes in rates were calculated between 2006 and 2013. We analysed how BZD dispensation varied by sex, psychiatric morbidity and epilepsy, concurrent dispensation of psychotropic medication, type of dispensed BZD, and type of healthcare provider prescribing the BZD. Prescribing patterns were established in relation to duration (3 months, >3 to ≤6 months, or >6 months), dosage ( 6 months). The study limitations included lack of information on actual consumption of the dispensed BZDs and unavailability of data on the indications for BZD prescriptions. Conclusions The overall increase in prevalence rates of BZD dispensations during the study period and the unexpectedly high proportion of individuals who were prescribed a BZD on a long-term basis at a young age indicate a lack of congruence with international and national guidelines. These findings highlight the need for close monitoring of prescribing practices, particularly in non-psychiatric settings, in order to build an evidence base for safe and efficient BZD treatment in young persons., Author summary Why was this study done? Benzodiazepines and benzodiazepine-related drugs (BZDs) are among the most widely used psychotropic medications in the world and have long raised public health concerns due to the risk for their users of developing dependence and severe adverse effects, in particular among long-term users. The prevalence rates and attributes of BZD use have been well described in adults and the elderly. In contrast, evidence regarding BZD prescribing for younger populations is scarce and fragmented, and factors influencing BZD utilisation in children, adolescents, and young adults remain largely unexplored. What did the researchers do and find? We linked nationwide Swedish health and administrative registers on 3,726,818 individuals aged 0–24 years living in Sweden between 2006–2013, among whom 17,500 children (0–11 years), 15,039 adolescents (12–17 years), and 85,200 young adults (18–24 years) were dispensed a BZD prescription at least once during that period. The prevalence rate of BZD dispensation has increased by 22% between 2006 and 2013, and has increased particularly in young adults. For nearly 65% of all study participants with 1 or more dispensed BZD prescriptions, the first prescription was issued outside specialised psychiatric services. Most first prescriptions originated from primary care (41%) and non-psychiatric specialist settings (24%) such as paediatrics and internal medicine. Over 75% of study participants were dispensed other psychotropic medication concurrently with a BZD, raising concerns about the potential risk of drug interactions. Almost 30% were prescribed a BZD for longer than 6 months, contradicting international and national guidelines that advise against BZD use beyond 2–4 weeks for adults and generally discourage prescribing BZDs for ages below 18 years. What do these findings mean? There is a need for clinicians, particularly those working in non-psychiatric services, to implement strategies to avoid potentially harmful patterns of prescribing BZDs to young people. Young individuals who are prescribed BZDs should be closely monitored, in particular, with respect to duration of BZD treatment and concurrent prescription of other psychotropic drugs.

OBJECTIVES: To investigate whether and how social class and social mobility in grandparents and parents predict alcohol-related disorders (ARDs) in males and females aged 12+ years, and whether intergenerational social prediction of ARDs varies across time periods. METHODS: The study sample included four successive generations (G) of Swedish families from the Uppsala Birth Cohort Multigenerational Study: G0 born 1851-1912; G1 born 1915-1929; G2 born 1940-1964 and G3 born 1965-1989. Two study populations were created, each consisting of grandparents, parents and offspring: population I 'G0-G1-G2' (offspring n = 18 430) and population II 'G1-G2-G3' (offspring n = 26 469). Registers and archives provided data on ancestors' socio-demographic factors and ARD history, together with offspring ARD development between 1964-2008. Cox regression models examined the hazard of offspring ARD development according to grandparental social class and grandparental-to-parental social trajectories, controlling for offspring birth year, grandmother's and mother's marital status and parental ARDs. RESULTS: Disadvantaged grandparental social class predicted increased ARD risk in offspring in population I, although the effect attenuated and became non-significant in males after adjusting for parental characteristics (adjusted hazard ratio (HR) = 1.80 (95%CI; 1.07, 3.03) in females, HR = 1.32 (95%CI; 0.93, 1.89) in males). In population II, no increase in ARD risk by grandparental social was evident. In both populations, males were at the highest ARD risk if both parents and grandparents belonged to disadvantaged social class (population I: HR = 1.82 (95%CI; 1.22-2.72); population II: HR = 1.68 (95%CI; 1.02-2.76)). CONCLUSIONS: Intergenerational social patterning of ARDs appears to be time-contextual and gender-specific. The role of grandparental social class in developing ARDs in grandchildren seems to decline over time, while persistent grandparental-to-parental social disadvantage remains associated with higher ARD risk in males. When targeting higher risk groups, continuity of familial social disadvantage, particularly among males, should be considered.

Background: Given current drug policy reforms to decriminalize or legalize cannabis in numerous countries worldwide, the current study assesses the relation between cannabis use and the development of testicular cancer. Methods: The study included a population-based sample (n = 49,343) of young men ages 18–21 years who underwent conscription assessment for Swedish military service in 1969–1970. The conscription process included a nonanonymous questionnaire eliciting information about drug use. Conscription information was linked to Swedish health and administrative registry data. Testicular cancers diagnosed between 1970 and 2011 were identified by International Classification of Diseases-7/8/9/10 testicular cancer codes in the Swedish National Patient Register, the Cancer Register, or the Cause of Death Register. Cox regression modeling was used to estimate the hazards associated with cannabis use and time to diagnosis of testicular cancer. Results: No evidence was found of a significant relation between lifetime “ever” cannabis use and the subsequent development of testicular cancer [n = 45,250; 119 testicular cancer cases; adjusted HR (aHR), 1.42; 95% confidence interval (CI), 0.83–2.45]. “Heavy” cannabis use (defined as usage of more than 50 times in lifetime, as measured at conscription) was associated with the incidence of testicular cancer (n = 45,250; 119 testicular cancer cases; aHR 2.57; 95% CI, 1.02–6.50). Conclusions: The current study provides additional evidence to the limited prior literature suggesting cannabis use may contribute to the development of testicular cancer. Impact: Emerging changes to cannabis drug policy should consider the potential role of cannabis use in the development of testicular cancer. Cancer Epidemiol Biomarkers Prev; 26(11); 1644–52. ©2017 AACR.

Objectives Unemployment and temporary employment are known to impact psychological health. However, the extent to which the effect is altered by migration-related and sociodemographic determinants is less clear. The purpose of this study was to investigate whether the association between employment status and psychological distress differs between immigrants and Swedish-born and to what extent, the association is modified by gender and reason for immigration. Design Cross-sectional survey study. Participants and setting Data from public health surveys undertaken in 2002, 2006 and 2010 from random samples of Stockholm County residents, Sweden, were used to analyse a weighted sample of 51 118 individuals aged 18–64 (43 444 Swedish-born, 4055 non-refugees, 3619 refugees). According to their activity in the labour market, the participants were categorised into permanently/self-employed, temporarily employed and unemployed. Outcomes measures Associations between self-reported employment and psychological distress measured by a 12-item version of the General Health Questionnaire were explored across individuals with different migration status and reasons for immigration using logistic regression and pairwise comparisons. The analyses were stratified by gender and adjusted for age, socioeconomic characteristics and survey year. Results Unemployment was associated with elevated likelihood of psychological distress across the study population, regardless of migration status and gender. Fully adjusted models revealed nearly a 3-fold higher odds of distress in unemployed Swedish-born (OR 3.05, 95% CI 2.66 to 3.51), non-refugees (OR 3.51, 95% CI 2.44 to 5.05) and refugees (OR 2.91, 95% CI 2.20 to 3.85) when compared with permanently/self-employed. Temporary employment also increased the likelihood of distress, particularly among refugees and Swedish-born. Conclusions The effect of unemployment on increased likelihood of poor psychological well-being overcomes gender-specific and migration-specific differences and is equally pronounced for Swedish-born, non-refugees and refugees. Exclusion from the labour market appears to be a major determinant of psychological health inequalities in contemporary Sweden.

ObjectiveTo investigate whether poor self-rated health and psychological distress are differentially associated with drinking trajectories over time.MethodsFrom the Stockholm Public Health Cohort, two subcohorts surveyed in 2002–2010–2014 and 2006–2010–2014 (n=23 794 and n=34 667 at baseline, respectively) were used. Alcohol consumption, self-rated health, psychological distress (measured by General Health Questionnaire-12), lifestyle factors and longstanding illness were assessed by questionnaires. Demographic and socioeconomic variables were obtained by register linkage. Logistic regression was fitted to assess the associations with eight alcohol consumption trajectories, which were constructed among 30 228 individuals (13 898 and 16 330 from the 2002 and 2006 subcohorts, respectively) with measures of consumption at three time points.ResultsCompared with stable moderate drinkers, all other trajectories were associated with poor self-rated health with multiadjusted OR for stable non-drinkers of 2.35 (95% CIs 1.86 to 2.97), unstable non-drinkers (OR=2.58, 95% CI 1.54 to 3.32), former drinkers (OR=2.81, 95% CI 2.31 to 3.41) and stable heavy drinkers (OR=2.16, 95% CI 1.47 to 3.20). The associations were not fully explained by sociodemographic and lifestyle factors and longstanding illness. Former drinking, but no other trajectories, was associated with psychological distress (OR=1.24; 95% CI 1.10 to 1.41).ConclusionWe found a U-shape association between alcohol trajectories and self-rated health, but not with psychological distress. Compared with stable moderate drinking, former drinking was associated with the highest odds of both poor self-rated health and psychological distress. The study confirms the importance of a life-course approach to examining the effect of alcohol consumption on health and highlights the poorer general and mental health status of non-drinkers who were former drinkers.

Cannabis (marijuana) smoke and tobacco smoke contain many of the same potent carcinogens, but a critical—yet unresolved—medical and public-health issue is whether cannabis smoking might facilitate the development of lung cancer. The current study aimed to assess the risk of lung cancer among young marijuana users. A population-based cohort study examined men (n = 49,321) aged 18–20 years old assessed for cannabis use and other relevant variables during military conscription in Sweden in 1969–1970. Participants were tracked until 2009 for incident lung cancer outcomes in nationwide linked medical registries. Cox regression modeling assessed relationships between cannabis smoking, measured at conscription, and the hazard of subsequently receiving a lung cancer diagnosis. At the baseline conscription assessment, 10.5 % (n = 5,156) reported lifetime use of marijuana and 1.7 % (n = 831) indicated lifetime use of more than 50 times, designated as “heavy” use. Cox regression analyses (n = 44,284) found that such “heavy” cannabis smoking was significantly associated with more than a twofold risk (hazard ratio 2.12, 95 % CI 1.08–4.14) of developing lung cancer over the 40-year follow-up period, even after statistical adjustment for baseline tobacco use, alcohol use, respiratory conditions, and socioeconomic status. Our primary finding provides initial longitudinal evidence that cannabis use might elevate the risk of lung cancer. In light of the widespread use of marijuana, especially among adolescents and young adults, our study provides important data for informing the risk–benefit calculus of marijuana smoking in medical, public-health, and drug-policy settings.

We estimated the degree to which the relationship between socio-economic position (SEP) and alcohol-related disorders is attenuated after adjustment for levels and patterns of drinking, behavioural, material and social factors.A longitudinal cohort study with baseline in 2002, with linkage to register data on patient care and deaths in 2002-11 to yield the outcome measures.Stockholm County, Sweden.Respondents to baseline survey aged 25-64 (n = 17 440) with information on all studied covariates.Occupational class was the studied SEP indicator and a combined measure of volume of weekly alcohol consumption and frequency of heavy episodic drinking, smoking, employment status, income, social support, marital status and education, all at baseline, were the studied covariates. Alcohol-related disorders (n = 388) were indicated by first register entries on alcohol-related medical care or death during the follow-up.Unskilled workers had an approximately four times greater risk of alcohol-related disorders than higher non-manual employees, hazard ratio (HR) = 4.08 (2.78, 5.98). After adjustment for alcohol use, the SEP difference in risk for alcohol-related harm fell by a fourth for the same group, HR = 2.91 (1.96, 4.33). The difference was reduced further when behavioural factors and material factors were taken into account, HR = 2.09 (1.34, 3.26), whereas adjusting for social factors and attained education resulted in smaller reductions.Socio-economic differences in alcohol use explain one fourth of the socio-economic position differences in alcohol-related disorders in Stockholm, Sweden. Hazardous alcohol use and other behavioural, material and social factors together explain nearly 60% of the socio-economic position differences in alcohol-related disorders.

We conducted a systematic review and meta-analysis, the first to our knowledge, summarizing and quantifying the published evidence on associations between type 2 diabetes incidence and socio-economic position (SEP) (measured by educational level, occupation and income) worldwide and when sub-divided into high-, middle- and low-income countries.Relevant case-control and cohort studies published between 1966 and January 2010 were searched in PubMed and EMBASE using the keywords: diabetes vs educational level, occupation or income. All identified citations were screened by one author, and two authors independently evaluated and extracted data from relevant publications. Risk estimates from individual studies were pooled using random-effects models quantifying the associations.Out of 5120 citations, 23 studies, including 41 measures of association, were found to be relevant. Compared with high educational level, occupation and income, low levels of these determinants were associated with an overall increased risk of type 2 diabetes; [relative risk (RR) = 1.41, 95% confidence interval (CI): 1.28-1.51], (RR = 1.31, 95% CI: 1.09-1.57) and (RR = 1.40, 95% CI: 1.04-1.88), respectively. The increased risks were independent of the income levels of countries, although based on limited data in middle- and low-income countries.The risk of getting type 2 diabetes was associated with low SEP in high-, middle- and low-income countries and overall. The strength of the associations was consistent in high-income countries, whereas there is a strong need for further investigation in middle- and low-income countries.

Sweden has a long history of conducting questionnaire-based Public Health Surveys (PHS) to monitor health determinants. As Sweden has become a multi-ethnic society a linguistically adapted instrument to collect data was first used in Stockholm PHS 2006 to overcome the barrier of lack of Swedish language proficiency, but more importantly to overcome the psychological barrier of being excluded. The questionnaire was translated into the six most spoken languages among Swedish immigrants, namely Arabic, English, Farsi, Finnish, Spanish, and Turkish. In spite of a decrease in participation rate (—2.9%, p < 0.0001) among native Swedes in PHS 2006 compared with PHS 2002, there was a substantial increase in participation rate among immigrants in PHS 2006 who received a translated questionnaire or were interviewed in their mother tongue. The increase in response rate varied from 2.1% among Finnish-speaking immigrants up to 12.4% among Turkish-speaking immigrants and was significant for Arabic-speaking (p < 0.0001), Farsi-speaking (p = 0.003), Spanish-speaking (p < 0.0001) and Turkish-speaking (p < 0.0001) immigrants. Various attempts to increase participation rate will be of importance to policy makers involved in the integration of the immigrant population, to healthcare professionals, and obviously to the public.

Background Survival has steadily improved for major cancer types in most parts of the world. We compared all-cause mortality between foreign-born and Sweden-born residents of Sweden who were diagnosed with cancer of the colon, lung, stomach, prostate, breast, cervix, and all site. Methods We used Swedish national vital status and health registers to follow a cohort of 1,556,108 patients 45 years of age and older diagnosed with cancer between 1961 and 2009 in Sweden. Among them, 109,915 were born abroad. We estimated hazard ratios (HR) and 95% confidence interval (CI) using multivariable Cox proportional hazard models. Results We identified 604,035 and 540,138 deaths among men and women, respectively. Among them 33,595 men and 34,174 women were born abroad. At the time of diagnosis, patients born abroad were on average 4 years younger than patients born in Sweden. All-cause mortality was generally lower in the former than in the latter group of patients before 1990 but higher after 2000. The mortality trend was similar for prostate and breast cancer. Conclusions Whilst national policy in Sweden aims at achieving equal access to health care, the mortality trend observed among cancer patients born in Sweden was different from that observed among patients born elsewhere. Mortality after diagnosis of major types of cancer has worsened among foreign-born after the year 2000. The possible determinants of disparities need be identified and investigated.

A rare collection of serum samples from patients with hepatitis C virus (HCV) infection followed up from the onset of clinical symptoms was acquired. RNA corresponding to the hypervariable region 1 (HVR1) of E2 protein of HCV isolated from nine patients was reverse-transcribed, amplified, sequenced, and HVR1 amino acid sequences were deduced. These sequences and a selection of HVR1 amino acid sequences of matching HCV genotypes from protein and translated DNA sequence databanks were used to create the HVR1 amino acid consensus. The degenerated peptides mimicking N- and C-termini of the consensus were synthesized. Most (76%) of 17 patients followed up for the period from 1 week to a minimum of 7 months from the onset of acute symptoms developed antibodies reacting with peptides representing N- and/or C- termini of HVR1. Antibody recognition of the consensus HVR1 peptides indicates that the variability of HVR1 sequence on the protein level is limited with certain conserved structure(s) being untouched. A tendency was observed for a slower development of anti-HVR1 antibody response in patients developing chronic HCV, as compared to those with self-limiting HCV infection.

BackgroundThe role of alcohol consumption for disability pension (DP) is controversial and systematic reviews have not established causality. We aimed to assess the role of adolescent alcohol use for future DP. We wanted to find out whether an increased risk mainly would affect DP occurring early or late in life as well as whether the level of alcohol consumption and patterns of drinking contribute differently in DP receiving.Methodology/principal findingsThe study is a 39-year follow-up of 49 321 Swedish men born in 1949-1951 and conscripted for compulsory military service in 1969-1970. As study exposures (i) "risk use" of alcohol composed of measures related to pattern of drinking, and (ii) the level of consumption based on self-reported volume and frequency of drinking had been used. Information on DP was obtained from social insurance databases through 2008. "Risk use" of alcohol was associated with both "early DP" and "late DP", i.e. granted below and above the approximate age of 40 years, with crude hazard ratio (HR) of 2.89 (95% confidence intervals (CI) 2.47-3.38) and HR of 1.87 (95%CI: 1.74-2.02), respectively. After adjustment for covariates, HR was reduced to 1.32 (95%CI: 1.09-1.59) and 1.14 (95%CI: 1.05-1.25), respectively. Similar patterns were seen for moderate (101-250 g 100% alcohol/week) and high (>250 g) consumption, though the risk disappeared when fully adjusted.Conclusions/significanceAlcohol use in adolescence, particularly measured as "risk use", is associated with increased risk of future DP. The association is stronger for "early DP", but remains significant even for DP granted in older ages. Therefore, pattern of drinking in adolescent should be considered an important marker for future reduced work capacity.

International audience; Background: Negative socioeconomic gradient is established for coronary heart disease (CHD) mortality and survival, while socioeconomic pattering of disease incidence is less investigated. To study socioeconomic inequalities in incidence of acute myocardial infarction (AMI), the major component of CHD, we undertook meta-analysis to summarize existing evidence on the issue. Methods: A systematic search was performed in PubMed and EMBASE databases for observational studies on AMI incidence and socioeconomic position (SEP), published in English through April 2009. Random-effects model was used to pool the risks estimates from the individual studies. Results: Among 1,181 references, 70 studies fulfilled inclusion criteria. An overall increased risk of AMI among the lowest SEP was found for all three indicators: income (pooled RR=1.71, 95% CI 1.43 to 2.05), occupation (pooled RR=1.35, 95% CI 1.19 to 1.53) and education (pooled RR=1.34, 95% CI 1.22 to 1.47). The strongest associations were seen in high-income countries such us US/Canada and Europe, while the results were inconsistent for middle- and low-income regions. Conclusion: AMI incidence is associated with low SEP. The nature of social stratification at the level of economic development of a country could be involved in the differences of risk of AMI between social groups.

Objective To investigate the associations between various socioeconomic indicators and lung cancer incidence. Methods We searched PubMed and EMBASE databases for studies on socioeconomic position (SEP) and lung cancer incidence published through October 2007. Random-effect model was used to pool the risk estimates from the individual studies. We stratified the analysis by adjustment strategy to investigate the influence of smoking on socioeconomic gradient in lung cancer incidence. Results Out of 3,288 citations, we identified 64 studies eligible for inclusion. Compared to the highest SEP level, we observed an overall increased risk in lung cancer incidence among people with low educational SEP (61%), low occupational SEP (48%), and low income-based SEP (37%). The negative social gradient for lung cancer incidence remained for most of the possible sets of pooled estimates obtained in subgroup analyses for occupational and educational SEP with less consistency for SEP based on income in studies adjusted and unadjusted for smoking. No evidence of publication bias was apparent. Conclusion Lung cancer incidence was associated with low educational, occupational, and income-based SEP. The association, adjusted or unadjusted for smoking, points out the importance of social position to be addressed in all discussions on cancer preventive measures.

Background Chronic replication of cytomegalovirus and EBV in early life may affect the immune system and play a role in the development of allergy in children. Objective To assess the relation between cytomegalovirus infection and allergic disorders in children, including a possible interaction with EBV infection. Methods From a prospective birth cohort study in Stockholm, on factors of importance for development of allergy, 2581 four-year-old children were enrolled. The classification of allergic diseases was based on questionnaire answers and determination of IgE antibodies to common airborne and food allergens. IgG to cytomegalovirus was determined by a commercial ELISA and to EBV by indirect immunofluorescence. Results A total of 1191 (46%) children were cytomegalovirus-seropositive. There were no significant associations between seropositivity to cytomegalovirus and allergic manifestations, such as bronchial asthma, suspected allergic rhinitis, or atopic dermatitis. Seropositivity to cytomegalovirus alone, ie, without seropositivity to EBV, was related to IgE antibodies to airborne and food allergens (adjusted odds ratio, 1.8; 95% CI, 1.2-2.9).An antagonism between cytomegalovirus and EBV in relation to sensitization to airborne and food allergens was suggested ( P =.05). Conclusion The study does not support the hypothesis that previous cytomegalovirus infection plays an important role in the pathogenesis of bronchial asthma, suspected allergic rhinitis, or atopic dermatitis in children. However, in the absence of EBV infection, cytomegalovirus infection may be related to sensitization to airborne and food allergens.

Background Differences in concentrations of antibodies to Epstein-Barr virus (EBV) in atopic and nonatopic children have been observed, suggesting that EBV infection may play a role in allergic diseases. AIM To assess the association between EBV infection and atopy in Swedish children at 4 years of age. Materials and methods Were studied 2561 children born in 1994 through 1996 in Stockholm, Sweden. The children were enrolled in a prospective birth cohort study focusing on the relation of exposure to various environmental and life style factors during early childhood and development of atopy. Blood samples were obtained when the children were approximately 4 years old, and immunoglobulin G to EBV was determined by indirect immunofluorescence. The relationship between the seroprevalence to EBV and various allergic disorders was assessed, withthe use of logistic regression analysis to account for other risk factors. Results Totally 1347 of 2561 (52%) children were EBV-seropositive. Associations between EBV seropositivity and the occurrence of asthma [adjusted odds ratio (OR(adj)), 1.10; 95% confidence interval (95% CI) 0.81 to 1.49] or suspected allergic rhinitis (OR(adj) 0.97; 95% CI 0.76 to 1.25) were not apparent. In children whose mothers were up to 25 years old, a higher EBV seroprevalence was observed than in children of older mothers (OR(adj) 1.34; 95% CI 1.04 to 1.71). Also in children whose mothers smoked, the seroprevalence was higher than in children of nonsmokers (OR(adj) 1.29; 95% CI 1.02 to 1.63). Conclusions The study does not support the hypothesis that EBV infection in early childhood plays an important role in the pathogenesis of allergic diseases in children.