Autistic Traits and Suicidal Thoughts, Plans, and Self-Harm in Late Adolescence: Population-Based Cohort Study

OBJECTIVE

To examine the hypothesis that autism spectrum disorders (ASD) diagnosis and traits in childhood are associated with suicidal thoughts, plans and self-harm at 16 years, and that any observed associations are explained by depression at 12 years.

METHOD

We examined associations between ASD diagnosis and 4 dichotomized ASD traits (social communication, pragmatic language, repetitive behavior, and sociability) with suicidal and nonsuicidal self-harm, suicidal thoughts, and suicidal plans at age 16 years in 5,031 members of the United Kingdom-based birth cohort study the Avon Longitudinal Study of Parents and Children. We assessed whether any associations were explained by depressive symptoms in early adolescence measured by the Short Moods and Feelings Questionnaire at 12 years.

RESULTS

Children with impaired social communication had a higher risk of self-harm with suicidal intent (relative risk [RR] = 2.14, 95% CI = 1.28-3.58), suicidal thoughts (RR = 1.42, 95% CI = 1.06-1.91), and suicidal plans (RR = 1.95, 95% CI = 1.09-3.47) by age 16 years as compared to those without. There was no evidence for an association between ASD diagnosis and outcomes, although these analyses were imprecise because of small numbers. There was also no evidence of an association between other autism traits and the outcomes. Approximately 32% of the total estimated association between social communication impairment and self-harm was explained by depressive symptoms at 12 years.

CONCLUSION

Social communication impairments are an important autistic trait in relation to suicidality. Early identification and management of depression may be a preventative mechanism, and future research identifying other potentially modifiable mechanisms may lead to interventions against suicidal behavior in this high-risk group.

Gestational age at birth and risk of intellectual disability without a common genetic cause

Preterm birth is linked to intellectual disability and there is evidence to suggest post-term birth may also incur risk. However, these associations have not yet been investigated in the absence of common genetic causes of intellectual disability, where risk associated with late delivery may be preventable. We therefore aimed to examine risk of intellectual disability without a common genetic cause across the entire range of gestation, using a matched-sibling design to account for unmeasured confounding by shared familial factors. We conducted a population-based retrospective study using data from the Stockholm Youth Cohort (n = 499,621) and examined associations in a nested cohort of matched outcome-discordant siblings (n = 8034). Risk of intellectual disability was greatest among those born extremely early (adjusted OR_{24 weeks} = 14.54 [95% CI 11.46-18.44]), lessening with advancing gestational age toward term (aOR_{32 weeks} = 3.59 [3.22-4.01]; aOR_37weeks = 1.50 [1.38-1.63]); aOR_{38 weeks} = 1.26 [1.16-1.37]; aOR₃₉ weeks = 1.10 [1.04-1.17]) and increasing with advancing gestational age post-term (aOR_{42 weeks} = 1.16 [1.08-1.25]; aOR_{43 weeks} = 1.41 [1.21-1.64]; aOR_{44 weeks} = 1.71 [1.34-2.18]; aOR_{45 weeks} = 2.07 [1.47-2.92]). Associations persisted in a cohort of matched siblings suggesting they were robust against confounding by shared familial traits. Risk of intellectual disability was greatest among children showing evidence of fetal growth restriction, especially when birth occurred before or after term. Birth at non-optimal gestational duration may be linked causally with greater risk of intellectual disability. The mechanisms underlying these associations need to be elucidated as they are relevant to clinical practice concerning elective delivery around term and mitigation of risk in post-term children.

Clinical-Scale Cell-Surface-Marker Independent Acoustic Microfluidic Enrichment of Tumor Cells from Blood

Enumeration of circulating tumor cells (CTCs) predicts overall survival and treatment response in metastatic cancer, but as many commercialized assays isolate CTCs positive for epithelial cell markers alone, CTCs with little or no epithelial cell adhesion molecule (EpCAM) expression stay undetected. Therefore, CTC enrichment and isolation by label-free methods based on biophysical rather than biochemical properties could provide a more representative spectrum of CTCs. Here, we report on a clinical-scale automated acoustic microfluidic platform processing 5 mL of erythrocyte-depleted paraformaldehyde (PFA)-fixed blood (diluted 1:2) at a flow rate of 75 μL/min, recovering 43/50 (86 ± 2.3%) breast cancer cell line cells (MCF7), with 0.11% cancer cell purity and 162-fold enrichment in close to 2 h based on intrinsic biophysical cell properties. Adjustments of the voltage settings aimed at higher cancer cell purity in the central outlet provided 0.72% cancer cell purity and 1445-fold enrichment that resulted in 62 ± 8.7% cancer cell recovery. Similar rates of cancer-cell recovery, cancer-cell purity, and fold-enrichment were seen with both prostate cancer (DU145, PC3) and breast cancer (MCF7) cell line cells. We identified eosinophil granulocytes as the predominant white blood cell (WBC) contaminant (85%) in the enriched cancer-cell fraction. Processing of viable cancer cells in erythrocyte-depleted blood provided slightly reduced results as to fixed cells (77% cancer cells in the enriched cancer cell fraction, with 0.2% WBC contamination). We demonstrate feasibility of enriching either PFA-fixed or viable cancer cells with a clinical-scale acoustic microfluidic platform that can be adjusted to meet requirements for either high cancer-cell recovery or higher purity and can process 5 mL blood samples in close to 2 h.

Maternal Polycystic Ovary Syndrome and Risk for Attention-Deficit/Hyperactivity Disorder in the Offspring

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood neurodevelopmental disorder, and boys are two to three times more likely to develop ADHD. Maternal polycystic ovary syndrome (PCOS), a common metabolic disorder associated with excess circulating androgens, has been associated with increased risk for autism spectrum disorder in the offspring. In this study, we aimed to investigate whether maternal PCOS increases the risk for ADHD in the offspring.

METHODS

We conducted a matched case-control study using health and population data registers for all children born in Sweden from 1984 to 2008. Maternal PCOS was defined by ICD-coded register diagnosis. The outcome of ADHD was defined as an ICD-coded register diagnosis of ADHD and/or registered prescription of medications to treat ADHD. A total of 58,912 ADHD cases (68.8% male) were identified and matched to 499,998 unaffected controls by sex and birth month and year.

RESULTS

Maternal PCOS increased the odds of offspring ADHD by 42% after adjustment for confounders (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.26-1.58). Exclusion of ADHD cases with comorbid autism spectrum disorder attenuated but did not explain the relationship (OR, 1.34; 95% CI, 1.18-1.52). The risk was somewhat elevated for ADHD with comorbid autism spectrum disorder (OR, 1.76; 95% CI, 1.37-2.26). The risk for ADHD was higher among obese mothers with PCOS (OR, 1.68; 95% CI, 1.31-2.17) and was highest among obese mothers with PCOS and other features of metabolic syndrome (OR, 2.59; 95% CI, 1.02-6.58).

CONCLUSIONS

This study provides evidence that maternal PCOS may subtly influence the neurodevelopment of the offspring, resulting in increased risk for neurodevelopmental disorders such as ADHD.

Prevalence of Autism Spectrum Disorders with and without Intellectual Disability by Gestational Age at Birth in the Stockholm Youth Cohort: a Register Linkage Study

BACKGROUND

Preterm birth has been linked to increased risk of autism spectrum disorders (ASD), but how this risk changes with gestational age at birth has not been well characterised, especially with regard to co-occurring intellectual disability (ID).

METHODS

Register-based cohort study of singleton births in 1984-2007 in Stockholm County, Sweden (N total: 480 728; n ASD: 10 025). We assessed overall and sex-specific, gestational week-specific prevalence estimates and risk ratios of ASD with and without ID.

RESULTS

Preterm and postterm births were associated with elevated risk of ASD, and the relationship between gestational age at birth and ASD with and without ID differed in males and females. Risk of ASD without ID was higher in preterm births among both sexes and decreased continuously with increasing length of gestation. Risk of ASD with ID was higher in both preterm and postterm births among both sexes, with postterm birth in females being more highly associated with ASD with ID than that in males.

CONCLUSIONS

The relationship between gestational age at birth and ASD differs by the presence/absence of co-occurring ID and fetal sex. Both preterm and postterm birth are associated with increased risk of ASD. Risk of ASD is not constant within conventionally defined gestational age at birth periods. Further research on mechanism underlying these associations is needed.

Smokeless tobacco (snus) use and colorectal cancer incidence and survival: Results from nine pooled cohorts

AIMS

Although smoking is considered to be an established risk factor for colorectal cancer, the current evidence on the association between smokeless tobacco and colorectal cancer is scant and inconclusive. We used pooled individual data from the Swedish Collaboration on Health Effects of Snus Use to assess this association.

METHODS

A total of 417,872 male participants from nine cohort studies across Sweden were followed up for incidence of colorectal cancer and death. Outcomes were ascertained through linkage to health registers. We used shared frailty models with random effects at the study level to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

During 7,135,504 person-years of observation, 4170 men developed colorectal cancer. There was no clear association between snus use and colorectal cancer overall. Exclusive current snus users, however, had an increased risk of rectal cancer (HR 1.40: 95% CI 1.09, 1.79). There were no statistically significant associations between snus use and either all-cause or colorectal cancer-specific mortality after colorectal cancer diagnosis.

CONCLUSIONS

Our findings, from a large sample, do not support any strong relationships between snus use and colorectal cancer risk and survival among men. However, the observed increased risk of rectal cancer is noteworthy, and in merit of further attention.

Antenatal nutritional supplementation and autism spectrum disorders in the Stockholm youth cohort: population based cohort study

Objective To determine whether nutritional supplementation during pregnancy is associated with a reduced risk of autism spectrum disorder (ASD) with and without intellectual disability in offspring.Design Observational prospective cohort study using multivariable logistic regression, sibling controls, and propensity score matching.Setting Stockholm County, Sweden.Participants 273 107 mother-child pairs identified through population registers. The study sample was restricted to children who were aged 4 to 15 years by the end of follow-up on 31 December 2011 and were born between 1996 and 2007.Exposures Multivitamin, iron, and folic acid supplement use was reported at the first antenatal visit.Main outcome measure Diagnosis of ASD with and without intellectual disability in children determined from register data up to 31 December 2011.Results Prevalence of ASD with intellectual disability was 0.26% (158 cases in 61 934) in the maternal multivitamin use group and 0.48% (430 cases in 90 480) in the no nutritional supplementation use group. Maternal multivitamin use with or without additional iron or folic acid, or both was associated with lower odds of ASD with intellectual disability in the child compared with mothers who did not use multivitamins, iron, and folic acid (odds ratio 0.69, 95% confidence interval 0.57 to 0.84). Similar estimates were found in propensity score matched (0.68, 0.54 to 0.86) and sibling control (0.77, 0.52 to 1.15) matched analyses, though the confidence interval for the latter association included 1.0 and was therefore not statistically significant. There was no consistent evidence that either iron or folic acid use were inversely associated with ASD prevalence.Conclusions Maternal multivitamin supplementation during pregnancy may be inversely associated with ASD with intellectual disability in offspring. Further scrutiny of maternal nutrition and its role in the cause of autism is recommended.

Antidepressants during pregnancy and autism in offspring: population based cohort study

Objectives To study the association between maternal use of antidepressants during pregnancy and autism spectrum disorder (ASD) in offspring.Design Observational prospective cohort study with regression methods, propensity score matching, sibling controls, and negative control comparison.Setting Stockholm County, Sweden.Participants 254 610 individuals aged 4-17, including 5378 with autism, living in Stockholm County in 2001-11 who were born to mothers who did not take antidepressants and did not have any psychiatric disorder, mothers who took antidepressants during pregnancy, or mothers with psychiatric disorders who did not take antidepressants during pregnancy. Maternal antidepressant use was recorded during first antenatal interview or determined from prescription records.Main outcome measure Offspring diagnosis of autism spectrum disorder, with and without intellectual disability.Results Of the 3342 children exposed to antidepressants during pregnancy, 4.1% (n=136) had a diagnosis of autism compared with a 2.9% prevalence (n=353) in 12 325 children not exposed to antidepressants whose mothers had a history of a psychiatric disorder (adjusted odds ratio 1.45, 95% confidence interval 1.13 to 1.85). Propensity score analysis led to similar results. The results of a sibling control analysis were in the same direction, although with wider confidence intervals. In a negative control comparison, there was no evidence of any increased risk of autism in children whose fathers were prescribed antidepressants during the mothers' pregnancy (1.13, 0.68 to 1.88). In all analyses, the risk increase concerned only autism without intellectual disability.Conclusions The association between antidepressant use during pregnancy and autism, particularly autism without intellectual disability, might not solely be a byproduct of confounding. Study of the potential underlying biological mechanisms could help the understanding of modifiable mechanisms in the aetiology of autism. Importantly, the absolute risk of autism was small, and, hypothetically, if no pregnant women took antidepressants, the number of cases that could potentially be prevented would be small.

Use of moist oral snuff (snus) and pancreatic cancer: Pooled analysis of nine prospective observational studies

While smoking is a well-established risk factor for pancreatic cancer, the effect of smokeless tobacco is less well understood. We used pooled individual data from the Swedish Collaboration on Health Effects of Snus Use to assess the association between Swedish snus use and the risk of pancreatic cancer. A total of 424,152 male participants from nine cohort studies were followed up for risk of pancreatic cancer through linkage to health registers. We used shared frailty models with random effects at the study level, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for confounding factors. During 9,276,054 person-years of observation, 1,447 men developed pancreatic cancer. Compared to never-snus use, current snus use was not associated with risk of pancreatic cancer (HR 0.96, 95% CI 0.83-1.11) after adjustment for smoking. Swedish snus use does not appear to be implicated in the development of pancreatic cancer in men. Tobacco smoke constituents other than nicotine or its metabolites may account for the relationship between smoking and pancreatic cancer.

Smokeless tobacco (snus) is associated with an increased risk of type 2 diabetes: results from five pooled cohorts

BACKGROUND

Smoking and nicotine exposure increase insulin resistance and the risk of type 2 diabetes. Swedish smokeless tobacco (snus) is high in nicotine, and its use is prevalent in Scandinavian countries, but few studies have investigated snus use in relation to diabetes risk.

OBJECTIVE

To explore the association between snus use and risk of type 2 diabetes using pooled data from five cohorts.

METHODS

Analyses were based on prospective studies conducted between 1990 and 2013 including 54 531 never-smoking men and 2441 incident cases of type 2 diabetes identified through screening, self-reporting and hospital and prescription registries. Hazard ratios (HRs) and 95% confidence intervals (CIs) were assessed and adjusted for age, body mass index, educational level, alcohol consumption and physical activity.

RESULTS

Compared to never users, the HR of type 2 diabetes was 1.15 (95% CI: 1.00-1.32) in current users of snus. In individuals consuming 5-6 boxes per week, the HR was 1.42 (95% CI: 1.07-1.87); in those consuming ≥7 boxes per week, the HR was 1.68 (95% CI: 1.17-2.41). Each additional box of snus consumed per week yielded an HR of 1.08 (95% CI: 1.01-1.16).

CONCLUSION

Our findings indicate that high consumption of snus is a risk factor for type 2 diabetes. The risk was similar to that in smokers, implying that smokers will not reduce their risk of type 2 diabetes by changing to snus use. The results also support the notion that nicotine increases the risk of type 2 diabetes.

Development of a pathway model to assess the exposure of European pine trees to pine wood nematode via the trade of wood

Pine wood nematode (PWN), Bursaphelenchus xylophilus, is a threat for pine species (Pinus spp.) throughout the world. The nematode is native to North America, and invaded Japan, China, Korea, and Taiwan, and more recently Portugal and Spain. PWN enters new areas through trade in wood products. Once established, eradication is not practically feasible. Therefore, preventing entry of PWN into new areas is crucial. Entry risk analysis can assist in targeting management to reduce the probability of entry. Assessing the entry of PWN is challenging due to the complexity of the wood trade and the wood processing chain. In this paper, we develop a pathway model that describes the wood trade and wood processing chain to determine the structure of the entry process. We consider entry of PWN through imported coniferous wood from China, a possible origin of Portuguese populations, to Europe. We show that exposure increased over years due to an increase in imports of sawn wood. From 2000 to 2012, Europe received an estimated 84 PWN propagules from China, 88% of which arose from imported sawn wood and 12% from round wood. The region in Portugal where the PWN was first reported is among those with the highest PWN transfer per unit of imported wood due to a high host cover and vector activity. An estimated 62% of PWN is expected to enter in countries where PWN is not expected to cause the wilt of pine trees because of low summer temperatures (e.g., Belgium, Sweden, Norway). In these countries, PWN is not easily detected, and such countries can thus serve as potential reservoirs of PWN. The model identifies ports and regions with high exposure, which helps targeting monitoring and surveillance, even in areas where wilt disease is not expected to occur. In addition, we show that exposure is most efficiently reduced by additional treatments in the country of origin, and/or import wood from PWN-free zones. Pathway modelling assists plant health managers in analyzing risks along the pathway and planning measures for enhancing biosecurity.

Perinatal Exposure to Traffic-Related Air Pollution and Autism Spectrum Disorders

BACKGROUND

Studies from the United States indicate that exposure to air pollution in early life is associated with autism spectrum disorders (ASD) in children, but the evidence is not consistent with European data.

OBJECTIVE

We aimed to investigate the association between exposure to air pollution from road traffic and the risk of ASD in children, with careful adjustment for socioeconomic and other confounders.

METHOD

Children born and residing in Stockholm, Sweden, during 1993-2007 with an ASD diagnosis were identified through multiple health registers and classified as cases (n = 5,136). A randomly selected sample of 18,237 children from the same study base constituted controls. Levels of nitrogen oxides (NOx) and particulate matter with diameter ≤ 10 μm (PM10) from road traffic were estimated at residential addresses during mother's pregnancy and the child's first year of life by dispersion models. Odds ratios (OR) and 95% confidence intervals (CI) for ASD with or without intellectual disability (ID) were estimated using logistic regression models after conditioning on municipality and calendar year of birth as well as adjustment for potential confounders.

RESULT

Air pollution exposure during the prenatal period was not associated with ASD overall (OR = 1.00; 95% CI: 0.86, 1.15 per 10-μg/m3 increase in PM10 and OR = 1.02; 95% CI: 0.94, 1.10 per 20-μg/m3 increase in NOx during mother's pregnancy). Similar results were seen for exposure during the first year of life, and for ASD in combination with ID. An inverse association between air pollution exposure and ASD risk was observed among children of mothers who moved to a new residence during pregnancy.

CONCLUSION

Early-life exposure to low levels of NOx and PM10 from road traffic does not appear to increase the risk of ASD. Citation: Gong T, Dalman C, Wicks S, Dal H, Magnusson C, Lundholm C, Almqvist C, Pershagen G. 2017. Perinatal exposure to traffic-related air pollution and autism spectrum disorders. Environ Health Perspect 125:119-126; http://dx.doi.org/10.1289/EHP118.

Maternal smoking during pregnancy and offspring's tobacco dependence. A study of exposure-discordant sibling pairs

BACKGROUND

Prenatal exposure to maternal smoking has previously been linked to tobacco dependence, but confounding from genetic and early-environmental factors is of concern. The aim of this study was to clarify if maternal smoking during pregnancy may affect the onset and manifestations of tobacco dependence after taking such factors into account.

METHODS

The study is based on a matched cohort of 1538 siblings discordant for prenatal exposure to maternal smoking, who participated in a survey conducted in 2010 in Sweden. Analyses were based on pairs where both siblings had been daily smokers (193 pairs) or snus users (173 pairs) at some time in their life. Participants were 19-27 years old at the time of participation. Outcomes were tobacco dependence measured with the Cigarette Dependence Scale (CDS-12) in smokers and with the adapted Smokeless Tobacco Dependence Scale (STDS-12) in snus users, and previous quit attempts. Exposure to maternal smoking during pregnancy was retrieved from the Swedish Medical Birth Register.

RESULTS

There was no difference in dependence scores in exposure-discordant siblings (mean difference 0.36 on CDS-12 [95% confidence interval: -1.23 to 1.95] and 0.61 on STDS-12 [95% confidence interval: -1.20 to 2.43]). Neither did the siblings differ with regard to previous quit attempts.

CONCLUSIONS

Maternal smoking during pregnancy does not appear to influence tobacco dependence in adult offspring. A potential effect of heavy maternal smoking during pregnancy cannot be excluded, but genetic and environmental influences seem to be more influential for the onset of tobacco dependence.

Do overeducated individuals have increased risks of ill health?: a Swedish population-based cohort study

Previous studies indicate that the increasing educational level in many post-industrial nations may imply that subgroups of the population work in occupations for which they are overeducated. We aimed to investigate whether overeducation is associated with future self-rated health and psychological distress. The analytical sample consisted of 21,159 participants from the Stockholm Public Health Cohort. Individuals with upper secondary or university education, who in 2006 or 2007 had occupations requiring less education, were considered overeducated. The outcomes were self-rated health (SRH) and psychological distress in 2010. Overeducated women had an increased risk of less than good SRH, compared to university-educated women in matching occupations (adjusted odds ratios (OR): 2.44 confidence intervals (CI): 1.32-4.51 for overeducated women with secondary school education), but not compared to less educated women in the same occupational class (adjusted OR: 0.87 CI:0.32-2.38 for overeducated women with secondary school education). We found no increased risk of less than good SRH for overeducated men, and no association between overeducation and psychological distress for either sex. The results indicate that overeducation is not per se associated with onset of less than good SRH or psychological distress in a short-term perspective, and the findings support education expansion as a means of improving public health.

The impact of work related physical activity and leisure physical activity on the risk and prognosis of neck pain - a population based cohort study on workers

BACKGROUND

The effect of physical activity on risk and prognosis for neck pain has been studied earlier with inconclusive results. There is a need for large prospective studies on the subject. The aim of this study was to investigate if work related physical activity and physical activity during leisure time are of importance for the risk and prognosis of neck pain in men and women.

METHODS

We used the Stockholm Public Health Cohort and formed two sub-cohorts of the working population based on data from 2002. Cohort I (risk cohort) included persons without neck pain (n = 4681), and cohort II (prognostic cohort) included persons with occasional neck pain (n = 6820) during the previous six months. Both cohorts were assessed for the outcome long duration troublesome neck pain (LDNP) in 2007. The exposures and potential confounders were assessed through a questionnaire in 2002. The question regarding work related physical activity over the past 12 months had five answering categories ranging from "sedentary" to"heavy". The question regarding leisure physical activity for the past 12 months had five answering categories ranging from "sedentary" to "regular physical activity". LDNP in 2007 was defined as having had troublesome neck pain lasting ≥ 3 consecutive months during the previous five years. Associations between work related physical activity and LDNP, as well as leisure physical activity and LDNP, were investigated by multivariable logistic regression, considering potential confounding factors.

RESULTS

In cohort I (risk cohort) we found an association between leisure physical activity and LDNP. In cohort II (prognostic cohort) we found no association between the exposures and the outcome.

CONCLUSION

The results suggest that leisure physical activity has a protective effect on the risk of developing LDNP in a population free from neck pain. It did not, however, affect the prognosis of occasional neck pain. Neither the risk nor the prognosis of neck pain was affected by work related physical activity in this study.

The influence of school on whether girls develop eating disorders

Background: Clinical anecdote suggests that rates of eating disorders (ED) vary between schools. Given their high prevalence and mortality, understanding risk factors is important. We hypothesised that rates of ED would vary between schools, and that school proportion of female students and proportion of parents with post-high school education would be associated with ED, after accounting for individual characteristics.

Method: Multilevel analysis of register-based, record-linkage data on 55 059 females born in Stockholm County, Sweden, from 1983, finishing high school in 2002-10. Outcome was clinical diagnosis of an ED, or attendance at a specialist ED clinic, aged 16-20 years.

Results: The 5-year cumulative incidence of ED diagnosis aged 16-20 years was 2.4%. Accounting for individual risk factors, with each 10% increase in the proportion of girls at a school, the odds ratio for ED was 1.07 (1.01 to 1.13), P = 0.018. With each 10% increase in the proportion of children with at least one parent with post-high school education, the odds ratio for ED was 1.14 (1.09 to 1.19), P < 0.0001. Predicted probability of an average girl developing an ED was 1.3% at a school with 25% girls where 25% of parents have post-high school education, and 3.3% at a school with 75% girls where 75% of parents have post-high school education.

Conclusions: Rates of ED vary between schools; this is not explained by individual characteristics. Girls at schools with high proportions of female students, and students with highly educated parents, have higher odds of ED regardless of individual risk factors.

Refugee migration and risk of schizophrenia and other non-affective psychoses: cohort study of 1.3 million people in Sweden

OBJECTIVE

To determine whether refugees are at elevated risk of schizophrenia and other non-affective psychotic disorders, relative to non-refugee migrants from similar regions of origin and the Swedish-born population.

DESIGN

Cohort study of people living in Sweden, born after 1 January 1984 and followed from their 14th birthday or arrival in Sweden, if later, until diagnosis of a non-affective psychotic disorder, emigration, death, or 31 December 2011.

SETTING

Linked Swedish national register data.

PARTICIPANTS

1,347,790 people, including people born in Sweden to two Swedish-born parents (1,191,004; 88.4%), refugees (24,123; 1.8%), and non-refugee migrants (132,663; 9.8%) from four major refugee generating regions: the Middle East and north Africa, sub-Saharan Africa, Asia, and Eastern Europe and Russia.

MAIN OUTCOME MEASURES

Cox regression analysis was used to estimate adjusted hazard ratios for non-affective psychotic disorders by refugee status and region of origin, controlling for age at risk, sex, disposable income, and population density.

RESULTS

3704 cases of non-affective psychotic disorder were identified during 8.9 million person years of follow-up. The crude incidence rate was 38.5 (95% confidence interval 37.2 to 39.9) per 100,000 person years in the Swedish-born population, 80.4 (72.7 to 88.9) per 100,000 person years in non-refugee migrants, and 126.4 (103.1 to 154.8) per 100,000 person years in refugees. Refugees were at increased risk of psychosis compared with both the Swedish-born population (adjusted hazard ratio 2.9, 95% confidence interval 2.3 to 3.6) and non-refugee migrants (1.7, 1.3 to 2.1) after adjustment for confounders. The increased rate in refugees compared with non-refugee migrants was more pronounced in men (likelihood ratio test for interaction χ(2) (df=2) z=13.5; P=0.001) and was present for refugees from all regions except sub-Saharan Africa. Both refugees and non-refugee migrants from sub-Saharan Africa had similarly high rates relative to the Swedish-born population.

CONCLUSIONS

Refugees face an increased risk of schizophrenia and other non-affective psychotic disorders compared with non-refugee migrants from similar regions of origin and the native-born Swedish population. Clinicians and health service planners in refugee receiving countries should be aware of a raised risk of psychosis in addition to other mental and physical health inequalities experienced by refugees.

Maternal vitamin D deficiency and the risk of autism spectrum disorders: population-based study

BACKGROUND

Maternal vitamin D deficiency may increase risk of autism spectrum disorder (ASD), but direct evidence is lacking.

AIMS

To clarify the relationship between maternal vitamin D deficiency and offspring risk of ASD with and without intellectual disability.

METHOD

Using a register-based total population study (N=509 639), we calculated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of ASD with and without intellectual disability in relation to lifetime diagnoses of maternal vitamin D deficiency. Although rare, such deficiency was associated with offspring risk of ASD with, but not without, intellectual disability (aORs 2.51, 95% CI 1.22-5.16 and 1.28, 0.68-2.42). Relationships were stronger in non-immigrant children.

CONCLUSIONS

If reflecting associations for prenatal hypovitaminosis, these findings imply gestational vitamin D substitution as a means of ASD prevention.

DECLARATION OF INTEREST

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Associations of Parental Depression With Child School Performance at Age 16 Years in Sweden

IMPORTANCE

Depression is a common cause of morbidity and disability worldwide. Parental depression is associated with early-life child neurodevelopmental, behavioral, emotional, mental, and social problems. More studies are needed to explore the link between parental depression and long-term child outcomes.

OBJECTIVE

To examine the associations of parental depression with child school performance at the end of compulsory education (approximately age 16 years).

DESIGN, SETTING, AND PARTICIPANTS

Parental depression diagnoses (based on the International Classification of Diseases, Eighth Revision [ICD-8], International Classification of Diseases, Ninth Revision [ICD-9], and the International Statistical Classification of Diseases, 10th Revision [ICD-10]) in inpatient records from 1969 onward, outpatient records beginning in 2001, and school grades at the end of compulsory education were collected for all children born from 1984 to 1994 in Sweden. The final analytic sample size was 1,124,162 biological children. We examined the associations of parental depression during different periods (before birth, after birth, and during child ages 1-5, 6-10, and 11-16 years, as well as any time before the child's final year of compulsory schooling) with the final school grades. Linear regression models adjusted for various child and parent characteristics. The dates of the analysis were January to November 2015.

MAIN OUTCOME AND MEASURE

Decile of school grades at the end of compulsory education (range, 1-10, with 1 being the lowest and 10 being the highest).

RESULTS

The study cohort comprised 1,124,162 children, of whom 48.9% were female. Maternal depression and paternal depression at any time before the final compulsory school year were associated with worse school performance. After covariate adjustment, these associations decreased to -0.45 (95% CI, -0.48 to -0.42) and -0.40 (-0.43 to -0.37) lower deciles, respectively. These effect sizes are similarly as large as the observed difference in school performance between the lowest and highest quintiles of family income but approximately one-third of the observed difference between maternal education of 9 or less vs more than 12 years. Both maternal depression and paternal depression at different periods (before birth, after birth, and during child ages 1-5, 6-10, and 11-16 years) generally were associated with worse school performance. Child sex modified the associations of maternal depression with school performance such that maternal depression had a larger negative influence on child school performance for girls compared with boys.

CONCLUSIONS AND RELEVANCE

Diagnoses of parental depression throughout a child's life were associated with worse school performance at age 16 years. Our results suggest that diagnoses of parental depression may have a far-reaching effect on an important aspect of child development, with implications for future life course outcomes.

Associations Between Maternal Infection During Pregnancy, Childhood Infections, and the Risk of Subsequent Psychotic Disorder--A Swedish Cohort Study of Nearly 2 Million Individuals

OBJECTIVE

Recent studies question whether the risk for psychotic disorder associated with prenatal exposure to infection are due to infections per se, or to shared susceptibility of both infections and psychiatric disorders. Moreover, the potential link between prenatal infection and serious infections during childhood, another alleged risk factor for psychotic disorder, remains unknown. The aim of this study was to investigate the role of maternal infections during pregnancy in context of parental psychiatric disorders and subsequent childhood infections.

METHOD

All children born in Sweden 1978-1997 were linked to the National Patient Register. Hazard ratios of nonaffective psychosis were estimated in relation to maternal infection during pregnancy and odds ratios of childhood infection were calculated in relation to maternal infection during pregnancy. Relative excess risk due to interaction (RERI) estimated biological synergism between parental psychiatric disorder and maternal infection during pregnancy, and between maternal infection during pregnancy and childhood infection.

RESULTS

Maternal infection during pregnancy was not statistically significantly associated with offspring psychosis (adjusted hazard ratio: 1.06, 95% CI 0.88-1.27). However, maternal infection during pregnancy and maternal psychiatric disorders acted synergistically in offspring psychosis development (RERI 1.33, 95% CI 0.27-2.38). Maternal infection during pregnancy increased the risk of offspring childhood infections (OR 1.50, 95% CI 1.45-1.54). These 2 factors also interacted in psychosis development (RERI 0.63, 95% CI 0.12-1.14).

CONCLUSIONS

Among mothers with a history of psychiatric disease, infection during pregnancy increases the risk of psychosis in offspring. Maternal infections during pregnancy appear to contribute to the risk of childhood infections, which together render the child more vulnerable to psychosis development.

Changes in prevalence of autism spectrum disorders in 2001-2011: findings from the Stockholm youth cohort

In a record-linkage study in Stockholm, Sweden, the year 2011 prevalence of diagnosed autism spectrum disorders (ASD) was found to be 0.40, 1.74, 2.46, and 1.76% among 0-5, 6-12, 13-17, and 18-27 year olds, respectively. The corresponding proportion of cases with a recorded diagnosis of intellectual disability was 17.4, 22.1, 26.1 and 29.4%. Between 2001 and 2011, ASD prevalence increased almost 3.5 fold among children aged 2-17 years. The increase was mainly accounted for by an eightfold increase of ASD without intellectual disability (from 0.14 to 1.10 %), while the prevalence of ASD with intellectual disability increased only slightly (from 0.28 to 0.34%). The increase in ASD prevalence is likely contributed to by extrinsic factors such as increased awareness and diagnostics.