Sociodemographic Risk Factors for Autism in a US Metropolitan Area
ABSTRACT The present study examined the association between autism and sociodemographic factors, overall and in subgroups of children with autism with and without mental retardation (Autism/MR and Autism/No MR, respectively); the association was further examined in subanalyses by child's source of ascertainment to assess the presence of ascertainment bias. In the main analyses, one marker of higher social class (higher median family income) was significantly associated with autism overall. Both markers of higher social class (higher maternal education and higher median family income) were significantly associated with autism/no MR, but not associated with autism/MR. In the subanalyses, associations with social class varied by ascertainment source. Future studies should consider phenotypic subgroups of children with autism and must consider potential ascertainment bias.
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ABSTRACT: Background: Recent studies have reported associations between air pollution exposure and neurodevelopmental disorders in children, but the role of pre- and postnatal exposure has not been elucidated. Aim: We aimed to explore the risk for autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) among children in relation to pre- and postnatal exposure to air pollution from road traffic. Methods: Parents of 3,426 twins born in Stockholm during 1992-2000 were interviewed, when their children were 9 or 12 years old, for symptoms of neurodevelopmental disorders. Residence time-weighted concentrations of particulate matter with a diameter <10 μm (PM10) and nitrogen oxides (NOx) from road traffic were estimated at participants' addresses during pregnancy, the first year, and the ninth year of life using dispersion modeling, controlling for seasonal variation. Multivariate regression models were used to examine the association between air pollution exposure and neurodevelopmental outcomes, adjusting for potential confounding factors. Results: No clear or consistent associations were found between air pollution exposure during any of the three time windows and any of the neurodevelopmental outcomes. For example, a 5-95% difference in exposure to NOx during pregnancy was associated with odds ratios (ORs) of 0.92 (95% confidence interval (CI): 0.44-1.96) and 0.90 (95% CI: 0.58-1.40) for ASD and ADHD respectively. A corresponding range in exposure to PM10 during pregnancy was related to ORs of 1.01 (95% CI: 0.52-1.96) and 1.00 (95% CI: 0.68-1.47) for ASD and ADHD. Conclusions: Our data do not provide support for an association between pre- or postnatal exposure to air pollution from road traffic and neurodevelopmental disorders in children.Twin Research and Human Genetics 09/2014; DOI:10.1017/thg.2014.58 · 1.92 Impact Factor
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ABSTRACT: Background: Few common traits separate the mothers of children with autism spectrum disorder (autism) and intellectual disability (ID) from mothers in the general population. Objectives: * To review research on the pre-existing characteristics which differentiate mothers of children with autism and/or ID of unknown cause from each other and from mothers of children without these disabilities * To provide a source for research into the determinants of autism and/or ID, including the role of genetic and modifiable risk factors. Methods: The papers considered for this review resulted from a search of the Medline, Web of Knowledge, Scopus and Google scholar databases. Combinations of the search terms associated with autism and ID, the hypothesised aetiologies of autism and ID and terms associated with traits of mothers of children with autism and/or ID were used. Examples from each of the three groups are ‘autis*, pervasive development disorder* and intellectual disability’, immigra*, migra*, ethnic*, immun*’ and ‘traits, characteristics, mothers, children’. A paper was included in the review if: * It was published in a peer-reviewed journal between 1990 and 2012 inclusive; * It was a full text article in English; * It described new research; * It compared a characteristic of parents or mothers of children with ASD and/or ID with parents or mothers of children without disability or with a population norm; * It assessed characteristics that were pre-existing and not likely to be a result of caring for a child with ASD and/or ID; and * It used methods of ascertainment and measurement of the characteristic(s) of interest that were assessed as unlikely to lead to bias. Results: Overall, autism was correlated positively with socio-economic status (SES), education and age. By contrast, ID had a negative correlation with each of these variables. A reversal was also apparent with parity where lower parity was associated with the autism group and higher with the ID group. More complex associations were found with immigrant status and ethnicity. With the former, excluding Californian population studies, the children of immigrant mothers consistently were associated with increased rates of autism (particularly autism with ID) and lower rates of Mild or moderate ID (mild ID). A reverse scenario was found in California with a higher proportion of mild ID and a lower proportion of autism in the children of immigrant mothers. With ethnicity and with the exception of Asian mothers, there are lower rates of autism and increased rates of ID in the mothers of ethnic minority groups. Asian mothers exhibited an opposite trend. Further, compared to the ID group, many more traits were associated with the mothers of children with autism in the three areas related to immunology, mental health, pregnancy/childbirth and behavioural traits. Possible explanations for these findings are discussed. Conclusions: Further research in these areas may yield more understanding of the genetic and aetiological aspects of autism and ID. In turn, primary and secondary prevention strategies may be refined and/or developed.2014 International Meeting for Autism Research; 05/2014
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ABSTRACT: The authors examined pregnancy and obstetric complications in association with autism spectrum disorders (ASD) in children of participants from the Nurses' Health Study II, a prospective national cohort with information collected through biennial mailed questionnaires since 1989. Logistic regression was used to obtain crude and adjusted odds ratios for ASD, and by diagnostic subgroup. Seven hundred and ninety-three cases were reported among 66,445 pregnancies. Pregnancy complications and obstetric suboptimality factors were assessed by maternal report of occurrence in first birth and, in secondary analyses, in any birth. Complications and a suboptimality score were significantly associated with having a child with ASD (OR 1.49, 95% CI 1.26, 1.77, P<0.0001 for pregnancy complications in first birth and 2.76, 95% CI 2.04, 3.74, P<0.0001 comparing individuals with four or more obstetric suboptimality factors in first birth to those with none; results similar when assessed in any birth). In particular, gestational diabetes was associated with a significantly increased risk of ASD in results of primary and sensitivity analyses (OR in primary analysis = 1.76, 95% CI 1.34, 2.32, P<0.0001); suboptimal parity and suboptimal age-at-first-birth were also individual factors associated with ASD. Associations were similar by diagnostic subgroup, suggesting autism, Asperger syndrome, and other Pervasive Developmental Disorders are all associated with pregnancy complications. Consistent with previous research, the general class of pregnancy complications was associated with ASD as a whole. Additional work will be required to more fully assess the role of gestational diabetes.Autism Research 02/2012; 5(1):21-30. DOI:10.1002/aur.228 · 4.53 Impact Factor