2016 Gatlinburg Conference Poster
PS-91
Title: Comparison of Parental and Gestational Age Risk Factors Associated with Autism Spectrum Disorder (ASD), Intellectual
Disability (ID), Co-occurring ASD and ID, and Individuals without ASD and ID
Authors: Kang Won Choi, Christy L. Hom, Ira T. Lott
Introduction: Autism Spectrum Disorder (ASD) is often comorbid with intellectual disability (ID) and associated with poorer
outcome. Past studies have found advanced paternal age to be a risk factor for ASD and ASD+ID, with a stronger association
than maternal age(1-2). Also, large differences (>10 years) between parental ages may increase the risk of ASD(3). Moreover,
low gestational age is believed to increase the risk of ASD or ID, or both(4-6). This retrospective study is the first to examine
whether the following four groups have different risk factors: 1) ASD, 2)ID, 3)ASD+ID, 4)No ASD/ID. We hypothesize that
advanced paternal age, large discrepancies between the mother and father's ages, and low gestational age all increase the risk of
ASD, regardless of patients' ID status. It is unknown whether the same risk factors predict a diagnosis of ID among individuals
without ASD.
Methods: We analyzed data drawn from 462 patients evaluated in a neurodevelopmental clinic between 2001 through 2013. All
were receiving services funded by the California Department of Disability Services due to ID, ASD, or conditions that require
treatment and services similar to an individual with developmental disability. Patients were grouped into the following diagnostic
categories: 1) ASD (n=48, 10.39%), 2) ID (n=192, 41.56%), 3) ASD+ID (n=204, 44.16%), and 4) No ASD/ID (n=18, 3.90%).
Results: Preliminary analysis of our data indicated that paternal age was associated with increased risk of comorbid ASD and ID
(χ2(1)=17.95, p<0.001, OR=1.057, 95% CI=1.029, 1.085), but not with a sole diagnosis of ASD or ID. Meanwhile, gestational age
was associated with increased risk of a sole diagnosis of ASD (χ2(1)=7.84, p<0.01, OR=1.21, 95% CI=1.044, 1.400), but not with ID
or the comorbid diagnosis of ASD and ID.
We will build a 2-stage model for each of the four diagnostic groups. In stage 1, we will use regression analysis to calculate the
residual between maternal age and the predicted maternal age in relation to the paternal age. In stage 2, we will use binary
logistic regression to determine the risk for being in each diagnostic category using paternal age, residual of maternal age in
relation to paternal age, and gestational age as predictor variables.
Discussion: Our study has found that the factors that predict a comorbid diagnosis of ASD and ID are different than factors that
predict ASD without ID. If we also find differences in the factors that predict ID status among individuals without ASD, we will
have further evidence that ASD and ID represent orthogonal constructs, not varying levels of severity along the same continuum.
This has important implications for how clinicians diagnose and treat these disorders as well as how educators teach children
with either or both disorders.
References/Citations:
• Vierck E & Silverman JM, Brief Report: Phenotypic differences and their relationship to paternal age and gender in
autism spectrum disorder, J Autism Dev Disord, 2015, 45:1915-1924.
• Idring S, et al., Parental age and the risk of autism spectrum disorders: findings from a Swedish population-based cohort,
International Journal of Epidemiology, (2014) 107-115.
• Sandin S, et al., Autism risk associated with parental age and with increasing difference in age between the parents,
Molecular Psychiatry (2015), 1-8, advanced online publication, June 9.
• Abel MA, et al., Deviance in Fetal Growth and Risk of Autism Spectrum Disorder, Am J Psychiatry, (2013) 170:391-398.
• Schieve LA, et al. Comparison of Perinatal Risk Factors Associated with Autism Spectrum Disorder (ASD), Intellectual
Disability (ID), and Co-occurring ASD and ID, J Autism Dev Disord (2015) 45:2361-2372.
• Quinlan CA, et al., Parental age and Autism Spectrum Disorders among New York City children 0-36 months of age,
Matern Child Health J (2015) 19: 1783-1790.