Prevalence of Overweight and Obesity in Youth with Autism Spectrum Disorders

Background:  Overweight and obese children are at an increased risk for physical, social, and psychological disorders as compared to the general population. In addition, early weight gain predisposes children to adult obesity.  Many developmental and psychiatric disorders have been associated with a higher prevalence of obesity and overweight, as compared to the general population.  Research has suggested that children with Autism Spectrum Disorders  (ASD) are at 2-3 times greater risk for obesity and overweight than typical peers. However, these results have been based on parent-reported height, weight, and diagnosis [1,2].

Objectives:  Our aim was to determine the prevalence of objectively measured obesity and overweight in a large group of ASD youth and compare it with measured rates in the US population.

Methods: We utilized the National Database for Autism Research (NDAR), which includes reports of standardized ASD diagnostic measures (ADI and ADOS), demographics and physical exams gathered from multiple studies.  We extracted height, weight, and demographic (gender, age, race/ethnicitydata for 249 children between the ages of 2 and 17 who met criteria for ASD by ADI and/or ADOS.  We calculated age- and sex-specific BMI percentiles for each subject and determined the percentage of subjects whose BMI percentiles met criteria for underweight (<5^th percentile), overweight (>/= 85^th percentile), and obesity (>/= 95^thpercentile).  These data were compared to those from the general population, as collected by the National Health and Nutrition Examination Survey (NHANES) (2009-2010) and reported by Ogden, et al [3].

Results: In the general population, 31.8% of children are overweight and 16.9% of children are obese [NHANES database; Ogden et al, 2012]. In comparison, we found that 43.8% of children meeting criteria for ASD by ADI and/or ADOS were overweight, and 25.7% were obese.  An increased prevalence of obesity and overweight amongst children with ASD was not specific to one particular demographic; the percent of overweight and obese children with ASD was elevated compared to the general population across the majority of ethnic, age, and gender groups considered.

Conclusions: Children with ASD have a much higher prevalence of obesity and overweight than the general population and are likely to experience more long-term health consequences.  Excessive weight  in ASD youth might be due to multiple factors including medication use, opportunities for prolonged physical activity and engagement in age appropriate activities.  We are particularly concerned about treatment with second generation antipsychotics,  which are the only agents with an FDA indication in ASD, but are also associated with heightened weight gain and insulin resistance. Further analyses incorporating additional data available from NDAR will examine the correlation of overweight/obesity with medication history, cognitive abilities and level of social functioning in order to help elucidate the particular aspects of ASD that predispose this population to increased weight.  The areas that appear most strongly associated should be targets of intervention development efforts.  

1. Curtin et al (2010) BMC Pediatrics, 10(1),11-5.
2. Rimmer et al (2010) J Intellectual Disability Research, 54(9), 787–794.
3. Ogden et al (2012) JAMA, 307(5), 483–490.