To determine whether adopted children with autism spectrum disorder (ASD) differ from the general ASD population in terms of diagnosis, internalizing and externalizing behaviors, sleep problems, and medications.
We studied 163 adoptees in the Autism Speaks Autism Treatment Network (ATN) in comparison with 5624 nonadopted ATN participants (aged 1.5–17.6 years; mean [SD] = 6.2 [3.4] years). Gender, age, race, ethnicity, IQ, and categorical Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, ASD diagnosis were tested for differences by group (adopted versus nonadopted) by using independent-samples t tests for continuous variables and Fisher’s exact tests for categorical variables. Logistic or linear regression models were used to examine the association between adoption status and several outcome variables, after controlling for covariates.
After controlling for demographics and diagnosis, there were significant differences in group characteristics, including greater propensity for externalizing behavior (P < .001), internalizing behavior (P = .001), and sleep problems (P < .001) in the adopted population. Adoptees were also prescribed psychotropic medications (P < .001) more often than the nonadoptees. Adoptees received a diagnosis of pervasive developmental disorder–not otherwise specified significantly more frequently than controls (odds ratio = 1.8; CI = 1.3–2.5; P < .001), despite no significant difference in symptoms on standardized measures.
These results suggest that the population of adopted children with ASD differs from the general ASD population both with regard to diagnostic subtype and co-occurring behavioral problems. Future research should evaluate the contributions of specific factors associated with adoption such as biological family history, pregnancy history, early childhood experience, and age at adoption.