Parent-reported medical comorbidities in children with autism spectrum disorders

Thesis (M.A.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Objective: Autism Spectrum Disorders (ASDs) are a group of behaviorally defined neurodevelopmental disorders with core deficits in three domains, including social interaction, communication, and restricted and repetitive stereotyped patterns of behavior. Calculating the prevalence of medical comorbidities in individuals with ASD has been difficult and inconsistent across the literature. Previously reported prevalence rates of medical comorbidities in children with ASD have ranged from less than 10% to over 30%. The most commonly cited medical comorbidities have been neurologic in origin since most of the research has attempted to explain ASDs neurobiological etiology. Co-occurring psychiatric comorbidities and gastrointestinal complications are also commonly cited in the literature. Due to limitations in previous studies investigating medical comorbidities in ASDs, prevalence rates and their implications have been varied and still remain ambiguous. This study seeks to investigate systemic organ-specific medical complications, as well as, psychiatric comorbidities in a large population of children with ASDs using well-defined diagnostic criteria and data collection methods. Correlating these comorbidities with intellectual functioning, gender, and ASD diagnosis will provide guidance for therapeutic approaches and services necessary for high-risk children with ASDs. Methods: The study sample consisted of 2493 children and adolescents between the ages of 4 and 18 years (M=8.9, SD=3.5) who participated in the Simons Simplex Collection (SSC). An extensive medical history interview (MHI) was administered by a clinician to a parent of each participant in the study. Data pertaining to ten organ-specific comorbidities was collected and analyzed for each participant, including: neurological, psychiatric, gastrointestinal, autoimmune, respiratory, heart, kidney, genital, hearing, and visual histories. Prevalence rates of having one or more comorbidities, overall and by organ system and their specific symptoms were calculated. A one-way ANOVA was used to compare ASD diagnosis and number of medical comorbidities present. Similar analyses were conducted for the number of psychiatric symptoms. Independent samples t-tests were used to examine differences by gender and intellectual disability in the number of medical and psychiatric comorbidities. Results: A total of 80.0% of the ASD population had at least one or more medical comorbidities. The top three comorbidities were gastrointestinal complications (4 7.9%), followed by neurological co morbidities (34.1%), and psychiatric comorbidity (19.0%). ANOVA analyses revealed a significant difference in the amount of medical comorbidities amongst the diagnostic groups (F (2,2490) = 11.476, p less than 0.01), with Asperger's Disorder having the highest average number of comorbidities. There were no significant differences between genders in the number of medical comorbidities present (t (2491) = .034, p > 0.05). Individuals without intellectual disability had the highest amount of comorbidities endorsed, displaying a mean of 1.63 (SD= 1.29), however, the differences between of the number of medical comorbidities and intellectual disability were not significant (t (2491) = 1.055, p > 0.05). When examining psychiatric symptoms, a significant difference was found in the amount of psychiatric symptoms present and ASD diagnosis (F (2,2490) = 31.77, p less than .000) and individuals with Asperger's Disorder had more psychiatric symptoms than those with ASD or POD-NOS (p less than 0.01, p less than 0.01, respectively). Conclusion: The overall reported prevalence rate of 80.0% is the largest comorbidity rate that has been found to date in a population of individuals with ASD. The difference between ASD diagnosis and the amount of medical comorbidities present remains discrepant with some previous research findings and perhaps supports the future DSM-V changes collapsing the three ASD groups into one diagnostic category. This is the largest sample size studied to date, providing greater insight to the medical comorbidities frequently seen in this neurodevelopmental disorder