Repetitive Behavior and Restricted Interests of Offspring in Adults with ASD and Other Neuropsychiatric Disorders

Background:  The broader autism phenoptype (BAP) is an emerging construct suggesting that first-degree relatives of those diagnosed with autism spectrum disorders (ASD) exhibit behaviors that encompass the ASD spectrum without necessarily reaching diagnostic thresholds for clinical disorder. Generally the BAP refers to behaviors of parents or "unaffected" siblings of children with ASD. Some aspects of the BAP are relevant to other disorders as well. Repetitive Behaviors and Restricted Interests (RBRI) for example not only define ASD (and the BAP) but they also appear in a wide range of other neurodevelopmental and neuropsychiatric disorders, including, but not limited to, obsessive-compulsive disorder (OCD), tic disorders, intellectual and developmental disabilities, and psychotic disorders. What is not well understood is the manifestation of RBRI in the offspring of adults diagnosed with these disorders, as well as (high functioning) ASD. We know virtually nothing, about the trajectory of RBRI in children who are at risk for various neurodevelopmetnal and neuropsychiatric disorders, by virtue of parental diagnostic status.

Objectives:  To examine the frequency/intensity, as well as the cross-sectional trajectory, of RBRI in offspring of adults diagnosed with a range of neurodevelopmental and neuropsychiatric disorders who represent a nationally-representative cohort.

Methods: 2897 adults who were ascertained from a representative United States cohort of adults with at least one children ranging in age from 1-17;11 years of age. Families were sent an online battery of surveys indicating demographic status including clinical neurodevelopmental and neuropsychatric diagnostic family history. Parents also completed the Childhood Routines Inventory-Revised (CRI-R) to assess Total RBRI, Repetitive Motor Behaviors/Compulsions (RMBC), and Resistence/Insistence on Sameness (RIS). Parents were grouped into several diagnostic clusters basad on their psychiatric history: ASD (n=38); OCD/tic disorders (n=66); bi-polar/schizophrenia (n=157); no diagnosis (n=1914); "other" diagnosis (n=738). Children were placed into one of three age groups (1-6 years, 7-12 years, 13-17;11 years).

Results: A 4 (parent diagnosis) X 3 (age group) analysis of variance revealed a significant interaction for RMBC (F(2882,8)= 2.08, p= 0.03), main effects for parent diagnosis for all three CRI-R factors (All p < 0.0001), and main effects for age group for Total CRI-R (p = 0.03) and RMBC (p= 0.02).

Conclusions: The offspring of adults with an ASD demonstrated signficantly higher RBRI relative to all other diagnositic groups, followed by OCD/tic disorders, bi-polar/schizophrenia, any other diagnosis, and no diagnosis. Children of parents with ASD had unique developmental trajectories that indicated progressive age effects across all three age groups, whereas all offspring of all other parental diagnostic groups showed a characteristic increase from agegroup 1 to agegroup 2, with a decrease for age group 3. These data indicate that the frequency/intensity and developmental trajectories of RBRI in children are impacted by parental diagnostic status.