The Extended Family History of Children with ASD

Background: Given the growing evidence for genetic linkages within ASD, examination of the family history of heritable disorders that may contribute to the risk of ASD may be useful. Past research has found an increased risk of ASD for those with a parental history of a mental health disorders, however, much of the family research to date has examined only first-degree relatives. Thus, little is known about the prevalence of disorders in the extended families of individuals with ASD.

Objectives: To examine the prevalence of mental health disorders within first- and second-degree relatives of children diagnosed with ASD as compared to those of typically developing (TD) peers.

Methods: Participants included 48 children with ASD (mean CA=34.9 mos, range 30-40 mos) and 26 TD children (mean CA = 30.7 mos, range 29-44 mos). Family history was collected via semi-structured interview with one or both parents of each child. Parents were asked to report the presence of any mental health disorders in their extended families.

Results: Overall, similar rates of mental health disorders were found across ASD and TD families (68.75% vs 61.45%). A significantly higher prevalence of bipolar disorder (21% vs 4%, p=.05) and marginally higher prevalence of ADHD (33% vs 16%, p=.08) was found in the extended families of children with ASD in comparison to the extended families of TD children.

Conclusions: While overall rates of mental health disorders in extended families of children with and without ASD are comparable, those with an extended family history of bipolar disorder and/or ADHD may be at an increased risk for having a child with ASD.