Family History of Depression and Repetitive Behaviors in ASD

Background:  

Several studies have suggested an association between familial psychiatric disorders, particularly depression, and autism spectrum disorders (ASD) (Delong, 2007; Piven & Palmer, 1999). Depression is significantly more common among relatives of individuals with ASD than individuals with Down syndrome (Delong, 2004; Piven & Palmer, 1999).  However, the relationship between ASD and the presence of depression is family members is unclear.  At least one study has identified a relationship between the presence of parental depression and higher scores on the ADI-R repetitive behavior domain (Wallace 2008).  

Objectives:  

The aim of this study is to test whether the presence of depression in parents of individuals with ASD is associated with an increased rate of repetitive behaviors in their affected offspring.

Methods:  

431 participants with ASD were identified from a larger dataset of families participating in a genetic study of ASD.  All participants were assessed with the Repetitive Behavior Scales-Revised (RBS-R) and Vineland Adaptive Behavior Scales (VABS or VABS-II).  Using a standard approach, family history data were collected for first- and second-degree relatives. Participants with ASD (mean age of 111 months, SD=59) were predominantly male (87%). Using family history data, we identified parents who were positive for a diagnosis of depression as reported by the family informant. We then divided probands into those with at least one parent who was positive for depression and those with parents who were negative for depression or other co-occurring neuropsychiatric or health issues.  We compared the two groups on RBS-R scales using MANOVA. 

Results:  

The groups did not differ on sex, ethnicity, race, or age.  The MANOVA, adjusting for developmental level (VABS), showed that the groups differed significantly on the dependent measures (Wilks’ λ=0.971, F(6,423)=2.136, p=0.048).  Univariate tests indicated that the ASD group in which a parent was positive for depression had significantly higher mean scores (i.e., greater impairment) on the RBS Self Injurious Behaviors scale (p=0.004). 

Conclusions:  

The presence of a parent with depression, based on family history data, is associated with an increased rate of self-injurious behaviors in ASD. There are several possible explanations for this association.  First, the presence of self-injury, a severe clinical feature, may affect parental mood. However, depression among parents of children with ASD is often elevated both before and after having a child with ASD (Bolton et al. 1998, Piven & Palmer, 1999).  Second, parental depression and repetitive behaviors may share a genetic susceptibility. Specifically, genes involved in the regulation of serotonin have been implicated in both repetitive behaviors (Brune et al. 2006) and depression (Kiyohara 2010).  Limitations include the lack of a control group, use of family history data, and parental report of repetitive behaviors.

This study suggests that inspection of family history data may prove valuable in genetic studies of ASD. The current study showed a link between parental depression and a specific feature in ASD. This relationship may reflect a shared underlying genetic basis. Future research should explore the complex relationship between parental traits and behaviors in their affected children.