Do Autism Spectrum Disorders and Obsessive Compulsive Disorders Share a Neuroanatomical Phenotype?

Background:  

Children with autism spectrum disorder (ASD) who have high scores in the repetitive behaviours domain of the ADI-R are more likely to have parents, especially fathers with Obsessive Compulsive Disorder (OCD) (Hollander et al., 2003) and those with high levels of ‘insistence on sameness’ have parents with clinically significant scores on the Yale-Brown Obsessive Compulsive Scale (Abramson et al., 2005). This suggests familiarity of obsessive compulsive/repetitive behaviours. Fronto-striatal volume differences relative to unaffected controls are associated with both OCD and autism spectrum indicating that similar genetic mechanisms may act upon this circuitry to drive these traits.

Objectives:  

To examine this issue we conducted a preliminary anatomical likelihood meta-analytic estimation (ALE, Turkeltaub et al. 2002) of the extent to which OCD and ASD have overlapping neuroanatomical phenotypes.

Methods:  

We used ‘dual-disorder’ ALE approach (Yu, Cheung et al., 2010) in which co-ordinates from voxel-based MRI studies of grey matter volume in 15 studies of ASD and 16 studies of OCD could be entered jointly into the analysis. This allowed a preliminary map of common and distinct regional volume differences in ASD and OCD to be generated.  More detailed analysis controlling for confounds including age, gender and medication is in progress.

Results:  

Relative to typically developing controls, grey matter volumes in bilateral caudate, frontal gyrus, thalamus, and right precuneus were increased in both OCD and ASD, whereas grey matter was decreased in both conditions in left paracentral lobe and precentral gyrus, and right precuneous and superior frontal gyrus.

Conclusions:  

Our preliminary results point to a shared neuroanatomical phenotype in OCD and ASD. This raises the possibility that similar aetiological mechanisms may drive common behavioural and neurobiological traits associated with these conditions. Thus what is inherited in ASD and OCD may not be the specific condition, but a neurodevelopmental vulnerability. These results also imply that advances made in unraveling causal factors and treatment approaches in either condition may have useful application to both.