A New Perspective: A Network Analysis of Repetitive Behaviors in Autism and Obsessive Compulsive Disorder

Background:  Associations between restricted and repetitive behaviors (RRBs) in autism and OCD have been of particular interest, due to elevated rates of comorbidity, as well as neurological and behavioral findings implying symptom overlap. Compulsions in OCD are maladaptive strategies used to cope with the perceived distress of the obsessions (Markarian et al., 2010).  However, the functional relationship between obsessions and compulsions lack valid evidence among individuals with autism due to difficulties in describing their mental states and experiences. Rather, it has been suggested that RRBs in autism may be a function of efforts to manage unusual sensory processing (Baker et al., 2008). Thus, the debate regarding symptom overlap is dependent on the interaction between RRBs. Yet, to date, standard methods have been limited in their ability to accurately reflect the interrelations of RRBs in autism and OCD.  

Objectives: To investigate the role of and interrelations between RRBs characteristic of autism and OCD through the use of Network Analysis. Specific aims were to: (1) assess whether autism and OCD represent distinct disorders (e.g., separate symptom clusters); (2) compare the frequency of causal symptom relations in autism and OCD; (3) and assess the importance of (e.g., centrality) of compulsions in the network. 

Methods:  Network analysis was used to assess relations between RRBs in autism and OCD. In the network perspective, symptoms exist as a dynamic interacting system, where a disorder is a cluster of highly correlated symptoms (Cramer, Waldorp, van der Maas, & Borsboom, 2010). Thus, what binds a set of symptoms is a dense set of direct causal relations between symptoms. This study constructed network models based on two samples. First, a network was constructed based on seven clinicians who were asked to rate casual association between RRBs characteristic of autism and OCD. Second, a network model was constructed based on a clinical sample of 213 children. The two networks were visually assessed and compared according to the three objectives previously stated. Characteristics of specific symptoms were analyzed by computing various centrality measures. 

Results:   Symptoms clustered in correspondence with autism and OCD. Within each disorder, symptom connections were stronger and more frequent. Compulsions were most central across both networks. However, autism symptoms were found to be more strongly connected and cause more symptoms than OCD symptoms in the clinical sample network. In addition, sensory symptoms and verbal rituals showed high centrality estimates in the network. 

Conclusions:   Autism and OCD are characterized by significantly different patterns of interaction between RRBs. Compulsive symptoms served as a main link between autism and OCD. Sensory symptoms and verbal rituals were found to be valuable in our understanding of RRB interactions. In addition, our results support proposed changes to the DSM-5 to include sensory symptoms and verbal rituals to the RRB domain of autism. While further research is needed, this study demonstrates the importance of symptom interrelations in understanding the association between autism and OCD.