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Repetitive and self-injurious behaviors: associations with caudate volume in autism and fragile X syndrome

Jason J Wolff1*, Heather C Hazlett12, Amy A Lightbody34, Allan L Reiss34 and Joseph Piven12

Author Affiliations

1 Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill School of Medicine, CB# 3367, Chapel Hill, NC, 27599, USA

2 Department of Psychiatry, University of North Carolina at Chapel Hill School of Medicine, CB# 7160, Chapel Hill, NC, 27599, USA

3 Center for Interdisciplinary Brain Science Research, Stanford University, 401 Quarry Rd., MC 5795, Stanford, CA, 94305, USA

4 Department of Psychiatry and Behavioral Sciences, Stanford University, 401 Quarry Rd., MC 5717, Stanford, CA, 94305, USA

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Journal of Neurodevelopmental Disorders 2013, 5:12  doi:10.1186/1866-1955-5-12

Published: 2 May 2013



Following from previous work suggesting that neurobehavioral features distinguish fragile X and idiopathic variants of autism, we investigated the relationships between four forms of repetitive behavior (stereotypy, self-injury, compulsivity, ritual behavior) and caudate nuclei volume in two groups: boys with fragile X syndrome, a subset of whom met criteria for autism, and a comparison group of boys with idiopathic autism.


Bilateral caudate nuclei volumes were measured in boys aged 3 to 6 years with fragile X syndrome (n = 41), the subset of boys with fragile X syndrome and autism (n = 16), and boys with idiopathic autism (n = 30). Repetitive behaviors were measured using the Repetitive Behavior Scales-Revised.


For boys with idiopathic autism, left caudate volume was modestly associated with self-injury, while both compulsive and ritual behaviors showed significant positive correlations with bilateral caudate nuclei volumes, replicating previous results. For boys with fragile X syndrome, there was no such association between caudate volume and compulsive behaviors. However, we did identify significant positive correlations between self-injury total scores and number of self-injury topographies with bilateral caudate nuclei volumes.


These findings suggest a specific role for the caudate nucleus in the early pathogenesis of self-injurious behavior associated with both idiopathic autism and fragile X syndrome. Results further indicate that the caudate may be differentially associated with compulsive behavior, highlighting the utility of isolating discrete brain-behavior associations within and between subtypes of autism spectrum disorder.

Autism; Caudate; Fragile X syndrome; Repetitive behavior; Self-injurious behavior