Abstract
Obsessive-compulsive disorder (OCD) is among the most debilitating psychiatric disorders. Comorbid autism spectrum disorder (ASD) or autistic traits may impair treatment response in OCD. To identify possible neurostructural deficits underlying autistic traits, we performed white matter tractography on diffusion tensor images (DTI) and assessed autistic trait severity using the Autism-Spectrum Quotient (AQ) in 33 OCD patients. Correlations between AQ and the DTI parameters, fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were examined in major white matter tracts that were suggested to be altered in previous OCD studies. We found a negative correlation between AQ and FA and positive correlations between AQ and MD, AD and RD in the left uncinate fasciculus using age, Beck Depression Inventory, Yale-Brown Obsessive-Compulsive Scale, intelligence quotient and medication as covariates. However, we could not detect the significant results between AQ and all DTI parameters when adding gender as a covariate. In addition, in the ASD comorbid group, FA in the left uncinate fasciculus was significantly lower than in the non-ASD comorbid group and MD and RD were significantly higher than in the non-ASD group. These results did not survive correction for multiple comparisons. In ASD, the socio-emotional dysfunction is suggested to be related to the alteration of white matter microstructure in uncinate fasciculus. Our results suggest that variations in white matter features of the left uncinate fasciculus might be partly explained by autistic traits encountered in OCD patients.
Highlights
Obsessive-compulsive disorder (OCD) is the fourth most common psychiatric disorder [1], with an approximate lifetime prevalence of 1–3% [2], and is ranked as one of the most debilitating disorders by the World Health Organization [3]
A significant negative correlation was observed between Autism-Spectrum Quotient (AQ) score and fractional anisotropy (FA) in the left uncinate fasciculus (UF) (r = −0.47, p = 0.015, d = 1.06) and FA in the left cingulum angular bundle (r = −0.43, p=0.034, d = 0.94), and significant positive correlations were observed between AQ score and mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the left UF (MD, r = 0.49, p = 0.012, d = 1.12; AD, r = 0.47, p = 0.016, d = 1.06; and RD, r = 0.49, p = 0.011, d = 1.12), MD in the right cingulum cingulate gyrus (r = 0.41, p = 0.048, d = 0.89), AD in the right cingulum angular bundle (r = 0.46, p = 0.024, d = 1.04)
We observed a negative correlation between AQ scores and FA and positive correlations between AQ scores and MD, AD, and RD in the left UF, FA in left cingulum angular bundle, MD in right cingulum cingulate gyrus, AD in right cingulum angular bundle using age, Beck Depression Inventory (BDI) score, Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), medication and FIQ as covariates (Figure 2), and significant differences in FA, MD, RD when we compared the white matter (WM) integration in the left UF according to the autism spectrum disorder (ASD) diagnosis of patient
Summary
Obsessive-compulsive disorder (OCD) is the fourth most common psychiatric disorder [1], with an approximate lifetime prevalence of 1–3% [2], and is ranked as one of the most debilitating disorders by the World Health Organization [3]. It is characterized by both obsessions, defined as recurrent thoughts, urges, or images experienced as intrusive and unwanted and compulsions, repetitive behaviors, or mental acts executed for preventing anxiety or some feared outcome [4]. Bejerot et al reported that approximately 20% of OCD patients have ASD traits. ASD traits were overlooked, which may have contributed to OCD treatment resistance
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