Autistic Traits as Predictors of Increased Obsessive-Compulsive Disorder Severity: The Role of Inflexibility and Communication Impairment

Due to similar manifestations, some authors have proposed a potential correlation between autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD). This link has long been recognized and debated, with some authors arguing that these disorders frequently occur comorbid but distinct while others believe they are part of the same spectrum. The aim of our study was to explore the prevalence and correlates of autistic traits in 55 OCD patients and 55 matched controls and to assess possible autistic dimensions predictive of higher OCD symptoms. All participants were assessed with the Obsessive-Compulsive Spectrum-Short Version (OBS-SV) and the Adult Autism Subthreshold Spectrum (AdAS Spectrum). The OCD group scored significantly higher in both questionnaires. Total OBS-SV scores and domains were significantly correlated with all AdAS Spectrum domains and total score. The AdAS Spectrum total, Verbal Communication and Inflexibility and adherence to routine domain scores were significant positive predictors of higher OBS-SV scores. Lastly, when two clusters of subjects (high and low autism) were determined, Inflexibility and adherence to routine domain presented the greatest influence in forming the clusters. Our findings support the association between OCD and autistic traits in the adult population, supporting the hypothesis of a neurodevelopmental basis for these psychiatric conditions.

Mapping the neuroanatomical abnormalities in a phenotype of male compulsive rats

Compulsivity is considered a transdiagnostic dimension in obsessive-compulsive and related disorders, characterized by heterogeneous cognitive and behavioral phenotypes associated with abnormalities in cortico-striatal-thalamic-cortical circuitry. The present study investigated the structural morphology of white and gray matter in rats selected for low- (LD) and high- (HD) compulsive drinking behavior on a schedule-induced polydipsia (SIP) task. Regional brain morphology was assessed using ex-vivo high-resolution magnetic resonance imaging (MRI). Voxel-based morphometry of segmented MRI images revealed larger white matter volumes in anterior commissure and corpus callosum of HD rats compared with LD rats. HD rats also showed significantly larger regional volumes of dorsolateral orbitofrontal cortex, striatum, amygdala, hippocampus, midbrain, sub-thalamic nucleus, and cerebellum. By contrast, the medial prefrontal cortex was significantly smaller in HD rats compared with LD rats with no significant group differences in whole brain, ventricular, or cerebrospinal fluid volumes. These findings show that limbic cortico-basal ganglia structures implicated in impulse control disorders are distinct in rats that are vulnerable to develop compulsive behavior. Such abnormalities may be relevant to the etiology of compulsive disorders in humans.

Common abnormality of gray matter integrity in substance use disorder and obsessive-compulsive disorder: A comparative voxel-based meta-analysis

The objective of the current study is to determine robust transdiagnostic brain structural markers for compulsivity by capitalizing on the increasing number of case‐control studies examining gray matter volume (GMV) alterations in substance use disorders (SUD) and obsessive‐compulsive disorder (OCD). Voxel‐based meta‐analysis within the individual disorders and conjunction analysis were employed to reveal common GMV alterations between SUDs and OCD. Meta‐analytic coordinates and signed brain volumetric maps determining directed (reduced/increased) GMV alterations between the disorder groups and controls served as the primary outcome. The separate meta‐analysis demonstrated that SUD and OCD patients exhibited widespread GMV reductions in frontocortical regions including prefrontal, cingulate, and insular. Conjunction analysis revealed that the left inferior frontal gyrus (IFG) consistently exhibited decreased GMV across all disorders. Functional characterization suggests that the IFG represents a core hub in the cognitive control network and exhibits bidirectional (Granger) causal interactions with the striatum. Only OCD showed increased GMV in the dorsal striatum with higher changes being associated with more severe OCD symptomatology. Together the findings demonstrate robustly decreased GMV across the disorders in the left IFG, suggesting a transdiagnostic brain structural marker. The functional characterization as a key hub in the cognitive control network and casual interactions with the striatum suggest that deficits in inhibitory control mechanisms may promote compulsivity and loss of control that characterize both disorders.

Relationship between symptom dimensions and brain morphology in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is known as a clinically heterogeneous disorder characterized by symptom dimensions. Although substantial numbers of neuroimaging studies have demonstrated the presence of brain abnormalities in OCD, their results are controversial. The clinical heterogeneity of OCD could be one of the reasons for this. It has been hypothesized that certain brain regions contributed to the respective obsessive-compulsive dimensions. In this study, we investigated the relationship between symptom dimensions of OCD and brain morphology using voxel-based morphometry to discover the specific regions showing alterations in the respective dimensions of obsessive-compulsive symptoms. The severities of symptom dimensions in thirty-three patients with OCD were assessed using Obsessive-Compulsive Inventory-Revised (OCI-R). Along with numerous MRI studies pointing out brain abnormalities in autistic spectrum disorder (ASD) patients, a previous study reported a positive correlation between ASD traits and regional gray matter volume in the left dorsolateral prefrontal cortex and amygdala in OCD patients. We investigated the correlation between gray and white matter volumes at the whole brain level and each symptom dimension score, treating all remaining dimension scores, age, gender, and ASD traits as confounding covariates. Our results revealed a significant negative correlation between washing symptom dimension score and gray matter volume in the right thalamus and a significant negative correlation between hoarding symptom dimension score and white matter volume in the left angular gyrus. Although our result was preliminary, our findings indicated that there were specific brain regions in gray and white matter that contributed to symptom dimensions in OCD patients.

Autism spectrum disorders in adult outpatients with obsessive compulsive disorder in the UK

OBJECTIVES

Patients with obsessive compulsive disorder (OCD) frequently show traits of autism spectrum disorders (ASD). This is one of the first studies to explore the clinical impact of the overlap between OCD and ASD as a categorical diagnosis.

METHODS

A cross-sectional survey in 73 adult outpatients with DSM-IV OCD. Autistic traits were measured using the Autism-Spectrum Quotient (AQ). A clinical estimate ASD diagnosis was made by interview using DSM-IV-TR criteria. OCD patients with and without autistic traits or ASD were compared on demographic and clinical parameters and level of OCD treatment-resistance based on treatment history.

RESULTS

Thirty-four (47%) patients scored above the clinical threshold on the AQ (≥26) and 21 (27.8%) met diagnostic criteria for ASD. These diagnoses had not been made before. Patients with autistic traits showed a borderline significant increase in OCD symptom-severity (Yale-Brown Obsessive Compulsive Scale (Y-BOCS); p = .054) and significantly increased impairment of insight (Brown Assessment of Beliefs Scale; p = .01). There was a positive correlation between AQ and Y-BOCS scores (p = .04), but not with OCD treatment resistance.

CONCLUSION

There is a high prevalence of previously undiagnosed ASD in patients with OCD. ASD traits are associated with greater OCD symptom-severity and poor insight.

White Matter Features Associated With Autistic Traits in Obsessive-Compulsive Disorder

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.