Systematic Review: Convergence and Divergence Between Autism Spectrum Disorder and Obsessive-Compulsive Disorder: Genetic, Neuroimaging, and Cognitive Findings.

This large review looked at 50 studies comparing autism and OCD (obsessive-compulsive disorder). While these are different conditions, they share some similarities. Both run in families and affect similar brain areas, particularly showing thinner brain tissue in certain regions. Children with both conditions can be inflexible in their thinking, but they differ in recognizing emotions and paying attention. More research is needed to better understand how these conditions are connected.

This systematic review examined 50 studies comparing autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD) across genetic, neuroimaging, and cognitive domains. The review found that while ASD and OCD are distinct conditions, they share some underlying features. Genetically, both conditions show shared heritability, though polygenic risk studies are limited. Neuroimaging revealed both disorders involve reduced temporal lobe cortical thickness, but ASD specifically shows increased frontal cortical thickness.

Cognitively, both conditions demonstrate inflexibility, but differ in facial emotion processing and sustained attention abilities. The research highlighted significant heterogeneity in the literature and emphasized the need for future quantitative trait studies.

Findings suggest ASD and OCD share some biological pathways but remain distinct conditions. Clinicians should consider both shared features (inflexibility) and differences (emotion processing, attention) when assessing and treating individuals with either or both conditions.

The review identified significant heterogeneity across studies and limited focus on quantitative traits. Polygenic risk studies were particularly limited, reducing confidence in genetic findings.

Autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD), albeit distinct diagnoses, overlap in presentation and frequently co-occur. However, the relationship between them remains poorly understood. We reviewed comparative studies of ASD and OCD to identify patterns of convergence and divergence across these diagnoses at cognitive, neurobiological, and genetic levels. We searched MEDLINE, Web of Science, and PsycInfo databases.

The systematic review was registered on PROSPERO (ID: CRD42023395895). Studies that compared individuals with ASD and OCD regarding cognition, neurobiology, or genetics were included. Articles were screened in 2 phases: (1) for relevancy, and (2) based on exclusion and inclusion criteria. We conducted a qualitative synthesis of the results.

The search yielded 2,009 articles. After excluding irrelevant articles (n = 1,623), including studies examining compulsivity without an OCD scale (n = 71), nonempirical reports (n = 97), nonhuman studies (n = 42), studies that were out of scope (n = 6), duplicates (n = 7), and studies with fewer than 20 participants in any comparator group (n = 111), 50 articles remained and were included in the qualitative synthesis. At a genetic level, ASD and OCD share heritability, but studies of polygenic risk are limited. At a neuroimaging level, both diagnoses are associated with reduced cortical thickness in the temporal lobe, but ASD is specifically associated with increased frontal cortical thickness.

At a cognitive level, inflexibility may be characteristic of both conditions, but performance in facial emotion processing and sustained attention may differ. The literature is limited by heterogeneity and reduced focus on quantitative traits. Future studies are needed to clarify these relationships. Autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD) are different diagnoses, but both involve repetitive behavior, and children with ASD are much more likely than neurotypical children to be diagnosed with OCD.

But the connection between ASD and OCD is not well understood. This systematic review examined the relationships of ASD and OCD at three levels: genetic, neurobiological, and cognitive. Similarities and differences were identified at all levels, though existing studies have some limitations. Future work is needed to better understand the relationships between these diagnoses.

Comparison of Genetic, Neurobiological, and Cognitive Underpinnings of Autism Spectrum Disorder and Obsessive-Compulsive Disorder: A Systematic Review; https://www.crd.york.ac.uk/PROSPERO/view/CRD42023395895.