A pioneering Yale-led genetic study offers new evidence that trichotillomania and excoriation disorder are biologically based, highlighting inherited risk and shared pathways with OCD, with implications for diagnosis and treatment.
A Yale-led study is adding weight to the idea that hair-pulling and skin-picking are not simply habits, but disorders with a measurable biological basis. Researchers examining trichotillomania and excoriation disorder, two forms of body-focused repetitive behaviour, say the conditions affect roughly 1% to 3% of people and often appear in families, pointing to inherited risk rather than a question of willpower or parenting.
The work, led by Emily Olfson at the Yale Child Study Centre, used a parent-offspring trio design, collecting DNA from more than 100 families and comparing what children inherited with what would be expected by chance. According to Yale and Psychiatric Times, the study is the first genomic trio analysis focused on these two disorders, which are often grouped with obsessive-compulsive and related conditions because of overlapping symptoms and frequent co-occurrence.
One of the main findings was that people with these disorders were more likely to inherit higher OCD-related polygenic scores from their parents. A polygenic score is not a single gene, but a summary of many small genetic effects that together can influence risk. Importantly, the pattern was seen even in participants who did not also have obsessive-compulsive disorder, suggesting shared biological pathways rather than a simple overlap in diagnosis.
Researchers also reported rare copy number variants in some participants. These are sections of DNA that are missing or duplicated and have been linked in other studies to neurodevelopmental conditions. The Yale team says the results strengthen the case for recognising trichotillomania and excoriation disorder as legitimate psychiatric conditions that deserve evidence-based treatment and support, while also helping to lay groundwork for larger genetic studies in the future.
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