After assault, OCD risk rises fastest in first year, pointing to a critical care window

Obsessive compulsive disorder (OCD) is a mental health condition characterized by recurring intrusive thoughts (i.e., obsessions) and repetitive behaviors (i.e., compulsions) aimed at reducing anxiety. This disorder is estimated to affect 1.2% to 2.3% of people every year.

While several past studies have investigated the neural, genetic and environmental factors that contribute to the emergence of OCD, these have not yet been clearly elucidated. Traumatic events, such as assaults, car accidents and other distressing experiences, have been found to play a role in post-traumatic stress disorders (PTSD) and some other mental health disorders, yet their relationship to OCD remains poorly understood.

Researchers at Karolinska Institute and Stockholm Health Care Services recently analyzed a large pool of mental health-related data collected in Sweden to explore the link between different traumatic events and the risk of developing OCD. Their paper, published in Nature Mental Health, reports an association between assaults or victimizations and a higher risk of OCD.

Exploring the relationship between trauma and OCD risk

The authors of this recent paper analyzed data collected in Sweden in the period spanning from 1975 to 2008 as part of a large cohort study. This data included official reports of traumatic events, such as assaults and transport accidents, as well as mental health records.

The researchers analyzed data related to 3.3 million individuals living in Sweden. They specifically looked at whether people who reported being assaulted or victimized and those who were involved in a transport accident were later diagnosed with OCD, comparing the mental health reports of people who experienced trauma with those of people who did not.

“The causal link between potentially traumatic events and OCD remains unclear due to reliance on retrospective self-reports and limited control for familial factors,” wrote Josep Pol-Fuster and his colleagues in their paper. “In this Swedish population-based cohort study, we identified 3,340,945 individuals born between 1975 and 2008 and prospectively examined the associations of objectively recorded assault/victimization and transport accidents with subsequent OCD diagnoses.”

The team’s analyses also included sibling comparisons, as this allowed them to control for effects linked with genetics, upbringing and other family-related factors. Ultimately, they used an approach called genetic modeling to estimate how much the risk of developing OCD arose from genetics and how much was linked to environmental factors.

“Individuals exposed to assault/victimization, but not transport accidents, had an increased OCD risk, especially within the first year, decreasing thereafter,” wrote Pol-Fuster and his colleagues. “The association persisted in discordant full sibling comparisons. Quantitative genetic modeling indicated that the phenotypic correlation was primarily due to additive genetics (69%) and unique environmental factors (31%).”

The implications for mental health research

Overall, the findings of this study suggest that assault and victimization are linked with a significantly greater risk of OCD, particularly within the year following a traumatic event. In addition, the team’s estimates suggest that most of the association between trauma and OCD is explained by genetic factors, while environmental experiences play a smaller—although still substantial—role.

“These findings highlight a complex relationship between assault/victimization and OCD, involving both genetic vulnerability and individual environmental exposure,” wrote the authors.

This research could inspire more studies focusing specifically on the relationship between being assaulted or victimized and the emergence of OCD. Concurrently, it could help to improve psychological services: for instance, informing the development of services designed to support victims of assaults or other violent crimes immediately after a traumatic event.

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