Obsessive-compulsive disorder (OCD) is a disabling psychiatric condition which often starts early in life. OCD may lead to high individual suffering and interference in many areas of life, for example education and work, as well as other health problems. The disorder involves high socio-economic costs at the societal level.

Given its known disabling and chronic course, there is a clear consensus that we should aim to prevent the onset of OCD or, if this were not possible, intervene as early as possible to prevent its long-term medical and socio-economic consequences. However, the causes of OCD remain unknown and, until we know more about them, the development of prevention strategies or more effective treatments will be slow.

We know that OCD runs in families and that it is a partially genetic disorder. However, at least 50% of the risk of OCD cannot be explained by these genetic factors, but by environmental causes. Because monozygotic (MZ) twins are genetically identical, sharing 100% of their genes, if only one of them is affected by OCD, but not the other (that is, pairs discordant for OCD), this can only be explained by differential exposure to environmental risk factors. Therefore, studying MZ twin pairs discordant for OCD provides a unique opportunity to generate new insights into the potentially modifiable causes of the disorder.

RATSS OCD (also called OCDTWIN) is an ambitious research project (principal investigator: David Mataix-Cols) recruiting MZ twin pairs discordant for OCD in order to identify specific environmental risk factors for the development of the disorder. In addition to discordant twin pairs, RATSS OCD is also recruiting MZ pairs concordant for OCD diagnosis (both twins of a MZ pair have OCD).

The RATSS OCD project collects biological samples (blood, saliva, urine, stool, hair, and brain imaging data) as well as clinical and questionnaire data from twin pairs with at least one affected sibling. Participation involves one full day of assessments and examinations at the Centre for Psychiatric Research at Karolinska Institutet (KI) Participants are reimbursed for their participation and time off work, and all travel and hotel expenses are covered.

Importantly, it is possible to participate in the study even if it is difficult for study participants to travel to Stockholm. They can still participate by providing a reduced number of measures and samples remotely (telephone interview, biological samples and questionnaires sent via mail).

Please contact

Elles de Schipper

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Jan Beucke

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Una Prosell