The relationship between symptoms of obsessive compulsive disorder and depression during therapy: A random intercept...

We know little about how symptoms of obsessive-compulsive disorder and depression interact during psychological therapy. Although some previous research suggests that reductions in the severity of depression are driven by reductions in OCD, support for this conclusion is limited due to the exclusion of individuals with severe depression and limitations of the statistical approaches used.

This study re-examined the interaction between symptoms of OCD and depression during therapy in a sample of 137 adults with a primary diagnosis of OCD and a full range of depression severity. All participants received a 12 to 16-week specialist residential treatment. Participants completed the Florida Obsessive Compulsive Inventory and Patient Health Questionnaire for depression weekly. The relationship between severity of OCD and depression was examined using a random intercept cross-lagged panel model.

Both cross-lagged paths were significant, with prior levels of OCD influencing subsequent levels of depression, and prior levels of depression influencing subsequent levels of OCD.

The present study was conducted in a residential setting, meaning the findings may not generalise to outpatient settings characterised by less severe OCD and depression.

Contrary to previous findings, which suggest that the influence of OCD on depression is far greater than the reverse, our findings suggest that OCD and depression influence each other equally. As improvements in mood can help to improve symptoms of OCD, it appears important to target depression concurrently during treatment for OCD. This would be a new treatment target for improvement outcomes in OCD.