(PS3-C65) Directionality of Change in Obsessive Compulsive Disorder (OCD) Symptoms and Depression Symptoms over Six Years in a Naturalistic Clinical Sample

Background: One of the most common comorbidities in patients with OCD is major depressive disorder (MDD) (Pallanti et al., 2011). The presence of depression in individuals with OCD has been associated with greater OCD severity and chronicity, greater comorbidity with other anxiety disorders, and higher rates of disability (Tukel et al., 2006; Besiroglu et al., 2007; Millet et al., 2004; Viswanath et al., 2012). Both OCD and depression have fluctuations in course and vary in severity of symptoms and have periods of remission and relapse (Eisen et al., 2013; Rickelt et al., 2016). Despite extant research on the negative implications of comorbid depression in OCD, the relationship between OCD and depression remains unclear. The current study aims to determine the directionality between OCD and depression symptoms over the course of six years. We hypothesized that over time reductions in OCD would be associated with reductions in depressive symptoms.

Methods: Participants (n=324) were part of the Brown Longitudinal Obsessive-Compulsive Study, an NIMH-funded naturalistic prospective study on the course of OCD (Pinto et al., 2006).  Participants completed annual follow-up interviews. The Hamilton Rating Scale for Depression (HAM-D) was used to assess the severity of depressive symptoms and OCD severity was measured using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Cross-lagged panel analyses were conducted to compare the association between OCD (Y-BOCS total score) and depression (HAM-D total score). Our analyses involved four iterations of model-testing to determine directionality.

Results: The autoregressive model (Model 1) was significantly improved with the addition of paths from Y-BOCS to HAM-D (Model 2), but not from HAM-D to Y-BOCS (Model 3). The fully saturated model did not significantly improve model fit compared to Model 2. Model 2 provided the most parsimonious fit to the data, 𝜒² (56) = 164.05, p < 0.01, CFI = .96, TLI = .93, RMSEA = .08, SRMR = .07.

Conclusion: OCD symptom severity predicted next year depression symptom severity. In contrast, depression symptom severity in a given year did not predict next-year OCD symptom severity in this OCD sample. These findings suggest that clinicians should provide empirically supported treatments for OCD rather than waiting for depression symptoms to resolve.