Content area
Full Text
(ProQuest: ... denotes formulae and/or non-US-ASCII text omitted; see image)
Original Articles
Introduction
Obsessive-compulsive disorder (OCD) is characterized by obsessions - intrusive thoughts, images, and urges that cause distress, and by compulsions - repetitive actions performed to reduce obsessional distress (American Psychiatric Association, 2013). Among American adults, OCD has 12-month and lifetime prevalence rates of 1.2% and 2.3%, respectively (Ruscio et al. 2010).
Many people with OCD become depressed. Epidemiological (Ruscio et al. 2010) and naturalistic clinical studies (Pinto et al. 2006) report lifetime rates of major depression in patients with OCD as high as 40% and 67.2%, respectively. Another survey of patients with OCD revealed rates of lifetime depression in 73.4% and 81.2% of early- and late-onset cases, respectively (Millet et al. 2004). Moreover, OCD usually precedes the emergence of depressive mood disorders (e.g. Welner et al. 1976; Ricciardi & McNally, 1995), especially in patients with early-onset OCD (Millet et al. 2004).
Co-morbid depression in people with OCD has important clinical implications. Severe depression can impede habituation to stimuli provocative of obsessions (Foa, 1979), thereby undermining otherwise efficacious behavior therapy for OCD (e.g. Foa et al. 2005). Certain symptoms of depression, including insomnia, fatigue and diminished motivation, may interfere with reduction in obsessional distress (e.g. Abramowitz et al. 2000), and addressing co-morbid depression symptoms may detract from the time needed to treat the primary OCD symptoms (e.g. Storch et al. 2008). Moreover, patients with OCD and depression are at elevated risk for attempting suicide (Torres et al. 2011). In one study, 27% of patients with OCD had a history of attempted suicide (Kamath et al. 2007); depression and hopelessness were major correlates of attempts.
As Ruscio et al. (2010) wrote, further research 'is needed to specify the causal mechanisms' (p. 61) producing high rates of co-morbid disorders, including depression, in people with OCD. Tackling this issue, Zandberg et al. (2015) conducted lagged multilevel mediational analyses to test whether improvement in OCD symptoms mediated improvement in depressive symptoms or vice versa in 40 patients with primary OCD who had undergone behavior therapy while taking a serotonin reuptake inhibitor. They found that reduction in OCD symptoms accounted for 65% of the reduction in depressive symptoms, whereas improvement in depressive symptoms only partially mediated subsequent improvement...