Task switching and backward inhibition in obsessive-compulsive disorder

The presumed involvement of the prefrontal cortex in the pathogenesis of obsessive-compulsive disorder (OCD) has fueled growing interest in cognitive paradigms with a putative sensitivity to this brain region. Measures of inhibition and executive functioning are thought to be promising in this regard. To our knowledge, this is the first study that has investigated task switching in OCD captures an important aspect of a paradigm that executive control, namely the preparation for an upcoming task. It was speculated that task switching costs would be enhanced in OCD patients, reflecting a fundamental deficit to quickly control the stream of thoughts. In addition, the paradigm allowed the measurement of backward inhibition, that is the time costs afforded for the reengagement of a previously irrelevant task. A sample of 40 OCD patients, 20 psychiatric controls with anxiety disorders other than OCD as well as 20 healthy controls was investigated. Contrary to expectation, task switching costs were not elevated in OCD patients. Although anxiety control patients failed to display robust backward inhibition, group comparisons did not reach significance. Implications for future research are discussed.