Procedural learning and cognitive self-consciousness across obsessive-compulsive disorder subtypes

Obsessive-compulsive disorder has been associated with abnormalities in the frontal-striatal network (Saxena & Rauch, 2000). Rauch and Savage (2000) have proposed a neurobiological model that conceptualizes OCD as resulting from impairment in the striatal structures responsible for procedural learning. OCD is considered to be a result of impairment in this nonconscious processing. When individuals were given a serial reaction time task, a measure of procedural learning, in combination with a PET scan Rauch et al. (1997), found that those with OCD did not display the expected striatal activation usually associated with procedural learning tasks. Rather regions associated with explicit learning were activated. Marker et al (2006) evaluated implicit and explicit learning in OCDs and normal controls. Individuals with OCD demonstrated impaired implicit learning and performed better than normal controls on an explicit learning task. This study attempted to replicate Marker's findings with an anxious control group (OAD). Additionally, it addresses possible differences in procedural learning across OCD subtypes. Preliminary neuroimaging studies have suggested that different patterns of frontal striatal circuit activation have been found in OCD subjects with different primary OCD symptoms. In order to determine if there were differences between the OCD group (n=56) and the OAD group (n=35) in serial reaction time test performance, a group by block repeated measures ANOVA was conducted. Individuals with OCD performed significantly slower than the OAD group across the learning trials and also demonstrated superior performance on the explicit task. Support for subgroup differences was found as well. When hoarders were compared to other OCDs and the OAD group, reactions times for individuals in the other OCD group and the OAD group decreased across trials while the reaction times for those in the hoarding subgroup remained the same over time suggesting that the hoarders were not learning across trials. The results suggest that impairments in procedural learning may be unique to OCD and that patterns of performance may differ across subgroups. Implications for treatment and future directions in research are discussed.