Clinical correlates of word recognition memory in obsessive–compulsive disorder: An event-related potential study

Abstract 

Memory disturbances found in obsessive–compulsive disorder (OCD) may partially be related to dysfunction of cortico–subcortical circuits. However, it is still unknown how OCD symptomatology is related to memory processing. To explore this question, event-related potentials (ERPs) were recorded in a continuous word-recognition paradigm in OCD patients with either severe or moderate scores on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) (group S and group M, n=8 each) and in normal healthy controls (n=16). Typically ERPs to repeated items are characterized by more positive waveforms beginning approximately 250 ms post-stimulus. This “old/new effect” has been shown to be relevant for memory processing. The early old/new effect (ca. 300–500 ms) with a frontal distribution is proposed to be a neural correlate of familiarity-based recognition. The late old/new effect (post-500 ms) is assumed to reflect conscious memory retrieval processes. The OCD group S showed a normal early old/new effect and a reduced late old/new effect compared with group M and the control group, but no difference was found between group M and the control group. Source analyses for the late old/new effect showed statistically reduced cerebral activation in the anterior cingulate for OCD group S in contrast to the control group. Additionally, the early old/new effect in OCD group S was negatively correlated with the Y-BOCS total scores, and the late old/new effect was negatively correlated with obsession sub-scores. The severely, not moderately, ill OCD patients showed an impaired conscious recollection of the word-to-be-remembered, which suggested an impairment of working memory capacity in these patients due to a dysfunction in the frontal and cingulate cortex.

Keywords: Obsessive–compulsive disorder, Y-BOCS, Event-related potential, Word recognition, Old/new effect, Source analysis