Memory disturbances found in obsessive-compulsive disorder (OCD) may partially be related to dysfunction of cortico-subcortical circuits. However, it is still unknown how clinical scoring of OCD influences on memory processing.

Event-related brain potentials (ERPs) were recorded in a continuous word recognition paradigm in OCD patients with either severe or moderate Y-BOCS scores (group S and group M, each 8) and in normal healthy controls.

Typically ERPs to repeated items are characterized by more positive waveforms. This “old/new effect” has been shown to be relevant for memory processing. The early old/new effect (ca. 300-500 ms) 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 to group M and the control group, no difference between group M and the control group. Source analyses for the late old/new effect showed statistically reduced cerebral activations in the anterior cingulate for the OCD group S in contrast to for the control group. Additionally, the early old/new effect in the OCD group S was negatively correlated with the Y-BOCS total scores and the late old/new effect negatively correlated with obsession sub-scores.

The severely, not moderately, ill OCD patients showed an impaired conscious recollection of the word memory, which suggested an impairment of working memory capacity in these patients due to a dysfunction in the frontal and cingulated cortex.