Visual memory impairment in medication-free obsessive-compulsive disorder without psychiatric comorbidity: A CANTAB...

A well-established feature of Obsessive-compulsive disorder (OCD) is distrust of one's own perception, with two principal contributing factors proposed: impaired objective visual memory and reduced memory confidence. Of these, whether a genuine objective visual memory impairment exists in OCD remains debated, as findings across individual studies are inconsistent, partly because most studies have not adequately controlled for psychotropic medication or psychiatric comorbidity. Focusing on objective visual memory, this study aimed to clarify disorder-specific visual memory characteristics in OCD using the Paired Associates Learning (PAL) task from the Cambridge Neuropsychological Test Automated Battery (CANTAB) in a rigorously selected sample. We compared 44 unmedicated patients with OCD and without psychiatric comorbidity to 77 healthy controls. Visual memory was assessed using two PAL indices: Total Errors (Adjusted) (TEA) and First Attempt Memory Score (FAMS). Group differences were examined using analysis of covariance, controlling for age, sex, and estimated intelligence quotient. Within the OCD group, partial correlations were conducted to examine associations between PAL performance and both overall symptom severity and individual symptom dimensions. The OCD group performed significantly worse than controls, with moderate effect sizes on both TEA and FAMS. However, neither overall symptom severity nor any symptom dimension was significantly associated with PAL performance. These findings may provide evidence for an objective visual memory impairment in OCD that is independent of psychotropic medication and psychiatric comorbidity.