Impact of comorbid depressive symptoms on nonverbal memory and visuospatial performance in obsessive-compulsive disorder

Introduction. Recent research has suggested that some executive dysfunctions in obsessive-compulsive disorder (OCD) represent an epiphenomenon of comorbid depressive symptoms. The present study investigated whether the impact of comorbid depressive symptoms on cognitive dysfunction in OCD extends to nonverbal memory impairment. Methods. A total of 32 OCD patients and 20 healthy controls took part in the study. Participants were administered a neurocognitive battery with a focus on nonverbal memory and visuospatial functions. Results. While evidence was provided that neurocognitive processes necessitating visuospatial transformation and visuoconstruction are deficient in OCD patients regardless of comorbid depressive symptoms, nonverbal memory dysfunctions were only apparent for patients with elevated scores in the Hamilton Depression (HDRS) Rating Scale (total score ≥ 8). Correlations with subscores of the HDRS revealed that core depressive symptoms are related to nonverbal memory deficits in OCD. Mental rotation, middle discrimination, and position discrimination were found to be unaffected in OCD. Y-BOCS scores, length of illness, onset of illness, number of hospital admissions, and checking compulsions were not associated with neurocognitive disturbances. Conclusions. Nonverbal memory is disturbed in only a subgroup of OCD patients displaying elevated HDRS scores (HDRS ≥ 8). It is claimed but awaits further empirical testing that differences in depression profile across OCD studies have contributed to inconsistencies in prior investigations on neurocognitive functioning in OCD. Our results are questioning the hypothesis that nonverbal deficits are a causal factor for the development of checking compulsions.