Visuoperceptual impairment in dementia with Lewy bodies

Background: In dementia with Lewy bodies (DLB), vision-related cognitive an d behavioral symptoms are common, and involvement of the occipital visual c ortices has been demonstrated in functional neuroimaging studies. Objectives: To delineate visuoperceptual disturbance in patients with DLB i n comparison with that in patients with Alzheimer disease and to explore th e relationship between visuoperceptual disturbance and the vision-related c ognitive and behavioral symptoms. Design: Case-control study. Setting: Research-oriented hospital. Patients: Twenty-four patients with probable DLB (based on criteria of the Consortium on DLB International Workshop) and 48 patients with probable Alz heimer disease (based on criteria of the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Dis orders Association) who were matched to those with DIB 2:1 by age, sex, edu cation, and Mini-Mental State Examination score. Main Outcome Measures: Four test items to examine visuoperceptual functions , including the object size discrimination, form discrimination, overlappin g figure identification, and visual counting tasks. Results: Compared with patients with probable Alzheimer disease, patients w ith probable DLB scored significantly lower on all the visuoperceptive task s (P < .04 to P < .001). In the DLB group, patients with visual hallucinati ons (n = 18) scored significantly lower on the overlapping figure identific ation (P = .01) than those without them (n = 6), and patients with televisi on misidentifications (n = 5) scored significantly lower on the size discri mination (P < .001), form discrimination (P = .01), and visual counting (P = .007) than those without them (n = 19). Conclusions: Visual perception is defective in probable DLB. The defective visual perception plays a role in development of visual hallucinations, del usional misidentifications, visual agnosias, and visuoconstructive disabili ty charcteristic of DLB.