A Study of Visual Hallucinations in Alzheimer's Disease.

The authors screened 98 patients with probable Alzheimer's disease for visual hallucinations. Each patient with visual hallucinations was matched by cognitive score to two patients without visual hallucinations and compared on variables including visual acuity and visual agnosia. Eighteen (18.4%) of the patients were found to have visual hallucinations. Variables significantly associated with hallucinations included older age, female sex, decreased visual acuity, and presence of visual agnosia. Although having a history of visual disorder approached statistical significance, logistic regression analysis revealed that three variables: age, visual acuity in the "best eye," and visual agnosia, correctly classified 91% of patients as hallucinators vs. non-hallucinators. This work supports a growing body of research showing a relationship between visual hallucinations and the visual system across a variety of disorders.