Prospective study of hallucinations and delusions in Parkinson's disease

Objective - This study was undertaken to determine the prevalence of halluc inations and delusions in Parkinson's disease, to describe such symptoms ph enomenologically, and possibly to determine factors associated with their d evelopment. In addition, the role of the visual system in relation to visua l hallucinations was examined. Method - 102 consecutive patients diagnosed with strictly defined Parkinson 's disease were examined for the presence of hallucinations and delusions a nd assessed for visual acuity, cognition, depression using the geriatric de pression scale, disease severity as measured by the UPDRS, and other clinic al variables. Results - Of 102 consecutive patients, 29.4% (n=30) had hallucinations or d elusions, four (3.9%) were determined to be psychotic due solely to deliriu m and were excluded from further analysis. Of the 98 remaining patients, 26 .5% (n=26) had visual hallucinations. Among these, one patient also had del usions, two had auditory hallucinations, and one had gustatory hallucinatio ns. Visual hallucinations were significantly associated with worse visual a cuity, lower cognitive score, higher depression score, and worse disease se verity. Hallucinations were not associated with history of psychiatric dise ase, dose or duration of levodopa or other antiparkinsonian medication trea tment, or duration of illness. Conclusions - Visual hallucinations are common symptoms in Parkinson's dise ase and are most likely of multifactorial origin. Although higher doses of levodopa are known to be related clinically to hallucinations in individual patients, the results suggest that several underlying characteristics of p atients with Parkinson's disease (disease severity, dementia, depression, w orse visual acuity) may be more important determinants of which patients ex perience hallucinations. The data also provide preliminary evidence that ab normality of the visual system may be related to visual hallucinations in P arkinson's disease, as has been found in other disorders with visual halluc inations.