title: Hallucinations in Parkinson disease.
abstract: Patients with Parkinson disease (PD) can experience hallucinations (spontaneous aberrant perceptions) and illusions (misinterpretations of real perceptual stimuli). Of such phenomena, visual hallucinations (VHs) and illusions are the most frequently encountered, although auditory, olfactory and tactile hallucinations can also occur. In cross-sectional studies, VHs occur in approximately one-third of patients, but up to three-quarters of patients might develop VHs during a 20-year period. Hallucinations can have substantial psychosocial effects and, historically, were the main reason for placing patients in nursing homes. Concomitant or overlapping mechanisms are probably active during VHs, and these include the following: central dopaminergic overactivity and an imbalance with cholinergic neurotransmission; dysfunction of the visual pathways, including specific PD-associated retinopathy and functional alterations of the extrastriate visual pathways; alterations of brainstem sleep-wake and dream regulation; and impaired attentional focus. Possible treatments include patient-initiated coping strategies, a reduction of antiparkinson medications, atypical neuroleptics and, potentially, cholinesterase inhibitors. Evidence-based studies, however, only support the use of one atypical neuroleptic, clozapine, and only in patients without dementia. Better phenomenological discrimination, combined with neuroimaging tools, should refine therapeutic options and improve prognosis. The aim of this Review is to present epidemiological, phenomenological, pathophysiological and therapeutic aspects of hallucinations in PD.
authors.affiliation: Department of Neurology, Center Hospitalier de Luxembourg, 4 rue Barblé, Luxembourg City, Luxembourg. diederdn@pt.lu
authors.forename: Nico J
authors.initials: NJ
authors.lastname: Diederich
authors.forename: Gilles
authors.initials: G
authors.lastname: Fénelon
authors.forename: Glenn
authors.initials: G
authors.lastname: Stebbins
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Goetz
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000627:therapeutic use; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use; D003072:Cognition Disorders / Q000150:complications / Q000209:etiology; D006212:Hallucinations / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007088:Illusions; D007980:Levodopa / Q000009:adverse effects; D008279:Magnetic Resonance Imaging; D018377:Neurotransmitter Agents / Q000378:metabolism; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy / Q000473:pathology; D012893:Sleep Wake Disorders / Q000209:etiology
chemical_list: D014150:Antipsychotic Agents; D002800:Cholinesterase Inhibitors; D018377:Neurotransmitter Agents; D007980:Levodopa