LAUSR

Recurrent visual hallucinations (VHs) are common in Parkinson disease (PD), with cross-sectional studies estimating a 22% to 38% overall prevalence.1 Neuropathologic brain bank studies show that a history of VHs is the strongest predictor of α-synuclein (Lewy bodies) neuronal pathology, i.e., of neuropathologically proven PD.2 Of note, the occurrence of VHs has importance for PD prognosis, being a harbinger of cognitive decline, nursing home placement, and increased mortality.3 VHs were initially considered as a dopaminergic drug-induced psychosis,4 but a substantial corpus of data have demonstrated that PD VHs occurred in the pre-levodopa era, and may be independent of, and are not linearly correlated with, dopaminergic drug treatments, although these drugs may act as precipitants.3 Reconsideration of the dopamine toxicity hypothesis has driven new studies on PD VH pathophysiologic mechanisms; for example, those focused on neuroimaging in order to identify neural network alterations, and to develop possible treatments based on manipulation of neurotransmitters involved in brain networks.