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.

Cognitive phenotype of psychotic symptoms in Alzheimer's disease: evidence for impaired visuoperceptual function in the misidentification subtype

“…Our findings are also consistent with integrative theories regarding the origins of visual hallucinations within the context of neurodegenerative disease (reviewed by Collerton and Taylor, 2013), which suggest that deficits in attentional control and perceptual processing are necessary for visual misperceptions and hallucinations to occur (Collerton et al ., 2005; Diederich et al ., 2009; Shine et al ., 2011). On the basis of the present findings, it is tempting to speculate that psychotic symptoms in AD are underpinned by disruption of the cholinergic/dopaminergic axis within frontostriatal circuits, with additional pathology in the ventral visual pathway in patients with the misidentification subtype.…”

Parkinson's disease, visual hallucinations and apomorphine: A review of the available evidence

“…It is therefore recommended that in the absence of systemic illness, the dose of dopamine agonist should be reduced if VH develop and that they should be prescribed with caution in PD patients with significant cognitive impairment [62].…”

Pimavanserin, a Serotonin2A Receptor Inverse Agonist, for the Treatment of Parkinson's Disease Psychosis

“…Psychotic symptoms, particularly visual hallucinations and paranoid delusions, occur in up to 40% of patients with Parkinson's disease (PD) who receive dopamine (DA) replacement therapy (Chou et al, 2007;Fenelon et al, 2000;Fernandez et al, 2003: Friedman, 1991, Goetz et al, 2001Weintraub and Stern, 2005;Ravina et al, 2007;Diederich et al, 2009). Psychotic symptoms in PD psychosis (PDP) are a significant cause of distress to patients and their caregivers, and are associated with greater functional impairment, caregiver burden, nursing home placement, and increased mortality (Weintraub and Stern, 2005;Factor et al, 2003).…”