Hallucinations in Parkinson's disease: Prevalence, phenomenology and risk factors

Abstract

Hallucinations, mainly of a visual nature, are considered to affect about one-quarter of patients with Parkinson's disease. They are commonly viewed as a side-effect of antiparkinsonian treatment, but other factors may be involved. The aim of this study was to determine the phenomenology, prevalence and risk factors of hallucinations in Parkinson's disease. Two-hundred and sixteen consecutive patients fulfilling clinical criteria for Parkinson's disease were studied. Demographic and clinical variables were recorded, including motor and cognitive status, depressive symptoms and sleep-wake disturbances. Patients with and without hallucinations were compared using non-parametric tests, and logistic regression was applied to significant data. Hallucinations had been present during the previous 3 months in 39.8% of the patients, and fell into three categories: minor forms, consisting of a sensation of a presence (person), a sideways passage (commonly of an animal) or illusions were present in 25.5% of the patients (an isolated occurrence in 14.3%), formed visual hallucinations were present in 22.2% (isolated in 9.3%) and auditory hallucinations were present in 9.7% (isolated in 2.3%). Patients with minor hallucinations had a higher depression score than non-hallucinators but did not differ in other respects. Logistic regression analysis identified three factors independently predictive of formed visual hallucinations: severe cognitive disorders, daytime somnolence and a long duration of Parkinson's disease. These findings indicate that, when minor hallucinations are included, the total prevalence is much higher than previously reported. A simple side-effect of dopaminergic treatment is not sufficient to explain the occurrence of all visual hallucinations. The main risk factor in treated patients is cognitive impairment, although sleep-wake cycle disturbances, and possibly other factors related to the duration of the disease, act as cofactors.

Assessing cognitive dysfunction in Parkinson's disease: An online tool to detect visuo‐perceptual deficits

“…The lower prevalence rate of hallucinations here reflects the earlier disease‐stage, community‐based nature of our population when compared with other studies showing higher prevalence rates 9, 10…”

“…Misperception of objects in PD10 may be caused by top‐down processes, where patients are primed to see objects more readily, or to impaired object detection. We tested these 2 competing theories using object detection within a complex scene 11…”

Frequency and correlates of co-morbid psychosis and depression in Parkinson's disease

“…It was once thought that treatment with higher dosages or particular classes (e.g., dopamine agonists) of dopamine replacement therapies was the primary etiology of psychosis in PD [24]. While numerous case series, epidemiological studies, and treatment studies have found psychosis to be related to levodopa [25] and dopamine agonist [26,27] use, several other recent epidemiological studies have not found an association between antiparkinsonian medication and the occurrence of psychosis [6,28,29]. Regardless the exact association between antiparkinsonian medications and psychosis, it is now thought that the etiology of psychosis in PD is multi-factorial, including other risk factors such as increasing age [6], longer duration and greater severity of PD [5,6], executive [30] and other forms of cognitive impairment [5][6][7], visual impairment [5], and increasing severity of depression [5][6][7].…”

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).…”