Parkinson’s disease: The treatment of drug-induced hallucinations and psychosis

Abstract

Drug-induced psychosis is one of the most disabling complications of advancing Parkinson's disease. It has also been one of the most difficult to treat. Clozapine was the first medication shown to be safe and effective in this setting, and it remains the standard by which newer atypical antipsychotics are measured. However, due to the small but significant risk of agranulocytosis and the need for frequent blood testing, alternatives have been sought. Risperidone, olanzapine, and quetiapine are new atypical antipsychotics that have each been proposed as an alternative to clozapine, but the literature concerning their use in Parkinson's disease is conflicted and confusing. Although quetiapine appears to be the best current choice, none of these medications have equaled clozapine's ability to safely treat drug-induced psychosis without the risk of worsening parkinsonism.

A clinical profile of patients with Parkinson′s disease and psychosis

“…Most of the previous studies have reported auditory hallucinations occurring as a part of visual hallucinations[25273031] which was also seen in our study. Pure auditory hallucinations are rare in PD and there has been no systematic report of auditory hallucinations in PD.…”

“…Molho et al .,[30] reported visual hallucinations in about 30% of patients. They described the presence of animals and inanimate objects as a part of visual hallucinations.…”

“…Other studies have reported an incidence varying from 25% to 40%. [182531 Molho et al .,[30] reported auditory hallucinations which consisted of musical tunes of a particular type which the patient could not identify. Fenelon et al .,[25] also reported auditory hallucinations occurring as a “sound-track” of visual hallucinations.…”

Why people see things that are not there: A novel Perception and Attention Deficit model for recurrent complex visual hallucinations

“…Agents such as mescaline that affect catecholaminergic systems, promoting the release of dopamine, are said to result in multi-coloured images of fantasy. The dopaminergic system is frequently implicated in disease-related visual hallucinations, especially in Parkinson's disease, on the basis of symptomatic treatment with neuroleptics such as clozapine (Devanand & Levy 1995;Molho & Factor 2001), which commonly target the D2 receptor subtype (although other pharmacological actions may be implicated), and on the basis of the induction of hallucinations by levodopa (Ldopa) (Cannas et al 2001;Goetz et al 2001a;2001b;Holroyd et al 2001). However, in Parkinson's disease, evidence that L-dopa is the principal contributing factor to hallucinations is not consistent, since increasing L-dopa medication does not increase hallucination prevalence (Goetz et al 1997;1998a).…”

Believing is seeing in schizophrenia: The role of top-down processing

“…The dopaminergic system is frequently implicated in disease-related visual hallucinations, especially in Parkinson's disease, on the basis of symptomatic treatment with neuroleptics such as clozapine (Devanand & Levy 1995;Molho & Factor 2001), which commonly target the D2 receptor subtype (although other pharmacological actions may be implicated), and on the basis of the induction of hallucinations by levodopa (Ldopa) (Cannas et al 2001;Goetz et al 2001a;Holroyd et al 2001). The dopaminergic system is frequently implicated in disease-related visual hallucinations, especially in Parkinson's disease, on the basis of symptomatic treatment with neuroleptics such as clozapine (Devanand & Levy 1995;Molho & Factor 2001), which commonly target the D2 receptor subtype (although other pharmacological actions may be implicated), and on the basis of the induction of hallucinations by levodopa (Ldopa) (Cannas et al 2001;Goetz et al 2001a;Holroyd et al 2001).…”