Prevalence of psychosis in patients with Parkinson’s disease

Visual hallucinations appear to be the most common psychotic symptom in PD; estimates suggest that 16–38% of patients experience them at some point.¹ Auditory hallucinations are less common (0–22%) and usually occur alongside visual hallucinations.¹

Delusions are least common (1–7%), but occur more often in patients with dementia.1They are probably the most significant and disabling of all the psychotic symptoms.¹ Often paranoid in nature, delusions may cause great distress to the patient and their caregivers.³

A study that assessed patients with PD after 12 years of follow-up found that 60% had evidence of hallucinations or delusions.⁴ Those most likely to develop psychotic symptoms later during the disease were patients who:⁴

• were older at the onset of motor symptoms
• had a higher initial levodopa dose
• who had been suffering from REM sleep behaviour disorder (RBD).

References:
1. Chang A, Fox SH. Psychosis in Parkinson’s disease: epidemiology, pathophysiology, and management. Drugs 2016; 76 (11): 1093–1118.

2. Mack J, Rabins P, Anderson K, et al. Prevalence of psychotic symptoms in a community-based Parkinson disease sample. Am J Geriatr Psychiatry 2012; 20 (2): 123–132.

3. Friedman JH. Parkinson disease psychosis: update. Behav Neurol 2013; 27 (4): 469–477.

4. Forsaa EB, Larsen JP, Wentzel-Larsen T, et al. A 12-year population-based study of psychosis in Parkinson disease. Arch Neurol 2010; 67 (8): 996–1001.