This prospective pilot study in Lithuania compared 35 people with Parkinson’s disease (PD) to 35 age- and sex-matched controls to gauge the prevalence and phenomenology of minor psychotic experiences, with special attention to 20 distinct visual illusions. Minor hallucinations were far more common in PD than controls (45.7% vs 11.4%, p=0.003). Visual illusions, especially complex visual illusions, kinetopsia, and pelopsia, were reported by 37.1% of PD participants versus 8.6% of controls (p=0.009), and presence hallucinations by 22.9% vs 2.9% (p=0.028). Passage hallucinations were numerically higher in PD (20.0% vs 8.6%) but not significant. Among PD participants, those with visual illusions tended to have lower Montreal Cognitive Assessment scores, longer disease duration, and higher levodopa equivalent daily dose (non-significant). They were also much more likely to report presence hallucinations (53.8% vs 4.5%, p=0.002).
Notably, none of the PD participants with minor or visual hallucinations had disclosed these symptoms to their neurologist, underscoring underrecognition in routine care. Overall, minor hallucinations—particularly visual illusions—are common in PD without dementia. This supports the need for rapid, standardized screening tools to better characterize psychotic-spectrum symptoms and inform refinement of Parkinson’s disease psychosis diagnostic criteria.
Reference: Jucevičiūtė N, Balnytė R, Laucius O. Exploring the Spectrum of Visual Illusions and Other Minor Hallucinations in Patients with Parkinson’s Disease in Lithuania. Medicina (Kaunas). 2024;60(4):606. doi: 10.3390/medicina60040606.
