Minor Phenomena in Parkinson’s Disease–Prevalence, Associations, and Risk of Developing Psychosis

Abstract

Background Minor phenomena, including passage phenomena, feeling of presence, and illusions, are common and may represent a prodromal form of psychosis in Parkinson’s disease (PD). We examined the prevalence and clinical correlates of minor phenomena, and their potential role as a risk factor for PD psychosis. Methods A novel questionnaire, the Psychosis and Mild Perceptual Disturbances Questionnaire for PD (PMPDQ), was completed by Fox Insight cohort participants with and without PD. Additional assessments included the Non-Motor Symptoms Questionnaire (NMSQuest), REM Sleep Behavior Disorder Single Question Screen (RBD1Q), Movement Disorder Society-Unified Parkinson Disease Rating Scale Part II, demographic features, and medication usage. For participants with PD, we used regression models to identify clinical associations and predictors of incident psychosis over one year of follow-up. Results Among participants with PD (n = 5950) and without PD (n = 1879), the prevalence of minor phenomena was 43.1% and 31.7% ( P < .001). Of the 3760 participants with PD and no baseline psychosis, independent correlates of minor phenomena included positive responses on the NMSQuest apathy/attention/memory (OR 1.7, 95% CI 1.3-2.1, P < .001) or sexual function domain (OR 1.3, 95% CI 1.1-1.6, P = .01) and positive RBD1Q (OR 1.3, 95% CI 1.05-1.5, P = .01). Independent risk factors for incident PD psychosis included the presence of minor phenomena (HR 3.0, 95% CI 2.4-3.9, P < .001), positive response on the NMSQuest apathy/attention/memory domain (HR 1.8, 95% CI 1.3-2.6, P < .001), and positive RBD1Q (HR 1.5, 95% CI 1.1-1.9, P = .004). Conclusions Minor phenomena are common, associated with specific non-motor symptoms, and an independent predictor of incident psychosis in PD.

Defining the Importance of Minor Hallucinations in Parkinson's Disease

“…Fox Foundation for Parkinson's Research, 2 and found a high prevalence of minor hallucinations among individuals with PD. 3 We examined the incidence of PD psychosis at 1 year and found a higher incidence rate among those with minor hallucinations (20.1, 95% confidence interval (CI), 17.2-23.0) versus without minor hallucinations (5.1, 95% CI, 4.2-6.0). Minor hallucinations were the strongest independent risk factor for incident psychosis.…”

“…Indeed, in the above work, we introduced the term "PD Mild Perceptual Disturbances" to refer to the presence of isolated minor hallucinations and the associated increased risk for psychosis. 3 We hypothesize that mild perceptual disturbances represent a transitory state associated with a higher risk of psychosis, akin to the relationship between mild cognitive impairment and dementia. We also agree that the presence of minor hallucinations alone should not prompt initiation of treatment with an antipsychotic medication or prevent adjustments in dopaminergic medications.…”