Hallucinations in Parkinson’s Disease: What They Really Look Like and How They Affect the Quality of Life

Hallucinations in Parkinson’s disease (PD) are associated with longer disease duration, cognitive impairment, depression, dopaminergic therapy and also poorer quality of life (QoL). The objectives were (1) to estimate the prevalence and phenomenology of hallucinations and (2) to explore their association with QoL within the PD population in Central Slovakia. Patients with PD (N = 277) were divided into three groups: 1. hallucinating (H), 2. non-hallucinating (NH), 3. non-hallucinating, matched with duration of PD (duration matched, NHdm). The patients completed a questionnaire that revealed the phenomenology of hallucinations. The Parkinson’s Disease Questionnaire (PDQ-39) was used to evaluate QoL. The prevalence of hallucinations was 16.97% (N = 47). Visual hallucinations had a cumulative prevalence of 95.7%, with presence (80.8%), passage (53.2%) and well-formed hallucinations (34.0%) being the most common forms. Auditory, olfactory and tactile hallucinations occurred in 27.6, 12.7 and 8.5%, respectively, and multi-modal and multi-sensory hallucinations in 14.9% and 29.8%, respectively. The mean PDQ-39 summary score was higher in the H group (P < 0.0001). QoL was lower in all eight PDQ-39 dimensions, with greater significance in mobility, activities of daily living, emotional well-being, cognition and communication (P < 0.0001 in all). Comparing with the NHdm group, the scores were lower in mobility (P = 0.0019), emotional well-being (P = 0.0010), social support (P = 0.0479) and cognition (P < 0.0001) dimensions. This is the first study focusing on the prevalence, phenomenology and impact of hallucinations on QoL in the Slovak population with PD.