Psycho-sensory modalities of visual hallucinations and illusions in Parkinson's disease

Visual illusions (VI) in Parkinson's disease (PD) are generally considered part of the prodrome towards fully formed visual hallucinations (VH), and classified as minor hallucinations. However, this sequential relationship has not been clearly demonstrated and very little is known about the specific phenomenology of VI in regards to VH. We aimed to describe and compare psycho-sensory modalities associated with VI and VH in PD patients. PD patients with VI (PD-I, n=26) and VH (PD-H, n=28) were included in this case-controlled study. We compared qualitative and quantitative psycho-sensory modalities of VI and VH using the PsychoSensory hAllucinations Scale (PSAS), and demographical and clinical features of each group. PD-I perceptions were more often colored blots (P=0.05) or objects (P=0.005) compared to PD-H. Conversely, PD-H perceptions were more often described as animals (P