Hallucinations in schizophrenia and Parkinson’s disease: an analysis of sensory modalities involved and the repercussion on patients

Abstract

Hallucinations have been described in various clinical populations, but they are neither disorder nor disease specific. In schizophrenia patients, hallucinations are hallmark symptoms and auditory ones are described as the more frequent. In Parkinson’s disease, the descriptions of hallucination modalities are sparse, but the hallucinations do tend to have less negative consequences. Our study aims to explore the phenomenology of hallucinations in both hallucinating schizophrenia patients and Parkinson’s disease patients using the Psycho-Sensory hAllucinations Scale (PSAS). The main objective is to describe the phenomena of these clinical symptoms in those two specific populations. Each hallucinatory sensory modality significantly differed between Parkinson’s disease and schizophrenia patients. Auditory, olfactory/gustatory and cœnesthetic hallucinations were more frequent in schizophrenia than visual hallucinations. The guardian angel item, usually not explored in schizophrenia, was described by 46% of these patients. The combination of auditory and visual hallucinations was the most frequent for both Parkinson’s disease and schizophrenia. The repercussion index summing characteristics of each hallucination (frequency, duration, negative aspects, conviction, impact, control and sound intensity) was always higher for schizophrenia. A broader view including widespread characteristics and interdisciplinary works must be encouraged to better understand the complexity of the process involved in hallucinations.

Meta-analytic evidence for the plurality of mechanisms in transdiagnostic structural MRI studies of hallucination status

“…Anticipating differences in mechanisms of hallucinations between psychiatric illnesses and neurodegenerative diseases based on distinctions in phenomenology, modality, prevalence 51 , and the significant participant age separation amongst primary studies (t(25) = 17.324, p<0.001), we performed a meta-analysis including schizophrenia, first episode schizophrenia (FES), first episode psychosis (FEP), and young adults at clinical risk for psychosis (at-risk mental state long-term, ARMS-LT), and BD, and a second of neurodegenerative disorders, including PD and AD. Of the 16 studies included in these two cross-sectional meta-analyses, three (see Table 1) did not make an explicit comparison between a hallucination (H) and no-hallucinations (NH) group, though the majority of patients in each group respectively either did or did not have hallucinations, and were therefore included 52-54 .…”

Clinical and neurocognitive aspects of hallucinations in Alzheimer’s disease

“…Another tool is the Psycho-Sensory Hallucinations Scale (PSAS), a hetero-evaluation scale that includes four hallucination modalities (auditory, visual, olfactory/gustatory, and kinesthetic modalities) as well as the vivid sensation that somebody is present nearby [76, 77]. Future research should incorporate these assessments because research on hallucinations in other clinical groups (e.g., schizophrenia) provide considerably more detail about the phenomenology of hallucinatory experience than research in AD.…”

fMRI capture of auditory hallucinations: Validation of the two‐steps method

“…In schizophrenia, hallucinations are frequent and may cause long-term disability (Hor and Taylor, 2010). In adults, auditory-verbal hallucinations (AVHs) are most frequent (Andreasen and Flaum, 1991), although hallucinations may occur across every sensory modality (David et al, 2011;Llorca et al, 2016). Anatomical and functional disturbances in both primary and association sensory cortices (ASCs) have been proposed to account for AVHs (Allen et al, 2008;Jardri et al, 2011), but the detection of their occurrence while scanning a participant (hallucination capture methods) has long remained very challenging.…”