Hallucinations in Parkinson's Disease

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    Olaf Blanke
Updated on 25 January 2021


Investigation on how robotically mediated sensorimotor stimulation induces and triggers presence hallucinations in different clinical groups of parkinsonian patients, and in aged-matched controls


Parkinson's Disease (PD) is a condition mostly known and characterized by motor symptoms, such as tremors, rigidity, bradykinesia, amongst others. Yet, recent bodies of research have identified a significant number of non-motor symptoms that also accompany the unfolding of this disease. These non-motor symptoms mainly focus on hallucinations that will develop with the course of the disease, and will affect approximately 50% of the patients suffering from Parkinson's. This number rises to 70% if minor hallucinations, mild phenomena and poorly-structured hallucinations, are included. Despite the potential impact in the patients' lives, and previous efforts to study these phenomena, the brain changes that underly hallucinations in PD are still poorly understood. With the current study the investigators aim to improve this understanding, by studying the most common minor hallucination in Parkinson's Disease, the Presence Hallucination (PH), which can be defined as the strange sensation of perceiving someone behind when no one is actually there. To study it in a controlled manner, the investigators will induce this hallucination with an extensively verified paradigm, which gives rise to this sensation through robotically-mediated sensorimotor stimulation, in both healthy individuals, and PD patients. The researchers intend to discern the sensitivity of different groups of PD patients to the induction of this hallucination, by targeting PD patients, with hallucinations including PH, with hallucinations but without PH, without any hallucinations, and an aged match control group with no neurological comorbidities. The investigators intended to extend previous work on the induction of the PH in PD patients, by identifying the neural correlates of this induction in these patients, in a similar fashion to previous work in healthy individuals. Moreover, the researchers also intend to extend the general understanding of the basis for hallucinations in PD by extending what was done in previous work, to more stratified cohorts of PD patients, that will not only be analysed in terms of static during rest, but also in terms of dynamic connectivity, and will also perform the PH-inducing task in the scanner, as mentioned before.

Condition Parkinson Disease Psychosis
Treatment Clinical and neuropsychological assessments, Induction of PH and associated bodily states, Resting-state fMRI acquisition, Induction of PH and associated bodily states (MRI)
Clinical Study IdentifierNCT04592965
SponsorOlaf Blanke
Last Modified on25 January 2021


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Inclusion Criteria

Diagnosed with Parkinson's disease (expect for healthy controls)
Able to understand instructions and provide informed consent
Native speaking language of experimental site (or acquisition of language of experimental site before 6 years old)
Montreal Cognitive Assessment (Nasreddine & Patel, 2016) with score 22
Able to manipulate the robotic device

Exclusion Criteria

For PD patients only: Neurological comorbidities other than Parkinson's disease (e.g. Alzheimer's disease, vascular dementia, multiple sclerosis, stroke, traumatic brain injury, epilepsy, chronic migraine, etc.)
For healthy controls only: Parkinson's disease or other neurological illnesses
History or current condition of substance abuse and/or dependence (e.g., alcohol, drugs)
Suffering from or diagnosed with psychiatric illnesses according to DSM-V criteria (e.g., schizophrenia, bipolar disorders, autism, personality disorders, phobia etc.)
Family history (1st and 2nd degree) of psychiatric disorders (e.g., schizophrenia or bipolar disorders)
Severe somatic illnesses (e.g., cancer)
Severe tremors or physical disability preventing optimal use of robotic device
Participating in a pharmacological study
Local or general anaesthesia 30 days prior experiment
Inability to provide informed consent (legal guardianship)
For the MRI part only: body weight exceeding 160kg, implanted metallic devices, implant for deep brain stimulation, foreign metallic objects, unstable angina, cardio-vascular diseases, tattoos with metallic components, external metallic objects, claustrophobia, pregnancy
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