Presence Hallucinations is the Early Sign of Parkinson’s Disease

Have you ever had the strong feeling that someone is following you, so strong that you turn around only to find that no one is there? This is referred to as a “presence hallucination.” Presence hallucinations are common but underreported in Parkinson’s disease patients, and they might emerge early in the disease’s progression. They are sometimes neglected by patients, professionals, or dismissed as a minor side effect of medication.

EPFL researchers have discovered that people with Parkinson’s disease who have early hallucinations are at a higher risk of cognitive deterioration. The findings have been published in Nature Mental Health.

“We now know that early hallucinations are to be taken seriously in Parkinson’s disease,” says Olaf Blanke, Bertarelli Chair in Cognitive Neuroprosthetics, who leads EPFL’s Laboratory of Cognitive Neuroscience. “If you have Parkinson’s disease and experience hallucinations, even minor ones, then you should share this information with your doctor as soon as possible,” explains Fosco Bernasconi of EPFL’s Laboratory of Cognitive Neuroscience and lead author of the study. “So far, we only have evidence linking cognitive decline and early hallucinations for Parkinson’s disease, but it could also be valid for other neurodegenerative diseases.”

A long-term clinical trial of Parkinson’s disease patients

The scientists collected data from 75 Parkinson’s disease patients between the ages of 60 and 70 in a cooperation between EPFL and Sant Pau Hospital in Barcelona. The hospital’s physicians and scientists conducted a series of neuropsychological interviews to assess their cognitive health, neuropsychiatric interviews to determine whether or not they were having hallucinations, and electroencephalography (EEG) recordings of the brain’s activity at rest.

The investigators discovered that in Parkinson’s disease patients with early hallucinations, the cognitive deterioration of frontal executive function is more rapid in the next five years. The level of cognitive impairment over those five years is also associated with frontal theta (4-8Hz) oscillatory activity as evaluated by the EEG during the initial visit, but only if hallucinations are present at the start.

The only difference between clinically and demographically similar patients is that one group has early hallucinations while the other does not.

Early detection leads to early treatment

Neurodegenerative illnesses, such as Parkinson’s, are frequently identified after the disease has progressed, reducing the impact of prevention treatments and disease-modifying medications. Bernasconi, Blanke, and their colleagues hope to change that by looking for early signals of the disease, such as small hallucinations, and ways to promote early intervention for delaying the spread of cognitive and psychiatric symptoms.

Hallucinations are one of Parkinson’s disease’s lesser-known symptoms, and they are extremely common early on in the condition, with one out of every two people suffering hallucinations on a regular basis. Early hallucinations are of particular significance since they occur in one-third of Parkinson patients prior to the development of motor symptoms such as trembling.

Parkinson’s disease is generally classified as a movement condition characterized by resting tremor, stiffness, and bradykinesia, but it also causes a wide range of non-motor symptoms that manifest early in the disease’s progression.

Hallucinations are characterized by a spectrum of symptoms, ranging from modest symptoms such as presence hallucinations that develop early in the course of the disease to more severe symptoms such as visual hallucinations that appear later.

Complex visual hallucinations, such as seeing someone who isn’t there, have also been associated to cognitive loss and dementia in Parkinson’s disease and similar neurodegenerative conditions such as dementia with Lewy bodies. Complex visual hallucinations, on the other hand, frequently arise later in the disease, limiting their value as an early indicator of cognitive deterioration.

Detecting the earliest signs of dementia means early management of the disease, allowing us to develop improved and personalized therapies that try to modify the course of the disease and improve cognitive function,” continues Blanke.

“We aim to have an early marker to identify individuals at risk of a more severe form of Parkinson’s disease, characterized by a more rapid cognitive decline and dementia, based on hallucinations proneness. And ideally identify those individuals even before hallucinations actually occur. We are therefore developing neurotechnology methods and procedures for that purpose,” says Bernasconi.

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