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EPFL | New “brain stress test” for evaluating the mental status of patients with Parkinson’s disease

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Awakening “ghosts” in patients with Parkinson’s


EPFL scientists are developing a completely new “brain stress test” for evaluating the mental status of patients with Parkinson’s disease, the second most prevalent neurodegenerative disease worldwide. It involves awakening the “ghosts” hidden in specific networks of the brain to predict the onset of hallucinations.

“We’re developing something similar to a cardiac stress test, but instead of testing the heart, we’re testing the brain,” says EPFL neuroscientist Olaf Blanke.

EPFL scientists are providing a new way to evaluate the onset of hallucinations in patients with Parkinson’s disease with the help of a newly developed brain stress test, focusing their research on presence hallucinations. They also provide evidence of a promising biomarker for predicting the severity of the disease’s progression. The results of their three-tier study, involving 56 patients affected by the disease and recruited at several centers in Switzerland and Spain, are published in today’s edition of Science Translational Medicine (STM).

“An important challenge with hallucinations is that they occur spontaneously, that their occurrence cannot be predicted, that many patients may not openly report them, possibly out of fear, and that it is currently very challenging for physicians to quantify their occurrence, phenomenology and intensity,” says Fosco Bernasconi, co-first author of the paper. “We have established a robotic-medical device and procedure that can provoke a specific hallucination, the presence hallucination, safely and under controlled conditions in a hospital setting.”


A spectrum of hallucinations in Parkinson’s

Parkinson’s disease is well-known for leading to slowness of movement, muscle stiffness, as well as uncontrollable shaking of the limbs. But alterations of movement are far from being the only symptom of the disease.

Hallucinations are frequent in the disease, affecting both women and men. In fact, roughly half of people with Parkinson’s disease experience hallucinations of some sort, like presence hallucinations. Hallucinations of the peripheral vision that involve sightings of individuals or animals, passing by quickly in the corner of one’s eye, are also possible, as are visual misperception of objects, or even fully colored and formed visual hallucinations.


Presence hallucinations is underdiagnosed in Parkinson’s disease

Parkinson’s disease is the second most prevalent neurodegenerative disease worldwide after Alzheimer’s and affects primarily the elderly. It is a progressive neurodegenerative disease that has been traditionally defined as a movement disorder, characterised by tremor, rigidity and slowness of movement. But many patients also suffer from a wide array of symptoms that are not associated with movement and some may go on to suffer from mental symptoms like psychosis, depression, apathy, cognitive decline and even dementia.

A growing body of clinical evidence suggests that hallucinations might be precursors to these more severe mental and cognitive symptoms. But hallucinations, like presence hallucinations, remain underdiagnosed. It may be that patients are reluctant to report them to their doctors, and that non-specialised clinicians fail to ask about them or lack rigorous tools to assess them.


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