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Presence hallucinations early sign of Parkinson’s say scientists

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So-called ‘presence hallucinations’ where you have the strong feeling someone is standing behind you when they’re not, may be an early sign of Parkinson’s disease.

Scientists say the feeling is a common pointer to the progressive brain disorder that affects the nervous system.

But often patients and clinicians dismiss the hallucinations as a side effect of medication and not the symptoms of Parkinson’s disease itself.

Presence hallucinations may appear early on in the course of the disease, which affects around 10 million people globally, mostly in the 60-plus age group. But they are underreported.

Now, Ecole Polytechnique Fédérale de Lausanne (EPFL) scientists have warned they happen to around a third of Parkinson’s patients before the disease’s other more common symptoms, such as tremors, muscle stiffness, and slowness of movement, become evident.

Recognising the symptom is important because patients recently diagnosed with Parkinson’s disease who have early hallucinations are at greater risk of faster cognitive decline, the research team found.

Olaf Blanke, Bertarelli Chair in cognitive neuroprosthetics, who leads EPFL’s Laboratory of Cognitive Neuroscience, said: “We now know that early hallucinations are to be taken seriously in Parkinson’s disease.”

His colleague, Fosco Bernasconi of EPFL’s Laboratory of Cognitive Neuroscience and lead author of the study, added: “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.

“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.”

The EPFL team collaborated with medics at Sant Pau Hospital in Barcelona on the study, published in the journal Nature Mental Health.

Data was collected from 75 patients between the ages of 60 and 70 who were all diagnosed with Parkinson’s disease.

Early hallucinations in Parkinson’s disease are associated with frontal cognitive decline (triangles), and preceded by specific frontal neural oscillation (theta frequency band). Image: EPFL/Bernasconi

The clinicians and scientists at the hospital conducted a series of neuropsychological evaluations to assess the patients cognitive status, neuropsychiatric interviews about whether or not they were experiencing hallucinations, and electroencephalography (EEG) measurements of the brain’s activity at rest.

The scientists found that in patients with Parkinson’s disease, the cognitive decline was more rapid in the following five years for those who had suffered with early hallucinations.

The level of cognitive decline over those five years was further associated with frontal theta (4-8Hz) oscillatory activity as measured by the EEG during the first visit, but only if patients had hallucinations at the onset.  For clinically and demographically similar patients, the only difference at the outset was that one group had early hallucinations and the other did not.

Neurodegenerative diseases like Parkinson’s are often detected when it’s too late and the condition too advanced, limiting the impact of preventative measures and modifying therapies.

Dr Bernasconi, Professor Blanke and their collaborators want to change that, by looking for early signs – like minor hallucinations – and ways to promote intervention in good time for slowing down progression of cognitive and psychiatric symptoms of the disease.

Whilst hallucinations are among the lesser-known symptoms of Parkinson’s, they are highly prevalent early on in the disease, with one out of two individuals experiencing them regularly.

Parkinson’s disease is traditionally defined as a movement disorder, however, with the typical motor symptoms of resting tremor, rigidity, and slowness of movement. But it also leads to a wide variety of non-motor symptoms that appear early in the course of the disease.

Hallucinations can be described by a continuum of symptoms, from minor ones that usually occur early in the course of the disease, such as  presence hallucinations, to more severe indications like visual hallucinations that appear later.

It has also already been established that complex visual hallucinations, such as seeing someone who is not there, have been linked to cognitive decline and dementia in Parkinson’s disease and related neurodegenerative disorders like dementia with Lewy bodies.

However, complex visual hallucinations usually occur at a later stage of the disease, limiting their use as an early marker for cognitive decline, the research found.

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

Dr Bernasconi concluded: “We aim to have an early marker to identify individuals at risk of a more severe form of Parkinson’s disease, characterised by a more rapid cognitive decline and dementia, based on hallucinations proneness.”

Ideally, he said it was hoped to identify those individuals even before hallucinations actually occur. “We are therefore developing neurotechnology methods and procedures for that purpose.”

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