Sense Phantoms Standing Behind You? It May Be an Early Sign of Parkinson's

We have all at some point had the feeling that there is someone lurking behind us. But scientists have found that, in some cases, this could be an early sign of Parkinson's disease.

This sensation is known as a "presence hallucination." It is typically underreported in patients with Parkinson's disease, but may appear extremely early in the onset of the disease.

In research published in Nature Mental Health on June 29, scientists report that people who have recently been diagnosed with the disease and have these early hallucinations are at risk of great cognitive decline.

Parkinson's disease is a disorder of the central nervous system. It manifests in uncontrollable or unintended movements, such as difficulty with balance, shaking and stiffness. Symptoms often worsen gradually as the disease progresses. When the disease progresses, some people have extreme difficulty walking and talking.

The study suggests that presence hallucinations should be taken much more seriously in the context of the disease.

For the research, scientists and doctors from Swiss Federal Institute of Technology Lausanne (EPFL) and Sant Pau Hospital in Barcelona gathered data on 75 Parkinson's patients between the ages of 60 and 70.

The participants were interviewed to assess their brain activity. In patients who had experienced hallucinations, the disease progressed more rapidly in the following five years.

"Previous evidence has indicated that complex visual hallucinations in Parkinson's disease are associated with cognitive decline and dementia," the lead authors of the study—Fosco Bernasconi of EPFL's Laboratory of Cognitive Neuroscience and Olaf Blanke, Bertarelli chair in cognitive neuroprosthetics and lead at EPFL's Laboratory of Cognitive Neuroscience—told Newsweek in a joint statement.

"Yet visual hallucinations usually occur at a middle to advanced stage of the disease and this does not make them suitable as an early marker or predictor of the later appearing dementia, sometimes five years or more.

"However, growing evidence suggests that complex visual hallucinations are very often preceded by many of the so-called 'minor' hallucinations."

These findings could help to diagnose Parkinson's sooner. Neurodegenerative disorders are often diagnosed when it is too late to mitigate severe symptoms. The authors of this study are aiming to detect early signs, in order to change this.

"Those hallucinations may even precede motor symptoms and the diagnosis of Parkinson's disease. We therefore hypothesized that 'minor' hallucinations might also play a role in identifying cognitive decline," Blanke and Bernasconi said.

"We were surprised that our data aligned up beautifully when integrating the presence of these 'minor' hallucinations with frontal brain activity changes that were further associated with changes in frontal lobe function. Hence we were surprised to find this clear, selective and early involvement of changes in the frontal brain associated with minor hallucinations."

The hallucinations are not always a sign of Parkinson's, however. They can also occur in other neurodegenerative diseases such as dementia with Lewy bodies.

"Presence hallucinations have also been reported in neurological and psychiatric conditions, and in healthy individuals facing extreme situations and even bereavement. But they are most frequent and clinically relevant in Parkinson's disease and dementia with Lewy bodies," Blanke and Bernasconi said.

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