Scientists from the Swiss Polytechnic Federal School in Lausanne found that between 40 and 50% of people with Parkinson’s disease experience an unpleasant feeling of being watched. The authors of the journal article concluded that the presence of such hallucinations may also be associated with faster progression of the disease. Nature Mental Health.
Neuroscientists studied the effects of hallucinations in 75 Parkinson’s patients, ages 60 to 70. Each patient underwent a series of interviews with specialists to assess their level of cognitive impairment and psychiatric interviews, during which important information about their hallucinations was collected.
About half of the patients reported experiencing an unpleasant feeling of watching, known as presence hallucinations, at the beginning of their illness. Doctors often dismiss these complaints or attribute them to side effects of drugs.
Five years later, researchers found that people who reported presence hallucinations early in their illness experienced faster declines in cognitive functions related to the frontal lobe of the brain: memory, learning, spatial perception, and attention.
Using the EEG method, “increased frontal theta oscillations” were found in patients with presence hallucinations. This means that they have higher levels of oscillatory electrical activity in the frontal region of the brain, particularly in the theta frequency range. The theta fluctuation range is most closely associated with cognitive processes, where a rapid decline is observed in hallucinating patients.
The scientists noted that the link between cognitive decline and early hallucinations may also apply to other neurodegenerative diseases. This hypothesis can be tested in future studies.
It is estimated that around 8.5 million people worldwide suffer from Parkinson’s disease. The average age at diagnosis is about 60. Symptoms can include uncontrollable shaking of the limbs, slow movements and muscle stiffness, but experts say these symptoms usually only occur when about 80% of the nerve cells have already disappeared. Parkinson’s disease also has a great impact on a person’s mental functions.
The scientists’ results will allow to diagnose Parkinson’s disease earlier. It’s incurable, but early detection can provide more time for treatment with medications, such as drugs that correct a lack of dopamine in the brain, a neurotransmitter that plays an important role in movement and fine motor skills.
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