Parkinson's disease (PD) is different for everyone and we don't currently have any way of predicting what symptoms an individual with PD might experience or how they will progress. Identification of a biomarker -- an objective measurement of Parkinson's -- could be used to diagnose and track the disease, and would greatly assist in clinical management as well as in the development of new treatments.
To accelerate the search for a biomarker, The Michael J. Fox Foundation (MJFF) launched the Parkinson's Progression Markers Initiative (PPMI) in 2010. In this longitudinal, observational study, approximately 1,000 volunteers with and without Parkinson's are contributing invaluable data and biosamples that researchers can analyze to try to detect a biomarker, determine how the disease changes over time and evaluate risk factors for certain symptoms.
A recent study using data from PPMI, published in the Journal Neurology Neurosurgery Psychiatry, has identified risk factors that may predict the development of early psychosis in Parkinson's. Symptoms of Parkinson's disease psychosis primarily include hallucinations (seeing things that aren't there) or delusions (holding false, typically paranoid, beliefs). They may also encompass illusions (misinterpreting things that are there) or a false sense of presence (feeling that someone is nearby when no one is present). Symptoms of psychosis can affect up to 60 percent of people with PD and are typically more common in people with a longer duration (and increased severity) of disease, cognitive impairment or dementia, and older age. (Watch a webinar to learn more about hallucinations and delusions in Parkinson's.)
In this study, Dominic ffytche, MD, of the Institute of Psychiatry, King's College London, and colleagues used PPMI data to evaluate potential risk factors for early psychosis in Parkinson's disease. (Early means within three to four years of the time of diagnosis.) Compared to people who did not develop early psychosis, those who did were more likely to have a decreased sense of smell and increased symptoms of depression and REM sleep behavior (a sleep condition in which a person acts out his or her dreams) at the time of study enrollment. Participants with early psychosis also had lower levels of a protein called amyloid beta in their spinal fluid. And those who developed hallucinations as opposed to illusions had structural brain changes that were seen using imaging methods.
"We found that changes in the brain occur prior to the emergence of clinical symptoms. These findings could help us predict when symptoms of psychosis may occur and help us develop treatments to manage them," said Dr. ffytche. Note that having the above mentioned symptoms (e.g., lack of sense of smell, depression and REM sleep behavior disorder) does not imply that one will definitely develop early psychosis. More work needs to be done to determine the implications of these results for patients and clinical care. Currently, psychosis is managed with adjustments of Parkinson's drugs and/or adding an antipsychotic medication, such as Nuplazid (pimavanserin).
Researchers around the world, like Dr. ffytche and his colleagues, have access to de-identified data collected from PPMI in real time. By creating a rich database of information from those with PD, PPMI is helping to speed the recognition of Parkinson's risk factors and biomarkers.
"The beauty of PPMI is that it provides a comprehensive dataset and represents a unique opportunity to ask questions about changes in Parkinson's symptoms over time," said Dr. ffytche. He plans to explore other measures available in the PPMI dataset, such as specialized imaging of the dopamine cells in the brain (DaTScan) and specific aspects of cognitive (memory and thinking) performance, to continue this research.
Learn more about how you can participate in PPMI.