There’s some good news for people with Parkinson’s disease: The risk of developing dementia may be lower than previously thought, or dementia may occur later in the course of the disease than previously reported, according to a study published in the August 7, 2024, online issue of Neurology, the medical journal of the American Academy of Neurology.
Previous studies had indicated that about 80% of people with Parkinson’s disease would develop dementia within 15-20 years after being diagnosed with Parkinson’s.
For the study, researchers analyzed data from two large, prospective studies. An international study involved 417 participants with an average age of 62 who were newly diagnosed with Parkinson’s disease and had not yet received treatment for the disease at study enrollment. A study at the University of Pennsylvania involved 389 people with Parkinson’s with an average age of 69 who had been diagnosed with Parkinson’s an average of six years before the start of the study. The participants were followed to see whether they developed dementia.
The international study showed an estimated probability of being diagnosed with dementia 10 years after being diagnosed with Parkinson’s disease of 9%. For the Pennsylvania study, the probability of being diagnosed with dementia 10 years after the Parkinson’s diagnosis was 27%. For the latter study, researchers found an estimated risk of dementia at 50%, 15 years after a Parkinson’s diagnosis and 74%, 20 years after diagnosis.
Factors that increased the risk of dementia in the Pennsylvania study included being older when Parkinson’s was diagnosed, being male and having a lower level of education.
