A new study published in Aging-US reveals that Parkinson’s disease (PD) patients diagnosed in their 80s are significantly more likely to exhibit amyloid-beta buildup, which is an early marker of Alzheimer’s disease, even in the absence of dementia symptoms. The research, led by Keiko Hatano and Masashi Kameyama from the Tokyo Metropolitan Institute for Geriatrics and Gerontology, highlights a potential age-related vulnerability in older PD patients.

The study analyzed cerebrospinal fluid samples from 89 individuals with PD who had no signs of dementia. Participants were divided into two groups based on age at diagnosis: under 73 and 73 or older. Results showed that 30.6% of the older group tested positive for amyloid-beta, compared to just 10.0% in the younger group.

Interestingly, both PD groups had lower rates of amyloid positivity than cognitively normal individuals of similar age. This suggests that Parkinson’s may influence how Alzheimer’s-related changes develop in the brain, potentially shortening the silent phase of amyloid accumulation and accelerating cognitive decline.

The researchers also found age-related associations with other Alzheimer’s biomarkers, such as tau protein levels. These findings underscore the importance of early screening for Alzheimer’s-related changes in older PD patients, even before cognitive symptoms emerge.

As the aging population grows, understanding the interplay between Parkinson’s and Alzheimer’s pathology could inform future diagnostic strategies and therapeutic interventions aimed at delaying or preventing dementia.