A new autopsy study found that more than half of women with Parkinson’s disease carried heavy amyloid plaque buildup in their brains, the same sticky protein tied to Alzheimer’s disease.
Story Snapshot
- Mayo Clinic researchers examined 230 autopsy-confirmed Parkinson’s cases and found high amyloid plaque burden in 56.8% of women versus 39.7% of men.
- The gap held up even after accounting for age at death and the APOE ε4 gene, a known Alzheimer’s risk factor.
- Despite the pathology difference, men and women showed no significant gap in actual Alzheimer’s dementia rates or cognitive test scores.
- The findings come from brain tissue examined after death, not from scans or tests on living patients.
What The Brain Tissue Actually Showed
Researchers at Mayo Clinic Arizona studied 230 people who had Parkinson’s disease confirmed by autopsy. All came from the Arizona Study of Aging and Neurodegenerative Disorders and its linked brain donation program. Women in the group showed high cortical amyloid plaque burden far more often than men, 56.8% compared to 39.7%. The difference was not a fluke of chance. It hit statistical significance at p=0.015.
Amyloid plaques are clumps of protein that build up between brain cells. They are a hallmark marker doctors look for when diagnosing Alzheimer’s disease. Finding them at high levels in Parkinson’s patients means two brain diseases, usually studied separately, are showing up together in the same tissue, and more often in women than men.
The Gap Survived Scrutiny
Scientists often worry that a sex difference like this is really just an age difference in disguise, since women tend to live longer than men. The Mayo team adjusted for age at death and for APOE ε4, the gene variant that raises Alzheimer’s risk. The pattern held. Women remained more than twice as likely as men to carry high amyloid burden, with an odds ratio of 2.18 and a p-value of 0.014. That is a result built on direct brain tissue examination, not a symptom checklist or a family-reported memory complaint.
The strongest version of this finding showed up specifically in women who also had Parkinson’s disease dementia, according to Dr. Erika Driver-Dunckley, one of the study’s lead researchers at Mayo Clinic. Her team described the pattern as Alzheimer’s-related brain change layered on top of existing Parkinson’s pathology, a form of mixed disease that pathologists have documented before but rarely broken down by sex this clearly.
Why More Plaques Didn’t Mean More Memory Loss
Here is the twist that keeps this story honest. Even though women carried more amyloid plaques, the study found no significant difference between men and women in actual Alzheimer’s dementia rates or cognitive testing scores. More plaque buildup did not translate into more diagnosed dementia or worse test performance in this group. The brain tissue told one story. The clinical symptoms, while the patients were alive, told another.
That gap matters for how people should read this news. A high plaque count is a pathology marker, found after death, during an autopsy. It is not the same as a confirmed Alzheimer’s diagnosis in a living, thinking person. The researchers also found no sex difference in tau pathology, another protein tangle linked to Alzheimer’s, which means this story is specifically about amyloid, not every marker doctors use.
Putting The Number In Context
Mixed brain pathology in Parkinson’s patients is not new territory. Earlier autopsy reviews found that somewhere between a fifth and a third of all Parkinson’s cases met pathological criteria for Alzheimer’s disease, and among those with Parkinson’s dementia, moderate or severe amyloid pathology showed up in slightly more than half. The new Mayo finding sharpens that picture by sex, but it builds on a pattern pathologists already knew existed.
The study drew its subjects from a brain donation program, not a random sample of every person with Parkinson’s disease. People who enroll in these programs may differ in health history, disease severity, or care access from the wider Parkinson’s population. That does not undercut the result, but it is a reasonable reason the next step should be replicating these numbers in other autopsy cohorts before anyone treats the 56.8% figure as a universal rate for all women with Parkinson’s.
What Comes Next For Patients And Families
The practical path forward is testing whether this amyloid pattern can be spotted in living patients through brain scans or spinal fluid tests, long before autopsy. Researchers have already started that work, screening blood and spinal fluid markers in early Parkinson’s patients to see how amyloid buildup lines up with symptoms like mood changes and sleep disruption. If plaque burden can be caught early and tied reliably to future decline, doctors gain a tool to flag higher-risk women sooner, rather than finding out the full picture only after death.
Sources:
mindbodygreen.com, emjreviews.com, medicalxpress.com, pmc.ncbi.nlm.nih.gov, newsnetwork.mayoclinic.org, acnr.co.uk
