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An autopsy study of 230 people with Parkinson’s found higher rates of Alzheimer’s amyloid pathology in women, particularly women with Parkinson’s disease dementia. Researchers found no sex difference in tau pathology or cognitive impairment, and the results do not establish whether amyloid-targeting treatments would help people with Parkinson’s.
Women in an autopsy study of 230 people with Parkinson’s disease had higher rates of Alzheimer’s-related amyloid pathology than men, with the difference especially apparent among women with Parkinson’s disease dementia, researchers reported in the Journal of Parkinson’s Disease. The finding points to a sex difference in the brain changes that can accompany Parkinson’s, but does not show that amyloid causes dementia in these patients or that Alzheimer’s drugs will treat it.
The researchers examined autopsy cases collected through the Arizona Study of Aging and Neurodegenerative Disorders and its Brain and Body Donation Program. The study compared Alzheimer’s-related changes in the brains of women and men diagnosed with Parkinson’s. Its central finding was a higher burden of amyloid pathology among women, particularly those diagnosed with Parkinson’s disease dementia.
Amyloid is a protein that can accumulate in the brain as plaques, one of the changes associated with Alzheimer’s disease. The study found no sex difference in tau pathology, another Alzheimer’s-associated brain change, and reported no difference between women and men in levels of cognitive impairment. Those results mean the reported difference was specific to amyloid pathology in this sample, rather than a general difference across all the measures described.
The report did not present the finding as proof that the women had Alzheimer’s disease as a separate clinical diagnosis. Rather, the researchers identified co-pathology: brain changes associated with more than one neurodegenerative condition in people who had been diagnosed with Parkinson’s. The study was based on donated brains examined after death, not a trial of treatment or a test of amyloid-targeting drugs.
Why Amyloid Findings Matter
The findings add evidence that Parkinson’s and Alzheimer’s-related changes can coexist, and suggest that the pattern of co-occurring pathology may differ between women and men. That distinction may help researchers investigate why some people with Parkinson’s develop dementia and whether different biological processes contribute to cognitive symptoms in different groups.
It also raises a research question about treatments aimed at amyloid. Anti-amyloid medicines are approved for certain people with Alzheimer’s disease, but this study did not test those medicines in Parkinson’s disease dementia. Erika Driver-Dunckley, one of the lead researchers and a movement-disorder neurologist at Mayo Clinic, said the results could prompt researchers to examine whether some patients with Parkinson’s dementia and increased amyloid might benefit. That possibility remains unproven and would require dedicated clinical research.
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How Mixed Brain Pathology Fits
Parkinson’s disease is diagnosed through clinical signs and symptoms, while brain examination after death can reveal additional disease-related changes that were not necessarily identified during life. The researchers described this as mixed pathology: a person may have entered a brain donation program with one diagnosis, while autopsy later finds changes associated with multiple neurodegenerative diseases.
Driver-Dunckley told News-Medical that finding mixed pathology is not unusual in the program’s autopsy cases. She said the sex difference in amyloid, rather than the presence of overlapping pathologies itself, was what stood out to the researchers. The paper, by Dunckley and colleagues, was published in the journal’s 2026 volume 16, pages 1191–1200.
“In women, particularly those with Parkinson’s disease dementia, they had higher rates of Alzheimer’s amyloid pathology.”
— Erika Driver-Dunckley, lead researcher and movement-disorder neurologist at Mayo Clinic, as quoted by News-Medical
Limits of the Autopsy Findings
The study involved 230 autopsy cases, and the material provided does not give the number of women and men in each subgroup, the size of the difference, or details that would show how representative the sample is of people living with Parkinson’s. Because the analysis used brain tissue collected after death, it cannot by itself establish when amyloid accumulated or whether it contributed to dementia.
The report also does not establish why women had more amyloid pathology, whether the difference appears in other populations, or whether it predicts cognitive decline during life. No treatment outcomes were tested. The absence of a reported difference in tau pathology or cognitive impairment should not be read as evidence that amyloid has no relationship to symptoms; the study’s findings do not establish that relationship either.
Research Needed Before Treatment Changes
The next step is further research to test whether the reported sex difference holds in other groups and to clarify how amyloid pathology relates to cognition among people with Parkinson’s. Studies following patients during life, alongside biological measures and clinical assessments, could address questions that an autopsy comparison cannot answer.
Researchers would also need clinical trials before concluding that anti-amyloid medicines help people with Parkinson’s disease dementia, including patients whose brains show increased amyloid. For now, the finding is a research lead, not a treatment recommendation. People should discuss medical decisions with a qualified health professional.
Key Questions
What did the study find?
In an autopsy sample of 230 people with Parkinson’s, women had higher rates of Alzheimer’s-related amyloid pathology than men, especially among those with Parkinson’s disease dementia.
Did researchers find more tau pathology in women?
No. The report said researchers found no difference between women and men in tau pathology or levels of cognitive impairment.
Does the study show that amyloid causes dementia in Parkinson’s?
No. The autopsy findings show an association in the studied sample. They do not establish whether amyloid caused or contributed to dementia, or when the pathology developed.
Could Alzheimer’s drugs help people with Parkinson’s dementia?
The study did not test treatment. Its findings raise a question for future research, but they do not show that anti-amyloid medicines are effective for Parkinson’s disease dementia.
Source: news-medical.net
