56% Of Women With Parkinson's Had This Alzheimer's-Related Brain Finding
If you or someone you love has Parkinson's disease, the tremors and movement changes may be what you notice first.
But the condition can also affect memory, attention, and other aspects of thinking, adding another layer of concern for people navigating a diagnosis.
And there's still plenty researchers are learning about why these cognitive changes develop, and whether they affect men and women differently.
In an autopsy study of people with Parkinson's1, researchers found a difference in how much Alzheimer's-related brain pathology women and men carried, raising new questions about the relationship between the two conditions.
About the study
Parkinson's and Alzheimer's are two different conditions, but they can leave some of the same signs in the brain. In Parkinson's, a protein called alpha-synuclein can build up inside brain cells, forming clumps known as Lewy bodies.
Alzheimer's is associated with two other types of protein buildup: amyloid plaques and tau tangles. Both can disrupt how brain cells communicate and function.
Researchers wanted to know whether men and women with Parkinson's show different amounts of these Alzheimer's-related changes.
To find out, they examined brain tissue from 230 people with Parkinson's (74 women and 156 men) who had donated their brains to the Arizona Study of Aging and Neurodegenerative Disorders and Brain and Body Donation Program.
During their lives, participants also received regular checkups to assess their brain health, memory, and thinking skills.
This gave researchers a way to compare what was happening in their brains with how they were functioning day to day.
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Women had more Alzheimer's-related amyloid plaques
Women had higher levels of amyloid plaques than men. Their average plaque score was 6.5 out of 15, compared with 4.9 in men.
More than half of the women (56.8%) also had an elevated amyloid plaque burden, compared with 39.7% of men.
Researchers found a similar difference when looking specifically at neuritic plaques, a type of amyloid deposit associated with Alzheimer's disease.
Even after accounting for age at death, the genetic risk factor APOE ε4, and Lewy body levels, women had more than twice the odds of having an elevated amyloid burden.
Interestingly, this difference didn't extend to every Alzheimer's-related brain change. Researchers found no significant sex differences in tau buildup.
The amyloid gap was also most apparent among participants who had developed Parkinson's disease dementia, rather than those who had normal cognition or mild cognitive impairment.
More brain pathology didn't necessarily mean more dementia
Having more Alzheimer's-related changes in the brain doesn't automatically mean someone will experience more severe cognitive symptoms.
Despite the differences in amyloid plaques, women and men in the study had similar rates of clinically diagnosed dementia. Women also performed better on a verbal learning test, which measures how well someone can learn and recall information presented through language.
The researchers suggest this could point to differences in cognitive resilience, meaning some people may be better able to maintain their thinking abilities despite having more underlying brain changes.
However, the study can't explain exactly why this might happen or whether the difference would hold up in larger groups.
It also doesn't establish that women with Parkinson's are more likely to develop Alzheimer's. The researchers measured brain pathology after death, not future dementia risk.
What this means for people living with Parkinson's
For people with Parkinson's and their caregivers, the findings are a reminder that cognitive health deserves attention alongside movement symptoms.
Changes in memory, concentration, language, or problem-solving can sometimes develop as the condition progresses, so they're worth discussing with a neurologist.
A few things to keep on your radar:
- Memory changes: Notice whether someone is increasingly forgetting recent conversations, appointments, or familiar information.
- Attention and focus: Pay attention to new difficulties following conversations or completing familiar tasks.
- Changes in thinking: Bring up noticeable shifts in decision-making, language, or problem-solving with a care team.
These changes don't automatically mean someone has dementia, but keeping track of them can help healthcare providers understand what's happening and determine whether further assessment is needed.
The takeaway
Parkinson's and Alzheimer's can leave overlapping fingerprints on the brain, but this study suggests those patterns may look different in women and men.
Women had more amyloid plaques, yet that didn't translate into higher dementia rates in this group. Understanding why could help researchers get a clearer picture of cognitive health in Parkinson's, and eventually improve how it's monitored and managed.
