Parkinson’s Protein Accelerates Alzheimer’s Progression in Women, Study Finds

New research suggests a potential reason why Alzheimer’s disease progresses more rapidly in women than in men, linking the presence of a protein typically associated with Parkinson’s disease to a significantly faster rate of cognitive decline in female patients. The study, published in JAMA Network Open, highlights the need for sex-specific considerations in Alzheimer’s research, and treatment.

The Link Between Alpha-Synuclein and Alzheimer’s

Alzheimer’s disease is characterized by the buildup of tau protein in the brain, disrupting communication between brain cells. Yet, many individuals with Alzheimer’s also exhibit clumps of alpha-synuclein, a protein commonly associated with Parkinson’s disease and Lewy body dementia [1]. Researchers at the Mayo Clinic investigated the impact of this co-occurrence of alpha-synuclein and tau on disease progression.

20 Times Faster Decline in Women

The study, which analyzed data from 415 participants in the Alzheimer’s Disease Neuroimaging Initiative, found that women with both Alzheimer’s-related tau pathology and alpha-synuclein abnormalities experienced brain degeneration up to 20 times faster than those without the combination [1], [2], [3]. Notably, this accelerated decline was not observed in men with the same protein combinations [1].

Sex-Specific Vulnerability

“We cannot continue to treat Alzheimer’s disease as if it behaves exactly the same in everyone when we see disease-related changes unfolding at wildly different rates,” said Dr. Kejal Kantarsi, the study’s lead author [1]. The findings suggest a unique vulnerability in the female brain related to the interaction between tau and alpha-synuclein.

Implications for Diagnosis and Treatment

Researchers used advanced brain imaging and cerebrospinal fluid testing to track these protein interactions over time [1]. The discovery emphasizes that Alzheimer’s is not a “one-size-fits-all” disease and that women may require different screening approaches for Lewy body proteins to accurately predict their disease trajectory. “Identifying these sex-specific differences could help us design more targeted clinical trials and, more personalized treatment strategies,” Kantarci explained [1].

Alpha-Synuclein: A “Silent Passenger”

Even as primarily associated with Parkinson’s and Lewy Body dementia, alpha-synuclein often appears in Alzheimer’s patients, significantly worsening the prognosis for women [1], [2]. Study leader Dr. Elijah Mack stated, “This opens up a whole new direction in understanding why women bear a disproportionate burden of dementia” [1].

Alzheimer’s Disease Statistics

As of 2025, Alzheimer’s disease affects more than 7 million older adults in the United States, and scientists predict this number will double by 2060 [2]. The disease affects women at a higher rate than men, and women also tend to experience a faster rate of cognitive decline [2].

Further research is needed to fully understand the mechanisms behind this sex-specific vulnerability and to develop targeted therapies for women with Alzheimer’s disease.