An international study led by the University of Gothenburg has revealed that proteins typically associated with Alzheimer’s disease—β-amyloid and tau—are also found in people with other types of dementia.
This discovery could change how doctors approach dementia diagnosis and treatment, especially as new therapies targeting Alzheimer’s-related changes become more common.
The study, published in JAMA Neurology, looked at cerebrospinal fluid (CSF) samples from 13,882 individuals who had been diagnosed with various forms of dementia. All participants had samples taken within three years of diagnosis, and researchers measured three key proteins: β-amyloid (Aβ), total tau, and phosphorylated tau (p-tau).
These proteins are considered core biomarkers of Alzheimer’s disease because they reflect the buildup of toxic plaques and tangles in the brain.
As expected, people with Alzheimer’s—both early-onset and late-onset—showed the strongest presence of Alzheimer-type biomarkers.
However, to the researchers’ surprise, these same markers also appeared in people diagnosed with vascular dementia, dementia with Lewy bodies, Parkinson’s disease dementia, and frontotemporal dementia, though to varying degrees. Even people with unspecified types of dementia often showed some of these Alzheimer-like patterns.
In fact, 68% of the entire study population—regardless of dementia type—had abnormal β-amyloid levels in their spinal fluid, suggesting that Alzheimer-like brain changes are more widespread across different forms of dementia than previously believed.
The study also examined how these protein levels relate to cognitive function. The strongest links were seen in people diagnosed with Alzheimer’s disease, where lower β-amyloid and higher tau levels were clearly associated with worse memory test scores, based on the Mini-Mental State Examination (MMSE).
This pattern was less pronounced in other dementia types, showing that while the proteins may appear in many disorders, their impact on memory is most strongly tied to Alzheimer’s itself.
Interesting gender differences also emerged: women had higher tau levels in several dementia categories, while men with late-onset Alzheimer’s had higher Aβ-to-p-tau ratios. These differences could one day help personalize diagnosis and treatment based on sex-related biological patterns.
The findings present a double-edged sword for doctors. On the one hand, they highlight the value of using fluid biomarkers to spot Alzheimer’s-related changes, even in people with complex or unclear symptoms.
On the other hand, the overlap of protein abnormalities across different types of dementia complicates the task of pinpointing a precise diagnosis based on biomarkers alone.
Still, as new treatments that target amyloid plaques are developed and approved, early and accurate detection of Alzheimer’s pathology becomes more important. This study supports the use of cerebrospinal fluid testing to detect Alzheimer’s-type changes early—even in people who don’t show the typical symptoms or who may have more than one type of dementia at the same time.
In conclusion, while β-amyloid and tau abnormalities are not exclusive to Alzheimer’s, their presence remains highly relevant for early diagnosis and treatment planning. The findings suggest that Alzheimer’s-like brain changes may coexist with other dementia-related processes more often than previously assumed.
Broader use of biomarker testing could help ensure that patients get the right diagnosis and the most effective therapies—especially as disease-modifying treatments become more widely available.
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The research findings can be found in JAMA Neurology.
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