Alzheimer's Biomarkers Found in Other Dementias Could Obscure Diagnosis

Recent international research led by the University of Gothenburg has revealed that cerebrospinal fluid (CSF) biomarkers associated with Alzheimer's disease—specifically β-amyloid and tau proteins—are also detectable in individuals diagnosed with various other forms of dementia. These findings suggest that the pathological markers traditionally linked to Alzheimer's are more widespread across different dementia types than previously recognized, which may impact diagnostic accuracy. The study observed associations between these biomarkers and cognitive performance primarily in Alzheimer’s-related diagnoses.

Dementia affects millions worldwide and can stem from numerous underlying conditions, including Alzheimer’s disease, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, and Parkinson’s disease dementia. Often, symptoms overlap, with mixed pathologies common in many cases.

Therapeutic strategies targeting amyloid β have increased interest in early and precise diagnosis. However, the presence of amyloid and tau proteins in non-Alzheimer's dementias complicates this process, underscoring the importance of reliable biomarker testing to differentiate among different types of dementia. The study titled "Cerebrospinal Fluid Biomarkers for Alzheimer Disease Among Patients With Dementia," published in JAMA Neurology, analyzed data from nearly 14,000 individuals with dementia. All participants had CSF samples analyzed for β-amyloid, total tau, and phosphorylated tau, within three years of their diagnosis.

Results showed that Alzheimer’s-like biomarker profiles were most common in early-onset and late-onset Alzheimer’s, as well as mixed Alzheimer’s and vascular dementia cases. These profiles were also present in other diagnostic categories, such as dementia not otherwise specified, with the lowest prevalence found in Parkinson’s and frontotemporal dementias. Notably, MRI and cognitive scores, measured by the Mini-Mental State Examination, correlated strongly with biomarker levels in Alzheimer-related cases. Interestingly, women exhibited higher tau concentrations, whereas men had higher Aβ-to-phosphorylated tau ratios, especially in late-onset Alzheimer’s.

A significant portion of the study population—68%—had abnormal β-amyloid levels, including many with non-Alzheimer’s diagnoses, indicating overlapping pathological features across different dementias. These findings reveal that Alzheimer's-type brain changes frequently coexist with other disease processes, which could influence diagnosis and treatment decisions.

The study emphasizes the potential of cerebrospinal fluid biomarkers to improve early detection and diagnosis of Alzheimer’s pathology, especially as disease-modifying therapies become more accessible. Broader application of fluid biomarker testing could aid in distinguishing mixed or atypical dementia cases, ultimately leading to more targeted and effective interventions.

This research highlights the complexity of dementia diagnosis and the importance of biomarker analysis in clinical practice. Early identification of Alzheimer’s-related changes, even in cases with mixed pathology, may enhance treatment planning and improve patient outcomes.