A large international study has found that established blood-based markers of Alzheimer’s disease can also detect biological signals associated with the condition in people from Nigeria and Tanzania. But the same investigation reveals that the wider protein landscape in African populations differs from that observed in a comparable Canadian group, raising an urgent question for the future of global dementia diagnosis: can a blood test developed largely in Europe and North America be trusted to work equally well everywhere?
The study, led by Andrea Lessa Benedet of the Sahlgrenska Academy at the University of Gothenburg and Rufus Akinyemi of the University of Ibadan, is the largest Alzheimer’s biomarker investigation conducted in Africa to date. Published in Nature Communications, it analyzed blood samples from 949 Nigerians over the age of 50 and examined nearly 1,500 proteins circulating in the blood. The researchers then tested their principal findings in a separate group of 196 older adults in Tanzania and compared the results with detailed data from a Canadian cohort.
The findings are important because blood biomarkers are rapidly transforming Alzheimer’s research and may soon become part of routine clinical care. Until recently, identifying the biological changes linked to Alzheimer’s disease generally required expensive brain imaging, such as positron emission tomography, or an invasive cerebrospinal fluid procedure. Blood tests could offer a simpler and more affordable alternative, particularly in regions where advanced imaging equipment and specialist clinics are scarce. However, the accuracy of these tests depends on how well the underlying biological markers perform in different populations.
Alzheimer’s disease is characterized by several interacting processes in the brain, including the accumulation of amyloid-beta plaques, the formation of abnormal tau proteins, inflammation, and progressive neurodegeneration. Some of these changes release measurable molecules into the bloodstream. One of the most promising markers is phosphorylated tau, or p-tau, a chemically modified form of tau associated with Alzheimer’s-related pathology. In this study, p-tau217 showed broadly similar relationships with likely amyloid changes in the African and North American groups, suggesting that at least some established tau markers reflect comparable disease biology across geographically and genetically different populations.
Yet the study also found that similarity in a few established markers does not mean the entire biological signal is identical. When the researchers examined the broader plasma proteome—the complete collection of proteins detectable in blood—the Nigerian and Tanzanian profiles were more alike to each other than either was to the Canadian profile. These differences may reflect a complex combination of ancestry, diet, environmental exposures, immune activity, infections, cardiovascular health, and other medical conditions. They do not necessarily mean that Alzheimer’s disease itself is fundamentally different in Africa, but they do indicate that the biological context in which the disease develops and is measured can vary substantially.
Several proteins were associated not only with cognitive impairment and probable amyloid pathology, but also with conditions such as heart disease, previous infectious disease, and high cholesterol. Such findings matter because proteins measured in a blood test may be influenced by multiple processes at once. A marker that appears to signal Alzheimer’s in one population could be partly altered by inflammation, vascular disease, or a history of infection in another. Without accounting for these influences, clinicians could face an increased risk of false-positive results, false-negative results, or reference ranges that do not accurately reflect the population being tested.
“ As blood tests begin to be used to diagnose Alzheimer’s disease in different parts of the world, we need to know how well the markers work across different populations,” Benedet said. “Otherwise, we risk misdiagnosis because much of today’s knowledge is based on a limited part of the world’s population.” She added that people living in different regions may experience distinct risk factors, environmental exposures, and comorbidities, all of which can influence the proteins circulating in the blood and complicate interpretation of a diagnostic test.
The researchers caution that the study has an important methodological limitation. Amyloid pathology in the Nigerian and Tanzanian participants could not be confirmed directly with brain imaging or cerebrospinal fluid analysis. Instead, the investigators used blood p-tau217 concentrations and thresholds previously validated in non-Hispanic white populations. Those thresholds may not be optimally calibrated for African populations, meaning that some participants may have been classified as likely amyloid-positive or amyloid-negative with less certainty than would be possible using direct confirmation. The results therefore support the need for further validation rather than immediate adoption of universal cutoffs.
The study points toward a more inclusive model for Alzheimer’s diagnostics, in which core biomarkers such as p-tau217 are combined with population-specific reference values and additional clinical information. Future research will need to include larger African cohorts, direct amyloid imaging, cerebrospinal fluid comparisons, longitudinal follow-up, and deeper analysis of how infections, cardiovascular disease, genetics, and socioeconomic conditions influence blood proteins. As the global population ages, developing tests that are both biologically accurate and locally validated will be essential. The promise of a simple blood test for Alzheimer’s is enormous, but this research makes clear that global access must be matched by global evidence.
Subject of Research: People
Article Title: Plasma proteomic profiles of Alzheimer’s disease and neurodegeneration in African cohorts
Web References: https://doi.org/10.1038/s41467-026-74971-4
References: Nature Communications, “Plasma proteomic profiles of Alzheimer’s disease and neurodegeneration in African cohorts,” DOI: 10.1038/s41467-026-74971-4
Image Credits: University of Gothenburg
Keywords: Alzheimer’s disease, blood biomarkers, p-tau217, plasma proteomics, amyloid pathology, dementia, Nigeria, Tanzania, Africa, Canada, neurodegeneration, precision medicine, Nature Communications
