Study finds Alzheimer's clues by age 45

The University of Otago said on May 21, 2026 that researchers detected an Alzheimer’s‑related blood signal at midlife in participants of the Dunedin Multidisciplinary Health and Development Study. The researchers measured plasma phosphorylated tau 181 (pTau181) in same‑aged cohort members assessed at 45 and found higher concentrations among people reporting memory concerns, the university said. (pmc.ncbi.nlm.nih.gov) The team cautioned that the biomarker reflects elevated risk and that brain‑structure scans did not show measurable changes in those individuals. (otago.ac.nz) ### What did the research team actually measure at age 45? The Dunedin Study measured plasma pTau181 concentrations in 856 cohort members at age 45, the medRxiv preprint states. The preprint reports a mean pTau181 concentration of 13.6 pg/mL (SD 9.1) across the sample. ### Who showed higher pTau181 and how was that determined? Dr Ashleigh Barrett‑Young, lead author and research fellow at the University of Otago, said individuals who self‑reported concerns about memory and thinking tended to have higher pTau181 levels. The university news release summarizes that association but notes the biomarker indicates risk rather than a definitive diagnosis. (otago.ac.nz) ### Did brain imaging already show Alzheimer’s damage at midlife? MRI scans showed no detectable structural brain changes in the subset with elevated pTau181, the Dunedin report says. (pmc.ncbi.nlm.nih.gov) The authors wrote that cognitive complaints and blood biomarker elevations arose before measurable differences in MRI‑based brain structure. ### How does this finding fit with other recent Alzheimer’s biomarker research? Mass General Brigham researchers reported in April 2026 that plasma pTau217 can predict amyloid PET progression and cognitive decline in older adults, illustrating a broader trend of blood biomarkers showing promise across ages. (otago.ac.nz) The Mayo Clinic Study of Aging recently mapped age “breakpoints” when multiple Alzheimer’s biomarkers and cognition change steeply, placing some accelerated shifts later in the 50s and 60s. Those studies offer context for the Dunedin results, which focus on signals in midlife. ### What limitations did the authors and the university note? Dr Barrett‑Young and Dunedin Study director Professor Moana Theodore emphasized that pTau181 "reflects risk, not certainty" and that blood tests are not yet ready for routine clinical use, the university said. The medRxiv paper and the press release both underscore the observational design and the need to track outcomes as cohort members age. Researchers said they will continue following the Dunedin cohort into older ages and compare pTau181 levels with outcomes from the study’s recently completed age‑52 assessment and subsequent follow‑ups; the team said further peer‑reviewed analyses are planned. (massgeneralbrigham.org) (otago.ac.nz)