June 17, 2026
A blood test in midlife may help to predict your risk of developing Alzheimer’s disease decades later, researchers report. The scientists found that in healthy men and women in their 50s and 60s with no signs of serious memory problems, the presence of certain blood markers tied to Alzheimer’s disease correlated with subtle deficits in thinking and memory skills. The markers, which measured levels of beta-amyloid and tau, both hallmarks of Alzheimer’s, were also associated with an increased risk of cognitive decline and dementia years later.
The findings add to growing evidence that Alzheimer’s disease is a decades-long process that may begin in midlife or even earlier. Simple blood tests to detect increased risk may help spur people to undertake health and lifestyle measures that may curb or slow progression to dementia late in life.
“Alzheimer’s disease pathology begins years before symptoms emerge,” said Dr. Kristien Yaffee, the study’s senior author and vice chair in the University of California, San Francisco’s Department of Psychiatry and Behavioral Sciences. “Detecting the disease early means patients can target modifiable risk factors and maybe seek other care.”
Mounting evidence suggests that around 40 percent of cases of Alzheimer’s disease and other forms of dementia could be prevented or delayed by healthy lifestyle measures like regular physical activity, keeping blood pressure in check, quitting smoking, and regular social contact. The findings were published in The Lancet, a British medical journal.
For the study, researchers looked at 1,350 men and women who ranged in age from 53 to 69. At the start of the study they were generally healthy, with no signs of serious memory problems or other major health issues. All were long-term participants in the CARDIA study, which has tracked the effects of cardiovascular and metabolic problems on overall health among participants in four U.S. cities over many decades.
At the start of the study, 6 percent of the study group had high levels of the Alzheimer’s markers beta-amyloid and tau in their blood. High levels of these toxic proteins were linked with lower brain processing speeds, or the ability to respond quickly to changing information, such as to traffic signals or engaging in conversation. Those with elevated levels of the blood markers also had lower executive function, or the ability to plan, organize and stay on track, which is critical for tasks like keeping a schedule or handling finances. Executive function is one of the main abilities ravaged by Alzheimer’s disease.
Participants were given follow-up cognitive tests five years later. Those with high levels of the Alzheimer’s markers in their blood had up to four times greater risk of rapid declines in verbal memory and brain processing speeds, indicating an increased likelihood of developing Alzheimer’s down the road.
Blood tests for Alzheimer’s are easy to perform and relatively inexpensive compared to brain scans or spinal taps that look for signs of Alzheimer’s. However, they are currently approved only for those with memory loss and other symptoms of the disease.
More study is needed before blood testing can be recommended for routine testing of people without symptoms of Alzheimer’s. These findings suggest, however, that blood testing could one day help guide younger people about their risks of developing the disease. “For some people who discover they have the biomarkers, testing could open a window to embark on interventions that may postpone Alzheimer’s onset,” Dr. Yaffe said.
Even without a blood test, anyone worried about Alzheimer’s disease can take steps now to help lower their risk in the future, regardless of their age. Among the recommendations that experts advise:
- Try to keep systolic blood pressure (the top number) to 130 or less from age 40 and beyond.
- If you are having hearing trouble, make sure to get a hearing aid, and protect the ears from loud noises that can cause permanent damage.
- Avoid exposure to air pollution, including secondhand smoke.
- Take measures to avoid head injuries, whether at work or sports.
- If you drink alcoholic beverages, keep it moderate — no more than one to two drinks a day.
- If you smoke, quit. Quitting smoking at any age has benefits that begin immediately.
- Stay in school as long as possible.
- Get regular physical activity throughout life. Starting to exercise at any age has benefits that begin immediately.
- Try to maintain a healthy weight, which can lower the risk of diabetes and other chronic ailments tied to dementia.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, PhD, of The Fisher Center lab at The Rockefeller University.
Source: Xiaqing Jiang, PhD; Tina D. Hoang, MSPH; Leslie M. Shaw, PhD; et al: “Alzheimer’s disease neuropathology plasma biomarkers and cognition in midlife: a community-based cohort study.” The Lancet, May 30, 2026. University of California, San Francisco, press office.
