Blood test could flag Alzheimer’s risk long before memory symptoms emerge

A blood biomarker associated with Alzheimer’s disease may help estimate the likelihood of later memory and thinking problems years before symptoms appear. In older adults who had no signs of impairment at the start, higher levels of the marker were linked to a greater chance of developing problems later on.

The findings could support efforts to detect Alzheimer’s earlier. Because blood samples are far easier to collect than specialized brain scans, the marker may help researchers identify people who could be suited for prevention studies.

The research, led by Mass General Brigham and published in JAMA, analyzed data from 2,684 adults across six study groups. Unlike studies that only compare people who already have dementia with those who do not, this one followed participants over time.

The blood marker is known as p-tau217, a modified version of the tau protein that is tied to Alzheimer’s-related changes in the brain. Detecting it in blood can offer clues about disease processes that may begin well before everyday memory issues are noticeable.

Participants had blood tests and brain amyloid measurements, since amyloid is another protein linked to Alzheimer’s. Researchers also monitored memory and thinking test results and recorded whether participants developed signs of impairment.

The median starting age was about 70, and the average follow-up period was 5.4 years. Over that time, 478 participants went on to develop memory and thinking problems, though some were observed for much longer.

Higher p-tau217 levels at the beginning of the study were associated with a greater risk of later decline. That association remained even after researchers adjusted for other factors, including the amount of amyloid seen on brain scans.

For people with very high levels of the marker, the estimated five-year risk of impairment was 38%. Among those in the high group, the estimate was 24%, suggesting the marker provided more information than a simple positive-or-negative result.

Longer-range estimates indicated that risk kept increasing over a decade. But because fewer participants had data that far into follow-up, those projections were less certain than the five-year estimates.

The results also show that a high marker level does not predict an exact future for any one person. Even in the very high group, many participants did not develop impairment within five years.

More research is needed to determine how this information should be used outside of studies and whether testing people without symptoms improves outcomes. The study did not evaluate a treatment designed to prevent the decline it predicted.

For now, the work offers a clearer connection between an accessible blood test and later cognitive health. It may help move Alzheimer’s research beyond simply detecting signs of the disease and toward understanding when those signs are likely to become important.

Source: Mass General Brigham.

If you are interested in this topic, please read articles about Vitamin D supplements do not lower heart disease risk, study finds, and Study shows vitamin D supplements don’t lower heart disease risk.

For more information, please see articles about A Two-Year Lifestyle Program Helped Older Adults Sharpen Their Memory, and Chinese heart-healthy diet could lower blood pressure, study finds.