Alzheimer’s disease is the most common cause of dementia and slowly damages memory, thinking, and the ability to carry out everyday tasks.
Scientists know that changes inside the brain begin many years before symptoms appear, but finding people during this early stage has always been difficult.
A new study suggests that a simple blood test may one day help identify older adults who are most likely to develop Alzheimer’s symptoms years before memory problems begin.
The research was led by scientists at Mass General Brigham and published in JAMA. The findings were also presented at the Alzheimer’s Association International Conference in London.
Although the results are encouraging, the researchers stress that the test is not yet ready for healthy people to use in routine medical care.
The blood test measures a protein called p-tau217. This protein is linked to the abnormal tau changes that occur in Alzheimer’s disease and also reflects the buildup of amyloid plaques, another hallmark of the disease. Together, amyloid plaques and tau tangles gradually damage brain cells over many years.
The researchers analyzed information from 2,684 older adults who had no signs of memory or thinking problems when they joined long-term Alzheimer’s studies. Participants received a p-tau217 blood test at the beginning of the study and completed yearly cognitive assessments. Over time, 478 participants developed cognitive impairment.
The results showed that people with the highest p-tau217 levels had a much greater chance of developing symptoms. Their risk was about 38% within five years and increased to 78% within 10 years. In contrast, people with very low p-tau217 levels had a much lower chance of developing cognitive problems during the same period.
Researchers believe the blood test reflects how far a person has progressed along the biological pathway toward Alzheimer’s disease. As amyloid and tau slowly accumulate in the brain, p-tau217 levels appear to increase. The highest levels may indicate that the disease process is approaching the stage where symptoms become more likely.
Even with these promising findings, experts say the test should not yet be used to predict an individual’s future. Dr. Reisa Sperling explained that knowing someone has a higher risk would not currently change medical advice.
Healthy eating, regular exercise, good sleep, and staying socially and mentally active remain the best recommendations for everyone.
Independent experts also pointed out important limitations. Only a relatively small number of participants were followed for a full 10 years, making the longer-term risk estimates less certain. Other conditions, including heart disease and vascular dementia, can also affect brain health and may influence the results.
The researchers believe the greatest value of the test today is in research. It could help scientists quickly identify volunteers who are at high risk of Alzheimer’s for clinical trials testing medicines designed to prevent or delay the disease before symptoms appear.
This study provides important evidence that blood tests may one day play a major role in preventing Alzheimer’s disease rather than simply diagnosing it after memory problems begin. However, the findings should be interpreted carefully because the test is not yet accurate enough to predict an individual’s future with certainty.
Larger and longer studies, together with successful preventive treatments, will be needed before this approach becomes part of everyday medical care.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
Source: Mass General Brigham.
