Scientists showed in a new study published Thursday that they could use blood draws to build a “clock” for Alzheimer’s disease that could roughly predict when symptoms will develop, findings that could eventually transform how the illness is diagnosed and treated.
A simple blood test can help diagnose Alzheimer’s, but the study in the journal Nature Medicine shows how these kinds of tests could one day play a greater role in preventing the insidious, memory-robbing illness. In the new study, researchers built a model that could use blood test results to forecast symptom onset within a margin of three to four years.
The technique is not yet precise enough to predict the course of a patient’s trajectory. But it could be used to identify which patients would benefit if companies are able to develop drugs to treat the disease before symptoms develop.
In the short term, the approach could accelerate the research to identify such treatments by recruiting the ideal study participants: people with no symptoms, but who are at high risk for developing them soon.
Clinical trials are expensive and time-consuming to run, particularly for diseases such as Alzheimer’s in which the people being studied could begin to experience cognitive decline in a year or a decade.
Suzanne E. Schindler, a dementia specialist at Washington University School of Medicine in St. Louis who helped lead the study, said she’s been involved with research studies that are attempting to test treatments before people have cognitive impairment. When those people receive a positive test, she said, they immediately ask: “So how long do I have before I develop symptoms?”
“The kind of statistical models we’ve had in the past do not address that question. You’re positive, so you’re higher risk. But you could develop symptoms in one year, in 15 years, or never — we have no idea,” Schindler said.
Using blood tests to identify people who are likely to develop symptoms in the short term could offer a faster and more efficient way to find promising treatments, according to Schindler.
As the clock developed in the new study is refined, it could become part of the toolbox that has evolved radically in recent years for early diagnosis and treatment.
But the recently approved treatments have a relatively modest effect in slowing the advancement of Alzheimer’s. Two highly anticipated ongoing clinical trials test whether drugs given to people who are not yet cognitively impaired could be more beneficial.
“If that turns out to be the case, that really increases the potential role of a clock that could give a prediction of when symptoms are likely to develop,” said Andrew Saykin, director of the Indiana Alzheimer’s Disease Research Center who was not involved in the study. “If we could predict [disease onset] within a year or so, that would be really valuable. I think it’s closing in, but not there yet.”
Building an Alzheimer’s ‘clock’
The research team focused on one specific protein, called p-tau217, that is a sign that a hallmark of Alzheimer’s — clumps of misfolded proteins called amyloid plaques — has begun to build up in the brain. The new treatments remove the buildup of the plaques in the brain. Several commercially available tests measure this protein and are used to help diagnose people with cognitive problems.
The researchers cautioned that these tests are not intended to be used outside of a research setting in people without cognitive symptoms.
In the study, the team examined the levels of this protein over time in participants in two long-running Alzheimer’s databases and found that people with higher levels in their blood developed symptoms more quickly. They also found that age was another risk factor. When levels of this protein began to rise in a person who was 60, it took two decades for their symptoms to develop. At age 80, it took 11 years.
The research team sees this work as a first step and is making its work freely available in the hopes that other groups will use it to improve the model. It said other markers of Alzheimer’s in the blood may be used to refine their predictions.
Gil Rabinovici, a neurologist at the University of California at San Francisco who also was not involved in the study, said the work was exciting because it will help anchor abstract lab results to a timeline — something that would help clinicians, research participants and eventually patients understand risk. He predicted it could have clear benefits in helping researchers recruit the right patients for clinical trials to determine whether treatments are effective.
But before anyone could use these tests to predict individual risk, Rabinovici said the clock would need to be tested on larger, more diverse populations to see if the same patterns held up.
Several Alzheimer’s experts said the benefits of a predictive test will be closely linked to the development of drugs that slow or stop the progression of the disease when given early. Medicine involves balancing the risks of harm from a treatment from the benefit.
“When treatments for this population have received regulatory approval, those individuals who are at highest risk of developing symptoms will inevitably be prioritized for treatment,” Clifford Jack, a neuroradiologist at the Mayo Clinic who was not involved in the study, said in an email. “How soon a currently asymptomatic person is to developing symptoms will be a key piece of the decision-making matrix.”
The post New approach roughly predicts when Alzheimer’s symptoms begin appeared first on Washington Post.
