National Cancer Institute
By Stephen Beech
A simple new blood test can predict when dementia symptoms will start.
Estimating the onset of Alzheimer’s disease symptoms will speed up the development of preventive treatments, say American scientists.
Researchers at Washington University School of Medicine in St. Louis developed the method to predict when someone is likely to develop symptoms of Alzheimer’s using a single blood test.
The team showed that their models predicted the onset of Alzheimer’s symptoms within a margin of three to four years.
They say their findings, published in the journal Nature Medicine, could have implications both for clinical trials developing preventive Alzheimer’s treatments and for eventually identifying people likely to benefit from such treatments.
Study senior author Professor Suzanne Schindler said: “Our work shows the feasibility of using blood tests, which are substantially cheaper and more accessible than brain imaging scans or spinal fluid tests, for predicting the onset of Alzheimer’s symptoms.
Akram Huseyn
“In the near term, these models will accelerate our research and clinical trials.
“Eventually, the goal is to be able to tell individual patients when they are likely to develop symptoms, which will help them and their doctors to develop a plan to prevent or slow symptoms.”
The models that Schindler and her colleagues developed use a protein called p-tau217 in a patient’s plasma, the liquid part of the blood, to estimate the age when they will begin experiencing symptoms of the neurodegenerative disease.
Levels of p-tau217 in the plasma can currently be used to help doctors diagnose Alzheimer’s in patients with cognitive impairment.
But the tests are not currently recommended in cognitively unimpaired people outside of clinical trials or research.
To identify the interval between elevated p-tau217 levels and Alzheimer’s symptoms, Schindler and study lead author Dr. Kellen Petersen analysed data from volunteers in two independent long-running Alzheimer’s research initiatives.
The participants included 603 older adults who lived independently in the community.
Plasma p-tau217 has previously been shown to correlate strongly with the accumulation of amyloid and tau in the brain as shown on PET scans.
The key hallmarks of Alzheimer’s disease, the team explained that amyloid and tau are misfolded proteins that begin building up in the brain many years before Alzheimer’s symptoms develop.
Hush Naidoo Jade Photography
Dr. Petersen said: “Amyloid and tau levels are similar to tree rings - if we know how many rings a tree has, we know how many years old it is.
“It turns out that amyloid and tau also accumulate in a consistent pattern and the age they become positive strongly predicts when someone is going to develop Alzheimer’s symptoms.
"We found this is also true of plasma p-tau217, which reflects both amyloid and tau levels.”
He said older participants had a shorter time from when elevated p-tau217 appeared to the start of symptoms as compared to younger participants, suggesting that younger people’s brains may be more resilient to neurodegeneration and that older people may develop symptoms at lower levels of Alzheimer’s pathology.
For example, if a person had elevated p-tau217 in their plasma at age 60, they developed symptoms 20 years later. If p-tau217 wasn’t elevated until age 80, they developed symptoms only 11 years later.
The research team shared all code for development of the models so that other scientists can further refine the models.
Dr. Petersen also developed a web-based application allowing researchers to explore the clock models in greater detail.
He said: “These clock models could make clinical trials more efficient by identifying individuals who are likely to develop symptoms within a certain period of time.
“With further refinement, these methodologies have the potential to predict symptom onset accurately enough that we could use it in individual clinical care.”
Dr. Petersen added that additional blood biomarkers associated with cognitive symptoms in Alzheimer’s could be used to refine the estimates of symptom onset in future studies.
(0) comments
Welcome to the discussion.
Log In
Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
PLEASE TURN OFF YOUR CAPS LOCK.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.