Amyloid PET pinpoints ‘tipping point’ for developing Alzheimer’s dementia
A newly developed algorithm can harness the data from amyloid PET scans and determine when patients will likely begin experiencing dementia symptoms.
People who ultimately develop Alzheimer’s dementia have amyloid quietly building up in their brains for up to two decades before anything appears abnormal. Now, Washington University in St. Louis experts say they can estimate how far dementia has progressed and how much time is left before cognitive impairment sets in.
The full results were published on Sept. 9 in Neurology.
“I perform amyloid PET scans for research studies, and when I tell cognitively normal individuals about positive results, the first question is always, ‘how long do I have until I get dementia?’,” senior author Suzanne Schindler, MD, PhD, an assistant professor of neurology at the school, said Friday. “Until now, the answer I’d have to give was something like, ‘you have an increased risk of developing dementia in the next five years.’ But what does that mean? Individuals want to know when they are likely to develop symptoms, not just whether they are at higher risk.”
The findings are based on imaging from 236 participants who underwent at least two brain scans at an average of 4.5 years apart. Schindler et al. also pored over 1,300 clinical assessments, with many showing the evolution from cognitively normal to dementia.
Schindler and her team discovered a “tipping point” in which amyloid buildup abides by a reliable trajectory. People who reached this at age 50 typically took 20 years to develop symptoms. Those who reached it at 80, however, got there in less than a decade.
Amyloid PET scans are too expensive for routine use—about $6,000 out-of-pocket—but this study could help refine clinical trials and develop better treatments, the authors noted.
“Most participants in clinical trials designed to prevent or slow Alzheimer’s symptoms do not develop symptoms during the trials,” Schindler said. “That’s a lot of time and effort—for the participants as well as the researchers—that doesn’t yield useful data. If we could do trials only on people who are likely to develop symptoms in the next few years, that would make the process of finding therapies much more efficient.”
Matt joined Chicago’s TriMed team in 2018 covering all areas of health imaging after two years reporting on the hospital field. He holds a bachelor’s in English from UIC, and enjoys a good cup of coffee and an interesting documentary.