New Blood Test Could Indicate Alzheimer’s Risk in Older Adults

Researchers have reported that a new blood test might help predict whether healthy older adults are likely to develop Alzheimer’s symptoms within the next five to ten years.

This information could be both comforting and concerning. For now, it serves as a potential means to accelerate drug development by identifying high-risk individuals for studies on possible treatments or preventive measures for Alzheimer’s.

Currently, substantial clinical trials are underway to assess the efficacy of certain medications in preventing or at least postponing the disease. If any prove successful, physicians will need effective methods to determine which patients should try these options.

However, the researchers behind this study caution that it is too early for healthy individuals to pursue the p-tau217 test, which is primarily used to aid in diagnosing those already experiencing cognitive issues.

“It’s better to wait and get tested when you can potentially take action,” emphasized Dr. Reisa Sperling from the Mass General Brigham Neuroscience Institute, the senior author of the study. “Right now, I’d still recommend the same basic advice: eat well, sleep enough, stay active, and remain mentally engaged.”

The research revealed that older adults without symptoms who exhibited high levels of p-tau217 had a 38% likelihood of developing cognitive impairment within five years. This risk surged to 78% after ten years.

Published in JAMA and presented at the Alzheimer’s Association International Conference in London, the study explored the p-tau217 test, which gauges a type of tau protein linked to the accumulation of amyloid plaques in the brain, a hallmark of Alzheimer’s.

The Mass General Brigham team analyzed data from 2,684 older adults who were healthy when they joined various long-term Alzheimer’s studies, taking the p-tau217 blood test upon enrollment and undergoing cognitive assessments each year. Between 2004 and last year, about 478 of those participants developed cognitive impairment.

Participants with low p-tau217 levels had a similarly low risk of cognitive issues over the five- to ten-year timeframe.

However, predicting Alzheimer’s is complex. Many individuals show high levels of amyloid plaques yet never develop dementia. One prevailing theory suggests that this buildup sets off the formation of abnormal tau tangles, leading to symptoms.

Dr. Sperling mentioned that the findings from the blood test offer intriguing insights. While different levels of p-tau217 indicate varying risks, only those at the highest level correspond with other data concerning the threshold for developing symptoms.

“This gradual process involves the accumulation of amyloid and tau in the brain, and this blood biomarker indicates how far one is in that progression,” she explained.

Experts who were not part of the study acknowledged its value but advised caution. A concern is that only a small percentage of participants had been monitored for a full decade, meaning there’s less assurance in the ten-year predictions compared to the five-year ones.

Additionally, other factors could skew results—older individuals might face risks from other health issues or heart conditions that could lead to vascular dementia instead of Alzheimer’s, observed Drs. Suzanne Schindler from Washington University in St. Louis and David Wolk from the University of Pennsylvania in their commentary in JAMA.

“The blood tests are not yet accurate enough to provide individualized forecasts,” Schindler, who also investigates p-tau217’s predictive capability, stated. Still, they noted this research represents an essential part of the ongoing puzzle.

Interestingly, “we have individuals coming in saying, ‘I want this blood test because I have a family history of Alzheimer’s,’” remarked Jessica Langbaum from the Banner Alzheimer’s Institute in Phoenix, cautioning against such requests—for the moment at least.

“These results are pretty robust,” she added, believing a predictive blood test would be “incredibly important”—if further studies uncover a drug that could assist individuals before symptoms emerge.