New Blood Test Study for Alzheimer’s Risk
A groundbreaking study out of UC San Francisco revealed that a straightforward blood test could help determine which middle-aged individuals might experience cognitive decline, even if they don’t show any dementia symptoms.
Alzheimer’s disease, a degenerative neurological issue, continues to be a leading cause of death in the U.S. With its prevalence on the rise—expected to nearly double from 7.4 million to 13.8 million cases among those aged 65 and older by 2060, according to the Alzheimer’s Association—there’s growing urgency to identify who might be at risk.
Although Alzheimer’s is mainly diagnosed in older adults, it actually begins to manifest in the brain years before symptoms appear. Yet, the challenge remains: pinpointing those at risk when they are in their 40s or 50s is still very much a mystery.
Dr. Kristine Yaffe, who led the study and serves as the vice chair in UCSF’s Psychiatry and Behavioral Sciences Department, explained that diagnosing Alzheimer’s generally involves assessing clinical symptoms alongside expensive scans or invasive tests like spinal taps. However, advancements in recent years have enabled doctors to detect crucial proteins related to Alzheimer’s through a simple blood test.
Yaffe expressed enthusiasm about the potential of these blood tests, calling them a major breakthrough.
Still, there’s some uncertainty with this approach. For younger patients without any symptoms, the implications of elevated biomarkers are not fully clear. Moreover, there’s an increasing trend of companies targeting consumers who are anxious about dementia.
To enhance understanding of these tests for younger patients, Yaffe and her team analyzed data from 1,350 participants in the ongoing Coronary Artery Risk Development in Young Adults Study (CARDIA), which started in 1983. They focused on data collected from 2020 to 2022.
As these individuals entered midlife (roughly ages 45-65), the researchers aimed to assess whether those with Alzheimer’s biomarkers also demonstrated noticeable cognitive differences. Among the subjects, the average age was 61, with 58% being women and 42% men; the racial breakdown was 55% white and 45% Black.
The team employed blood tests to measure key Alzheimer’s-related biomarkers such as tau proteins and amyloid plaques. They found that while only 6% had elevated levels of both tau and amyloid, between 4% to 15% showed signs of high levels of at least one, indicating a “positive” result.
Subsequently, the participants underwent cognitive tests. It turned out that those testing positive for any biomarkers showed significant differences relative to those who tested negative.
The group with positive results exhibited slower processing speeds—basically, how quickly they could take in and respond to new information—and they scored lower on executive function tasks, which assess everyday planning abilities.
While the variations in results weren’t extremely large, Yaffe found the findings intriguing.
Importantly, after a five-year follow-up, those who initially tested positive had a significantly higher risk of experiencing substantial cognitive decline. They were between 2.5 and 4 times more likely to see a rapid decrease in their verbal memory and 3 to 4 times more likely to have accelerated declines in processing speed—a well-known Alzheimer’s risk factor.
Yaffe pointed out that these individuals were not yet showing actual symptoms of clinical Alzheimer’s disease, but continued monitoring is essential to see if they develop the condition. She also noted that there are numerous methods to mitigate the risk of Alzheimer’s and dementia, emphasizing healthy lifestyle choices while avoiding tobacco and excessive alcohol.
Xue Zhong, an assistant professor at Vanderbilt University Medical Center, echoed that this study could be valuable for clinicians because it looks at a broader community sample rather than limiting itself to memory clinic patients. However, Zhong also noted some limitations, like assessing biomarkers only once.
He suggested that the results should be seen as generating hypotheses rather than offering definitive predictions. Yaffe concurred, stressing the need for further research to interpret these findings in the long term, citing a pressing demand for such studies.
“Technology is moving faster than our understanding of it,” she remarked. “We’re optimistic that this study contributes to that understanding.”
