Could a simple blood test identify people who show no memory loss but already have Alzheimer's-related protein buildup in their brain?
Korea University Guro Hospital announced research findings on August 4 showing that irisin—a protein released by muscle tissue during exercise—could provide a crucial clue for early detection. Researchers discovered that individuals with toxic amyloid buildup in the brain had significantly lower blood irisin levels, even before any symptoms of dementia became apparent.
Amyloid is a protein that abnormally accumulates in the brain during the progression of Alzheimer’s disease, often beginning years before noticeable memory decline. However, confirming its presence currently requires expensive or invasive procedures, such as amyloid positron emission tomography (PET) scans or cerebrospinal fluid testing.
A research team led by Professor Kang Sung-hoon of the Department of Neurology at Korea University Guro Hospital conducted blood tests, amyloid PET scans, and cognitive assessments on 100 older adults. Participants were categorized into four distinct groups: cognitively normal individuals without amyloid, cognitively normal individuals with amyloid, patients with mild cognitive impairment, and patients with Alzheimer’s disease dementia.
Low Irisin Levels Observed Even in Cognitively Normal Group
Analysis revealed that all three groups with amyloid buildup in the brain exhibited lower blood irisin concentrations compared to the normal group without amyloid.
This disparity was clearly evident even among participants who showed no impairment in memory or cognitive function. In other words, individuals who appeared completely healthy but had silent amyloid accumulation in their brain demonstrated reduced irisin levels in their blood. The research team also identified an inverse correlation, where higher blood irisin concentrations corresponded to lower levels of amyloid accumulation in the brain.
Screening High-Risk Individuals Before Costly Brain Scans
The findings suggest that irisin could serve as an effective candidate blood biomarker for identifying individuals at high risk for Alzheimer’s disease at an early stage.
If further research validates the test's accuracy, clinicians could potentially use a blood test as a primary screening tool, reserving costly procedures like amyloid PET scans for those identified as high-risk. This approach could facilitate early detection of pathological brain changes before clinical symptoms emerge while significantly reducing overall diagnostic costs.
However, researchers cautioned against overinterpreting the findings. Lower irisin levels were associated with higher amyloid accumulation, but this does not imply that simply raising irisin levels through exercise will directly prevent Alzheimer’s disease. Because the study evaluated participants at a single point in time without separately tracking exercise volume or muscle mass, longitudinal follow-up studies involving larger populations are required to establish standardized reference values and clinical accuracy.
The study was published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, an international journal published by the Alzheimer’s Association.
