A recent study suggests that a simple blood test could potentially identify indicators of memory decline and cognitive impairment years before symptoms become apparent. This breakthrough could allow for earlier intervention and a better understanding of the development of dementia-related diseases. Researchers believe that biological changes associated with Alzheimer's disease may begin years, or even decades, before symptoms like memory loss occur.
The study, conducted by researchers at the University of Miami's Miller School of Medicine, analyzed four biomarkers and their relationship to cognitive decline. The study included 1,170 participants with an average age of 73, who underwent cognitive tests in 2016 and again in 2022. Blood tests were conducted only once, in 2016. The researchers found that elevated levels of the protein p-tau181, associated with Alzheimer's disease, were linked to poorer performance in memory and cognitive abilities six years later.
The protein p-tau181 was not associated with memory performance at the initial evaluation, but it was linked to memory performance six years later. This suggests that blood biomarkers may provide information about future cognitive decline that is not apparent when measuring cognitive abilities at the same time. The accumulation of abnormal tau protein is a hallmark of Alzheimer's disease, and previous studies have suggested that certain forms of the protein in the blood, such as p-tau181, may be associated with the disease.
The researchers also examined three other biomarkers: Aβ42/40, associated with the accumulation of amyloid-beta plaques; GFAP, indicating astrocyte activity in the brain; and NfL, released into the blood when nerve fibers are damaged. Cognitive tests included measures of memory, executive function, language, and visuospatial skills. At the beginning of the study, NfL and GFAP were more closely linked to cognitive abilities, including memory and executive function.
However, after six years, the results changed, with p-tau181 linked to lower memory scores and overall cognitive abilities, while GFAP was associated with decline in memory, executive function, and overall cognitive abilities. Most participants did not have cognitive problems at the start of the study, while some had been diagnosed with mild cognitive impairment or dementia. The main findings persisted even after analyzing participants with normal cognitive abilities separately.
The study suggests that a test combining p-tau181 and GFAP may help identify individuals at risk of developing cognitive problems in the following years. However, the researchers emphasized that the test cannot predict dementia. The study's results do not imply that a single blood test is the best option for early detection of Alzheimer's, but rather that a combination of tests may be used to detect different biomarkers at various stages of life.
Future studies could follow participants for longer periods, with more regular cognitive tests and blood analyses, to compare p-tau181 and GFAP levels with actual Alzheimer's disease and other dementia cases. The study focused on cognitive decline and memory problems associated with dementia, not on dementia diagnosis itself. Therefore, the results do not imply that a blood test can diagnose dementia before symptoms appear.
Key points
- A simple blood test may help detect indicators of memory decline and cognitive impairment years before symptoms appear.
- Elevated levels of p-tau181 protein are linked to poorer performance in memory and cognitive abilities six years later.
- A combination of tests may be used to detect different biomarkers at various stages of life to predict cognitive decline.
