EMBARGOED FOR RELEASE UNTIL 4 PM ET, August 04, 2021
Could Blood Tests Help Determine Risk of Alzheimer鈥檚 Disease Early?
MINNEAPOLIS 鈥 A new study used a simple blood test to find that people who later developed dementia or mild cognitive impairment had a lower level of a protein called amyloid beta 42 (A脽42) in their blood at midlife than those who did not. The research is published in the August 4, 2021, online issue of , the medical journal of the 好色先生. 鈥淩ight now we look at levels of the protein amyloid beta in the central nervous system as a biomarker of Alzheimer鈥檚 disease, but the only way to do that is through brain scans or looking at the cerebrospinal fluid via a lumbar puncture,鈥 said study author Kevin J. Sullivan, PhD, MPH, of the University of Mississippi Medical Center in Jackson. 鈥淭hese new results suggest that there is utility in using simple blood draws that would be less expensive and much less invasive for people.鈥 The study involved 2,284 people with an average age of 59 who did not have problems with memory or thinking skills at the start of the study. The people鈥檚 blood level of amyloid beta was tested with samples from the beginning of the study, which the researchers called the midlife test, and then again when they were about 77 years old, or the late life test. The people were given thinking and memory tests over the 25 years of the study to determine whether they developed dementia or mild cognitive impairment (MCI), which is problems with memory and thinking skills that can be a precursor to dementia. A total of 502 people developed dementia and 832 developed mild cognitive impairment. The researchers looked at levels of both A脽42 and amyloid beta 40 (A脽40), and the ratio between the two. They found that lower levels of A脽42 at midlife, but not late life, was associated with the higher risk of dementia and marginally higher risk of mild cognitive impairment. Every 10 picogram per milliliter (pg/mL) increase in the blood of A脽42 was associated with a 13% lower risk of MCI or dementia. But higher levels of A脽40 were associated with higher risk of dementia and MCI at both midlife and late life. Every 67 pg/mL increase in the blood of A脽40 was associated with a 15% increased risk of MCI or dementia. A lower ratio of A脽42 to A脽40 was associated with a higher risk of dementia and MCI, but only up to the median level. After that, an increase in the ratio was not related to risk of dementia. 鈥淎 doubling of this ratio under this threshold at midlife was associated with a 37% lower risk of MCI or dementia, which is comparable to about five years of younger age, and a doubling of this ratio under this threshold at late life was comparable to about three years younger age,鈥 Sullivan said. 鈥淎myloid in the blood may be useful as a biomarker for risk of future cognitive impairment.鈥 The results were the same after researchers adjusted for other factors that could affect cognitive impairment, such as age, education and cardiovascular risk factors. A limitation of the study was that an older testing method was used to estimate blood levels of amyloid beta that is not as precise as newer methods of testing. The study does not prove the blood test can be used to predict who will develop dementia later in life. The study was supported by the National Heart, Lung, and Blood Institute, National Institute for Neurological Disorders and Stroke, National Institute on Aging and National Institute on Deafness and Other Communication Disorders. Learn more about Alzheimer鈥檚 disease at , home of the 好色先生鈥檚 free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life庐 on , and . When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.