THURSDAY, Aug. 5, 2021 (HealthDay News) — Plasma concentrations of amyloid-beta at midlife are associated with the risk for mild cognitive impairment (MCI) and dementia later in life, according to a study published online Aug. 4 in Neurology.

Kevin J. Sullivan, Ph.D., M.P.H., from the University of Mississippi Medical Center in Jackson, and colleagues examined the association between midlife plasma Aß and the risk for MCI and dementia. In a subsample of the Atherosclerosis Risk in Communities cohort study, plasma Aß42 and Aß40 were measured retrospectively for 2,284 participants.

The researchers found that each doubling of midlife Aß42:Aß40 was associated with a significantly lower risk for MCI/dementia (relative risk ratio, 0.63), only up to about the median (spline model threshold, 0.20). Each standard deviation increase in plasma Aß42 (10 pg/mL) was associated with a lower risk for MCI-dementia (relative risk ratio, 0.87), while a higher risk for MCI/dementia was seen with every standard deviation increase in plasma Aß40 (67 pg/mL; relative risk ratio, 1.15). When repeating models using late-life plasma Aß predictors, the associations were comparable but slightly weaker statistically.

“A doubling of this ratio under this threshold at midlife was associated with a 37 percent 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,” Sullivan said in a statement. “Amyloid in the blood may be useful as a biomarker for risk of future cognitive impairment.”

Several authors disclosed financial ties to the pharmaceutical industry.

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