The heritability of blood-based biomarkers related to risk of Alzheimer's disease in a population-based sample of early old-age men

INTRODUCTION: Despite their increased application, the heritability of Alzheimer's disease (AD)-related blood-based biomarkers remains unexplored. METHODS: Plasma amyloid beta 40 (A beta 40), A beta 42, the A beta 42/40 ratio, total tau (t-tau), and neurofilament light (NfL) data came from 1035 men 60 to 73 years of age (mu = 67.0, SD = 2.6). Twin models were used to calculate heritability and the genetic and environmental correlations between them. RESULTS: Additive genetics explained 44% to 52% of A beta 42, A beta 40, t-tau, and NfL. The A beta 42/40 ratio was not heritable. A beta 40 and A beta 42 were genetically near identical (rg = 0.94). Both A beta 40 and A beta 42 were genetically correlated with NfL (rg = 0.35 to 0.38), but genetically unrelated to t-tau. DISCUSSION: Except for A beta 42/40, plasma biomarkers are heritable. A beta 40 and A beta 42 share mostly the same genetic influences, whereas genetic influences on plasma t-tau and NfL are largely unique in early old-age men. The absence of genetic associations between the A beta s and t-tau is not consistent with the amyloid cascade hypothesis.