Genetics account for 71% of Alzheimer’s disease risk, but known genes play only a small role

Heritability of Alzheimer’s disease
Twin studies indicate that Alzheimer’s disease is more heritable than what is explained by known genetic variants. To further investigate this, the heritability and genetics of Alzheimer’s disease were explored in the same twin sample. Three NEAR population-based studies: The Swedish Adoption/Twin Study of Aging (SATSA), Ageing in Women and Men: A Longitudinal Study of Gender Differences in Health Behavior and Health among Elderly (GENDER), and Origin of Variances in the Oldest-Old: Octogenarian Twins (OCTO-Twin), were used to explore this.

Photo: Gerd Altmann from Pixabay

71% of Alzheimer’s disease risk is attributed to genetics
In 1586 twins, the total genetic contribution to Alzheimer’s disease risk was 71%, while the environmental influences belonging to each twin accounted for 29%. Out of the genetic contribution, only 11% was explained by known genetic variants, mostly the known Alzheimer’s disease (AD) risk gene APOE, with smaller contributions from other measured polygenic influences. Much of the inherited vulnerability to Alzheimer’s disease risk is thereby left unexplained. Considering the global increase in Alzheimer’s disease, more research is needed to examine additional genetic contributions to AD.

Ida Karlsson, first author of the study. Photo: Gunilla Sonnebring

Publication
Karlsson IK, Escott-Price V, Gatz M, Hardy J, Pedersen NL, Shoai M, Reynolds CA Measuring heritable contributions to Alzheimer’s disease: polygenic risk score analysis with twins. Brain Commun. 2022; 4(1): fcab308. https://doi.org/10.1093/braincomms/fcab308