Societies are ageing, and the cognitive decline typical of Alzheimer’s disease has a major impact on public health. This condition is multifactorial; that is, several genetic and environmental factors contribute to the risk. The interaction between these factors is very complex, and we know that genomic ancestry can modify risks. Ancestry mixing can reveal details about genetic risk, including changing the effects of genetic variants in the APOE gene, considered most important for Alzheimer’s. The gene encodes a protein with many functions, including the transport of lipids, cholesterol and the myelination process—the formation of white matter fibers in the brain, responsible for transmitting nerve impulses between regions of the cerebral cortex. The project aims to study how the ancestry and miscegenation of Brazilians, including around the APOE gene, interferes with these brain structures. We will analyze neuroimaging and lipidomics of older adults with and without cognitive decline. The study may clarify how important the genetic factors of mixed-race people are in brain changes, contributing to diagnostic methods for Brazilians and potentially new therapies.