Previously, we reported evidence of genetic heterogeneity in late-onset familial Alzheimer's disease, based on sex of affected parent, demonstrating linkage to chromosome 10q, a region identified by other groups and implicated as a quantitative trait loci for Abeta levels, in families with an affected mother. Using functional magnetic resonance imaging and a memory encoding task, we now show differential brain activation patterns among asymptomatic offspring which correspond to the previous linkage finding. These results suggest the possibility that activation patterns may prove useful as a preclinical quantitative trait related to the putative familial late-onset AD gene in this chromosome 10 region.