Neuropathologic features of TOMM40 '523 variant on late-life cognitive decline.

INTRODUCTION: The study investigated the role of neuropathologies in the relationship between TOMM40 '523 genotype and late-life cognitive decline.

METHODS: Participants were community-dwelling older persons who had annual cognitive assessments and brain autopsies after death. Genotyping used DNA from peripheral blood or postmortem brain tissue. Linear mixed models assessed the extent to which the association of '523 genotype with cognitive decline is attributable to neuropathologies.

RESULTS: Relative to ε3/ε3 homozygotes with '523-S/VL or '523-VL/VL genotype, both '523-L carriers and ε3/ε3 homozygotes with '523-S/S genotype had faster cognitive decline. The association of '523-L with cognitive decline was attenuated and no longer significant after controlling for Alzheimer's and other neuropathologies. By contrast, the association of '523-S/S was unchanged.

DISCUSSION: There are two distinct TOMM40 '523 signals in relation to late-life cognitive decline. One signal primarily acts through AD and other common neuropathologies, whereas the other operates through a different mechanism.