A PET study of the male RELN-COLBOS carrier revealed less tau pathology in the entorhinal cortex, cingulate cortex, and precuneus than age-matched PSEN1-E280A carriers with MCI and dementia despite higher levels of cortical amyloid beta plaque burden compared to younger impaired PSEN1-E280A carriers in the study. This evidence concerns the gene RELN and dementia.