However, of the 53 subjects in the intermediate group, 29 displayed high Braak pathology raising the possibility that these may be cases of neurofibrillary tangle predominant dementia (NFTPD) in which the APOE ε4 allele is less prevalent and cognitive impairment is less severe relative to sporadic AD [50, 51]. This evidence concerns the gene APOE and Cognitive impairment.