Based on previous reports [12], we hypothesized that the frequency of the APOE ε4 allele will be increased in the MCI and AD groups and that the ε4 allele in the SCI group will show an intermediate frequency somewhere between the levels observed in the MCI and control groups, indicating that elderly patients with SCI may be predisposed to develop AD in the future. This evidence concerns the gene APOE and Alzheimer disease.