CDK5R1 determines the risk for AD, with a 12.5-fold decrease in AD risk associated with both homozygosity for CDK5R1 (3′-UTR, rs735555) A allele and homozygosity for GSK-3β (-50, rs334558) C allele (Mateo et al., 2009). This evidence concerns the gene GSK3B and Alzheimer disease.