Previous studies have shown APOE4 mice have cognitive deficits or decreased neuronal complexity from as early as three months and these deficits remain at later ages such as 21 months (Bour et al., 2008; Rodriguez et al., 2013; Speidell et al., 2019), consistent with APOE genotype dependent deficits seen in our study. The gene discussed is APOE; the disease is Cognitive impairment.