The statistical interactions were observed between rosuvastatin and APOE ε4 allele on the changes in MMSE (Padjusted = 0.018), MoCA (Padjusted = 0.020), DRS (Padjusted = 0.031), CDR (Padjusted = 0.027), and IQCODE (Padjusted = 0.022) and in the dementia (Padjusted = 0.022). The gene discussed is APOE; the disease is dementia.