Examples derived from the present results suggest (i) that the dose of anti-dementia drugs in APOE-4 carriers and in CYP2D6-PMs and CYP2D6-UMs be adjusted, (ii) that the dose of statins in CYP3A4-IMs be reduced and statins metabolized via CYP enzymes in CYP3A4-RMs avoided due to inefficacy, and (iii) that the dose of ACE inhibitors (or select a more effective anti-hypertensive agent) in APOE-4/4, NOS3-T/T, and GT-G/G carriers be adjusted. The gene discussed is ACE; the disease is dementia.