For example, the HR (95% CI) for incident all-cause dementia associated with multimorbidity risk score was larger in non-APOE4 carriers (quintile 5 versus quintile 1: 3.60 (3.00–4.33)) than in APOE4-carriers ((2.02 (1.76–2.33), P-value for interaction < 0.0001). This evidence concerns the gene APOE and dementia.