These analyses demonstrated that non-hypertensive ICH survivors with elevated BP (i.e. SBP of 120–129 mmHg and DBP <80 mmHg) were at increased risk for a composite endpoint of recurrent ICH, small vessel ischaemic stroke, dementia, depression and gait impairment only if they possessed one or more APOE ɛ4 copies: hazard ratio (HR) = 1.97, 95% confidence interval (CI) 1.17–3.31, P = 0.011 for comparison between participants with elevated BP with versus without APOE ɛ4 (Fig. 2A). This evidence concerns the gene APOE and dementia.