With longer life expectancies worldwide, the prevalence of Alzheimer's disease is increasing. Although evidence 1 Livingston G Huntley J Sommerlad A et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. suggests a decrease in age-specific incidence of dementia, possibly because of improvements in education, health care, and lifestyle, the prevention of Alzheimer's disease and other dementias is one of the biggest challenges societies face. Epidemiological studies 1 Livingston G Huntley J Sommerlad A et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. have identified at least 12 modifiable risk factors that account for around 40% of cases of dementia worldwide, which could theoretically be prevented or delayed. However, randomised controlled trials (RCTs) of interventions to prevent cognitive decline, dementia, or Alzheimer's disease have shown negative or very modest results. 2 Kivipelto M Mangialasche F Ngandu T Lifestyle interventions to prevent cognitive impairment, dementia and Alzheimer disease. In the absence of a gold standard, methods in RCTs to prevent cognitive decline are heterogeneous in timing, duration, type of intervention (eg, single-target vs multi-target or pharmacological vs non-pharmacological), population enrichment strategies (based on age, genetic profile, biomarker characterisation, or lifestyle and comorbidities), disease progression modelling, and outcome measures (sensitive vs clinically meaningful outcomes). 2 Kivipelto M Mangialasche F Ngandu T Lifestyle interventions to prevent cognitive impairment, dementia and Alzheimer disease.