Epidemiological evidence has identified key strategies that may be used in the prevention of both Alzheimer's disease and vascular dementia. These strategies may be loosely divided into three areas: treatment of vascular risk factors, neuroprotection and increasing neuronal reserves. Evidence from randomised controlled trials already exists for treatment of hypertension but results for statins have been disappointing. Most of the intervention trials currently in progress focus on one or two risk factors and include cognition or dementia only as a secondary outcome. The potential of intervention strategies awaits confirmation by randomised controlled trials that target multiple risk factors in at-risk people with mild cognitive impairment, with incident dementia as the primary outcome.