Most older people with memory loss do not have dementia. Those with mild cognitive impairment are at increased risk of progressing to dementia, but no tests have been shown to enhance the accuracy of assessing this risk. Although no intervention has been convincingly shown to prevent dementia, data from cohort studies and randomised controlled trials are compelling in indicating that physical activity and treatment of hypertension decrease the risk of dementia. There is no evidence that pharmaceutical treatment will benefit people with mild cognitive impairment. In people with Alzheimer's disease, treatment with a cholinesterase inhibitor or memantine (an N-methyl- D-aspartate receptor antagonist) may provide symptomatic relief and enhance quality of life, but does not appear to alter progression of the illness. Non-pharmacological strategies are recommended as first-line treatments for behavioural and psychological symptoms of dementia, which are common in Alzheimer's disease. Atypical antipsychotics have modest benefit in reducing agitation and psychotic symptoms but increase the risk of cardiovascular events. The role of antidepressants in managing depressive symptoms in patients with mild cognitive impairment is uncertain and may increase the risk of delirium and falls.