Dementia has often thought to be unavoidable and incurable. In recent years, risk factors, including lifestyle attributes, have been associated with the two commonest forms of dementia, Alzheimer's Disease and vascular dementia. There is also new evidence that the adult brain maintains plasticity and response to external stimuli. Beside considerable observational data of the effect of lifestyle factors there is now increasing empirical evidence that alterations in lifestyle factors may decrease an individual's risk of developing dementia. The evidence is strongest for increasing an individual's level of physical activity, followed by the cessation of smoking. These interventions carry few risks and have many additional health benefits, so can be recommended for most of the older population. Other interventions such as increasing social engagement, cognitive stimulation and homocysteine lowering vitamin supplements also appear promising, with considerable observational evidence supporting their uptake, although there is still a lack of empirical evidence for these interventions.