Dementia prevention is mainly aimed to the people who have various risk factors for developing dementia or who have mild cognitive impairments. The possible methods for this prevention may include the control of dementiarisk factors and the administration of drugs which may suppress the dementia progression. It is noteworthy that people with milc cognitive impairments (MCI) have 10 times higher risk for developing dementia compared to healthy aged people. Thus 25-50% of them may be progressed to dementia within 2-4 years. Here I describe various factors related to Alzheimer dementia, and possible way to control these factors.