Dementias are clinical neurodegenerative diseases characterized by permanent and progressive transformation of cognitive functions such as memory, learning capacity, attention, thinking, language, passing judgments, calculation or orientation. Dementias represent a relatively frequent pathology, encountered at about 10% of the population of 65year olds and 20% of the population of 80-year olds. This review presents the main etiological forms of dementia, which include Alzheimer form of dementia, vascular dementia, dementia associated with alpha-synucleionopathies, and mixed forms. Regarding vascular dementia, the risk factors are similar to those for an ischemic or hemorrhagic cerebrovascular accident: arterial hypertension, diabetes mellitus, dyslipidemia, smoking, obesity, age, alcohol consumption, cerebral atherosclerosis/ arteriosclerosis. Several studies show that efficient management of the vascular risk factors can prevent the expression and/ or progression of dementia. Thus, lifestyle changes such as stress reduction, regular physical exercise, decreasing dietary fat, multivitamin supplementation, adequate control of blood pressure and serum cholesterol, and social integration and mental stimulation in the elderly population are important factors in preventing or limiting the symptoms of dementia, a disease with significant individual, social, and economic implications.