Alzheimer's disease is a degenerative disorder of unknown cause, leading to the gradual damage of the brain cells structure and function. The name of the disease is due to Alois Alzheimer, who presented a case of dementia at the 37th Congress of the German Psychiatrists on 1906. The disease is the most common form of dementia representing more than 50% of the cases. Gradual loss of memory, deterioration of cognitive functions, confusion, change in mood and behavior and kinetic disturbances characterize Alzheimer's disease. These findings along with the patient's history, the complete clinical and neurological examination and the laboratory tests contribute to the diagnosis of the disease. Genetics, age, sex, low education level, Down syndrome and coexisting diseases flavor the appearance of Alzheimer's disease. The genes contributing to Alzheimer's disease are those of amyloid precursor protein (APP) located on chromosome 21, presenilin 1 (PS-1) on chromosome 14, presenilin 2 (PS-2) on chromosome 1 and apolipoprotein E (ApoE) on chromosome 19. These genes are inherited by the autosomal dominant pattern.