Avicenna (980-1037 CE) and his Early Description and Classification of Dementia.

According to the World Health Organization (WHO), dementia is a disorder that occurs as result of a neurodegenerative process in brain, and usually is chronic or progressive by nature. Most descriptions of senile dementia date back to Alois Alzheimer. In 1906, Alzheimer described the first patient, Auguste Deter, who suffered from the disorder that later became known as Alzheimer's disease. Although, the history of the disease before 1906 is quite rich, little has been said about the contributions of ancient and medieval physicians to the understanding of dementia. Over the centuries, the concept of senile dementia changed from an inevitable mental decline with aging, to different sets of clinical features with narrow limits of diagnosis of a disease in its own right. Documentation of the historical origins of prevention, diagnosis, and therapies of dementia would make an important contribution to a more complete understanding of this pathological degeneration of dementia. The present review focuses on the contributions of Avicenna (AD 980-1037) to the development of diagnosis and the discovery of etiology of different forms of dementia, with the goal of revealing the extent to which dementia was understood in the golden age of Islam in Persia.