- Alzheimer's disease is an incurable, degenerative brain disease characterized by memory loss and cognitive decline. It was first described in 1906 by Alois Alzheimer. - The disease results from an accumulation of beta-amyloid protein in the brain that leads to nerve cell death and formation of plaques and tangles. - Symptoms start with mild memory loss but progress to include problems with thinking, reasoning, language and perception as brain regions are damaged.