Dementia is considered to be a terminal disease, but it will take a long time before it can completely take effect on the person’s body. There is a form of Dementia that is very aggressive. This is called Pick’s disease, and people who get this would probably die within a year or two.
The reason why people die from Dementia is not because of the disease itself but because of the inability of the person to care for himself/herself after the disease has taken over the mental functions of the brain. People with Dementia are unable to do simple tasks such as walking and even talking during the late stage of the disease.