Dementia, among the other symptoms, can be found in certain brain disorders that are caused either by slow-acting viruses or by protein molecules known as prions. These brain disorders are known as transmissible spongiform encephalopathies. They are usually manifested a long time after infection but once they occur they develop very rapidly and death occurs in a few weeks or months. Besides impairment of the cognitive functions (dementia), motor functions (movements) are also affected.

Unlike transmissible spongiform encephalopathies, Alzheimer's disease is slowly progressive and mainly affects the cognitive functions (memory, thinking, intelligence, etc.). The patient doesn't die directly from Alzheimer's disease but from the compounding diseases like infections and heart failure.

You may assume an infective brain disease only if your father's dementia is very progressive, accompanied by motor disorders and if death occurs in a few months.

It is very important to know about the brain and its functions and the diseases which affects our brain. We should take certain steps to prevent us from brain disease. For example doing brain exercise, playing memory games, meditation and yoga these would help us to keep our brain active and smarter. We need not be a neurosurgeon to know about the brain diseases. Some of the brain disease are Brain Calcification, Brain Aneurysms, Vascular Accidents, etc.