Dementia is the mental process or syndrome which is caused by brain disease or injury and results in the memory loss, personality changes along with language and other thinking skills, visual perception, and impaired reasoning. It mainly affects old age people. It increases with the increase in the age of the people and also ranges with severity in the mild stage and to the most in most severe stage. Symptoms came into effect when nerve cells in the brain stop working lose connections with other brain cells, and die. Different types of dementia are: Alzheimer's disease, Lewy body dementia, Frontotemporal disorders, and vascular dementia. Signs and symptoms include: