Dementia is diminished mental faculties which include memory, language, personality, social behavior, abstract thinking and visuospatial skills. Brain being the master organ, like a captain of the ship, is the last one to fail and 40% of those who survive beyond 85 years develop dementia. The commonest type of dementia is Alzheimer’s disease which occurs in 60–70%. Memory has four steps recognition (which requires attention), registration, retention, and recollection. In dementia the registration is affected because of which activities performed on the same day or preceding days are the first to be forgotten. This chapter covers the differentiation between depression, minimal cognitive impairment and dementia, clinical features of normal pressure hydrocephalus (NPH), differentiation of vascular dementia from Alzheimer’s disease, and types of neurodegenerative dementia.