(from Latin dementia – insanity) – acquired mental impairment manifested in decreased cognitive abilities, or behavior change, extreme difficulty in using knowledge, and previous experience. In childhood, Dementia can occur as a result of organic brain diseases such as schizophrenia, epilepsy and inflammatory brain diseases (meningoencephalitis). and brain injuries (concussions, bruises). Unlike congenital mental retardation, Brain dysfunction in dementia occurs after a period of normal development of the child.