Classically there is loss of memory, often associated with disturbance of higher brain functions like thinking, orientation, comprehension, calculation, learning capacity, language and judgment. Generally recent memories are lost first.

This condition can be caused by a variety of reasons. There is disturbance of consciousness and attention, perception, thinking, memory, psychomotor behavior, emotion and the sleep wake cycle.

A condition associated and caused by alcohol. Often abrupt cessation of alcohol can cause it. Hallucinations and illusions like creeping small animals, having threatening voices are generally present.

Addiction of alcohol, opium and related compounds, cannabis (bhang, sulpha , ganja, charas), cocaine, tobacco, LSD and sleeping pills.

It is characterized by fundamental and characteristic distortions of thinking and perception. Delusions, hallucinations, persecutory thinking, excitement or negativism like stupor, social withdrawal are some of the common symptoms. Paranoid, hebephrenic, catatonic, simple and residual are some of the types of schizophrenia.

Underlying characteristic is elevated mood, and an increase in the quantity and speed of physical and mental activity.