<prompt> Amnesia typically occurs inPsychoneurotic statesManiaHead injurySchizophrenia  <response>: A variety of brain pathologies can give rise to severe memory impairment, the most common being the following: degenerative disorders paicularly Alzheimer disease and Huntington disease; chronic alcohol abuse giving rise to Korsakoff syndrome; traumatic head injury; temporal lobe surgery; encephalitis; cerebral vascular disorders including subarachnoid haemorrhage resulting from ruptured aneurysms; anoxic brain damage following, for example, myocardial infarction, carbon monoxide poisoning, or respiratory arrest; cerebral tumours. Reference: Shoer Oxford textbook of Psychiatry seventh edition, page no. 354. 