This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Organic mental disorders, Subject name: Psychiatry
Wernicke&;s encephalopathy is due to deficiency of 
Select and explain. 
A. Thiamine, B. Niacin, C. Folic acid, D. Pyridoxine
A: Thiamine
Answer: A: Thiamine 
Explanation: The commonest cause of the organic amnestic syndrome is chronic alcohol dependence. It is also called as Wernicke-korasakoff syndrome. Wernicke&;s encephalopathy is the acute phase of delirium proceeding to the organic amnestic syndrome, while korasakoff&;s syndrome is the chronic phase of the amnestic syndrome. (Ref: a sho textbook of psychiatry, Niraj Ahuja,7th edition, pg no. 27)