<prompt> Wernickes encephalopathy occurs due to the deficiency of:ThiamineRiboflavinFolateVitamin B12  <response>: Ans: A Thiamine Ref: Synopsis of Psychiatry, Kaplan Sadock. 10th edition.p.400.Explanation:Wernickes encepha lopathyIt is a condition which is acute in onset cf. Korsakoff psychosis is insidious,It is characterized by the triad:1. Confusion delirium tremens2. Ataxia in-coordination of movements3. Nystagmus due to opthalnioplegia and i or vestibular dysfunction. Chronic alcohol intake depletes thiamine Vitamin B1 by various mechanisms.During acute intoxication, such deficiency results in degeneration of parav entricular regions of brain mainmillary bodies, thalamus and hypothalamus.The treatment is THIAMINE IV 250-500mg day as slow infusion for first five days, followed by oral route 100mg tds for at least 15 days.It is reversible if treated early.Otherwise, the condition progresses into Korsakoffs psychosis, which is characterized by amnesia iboth anterograde retrograde? declarative memory deficit, confabulation to fill up the gaps in memory, apathy lack of insight.Less than 20 only respond to thiamine and often need as long as two years to show moderate improvement.Other neuropsychiatric disorders due to alcohol are:Cerebellar degeneration,Central Pontine Myelinosis Corpus callosum demyelination Marchiafava- Bignami disease.Riboflavin deficiency:Mucositis Chelitis, Stomatitis, GlossitisDermatitis SeborrheicNormochromic, normocytic anemia.Folate deficiency - Depression.Vitamin B12:Depression Psychosis both folate and Vit.B 12 cause mental disorders either directly or by increasing homocysteine levels in brain. 