Wernicke's encephalopathy occurs due to the deficiency of:

Ans: A (Thiamine) Ref: Synopsis of Psychiatry, Kaplan & Sadock. 10th edition.p.400.Explanation:Wernicke's encepha lopathyIt is a condition which is acute in onset (cf. Korsakoff psychosis is insidious),It is characterized by the triad:1. Confusion (delirium tremens)2. Ataxia (in-coordination of movements)3. 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 "Korsakoff's 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, Glossitis)Dermatitis (Seborrheic)Normochromic, 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).