The oxidative decarboxylation of pyruvate and a-ketoglutarate, which plays a key role in energy metabolism of most cells, is paicularly impoant in tissues of the nervous system. In thiamine deficiency, the activity of these two dehydrogenase-catalyzed reactions is decreased, resulting in a decreased production of ATP and, thus, impaired cellular function. 1. Beriberi: This is a severe thiamine-deficiency syndrome found in areas where polished rice is the major component of the diet. Signs of infantile beriberi include tachycardia, vomiting, convulsions, and, if not treated, death. The deficiency syndrome can have a rapid onset in nursing infants whose mothers are deficient in thiamine. Adult beriberi is characterized by dry skin, irritability, disordered thinking, and progressive paralysis. 2. Wernicke-Korsakoff syndrome:In the United States, thiamine deficiency, which is seen primarily in association with chronic alcoholism, is due to dietary insufficiency or impaired intestinal absorption of the vitamin. Some alcoholics develop Wernicke-Korsakoff syndrome--a thiamine deficiency state characterized by apathy, loss of memory, ataxia, and a rhythmic to-and-fro motion of the eyeballs (nystagmus). The neurologic consequences of Wernicke&;s syndrome are treatable with thiamine supplementation. Reference: Lippincott edition 5, pg no. 379