Brain disease
Wernickes encephalopathy (WE), Korsakoff syndrome (also called alcohol amnestic disorder), and Wernicke–Korsakoff syndrome are forms of dry beriberi.Wernickes encephalopathy is the most frequently encountered manifestation of thiamine deficiency in Western society, though it may also occur in patients with impaired nutrition from other causes, such as gastrointestinal disease, those with HIV/AIDS, and with the injudicious administration of parenteral glucose or hyperalimentation without adequate B-vitamin supplementation. This is a striking neuro-psychiatric disorder characterized by paralysis of eye movements, abnormal stance and gait, and markedly deranged mental function.Korsakoff syndrome, in general, is considered to occur with deterioration of brain function in patients initially diagnosed with WE. This is an amnestic-confabulatory syndrome characterized by retrograde and anterograde amnesia, impairment of conceptual functions, and decreased spontaneity and initiative.Alcoholics may have thiamine deficiency because of:

Inadequate nutritional intake:  Alcoholics tend to intake less than the recommended amount of thiamine. Decreased uptake of thiamine from the GI tract:  Active transport of thiamine into enterocytes is disturbed during acute alcohol exposure. Liver thiamine stores are reduced due to hepatic steatosis or fibrosis. Impaired thiamine utilization:  Magnesium, which is required for the binding of thiamine to thiamine-using enzymes within the cell, is also deficient due to chronic alcohol consumption. The inefficient use of any thiamine that does reach the cells will further exacerbate the thiamine deficiency.
In 1884, Takaki observed that beriberi was common among low-ranking crew who were often provided free rice, thus ate little else, but not among crews of Western navies, nor among Japanese officers who consumed a more varied diet. In 1897, Christiaan Eijkman, a Dutch physician and pathologist, demonstrated that beriberi is caused by poor diet, and discovered that feeding unpolished rice (instead of the polished variety) to chickens helped to prevent beriberi. The following year, Sir Frederick Hopkins postulated that some foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, and salt—that were necessary for the functions of the human body. In 1901, Gerrit Grijns, a Dutch physician and assistant to Christiaan Eijkman in the Netherlands, correctly interpreted beriberi as a deficiency syndrome, and between 1910 and 1913, Edward Bright Vedder established that an extract of rice bran is a treatment for beriberi. In 1929, Eijkman and Hopkins were awarded the Nobel Prize for Physiology or Medicine for their discoveries. Etymology
Although according to the Oxford English Dictionary, the term "beriberi" comes from a Sinhalese phrase meaning "weak, weak" or "I cannot, I cannot", the word being duplicated for emphasis, the origin of the phrase is questionable. It has also been suggested to come from Hindi, Arabic, and a few other languages, with many meanings like "weakness", "sailor", and even "sheep". Such suggested origins were listed by Heinrich Botho Scheube, among others. Edward Vedder wrote in his book Beriberi (1913) that "it is impossible to definitely trace the origin of the word beriberi".