Wernicke-Korsakoff syndrome is most commonly associated with deficiency of which vitamin?

• A. Vitamin C
• B. Vitamin D
• C. Thiamine
• D. Niacin

Answer: (C)

Thiamine deficiency is the key factor behind Wernicke-Korsakoff syndrome. Thiamine (vitamin B1) serves as a critical cofactor for several brain energy–producing enzymes, including pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, as well as transketolase in the pentose phosphate pathway. When thiamine is lacking, brain cells can’t generate enough ATP, leading to damage in areas with high metabolic demand such as the mammillary bodies and thalamus. This manifests acutely as Wernicke’s encephalopathy (ataxia, ophthalmoplegia, confusion) and can progress to Korsakoff syndrome, with prominent memory impairment and confabulation. This pattern is most commonly seen in chronic alcohol use and malnutrition. Deficiencies of the other listed vitamins produce different conditions (for example, vitamin C causes scurvy, vitamin D causes bone disorders, and niacin causes pellagra) and do not produce the Wernicke–Korsakoff syndrome.