Wernicke's Encephalopathy: The mammillary bodies are atrophic and discolored brown in this disease, which is associated with vitamin B1 (thiamine) deficiency. Microscopically there is capillary proliferation, gliosis and, in severe cases, neuronal loss and hemorrhage. It is commonly seen in chronic alcoholics but may be found in other nutritionally deprived populations. It may be associated with Korsakoff's psychosis.