Vitamin B1 (thiamine) deficiency is common in alcoholics, and chronic alcoholics who have liver disease can develop an altered mental state that is related to thiamine deficiency.

Known as Wernicke-Korsakoff syndrome, it manifests as confusion, disorientation, double vision, and difficulty walking, along with severe memory loss. It was first described in the late 1800s.

Excessive, long-term alcohol intake can cause thiamine deficiency by inhibiting the absorption of thiamine in the gastrointestinal tract.

In addition, thiamine requirements are increased in a high carbohydrate diet which is common in alcoholics.