Wernicke and Korsakoff first described their respective syndromes in the late nineteenth century, and they were linked to each other and to thiamine deficiency by the 1940s. Korsakoff's syndrome (alcohol amnestic disorder) became almost synonymous with alcohol-related organic mental disorder because of the apparent simplicity of its manifestations and pathology, while other, more diffuse cerebral dysfunction was relegated to the poorly defined term alcoholic dementia. Work in neuropsychology, pathology, and imaging studies during the last 15 years has resulted in a new understanding of the interactions of heavy drinking, nutritional deficiency states, premorbid factors, and associated medical pathology, such as head trauma. Heavy drinking appears to result in cortical deficits and mild to moderate amnesia (intermediate brain syndrome) through an interaction of direct neurotoxicity and premorbid and associated factors. Alcohol amnestic disorder seems to result from the synergistic combination of drinking, malnutrition, and genetic vulnerability to thiamine deficiency. Dementia associated with alcoholism is most likely a combination of intermediate brain syndrome and alcohol amnestic disorder.