Korsakoff syndrome
Also known as: korsakoff psychosis, amnestic-confabulatory syndrome
Korsakoff syndrome is a chronic memory disorder caused by severe thiamine (vitamin B1) deficiency, most often in the setting of long-term alcohol use. Its hallmarks are profound anterograde amnesia, retrograde amnesia, and confabulation.
Korsakoff syndrome results from thiamine deficiency damaging structures in the medial diencephalon, particularly the mammillary bodies and the dorsomedial nucleus of the thalamus. Thiamine is a cofactor for enzymes in glucose metabolism, so neurons in these high-demand regions are especially vulnerable when stores are depleted. Chronic alcohol use is the classic cause because it impairs thiamine absorption, storage, and utilization while often displacing dietary intake, though the deficiency can also follow prolonged vomiting, bariatric surgery, or severe malnutrition.
The syndrome most often emerges as the chronic phase following Wernicke encephalopathy, the acute presentation defined by the triad of confusion, ophthalmoplegia (classically lateral rectus palsy or nystagmus), and ataxia. When Wernicke encephalopathy goes untreated or is treated late, the acute signs may resolve while a permanent amnestic disorder remains; the combined course is called Wernicke-Korsakoff syndrome.
Clinically, the defining feature is a severe anterograde amnesia — an inability to form new declarative memories — accompanied by retrograde amnesia for events preceding the illness. Confabulation, in which the patient produces fabricated or distorted accounts without intent to deceive, is characteristic. Procedural memory, immediate attention span, and general intellectual function are relatively preserved, which is why patients can learn motor skills they do not remember practicing. Treatment centers on parenteral thiamine repletion, and an important teaching point is that thiamine must be given before or with glucose, since a glucose load can precipitate or worsen the encephalopathy in a deficient patient.
Korsakoff syndrome appears on the USMLE Step 1 in neuroscience and nutrition material, typically through a vignette pairing chronic alcohol use with memory loss and confabulation. On the NCLEX it arises in the context of substance use and addiction nursing care, where the emphasis is on recognizing thiamine deficiency, the thiamine-before-glucose sequence, and safety planning for a patient with permanent memory impairment.
Key takeaways
- Korsakoff syndrome is a chronic amnestic disorder caused by thiamine (vitamin B1) deficiency.
- Damage centers on the mammillary bodies and dorsomedial thalamus.
- Anterograde amnesia, retrograde amnesia, and confabulation are the defining features.
- It commonly follows untreated Wernicke encephalopathy, whose triad is confusion, ophthalmoplegia, and ataxia.
- Thiamine should be administered before or with glucose, because glucose alone can worsen the deficiency state.