Question

A chronic alcoholic with thiamine deficiency develops a memory disturbance in which he is unable to form new memories, though older memories are relatively preserved. This Korsakoff syndrome is characterised by which type of memory deficit?

• A. Anterograde amnesia
• B. Retrograde amnesia
• C. Transient global amnesia
• D. Dissociative amnesia

Hint:

Think of the inability to form NEW memories after a thiamine-deficiency insult.

Answer 1

The Correct Option is A

Step 1: Korsakoff syndrome is a chronic amnestic disorder caused by thiamine (vitamin B1) deficiency, classically seen in chronic alcoholics and often following an episode of Wernicke encephalopathy. The lesion involves the mammillary bodies and the dorsomedial nucleus of the thalamus.

Step 2: The hallmark feature is anterograde amnesia - the inability to form and lay down new memories after the onset of the illness. The patient cannot retain new information for more than a few minutes.

Step 3: Associated features include confabulation (filling memory gaps with fabricated accounts), variable retrograde amnesia, and relatively preserved immediate recall and procedural memory.

Step 4: Why the others are wrong - pure retrograde amnesia (loss of past memories) is not the defining feature of Korsakoff; transient global amnesia is a self-limited episodic disorder; dissociative amnesia is a psychogenic, stress-related loss of autobiographical memory without an organic thiamine basis.

Key fact: Korsakoff syndrome to thiamine deficiency to predominant anterograde amnesia with confabulation.