(Korsakoff Amnestic Syndrome; Korsakoff's Psychosis)
Korsakoff psychosis occurs in 80% of untreated patients with Wernicke encephalopathy; severe alcoholism is a common underlying condition. Why Korsakoff psychosis develops in only some patients with Wernicke encephalopathy is unclear. A severe or repeated attack of alcohol withdrawal–related delirium tremens can trigger Korsakoff psychosis whether or not a typical attack of Wernicke encephalopathy has occurred first.
Other triggers include head injury, subarachnoid hemorrhage, thalamic hemorrhage, thalamic ischemic stroke, and, infrequently, tumors affecting the paramedian posterior thalamic region (see Traumatic Brain Injury (TBI)).
Immediate memory is severely affected; retrograde and anterograde amnesia occur in varying degrees in patients with Korsakoff psychosis. Patients tend to draw on memory of remote events, which appears to be less affected than memory of recent events. Disorientation to time is common. Emotional changes are common; they include apathy, blandness, or mild euphoria with little or no response to events, even frightening ones. Spontaneity and initiative may be decreased.
Confabulation is often a striking early feature. Bewildered patients unconsciously fabricate imaginary or confused accounts of events they cannot recall; these fabrications may be so convincing that the underlying disorder is not detected.
Diagnosis of Korsakoff psychosis is based on typical symptoms in patients with a history of severe chronic alcohol dependence. Other causes of symptoms (eg, central nervous system injury or infection) must be ruled out.