Random generation deficit in alcoholic Korsakoff patients.

Korsakoff's syndrome often affects "executive" functions [Baddeley, A. Human Memory, Theory and Practice, 1990], which in anatomical terms are associated with the frontal lobes. However, in a previous study, Wiegersma, S. and de Jong, E. [J. clin. exp. Neuropsychol. 13, 847-853, 1991] failed to observe a diminished performance on the random generation task, although this task is thought to be sensitive to "executive" deficits. In the present study, we sought to replicate and clarify these earlier findings of Wiegersma and de Jong with a group of Korsakoff patients in whom frontal lobe dysfunction was indicated by a reduced performance on fluency tasks. Patients and controls were presented with three tasks. Digit span was used as an index of short-term memory capacity; memory search and comparison processes were measured with the missing item scan; and the randomisation task was used to assess the ability to produce non-routine, random sequences. The results showed that the performance of Korsakoff patients declined on the randomisation task while short-term retention and scanning were intact. Analysis of the responses indicated that the Korsakoff patients are able to suppress the dominant response, but have problems in generating and carrying out alternative strategies in novel problem situations.