Sleep-dependent memory consolidation of a new task is inhibited in psychiatric patients

Abstract

Schizophrenic and depressive patients show impeded sleep-dependent procedural memory consolidation. But this has been shown mainly for tasks testing the adaptation of old skills. This study tested the overnight memory consolidation of a new task and the transfer of this new skill to a similar task. Using an adapted version of the sequential finger tapping task, keyboard-naïve Ethiopian depressive (n = 8) and schizophrenic (n = 15) patients and healthy controls (n = 11 and n = 17) were tested twice, 24 h apart. In addition the subjects underwent training in a second sequence after the retest of the first sequence. Both schizophrenic and depressive patients did not show a significant overnight change in performance (1% and 4% improvement respectively) in the task and differed significantly from the healthy control groups who did show significant improvement (16% and 22%). Further in contrast to the healthy controls both patients groups showed no significant transfer of the newly acquired skill to the second sequence. This study shows that depressive and schizophrenic patients are not only deficient in the overnight memory consolidation of a new task, but also fail to show a transfer of this new skill to similar tasks.