Changes of procedural memory in patients with primary insomnia

Abstract

Objective To explore changes of procedural memory in patients with primary insomnia (PI) and its characteristics. Methods Thirty-six PI patients and 36 controls were enrolled. The procedural memory was respectively detected with category exemplar generation and motor sequence tasks, and the declarative memory was assessed by free recall task. Results Compared with the controls, PI patients showed few correct numbers in the category exemplar generation (7.0 (6.0, 8.8) vs 9.0 (9.0, 11.0), Z= 5.537，P<0.01) and motor sequence task (8.0±3.3 vs 11.5 (8.6, 13.8), Z= 4.152，P< 0.01) and the phases of immediate recall (3.0 (2.3, 4.0) vs 6.0 (5.0, 7.0), Z= 6.479，P＜0.01), delayed recall (9.0±2.2 vs 11.0 (10.0, 12.0), Z= 4.747，P＜0.01) and delayed recognition (15.0 (13.0, 15.0) vs 15.0 (15.0, 15.0), Z= 4.637，P＜0.01) of the free recall task. Furthermore, the early morning awakening group had significantly lower correct numbers in the motor sequence task, the delayed recall and recognition phases of the free recall task than the difficulty initiating and maintaining sleep groups. Conclusion The procedural and declarative memories are impaired in the PI patients, especially the early morning awakening insomniacs. Key words: Sleep initiation and maintenance disorders; Memory; Memory disorders