Correlation between spatial memory and sleep architecture and hippocampal volumes in patients with chronic insomnia disorder / 中华神经科杂志

ABSTRACT

Objective To investigate the correlation between spatial memory and sleep architecture and hippocampal volumes in patients with chronic insomnia disorder.Methods Twenty-two chronic insomnia patients and 17 normal sleepers (controls) were selected to evaluate the subjective insomnia using Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI) and the objective insomnia by polysomnography (PSG).The cognitive function was measured by Montreal Cognitive Assessment (MoCA).Spatial memory and object-memory were measured by Nine-box Maze, and object-recognition memory was detected by picture recognition test.MRI was used to detect hippocampus volumes.Results Compared with controls, a significant reduction in total sleep time (328.3 (310.4, 387.9) min vs 418.0 (375.8, 45.5) min, Z=2.607, P=0.009), sleep efficiency (%) (77.7 (73.1, 84.0) vs 93.0 (87.2, 93.9), Z=3.739,P=0.000), proportion of N3 (%) (5.5 (0.4, 14.4) vs 13.7 (7.7, 18.3), Z=2.664, P=0.008) and proportion of rapid eye movement (REM) (%) (14.4 (10.7, 17.2) vs 17.3 (15.9, 23.3), Z=2.890, P=0.004) was seen in insomnia patients, whereas sleep latency was delayed.The error numbers of spatial working-memory (4.5 (2.0, 7.3) vs 1.0 (0.0, 3.0), Z=3.007, P=0.003) in chronic insomnia patients were more than those in controls.There was no statistically significant difference in object reference memory, spatial reference memory and object recognition in two groups.A significant reduction of the left (2 818.0 (2 534.9, 3 191.8) mm3 vs 3 453.3 (3 081.2, 3 764.4) mm3, Z=3.314, P=0.001), right (2 780.5 (2 451.2, 3 191.8) mm3 vs 3 479.8 (3 024.1, 3 786.7) mm3, Z=3.484,P=0.000) and whole hippocampal volumes (5 561.7 (4 956.6, 6 396.9) mm3 vs 6 898.9 (6 017.1, 7 540.1) mm3, Z=3.455, P=0.001) was seen in chronic insomnia patients compared with controls.The hippocampal volumes were negatively correlated with sleep latency (r=-0.432, P=0.006), but positively correlated with sleep efficiency, proportion of N3 (r=0.323, 0.376;P=0.045, 0.018).There was a negative correlation between the error numbers of spatial working-memory and hippocampal volumes (r=-0.351, P=0.029).The hippocampal volumes were negatively correlated with the duration of disease in chronic insomnia patients (r=-0.734, P<0.01).Conclusion The spatial memory may be associated with decreased proportion of REM and reduced hippocampal volumes in chronic insomnia patients.