T-D-022 RELATIONSHIP BETWEEN COGNITIVE FUNCTION AND HIPPOCAMPAL VOLUMES IN PATIENTSWITH PRIMARY INSOMNIA

Abstract

Introduction and Objectives: To investigate the relationship between cognitive function and hippocampal volumes in patients with primary insomnia (PI). Materials and Methods: We enrolled 20 female patients with PI and 20 good sleepers (GS) (mean age 50.8 yrs) matched by age and educational status. Patients were diagnosed with PI according to ICSD-2 criteria and all of them reported subjective memory decline. All subjects had undergone night polysomnography, neuropsychological tests, and brain MRI (1.5T). The hippocampal volumes (HV) were manually measured bilaterally. HV was corrected for intracranial volume. Results: Mean insomnia duration was 7.2 yrs, mean education period was 11.8 yrs, mean number of sleep-aid pills was 2.1, and mean duration of taking sleep pills was 3.7 yrs in PI. Mean HV of right hemisphere was 3265.2±255.1 mm3 in PI and 3151.3±295.7 mm3 in GS (p=0.185) and that of left side was 3000.3±214.7 mm3 in PI and 2897.4±390.5 mm3 in GS (p=0.265). Right HV was significantly correlated with insomnia duration (r=0.885) and duration of taking sleep medication (r=0.488) and left HV was negatively correlated with insomnia duration (r=0.536) and duration of taking sleep medication (r=0.539). PI showed significant impairment for attention, frontal lobe function, and non-verbal/verbal memory compared to GS. Recognition in the non-verbal memory test was positively correlated with right (r=0.913) and left HV (r=0.969). Short delay free recall in the verbal memory test was positively correlated with left HV (r=0.759). Conclusion: Although there was no significant difference in HV and ICV between PI and GS, long insomnia duration had negative influence on HV. PI had impaired cognitive function compared to GS and HV was positively correlated with memory function in PI. Chronic insomnia may deteriorate daytime cognitive impairment in PI, which was related to the HV.