Ability and Functional Connectivity of Hippocampus in Primary Insomnia

Object: This study intends to explore the changes of WHO-UCLA word study and the Digital Pin Test, as well as the functional connectivity on hippocampus with the whole brain, in order to find cognitive damage mechanism in primary insomnia (PI). Method: 40 primary insomniacs are chosen according to the Diagnostic and Statistical Manual of Mental Disorders (4 edition, DSM-IV) and International Classification of Sleep Disorders (ICSD) criteria as well as 50 healthy subjects. The WHO-UCLA word learning and the Digital Pin Test are applied to evaluate the subjects’ word study ability and vigilance. The above-mentioned subjects take a fMRI on the whole brain in a resting state, with left and right hippocampus as the seed points to establish functional connection with other encephalic regions, followed by a comparison of the test results of the two groups. Results: Pittsburgh Sleep Quality Index (PSQI) (t=18.181,p<0.01) and HAMA (t=29.242,p<0.01) of PI patients were significantly higher than those of the healthy control group, but the PI group’s Digital Pin Test efficiency and WHO-UCLA word learning were significantly lower than those of the HC group. There exists a positive correlation between the PI group’s subjective insomnia degree and their anxiety and the course of a disease. The PI group’s WHO-UCLA word study ability has a negative correlation between the total PSQI score and the Digital Pin Test efficiency, and a positive correlation occurs in relation with an educational background. The right hippocampus of PI patients showed strengthened functional connection with the left limbic lobe, the right thalamus and the left brainstem. The left hippocampus of PI patients displayed enhanced functional connection with the bilateral thalamus. Conclusion: The ability of the PI patients on the WHO-UCLA word study and the Digital Pin Test efficiency decline, which keeps a negative correlation with depression, in relation with the course of the disease, sleep quality, and a positive correlation occurs with an educational background. The patients’ hippocampus has a stronger functional connection with the bilateral thalamus, left limbic lobe, left brainstem, which is the mechanism leading to the cognitive damage of PI patients. [Hongju Zhang, Enfeng Wang, Shewei Dou, Liya Liu, Li Tong, Junfang Teng, Yongli Li: Research on Study Ability and Functional Connectivity of Hippocampus in Primary Insomnia. Life Sci J 2014;11(8):802-809]. (ISSN:1097-8135). http://www.lifesciencesite.com. 120