Changes in Cognitive Function in Patients with Primary Insomnia.

Background: Neuropsychological evidence is not sufficient concerning whether there is cognitive impairment in patients with primary insomnia. Further study is needed in this regard.

Aims: To measure the changes in cognitive functioning in patients with primary insomnia.

Methods: 40 patients with insomnia (insomnia group) and 48 normal sleepers (control group) were tested using the Pittsburgh Sleep Quality Index (PSQI), episodic memory test, and Montreal Cognitive Assessment (MoCA).

Results: The insomnia group had significantly lower scores than the control group in the naming (t=3.17, p=0.002), immediate memory (t=3.33, p=0.001), and delayed recall (t=6.05, p=0.001) sections of the MoCA, as well as a lower overall score on the MoCA (t=3.24, p=0.002). Participants with different degrees of insomnia also had significantly different scores in naming (F=7.56, p=0.001), language (F=3.22, p=0.045), total score (F=6.72, p=0.002), delayed memory (F=8.41, p=0.001), and delayed recall (F=22.67, p=0.001) sections of the MoCA. The age of primary insomnia patients was correlated to MoCA total score, immediate memory, delayed recall, and delayed recognition function, also with statistical significance. The years of education of primary insomnia patients was also significantly correlated to overall MoCA score, as well as visuospatial and executive function, naming, attention, language, and abstraction sections of the MoCA.

Conclusion: Primary insomnia patients have cognitive impairment. The more severe the insomnia is, the wider the range of and the more serious the degree of cognitive impairment is.