Sleep Med Psychophysiol.  2020 Jun;27(1):16-23. 10.14401/KASMED.2020.27.1.16.

A Study on the Relationship between Sleep Quality and Cognitive Function in Community Elderly

• Oh YK
• Kim BJ
• Park CS
• Lee CS
• Cha BS
• Lee SJ
• Lee DY
• Seo JY
• Lee YJ
• Choi JW
• Lee JH
• Lee YJ

• KMID: 2504231
• DOI: http://doi.org/10.14401/KASMED.2020.27.1.16

Abstract

Objectives
Sleep disturbance in the elderly is associated with cognitive decline. Sleep quality is known to deteriorate with age, and prospective studies seldom have examined the relationship between sleep quality and cognitive function. This study investigates the relationship between early sleep quality and cognitive function based on six-year follow-up data of community individuals older than 60 years.
Methods
The participants included 622 community elderly people older than 60 years from Jinju-Si. The final analysis comprised 322 elderly people. Pittsburgh sleep quality index (PSQI) and the Korean version of Consortium to Establish a Registry for Alzheimer’s Disease (CERAD-K) were used to assess early sleep quality and cognitive function after six years. Multiple linear regression analysis was performed to investigate the association between early sleep quality and cognitive function in the elderly.
Results
Early sleep quality (PSQI) was significantly associated with the results of the digit span test, clock drawing test (clox 1), and word recall test after six years. Sleep quality (PSQI) decreased significantly after six years, and lower quality of sleep (PSQI) score was associated with higher digit span test score (β = -0.167, p = 0.026) and higher clock drawing test score (β = -0.157, p = 0.031). Lower quality of sleep (PSQI) score was associated with higher word recall test (β = -0.140, p = 0.039).
Conclusion
The digit span test, word recall test, and clock drawing task (CLOX 1) shown to be significantly associated to sleep quality can be performed fast and easily in clinical practice. It is important to assess early cognitive function in the elderly with poor sleep quality, and further studies could suggest that these tests may be useful screening tests for early dementia in elderly with poor sleep quality.

Keyword

Aged; Clock drawing task 1; Cognition; Digit span test; Quality of sleep; Word list recall test