Sleep Quality, Depression, and Cognitive Function in Non-Demented Older Adults

Area of Science:

• Gerontology
• Neuroscience
• Psychiatry

Background:

• Cognitive performance in older adults is influenced by both sleep quality and depression.
• Bi-directional relationships between sleep quality and depression are suggested by prior research.
• Sleep quality may impact cognition through depression, and vice versa.

Purpose of the Study:

• To assess the mediation effects of sleep quality and depression on their relationships with cognitive functions.
• To investigate these effects in non-demented older adults.
• To differentiate between cognitively normal and mild cognitive impairment populations.

Main Methods:

• Examined correlations between sleep quality, depression severity, and cognitive functions (memory recall, processing speed).
• Analyzed mediation effects using the bias-corrected Bootstrap method.
• Included cognitively normal (CN) and mild cognitive impairment (MCI) older adults.

Main Results:

• Both sleep disturbance and depression correlated with memory recall and processing speed.
• In CN individuals, depression mediated sleep disturbance's effect on both cognitive functions.
• Sleep disturbance mediated depression's effect on processing speed but not memory recall in CN individuals.
• In the overall group, sleep disturbance mediated depression's effect on both cognitive functions.

Conclusions:

• Differential mediation effects in CN older adults suggest distinct pathways from sleep disturbance and depression to cognition.
• Mediation results in the combined group indicate differing mechanisms for memory recall between MCI and CN individuals.