Examining mental health and autonomic function as putative mediators of the relationship between sleep and trajectories of cognitive function: findings from the Irish longitudinal study on ageing (TILDA)

Abstract

Objectives

This study investigates the mediating roles of autonomic function and mental health in the association between sleep and cognitive decline in adults aged 50 and above.

Method

A total of 2,697 participants with observations on sleep and mediators at baseline and repeated measures of cognitive function (MMSE) were included. Clusters of individuals with similar cognitive trajectories (high-stable, mid-stable and low-declining) were identified. Multinomial logistic regressions were used to estimate the likelihood of membership to each trajectory group based on sleep duration and disturbance. Finally, mediation analysis tested potential mediating effects of autonomic function and mental health underpinning the sleep–cognition relationship.

Results

Short (p = .028), long (p =.019), and disturbed sleep (p =.008) increased the likelihood of a low-declining cognitive trajectory. Mental health measures fully attenuated relationships between cognitive decline and short or disturbed sleep but not long sleep. No autonomic function mediation was observed.

Conclusion

Older adults with short or disturbed sleep are at risk of cognitive decline due to poor mental health. Individuals with long sleep are also at risk, however, the acting pathways remain to be identified. These outcomes have clinical implications, potentially identifying intervention strategies targeting mental health and sleep as prophylactic measures against dementia.

Keywords:

• Cognitive function
• sleep
• depression
• stress
• autonomic function
• mediation

Acknowledgments

The authors would like to acknowledge the continued commitment and cooperation of the TILDA participants and research team.

Author contributions

David J. Ryan and Céline De Looze conceived, designed, performed the analyses and wrote the paper; Siobhán Scarlett and Christine A. McGarrigle contributed to data analysis and codes; Rose Anne Kenny provided feedback on manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

TILDA provides access to the datasets for research use through pseudonymised publicly accessible dataset files, and through an on-site Hot Desk Facility.

The publicly accessible dataset files are hosted by the Irish Social Science Data Archive based in University College Dublin, and the Interuniversity Consortium for Political and Social Research (ICPSR) based in the University of Michigan.

Researchers wishing to access the data must complete a request form, available on either the ISSDA* or ICPSR website.

Additional information

Funding

Funding for the Irish Longitudinal Study on Ageing (TILDA) is provided by the Irish Government (The Department of Health), the Health Research Board (HRB), The Atlantic Philanthropies, and Irish Life PLc.