Cardiorespiratory Fitness as a Moderator of Sleep-Related Associations with Hippocampal Volume and Cognition

Alfonso J Alfini; Junyeon Won; Lauren R Weiss; Casandra C Nyhuis; Vadim Zipunnikov; Adam P Spira; Teresa Liu-Ambrose; Alexander J Shackman; J Carson Smith

doi:10.3390/brainsci12101360

Cardiorespiratory Fitness as a Moderator of Sleep-Related Associations with Hippocampal Volume and Cognition

Brain Sci. 2022 Oct 7;12(10):1360. doi: 10.3390/brainsci12101360.

Authors

Alfonso J Alfini¹, Junyeon Won², Lauren R Weiss^{2

3}, Casandra C Nyhuis⁴, Vadim Zipunnikov⁵, Adam P Spira^{6

7

8}, Teresa Liu-Ambrose^{9

10

11}, Alexander J Shackman^{3

12

13}, J Carson Smith^{2

3

13}

Affiliations

¹ National Center on Sleep Disorders Research, Division of Lung Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20817, USA.
² Department of Kinesiology, University of Maryland School of Public Health, College Park, MD 20742, USA.
³ Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA.
⁴ Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
⁵ Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
⁶ Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
⁷ Center on Aging and Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
⁸ Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
⁹ Department of Physical Therapy, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
¹⁰ Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
¹¹ Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, BC V5Z 1M9, Canada.
¹² Department of Psychology, University of Maryland, College Park, MD 20742, USA.
¹³ Maryland Neuroimaging Center, University of Maryland, College Park, MD 20742, USA.

Abstract

The objective of this study was to understand the associations of sleep and cardiorespiratory fitness with hippocampal volume and global cognition among older adults (n = 30, age = 65.8 years, female = 73.3%). Wrist actigraphy provided objective measures of nighttime sleep including sleep duration, average wake bout length (WBL; sleep disturbance), and wake-to-sleep transition probability (WTSP; sleep consolidation). Cardiorespiratory fitness was quantified via cycle exercise using a modified heart rate recovery approach. Magnetic resonance imaging was used to determine hippocampal volume and the Mini-Mental State Examination was used to assess global cognition. Fitness moderated associations of sleep with hippocampal volume and cognitive performance, whereby the association of WBL-an index of poor sleep-with hippocampal atrophy was stronger among less-fit individuals, and the association of sleep duration with cognitive performance was stronger among more-fit individuals. Across the fitness levels, a longer WBL was associated with lower cognitive performance, and a higher WTSP-an index of more consolidated sleep-was associated with greater hippocampal volume. Sleep and fitness were unrelated to the volume of an amygdala control region, suggesting a degree of neuroanatomical specificity. In conclusion, higher cardiorespiratory fitness may attenuate sleep disturbance-related hippocampal atrophy and magnify the cognitive benefits of good sleep. Prospective studies are needed to confirm these findings.

Keywords: actigraphy; aging; brain volume; heart rate recovery; sleep.

Grants and funding

This study was partially supported by the National Institutes of Health (T32-AG027668, R01-AG050507, R01-MH125370, R01-MH121409, R01-MH107444, R01-MH131264), the American Academy of Sleep Medicine Foundation (#223-BS-19), and the Department of Kinesiology at the University of Maryland, College Park. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.