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Naismith SL, Duffy SL, Cross N, Grunstein R, Terpening Z, Hoyos C, D'Rozario A, Lagopoulos J, Osorio RS, Shine JM, McKinnon AC. Nocturnal Hypoxemia Is Associated with Altered Parahippocampal Functional Brain Connectivity in Older Adults at Risk for Dementia. J Alzheimers Dis 2020; 73:571-584. [PMID: 31815696 DOI: 10.3233/jad-190747] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Obstructive sleep apnea is associated with an increased risk of developing mild cognitive impairment and dementia. Intermittent nocturnal hypoxemia in obstructive sleep apnea is associated with brain changes in key regions that underpin memory. OBJECTIVE To determine whether older adults with severe nocturnal hypoxemia would exhibit reduced functional connectivity within these regions, with associated deficits in memory. METHODS Seventy-two participants 51 years and over underwent polysomnography with continuous blood oxygen saturation recorded via oximetry. The oxygen desaturation index (ODI, 3% dips in oxygen levels per hour) was the primary outcome measure. ODI was split into tertiles, with analyses comparing the lowest and highest tertiles (N = 48). Thirty-five of the 48 participants from these two tertiles had mild cognitive impairment. Participants also underwent resting-state fMRI and comprehensive neuropsychological, medical, and psychiatric assessment. RESULTS The highest ODI tertile group demonstrated significantly reduced connectivity between the left and right parahippocampal cortex, relative to the lowest ODI tertile group (t(42) = -3.26, p = 0.041, beta = -1.99).The highest ODI tertile group also had poorer working memory performance. In the highest ODI tertile group only, higher left-right parahippocampal functional connectivity was associated with poorer visual memory recall (between-groups z = -2.93, p = 0.0034). CONCLUSIONS Older adults with severe nocturnal hypoxemia demonstrate impaired functional connectivity in medial temporal structures, key regions involved in sleep memory processing and implicated in dementia pathophysiology. Oxygen desaturation and functional connectivity in these individuals each relate to cognitive performance. Research is now required to further elucidate these findings.
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Affiliation(s)
- Sharon L Naismith
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Charles Perkins Centre, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
| | - Shantel L Duffy
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Charles Perkins Centre, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
| | - Nathan Cross
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,Sleep and Circadian Group, Woolcock Institute of Medical Research, Sydney Health Partners, Sydney, Australia
| | - Ron Grunstein
- Sleep and Circadian Group, Woolcock Institute of Medical Research, Sydney Health Partners, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
| | - Zoe Terpening
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Camilla Hoyos
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,Sleep and Circadian Group, Woolcock Institute of Medical Research, Sydney Health Partners, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
| | - Angela D'Rozario
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,Sleep and Circadian Group, Woolcock Institute of Medical Research, Sydney Health Partners, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
| | - Jim Lagopoulos
- Sunshine Coast Mind and Neuroscience Thompson Institute University of Sunshine Coast, Queensland, Australia
| | - Ricardo S Osorio
- Department of Psychiatry, Sleep Aging and Memory Lab, NYU School of Medicine, New York, NY, USA.,Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - James M Shine
- Brain & Mind Centre, University of Sydney, Sydney, Australia
| | - Andrew C McKinnon
- Healthy Brain Ageing Program, School of Psychology, University of Sydney, Sydney, Australia.,Brain & Mind Centre, University of Sydney, Sydney, Australia.,NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep), Australia
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