Effects of Intermittent Hypoxia Protocols on Cognitive Performance and Brain Health in Older Adults Across Cognitive States: A Systematic Literature Review

Article type: Systematic Review

Authors: Boulares, Ayoub^{a; *} | Pichon, Aurélien^a | Faucher, Corentin^a | Bragazzi, Nicola Luigi^{b; c; d; e} | Dupuy, Olivier^{a; f; *}

Affiliations: [a] Laboratory Mobility, Aging & Exercise-ER20296 (MOVE), Faculty of Sport Sciences-STAPS, University of Poitiers, Poitiers, France | [b] Department of Mathematics and Statistics, Laboratory for Industrial and Applied Mathematics (LIAM), York University, Toronto, ON, Canada | [c] Department of Food and Drugs, Medical School, Human Nutrition Unit (HNU), University of Parma, Parma, Italy | [d] United Nations Educational, Scientific and Cultural Organization (UNESCO) Chair, Health Anthropology Biosphere and Healing Systems, University of Genoa, Genoa, Italy | [e] Department of Health Sciences (DISSAL), Postgraduate School of Public Health, University of Genoa, Genoa, Italy | [f] School of Kinesiology and Physical Activity Sciences (EKSAP), Faculty of Medicine, University of Montreal, Montreal, QC, Canada

Correspondence: [*] Correspondence to: Ayoub Boulares and Olivier Dupuy, Laboratory Mobility, Aging & Exercise-ER20296 (MOVE), University of Poitiers, Faculty of Sport Sciences-STAPS, Poitiers, France. E-mails: [email protected] (Ayoub Boulares) and [email protected].

Abstract: Background:The rise in the aging population highlights the need to address cognitive decline and neurodegenerative diseases. Intermittent hypoxia (IH) protocols show promise in enhancing cognitive abilities and brain health. Objective:This review evaluates IH protocols’ benefits on cognition and brain health in older adults, regardless of cognitive status. Methods:A systematic search following PRISMA guidelines was conducted across four databases (PubMed, Scopus, Web of Science, and Cochrane Library) and two registers, covering records from inception to May 2024 (PROSPERO: CRD42023462177). Inclusion criteria were: 1) original research with quantitative details; 2) studies involving older adults, with or without cognitive impairment; 3) studies including IH protocols; 4) articles analyzing cognition and brain health in older adults. Results:Seven studies and five registered trials met the criteria. Findings indicate that Intermittent Hypoxia Training (IHT) and Intermittent Hypoxia-Hyperoxia Training (IHHT) improved cognitive functions and brain health. Intermittent Hypoxic Exposure (IHE) improved cerebral tissue oxygen saturation, middle cerebral arterial flow velocity, and cerebral vascular conductance, particularly in cognitively impaired populations. IHT and IHHT had no significant effect on BDNF levels. There is a lack of studies on IHHE in older adults with and without cognitive impairment. Conclusions:IH protocols may benefit cognition regardless of cognitive status. IHT and IHE positively affect cerebral outcomes, with all protocols having limited effects on BDNF levels. Future research should standardize IH protocols, investigate long-term cognitive effects, and explore neuroprotective biomarkers. Combining these protocols with physical exercise across diverse populations could refine interventions and guide targeted therapeutic strategies.

Keywords: Aging, Alzheimer’s disease, cognitive impairment, cognitive performance, intermittent hypoxia, mild cognitive impairment, older adults, physical exercise

DOI: 10.3233/JAD-240711

Journal: Journal of Alzheimer's Disease, vol. 101, no. 1, pp. 13-30, 2024