Heat adaptation in older/elderly individuals
Whilst traditionally heat adaptation has been a priority for athletes and occupational workers ahead of exposure to hot/hot-humid environments, forecast increases in the frequency and intensity of heatwaves as a result of climate change means the general public is likely to be exposed to extreme environments as part of their daily life. At a population level, morbidity and mortality increase by up to 30% during a heatwave (2, 12) with older individuals most at risk due to impaired heat loss pathways (10). For example, the 2019 UK summer saw three heat waves with 892 excess deaths in 65+ year olds (13), and a concurrent increase in the financial burden on healthcare providers for those non-fatal cases requiring medical intervention.
The interaction between climate change, heat waves, and the elderly is a pressing concern given the number of older individuals is increasing (1). Further to this, whilst heatwave policies propose heat avoidance strategies for older individuals (14), many of this group have low socio-economic support thus facilitating these actions is challenging (17). Whilst recent evidence points to the most numerous heat-related challenges occurring in 65+ years old, an impairment in thermoregulation can be detected at ~40 years of age (11) and, by ~55 years an increased risk of hyperthermia occurs during physical activity in the heat (3). Add to this more individuals are working into later life, and the number of individuals at risk of heat-related illness/death is large.
A largely unexplored approach to attenuate the impact of unavoidable heat stress on ageing individuals is the induction of heat adaptation via an intervention known as heat acclimation. Heat acclimation is a term given to the rapid induction of heat adaptations in a controlled thermal environment to improve resistance to subsequent heat stress at rest, during exercise, and/or sport. Heat adaptations have been safely and effectively induced in young healthy individuals in a myriad of ways including active and passive approaches (5). The paucity of data examining heat adaptation in older individuals against the backdrop of increased heat waves suggests there is a necessity to conduct experimental work to increase our understanding of the extent to which this heat acclimation benefits older individuals.
The proposed body of work within this project will investigate the induction, retention, and decay of heat adaptation using an ecologically valid heat acclimation approach to improve physiological function e.g. thermoregulatory, sudomotor and cardiovascular adaptation (7), cellular/molecular perturbations e.g. endotoxin, inflammatory, and heat shock protein changes (4, 6, 8, 9, 15), and perceptual responses e.g. thermal comfort/sensation, heat-related fatigue, cognitive function, decision making (7, 16), to heat stress in older individuals.
Candidates for this project will likely have a background in exercise, sport, environmental, and/or cardiovascular physiology, though full training will be received as required. The lead supervisor will be Dr Oliver Gibson (https://www.brunel.ac.uk/people/oliver-gibson).
- Caley M, Sidhu K. Estimating the future healthcare costs of an aging population in the UK: expansion of morbidity and the need for preventative care. J Public Health (Bangkok) 33: 117–122, 2011.
- D’Ippoliti D, Michelozzi P, Marino C, De’Donato F, Menne B, Katsouyanni K, Kirchmayer U, Analitis A, Medina-Ramón M, Paldy A, Atkinson R, Kovats S, Bisanti L, Schneider A, Lefranc A, Iñiguez C, Perucci CA. The impact of heat waves on mortality in 9 European cities: Results from the EuroHEAT project. Environ Heal A Glob Access Sci Source 9, 2010.
- Flouris AD, McGinn R, Poirier MP, Louie JC, Ioannou LG, Tsoutsoubi L, Sigal RJ, Boulay P, Hardcastle SG, Kenny GP. Screening criteria for increased susceptibility to heat stress during work or leisure in hot environments in healthy individuals aged 31–70 years. Temperature 5: 86–99, 2018.
- Gibson OR, Dennis A, Parfitt T, Taylor L, Watt PW, Maxwell NS. Extracellular Hsp72 concentration relates to a minimum endogenous criteria during acute exercise-heat exposure. Cell Stress Chaperones 19: 389–400, 2014.
- Gibson OR, James CA, Mee JA, Willmott AGB, Turner G, Hayes M, Maxwell NS. Heat alleviation strategies for athletic performance: A review and practitioner guidelines. Temperature ( October 12, 2019). doi: 10.1080/23328940.2019.1666624.
- Gibson OR, Mee JA, Taylor L, Tuttle JA, Watt PW, Maxwell NS, Taylor L, Watt PW, Maxwell NS. Isothermic and fixed-intensity heat acclimation methods elicit equal increases in Hsp72 mRNA. Scand J Med Sci Sports 25: 259–268, 2015.
- Gibson OR, Mee JA, Tuttle JA, Taylor L, Watt PW, Maxwell NS. Isothermic and fixed intensity heat acclimation methods induce similar heat adaptation following short and long-term timescales. J Therm Biol 49–50: 55–65, 2015.
- Gibson OR, Turner G, Tuttle JA, Taylor L, Watt PW, Maxwell NS. Heat acclimation attenuates physiological strain and the HSP72, but not HSP90α, mRNA response to acute normobaric hypoxia. J Appl Physiol 119: 889–99, 2015.
- Gibson OR, Tuttle JA, Watt PW, Maxwell NS, Taylor L. Hsp72 and Hsp90α mRNA transcription is characterised by large, sustained changes in core temperature during heat acclimation. Cell Stress Chaperones 21, 2016.
- Kenny GP, Notley SR, Flouris AD, Grundstein A. Climate Change and Heat Exposure: Impact on Health in Occupational and General Populations. In: Exertional Heat Illness. Springer International Publishing, 2020, p. 225–261.
- Larose J, Boulay P, Wright-Beatty HE, Sigal RJ, Hardcastle S, Kenny GP. Age-related differences in heat loss capacity occur under both dry and humid heat stress conditions. J Appl Physiol 117: 69–79, 2014.
- Michelozzi P, Accetta G, De Sario M, D’Ippoliti D, Marino C, Baccini M, Biggeri A, Anderson HR, Katsouyanni K, Ballester F, Bisanti L, Cadum E, Forsberg B, Forastiere F, Goodman PG, Hojs A, Kirchmayer U, Medina S, Paldy A, Schindler C, Sunyer J, Perucci CA. High Temperature and Hospitalizations for Cardiovascular and Respiratory Causes in 12 European Cities. Am J Respir Crit Care Med 179: 383–389, 2009.
- Public Health England. Heatwave mortality monitoring. 2019.
- Public Health England. Heatwave plan for England Protecting health and reducing harm from severe heat and heatwaves. 2019.
- Willmott AGB, Hayes M, James CA, Dekerle J, Gibson OR, Maxwell NS. Once- and twice-daily heat acclimation confer similar heat adaptations, inflammatory responses and exercise tolerance improvements. Physiol Rep 6: e13936, 2018.
- Willmott AGB, James CA, Hayes M, Gibson OR, Maxwell NS. Heat acclimation attenuates the increased sensations of fatigue reported during acute exercise-heat stress. Temperature (2019). doi: 10.1080/23328940.2019.1664370.
- Yardley J, Sigal RJ, Kenny GP. Heat health planning: The importance of social and community factors. Glob Environ Chang 21: 670–679, 2011
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This is a self funded topic
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