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Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults

Melitta McNarry Orcid Logo, Kelly Mackintosh Orcid Logo

Experimental Physiology

Swansea University Authors: Melitta McNarry Orcid Logo, Kelly Mackintosh Orcid Logo

Abstract

Ageing is associated with cognitive decline and increased risk of developing neurodegenerative disease. Repeated passive heating, using hot water immersion (HWI), may improve cognitive performance via improved cerebral oxygenation, but this is yet to be examined in older adults. Twelve healthy older...

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Published in: Experimental Physiology
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URI: https://cronfa.swan.ac.uk/Record/cronfa71737
first_indexed 2026-04-13T19:52:57Z
last_indexed 2026-04-14T04:53:28Z
id cronfa71737
recordtype SURis
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spelling 2026-04-13T20:52:55.9476808 v2 71737 2026-04-13 Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults 062f5697ff59f004bc8c713955988398 0000-0003-0813-7477 Melitta McNarry Melitta McNarry true false bdb20e3f31bcccf95c7bc116070c4214 0000-0003-0355-6357 Kelly Mackintosh Kelly Mackintosh true false 2026-04-13 EAAS Ageing is associated with cognitive decline and increased risk of developing neurodegenerative disease. Repeated passive heating, using hot water immersion (HWI), may improve cognitive performance via improved cerebral oxygenation, but this is yet to be examined in older adults. Twelve healthy older adults (aged: 69.2 ± 10.0 years; body mass index: 25.2 ± 4.1 kg·m2) completed a six-week pre-post intervention study consisting of two to three weekly one-hour HWIs in 40°C water. Rectal temperature was maintained in a target range of 38.5-39.0°C during HWI. Cognitive performance (working memory via 1 and 2-back, inhibition via 2-choice reaction time, logical reasoning via logical relations) and cerebral oxygenation (Δoxyhaemoglobin, Δdeoxyhaemoglobin, Δtotal haemoglobin, and Δtissue saturation index) were assessed during the first and final HWI sessions (pre-, immediately post-, and 3-hours post-HWI). Common carotid artery blood flow (CCA-BF), sleep quality (7-day baseline and final week), plasma [amyloid-beta] 42 (Aβ42), and [phosphorylated tau] (p-tau), were measured pre- and post-intervention. Repeated HWI improved 1-back (P = 0.023) and logical reasoning (P = 0.002) performance, but not 2-back or 2-choice reaction time (P > 0.05). Cerebral oxygenation was acutely reduced immediately post-HWI (all parameters P < 0.05), but returned to baseline three hours post-HWI, with no chronic adaptation. CCA-BF, sleep quality, [Aβ42], and [p-tau] all remained unchanged at 6-weeks (P > 0.05). Repeated HWI improves cognitive domains of logical reasoning and working memory without altering cerebral oxygenation, CCA-BF, sleep or neurodegenerative biomarkers. Further investigation into the underlying mechanisms for cognitive performance improvements via HWI is warranted. Journal Article Experimental Physiology 0 0 0 0001-01-01 COLLEGE NANME Engineering and Applied Sciences School COLLEGE CODE EAAS Swansea University 2026-04-13T20:52:55.9476808 2026-04-13T20:49:37.9622244 Melitta McNarry 0000-0003-0813-7477 1 Kelly Mackintosh 0000-0003-0355-6357 2
title Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
spellingShingle Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
Melitta McNarry
Kelly Mackintosh
title_short Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
title_full Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
title_fullStr Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
title_full_unstemmed Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
title_sort Effect of repeated hot water immersion on cognitive performance, cerebrovascular function, sleep, and biomarkers of neurodegeneration in older adults
author_id_str_mv 062f5697ff59f004bc8c713955988398
bdb20e3f31bcccf95c7bc116070c4214
author_id_fullname_str_mv 062f5697ff59f004bc8c713955988398_***_Melitta McNarry
bdb20e3f31bcccf95c7bc116070c4214_***_Kelly Mackintosh
author Melitta McNarry
Kelly Mackintosh
author2 Melitta McNarry
Kelly Mackintosh
format Journal article
container_title Experimental Physiology
institution Swansea University
document_store_str 0
active_str 0
description Ageing is associated with cognitive decline and increased risk of developing neurodegenerative disease. Repeated passive heating, using hot water immersion (HWI), may improve cognitive performance via improved cerebral oxygenation, but this is yet to be examined in older adults. Twelve healthy older adults (aged: 69.2 ± 10.0 years; body mass index: 25.2 ± 4.1 kg·m2) completed a six-week pre-post intervention study consisting of two to three weekly one-hour HWIs in 40°C water. Rectal temperature was maintained in a target range of 38.5-39.0°C during HWI. Cognitive performance (working memory via 1 and 2-back, inhibition via 2-choice reaction time, logical reasoning via logical relations) and cerebral oxygenation (Δoxyhaemoglobin, Δdeoxyhaemoglobin, Δtotal haemoglobin, and Δtissue saturation index) were assessed during the first and final HWI sessions (pre-, immediately post-, and 3-hours post-HWI). Common carotid artery blood flow (CCA-BF), sleep quality (7-day baseline and final week), plasma [amyloid-beta] 42 (Aβ42), and [phosphorylated tau] (p-tau), were measured pre- and post-intervention. Repeated HWI improved 1-back (P = 0.023) and logical reasoning (P = 0.002) performance, but not 2-back or 2-choice reaction time (P > 0.05). Cerebral oxygenation was acutely reduced immediately post-HWI (all parameters P < 0.05), but returned to baseline three hours post-HWI, with no chronic adaptation. CCA-BF, sleep quality, [Aβ42], and [p-tau] all remained unchanged at 6-weeks (P > 0.05). Repeated HWI improves cognitive domains of logical reasoning and working memory without altering cerebral oxygenation, CCA-BF, sleep or neurodegenerative biomarkers. Further investigation into the underlying mechanisms for cognitive performance improvements via HWI is warranted.
published_date 0001-01-01T05:43:14Z
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score 11.102276

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