Association between surgical admissions, cognition, and neurodegeneration in older people: a population-based study from the UK Biobank

Background Previous studies have shown that major surgical and medical hospital admissions are associated with cognitive decline in older people (aged 40-69 years at recruitment), which is concerning for patients and caregivers. We aimed to validate these findings in a large cohort and investigate associations with neurodegeneration using MRI. Methods For this population-based study, we analysed data from the UK Biobank collected from March 13, 2006, to July 16, 2023, linked to the National Health Service Hospital Episode Statistics database, excluding participants with dementia diagnoses. We constructed fully adjusted models that included age, time, sex, Lancet Commission dementia risk factors, stroke, and hospital admissions with a participant random effect. Primary outcomes were hippocampal volume and white matter hyperintensities, both of which are established markers of neurodegeneration, and exploratory analyses investigated the cortical thickness of Desikan-Killiany-Tourville atlas regions. The main cognitive outcomes were reaction time, fluid intelligence, and prospective and numeric memory. Surgeries were calculated cumulatively starting from 8 years before the baseline evaluation. Findings Of 502 412 participants in the UK Biobank study, 492 802 participants were eligible for inclusion in this study, of whom 46 706 underwent MRI. Small adverse associations with cognition were found per surgery: reaction time increased by 0<middle dot>273 ms, fluid intelligence score decreased by 0<middle dot>057 correct responses, prospective memory (scored as correct at first attempt) decreased (odds ratio 0<middle dot>96 [95% CI 0<middle dot>95 to 0<middle dot>97]), and numeric memory maximum correct matches decreased by 0<middle dot>025 in fully adjusted models. Surgeries were associated with smaller hippocampal volume (beta=-5<middle dot>76 mm(3) [-7<middle dot>89 to -3<middle dot>64]) and greater white matter hyperintensities volume (beta=100<middle dot>02 mm(3) [66<middle dot>17 to 133<middle dot>87]) in fully adjusted models. Surgeries were also associated with neurodegeneration of the insula and superior temporal cortex. Interpretation This population-based study corroborates that surgeries are generally safe but cumulatively are associated with cognitive decline and neurodegeneration. Perioperative brain health should be prioritised for older and vulnerable patients, particularly those who have multiple surgical procedures. Copyright (c) 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).