Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea

Abstract The progression of Alzheimer’s disease (AD) and its interaction with COVID-19-induced social isolation remains poorly understood. This study investigated the longitudinal trajectories of AD severity on cognitive function, functional ability, and neuropsychiatric symptoms, and examined the i...

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Main Authors: Hahyun Lee, Soojin Shin, Gieun Nam, Seyul Kwak, Yoon Soo Cho, Eunji Hwang, Sohee Oh, So Yoon Kim, So Young Yoo, Jun-Young Lee
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-92497-5
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author Hahyun Lee
Soojin Shin
Gieun Nam
Seyul Kwak
Yoon Soo Cho
Eunji Hwang
Sohee Oh
So Yoon Kim
So Young Yoo
Jun-Young Lee
author_facet Hahyun Lee
Soojin Shin
Gieun Nam
Seyul Kwak
Yoon Soo Cho
Eunji Hwang
Sohee Oh
So Yoon Kim
So Young Yoo
Jun-Young Lee
author_sort Hahyun Lee
collection DOAJ
description Abstract The progression of Alzheimer’s disease (AD) and its interaction with COVID-19-induced social isolation remains poorly understood. This study investigated the longitudinal trajectories of AD severity on cognitive function, functional ability, and neuropsychiatric symptoms, and examined the impact of COVID-19 lockdown on AD patients in South Korea. In this retrospective longitudinal study, data from 253 adults (aged ≥ 55) diagnosed with mild cognitive impairment (MCI) or AD were analyzed, collected between 2018 and 2022. Participants were classified into four groups based on clinical dementia rating (CDR) scores: MCI, AD-CDR0.5, AD-CDR1, and AD-CDR2. Cognitive function, functional abilities, neuropsychiatric symptoms, depressive symptoms, and overall dementia severity were assessed. Linear mixed-effects models, along with mediation and moderation analyses were employed to analyze the data. Significant trajectories of decline in cognitive function and functional abilities were observed over time, with more pronounced declines in higher AD severity groups. The COVID-19 lockdown exacerbated cognitive decline and impairment in activities of daily living (ADL) specifically in the most severe AD group (AD-CDR2). Instrumental activities of daily living (IADL) mediated the relationship between mini-mental state examination (MMSE) scores and CDR sum of boxes (CDR-SB) in the MCI, AD-CDR0.5, and AD-CDR1 groups. A significant interaction between MMSE scores and neuropsychiatric symptoms was observed in the moderate AD group (AD-CDR1), indicating that worsening neuropsychiatric symptoms intensified cognitive decline. Neuropsychiatric Inventory (NPI) scores increased over time, indicating worsening neuropsychiatric symptoms, whereas depressive symptoms, measured by the short geriatric depression scale (SGDS), remained stable over the study period. This study highlights the impact of AD severity on cognitive and functional decline, further exacerbated by the COVID-19 lockdown. The mediating role of IADL suggests that maintaining complex daily activities may be crucial in slowing disease progression in AD patients. Additionally, the worsening of neuropsychiatric symptoms underscores the need for targeted mental health support, especially during periods of social isolation, to mitigate adverse effects on patients and caregivers.
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spelling doaj-art-de45eb0b463846ea9bd9bf9a38b9d2c42025-08-20T02:59:24ZengNature PortfolioScientific Reports2045-23222025-03-0115111210.1038/s41598-025-92497-5Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South KoreaHahyun Lee0Soojin Shin1Gieun Nam2Seyul Kwak3Yoon Soo Cho4Eunji Hwang5Sohee Oh6So Yoon Kim7So Young Yoo8Jun-Young Lee9Interdisciplinary Program in Cognitive Science, Seoul National UniversityDepartment of Psychiatry, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterDepartment of Psychiatry, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterDepartment of Psychiatry, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterKeimyung University School of MedicineDepartment of Psychiatry, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterMedical Research Collaborating Center, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterGraduate school of Public Health, Yonsei UniversityDepartment of Psychiatry, Seoul Metropolitan Government-Seoul National University Boramae Medical CenterInterdisciplinary Program in Cognitive Science, Seoul National UniversityAbstract The progression of Alzheimer’s disease (AD) and its interaction with COVID-19-induced social isolation remains poorly understood. This study investigated the longitudinal trajectories of AD severity on cognitive function, functional ability, and neuropsychiatric symptoms, and examined the impact of COVID-19 lockdown on AD patients in South Korea. In this retrospective longitudinal study, data from 253 adults (aged ≥ 55) diagnosed with mild cognitive impairment (MCI) or AD were analyzed, collected between 2018 and 2022. Participants were classified into four groups based on clinical dementia rating (CDR) scores: MCI, AD-CDR0.5, AD-CDR1, and AD-CDR2. Cognitive function, functional abilities, neuropsychiatric symptoms, depressive symptoms, and overall dementia severity were assessed. Linear mixed-effects models, along with mediation and moderation analyses were employed to analyze the data. Significant trajectories of decline in cognitive function and functional abilities were observed over time, with more pronounced declines in higher AD severity groups. The COVID-19 lockdown exacerbated cognitive decline and impairment in activities of daily living (ADL) specifically in the most severe AD group (AD-CDR2). Instrumental activities of daily living (IADL) mediated the relationship between mini-mental state examination (MMSE) scores and CDR sum of boxes (CDR-SB) in the MCI, AD-CDR0.5, and AD-CDR1 groups. A significant interaction between MMSE scores and neuropsychiatric symptoms was observed in the moderate AD group (AD-CDR1), indicating that worsening neuropsychiatric symptoms intensified cognitive decline. Neuropsychiatric Inventory (NPI) scores increased over time, indicating worsening neuropsychiatric symptoms, whereas depressive symptoms, measured by the short geriatric depression scale (SGDS), remained stable over the study period. This study highlights the impact of AD severity on cognitive and functional decline, further exacerbated by the COVID-19 lockdown. The mediating role of IADL suggests that maintaining complex daily activities may be crucial in slowing disease progression in AD patients. Additionally, the worsening of neuropsychiatric symptoms underscores the need for targeted mental health support, especially during periods of social isolation, to mitigate adverse effects on patients and caregivers.https://doi.org/10.1038/s41598-025-92497-5Alzheimer’s diseaseCOVID-19 lockdownCognitive declineFunctional abilityNeuropsychiatric symptoms
spellingShingle Hahyun Lee
Soojin Shin
Gieun Nam
Seyul Kwak
Yoon Soo Cho
Eunji Hwang
Sohee Oh
So Yoon Kim
So Young Yoo
Jun-Young Lee
Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
Scientific Reports
Alzheimer’s disease
COVID-19 lockdown
Cognitive decline
Functional ability
Neuropsychiatric symptoms
title Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
title_full Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
title_fullStr Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
title_full_unstemmed Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
title_short Longitudinal trajectories of cognitive, functional, and neuropsychiatric decline in Alzheimer’s disease during COVID-19 lockdown in South Korea
title_sort longitudinal trajectories of cognitive functional and neuropsychiatric decline in alzheimer s disease during covid 19 lockdown in south korea
topic Alzheimer’s disease
COVID-19 lockdown
Cognitive decline
Functional ability
Neuropsychiatric symptoms
url https://doi.org/10.1038/s41598-025-92497-5
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