Data from 253 adults with mild cognitive impairment or Alzheimer's disease revealed significant declines in cognitive function and functional abilities over time.
Cognitive function and functional abilities declined more sharply in individuals with higher Alzheimer's severity.
The COVID-19 lockdown was linked to increased cognitive decline and impairment in daily living activities, particularly in the most severe Alzheimer's group.
Instrumental activities of daily living were found to mediate the relationship between cognitive scores and overall dementia severity in less severe groups.
In the moderate Alzheimer's group, a significant interaction indicated that worsening neuropsychiatric symptoms intensified cognitive decline.
Neuropsychiatric symptoms worsened over time, while depressive symptoms remained stable throughout the study period.
Simplified
The progression of Alzheimer's disease () 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 (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.
Key numbers
0.137
Cognitive Decline Rate
Average decrease in scores per year
0.106
Dementia Severity Increase
Average increase in CDR-SB scores per year
0.002
ADL Decline During Lockdown
Significant decline in ADL performance in the -CDR2 group during lockdown
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Declarations. Competing interests: The authors declare no competing interests. Ethics approval and consent to participate: This study was approved by the Institutional Review Board (IRB) of Seoul National University Boramae Medical Center (Approval Number: 10-2020-295). The requirement for informed consent was waived due to the retrospective nature of the study, as all data were anonymized and de-identified prior to analysis. The study adhered to the principles of the Helsinki Declaration.
