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Long-term cognitive decline was common a year after older adults were hospitalized with SARS-CoV-2 infection, a study in Wuhan, China showed.

Among 1,438 COVID-19 survivors discharged from Wuhan hospitals in early 2020, the incidence of cognitive impairment 12 months later was 12.45%, reported Yan-Jiang Wang, MD, PhD, of Daping Hospital in Chongqing, and co-authors in .

Approximately 3% of COVID-19 survivors had incident dementia, and 9.1% had mild cognitive decline 12 months after discharge. Compared with controls, COVID-19 was associated with a higher risk of early-onset cognitive decline after adjusting for age, sex, education level, body mass index (BMI), and comorbidities, even among people with non-severe SARS-CoV-2 infection (OR 1.71, 95% CI 1.30-2.27).

"In this cohort study of COVID-19 survivors 60 years and older who were discharged from COVID-19-designated hospitals in Wuhan, China, SARS-CoV-2 infection, especially severe infection, was associated with an increase in risk of longitudinal cognitive decline," Wang and colleagues wrote. "The findings highlight the importance of immediate measures to deal with this challenge."

"Over the past 2 years of this pandemic, we've seen some people who have or had COVID-19 experience short- and long-term neurological symptoms, including loss of smell and taste, and cognitive and attention deficits," noted Heather Snyder, PhD, vice president of medical and scientific relations for the Alzheimer's Association in Chicago.

"For some, these neurological symptoms persist, and researchers are working to understand why this brain dysfunction occurs, in whom it occurs, and what that may mean for long-term cognitive health," Snyder told 名媛直播.

"This study adds to our evolving understanding about the connection of COVID-19 and our brains," she continued. "We've seen research with similar results over 6-month follow-up, including reports presented at the Alzheimer's Association International Conference 2021 that suggested an association between COVID-19 and persistent cognitive deficits, including the increased presence of Alzheimer's-related brain changes."

Wang and co-authors studied 1,438 COVID-19 survivors ages 60 and older who were discharged from three COVID-19 hospitals from February 10 to April 10, 2020. COVID-19 was with World Health Organization interim guidance and categorized as following the American Thoracic Society guidelines. A total of 438 uninfected spouses served as a control population.

The researchers excluded people with pre-COVID cognitive impairment, concomitant neurological disorder, family history of dementia, and people with severe cardiac, hepatic, or kidney disease or any kind of tumor. Follow-up monitoring of cognitive function and decline occurred at 6 and 12 months after hospital discharge.

Cognitive status was assessed using the Chinese version of the Telephone Interview of Cognitive Status-40 ), which includes 10 variables and has a maximum of 40 points. A score of 20 or lower indicated mild cognitive impairment, a score of 12 or lower indicated dementia, and a decrease of ≥3 points from 6 to 12 months was considered meaningful.

Of the COVID survivors who completed the 12-month assessment, 48% were men, and median age was 69. COVID survivors were not different from controls in age, sex distribution, education level, BMI, and frequency of comorbidities, including hypertension, diabetes, hyperlipidemia, stroke, coronary heart disease, and chronic obstructive pulmonary disease.

Survivors who had severe COVID had lower 12-month TICS-40 scores than those with non-severe cases and controls. For severe cases, the median TICS-40 score was 22.50; for non-severe cases it was 30.00, and for controls it was 31.00.

Among people with severe cases, incidences of dementia and mild cognitive impairment were 15.00% and 26.15%, respectively. Severe COVID was associated with higher risks of early-onset cognitive decline (OR 4.87, 95% CI 3.30-7.20), late-onset cognitive decline (OR 7.58, 95% CI 3.58-16.03), and progressive cognitive decline (OR 19.00, 95% CI 9.14-39.51) compared with controls.

"It is worth noting that 21% of individuals with severe cases in this cohort experienced progressive cognitive decline, suggesting that COVID-19 may cause long-lasting damage to cognition," Wang and co-authors wrote. "These findings imply that the pandemic may substantially contribute to the world dementia burden in the future."

The study had limitations, the researchers acknowledged. Due to emerging infection risk, validated telephone-based questionnaires were used to assess cognitive function, which may not be as accurate as face-to-face interviews. The researchers lacked information about cognition before SARS-CoV-2 infection, which may have led to an overestimation of the effect of COVID-19 on cognitive decline. The study did not include biomarkers of neuronal injury, and the etiology of cognitive decline could not be determined.

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