COVID-19 Infections and Cognitive Function

Abstract

Importance: Long-term health effects of COVID-19 infections are a major public health concern. This study investigates associations between COVID-19 infections and cognitive function.

Objective: To determine if COVID-19 infection has a detrimental effect on cognitive function.

Design: We use the nationally representative probability-based Understanding America Study (UAS) of approximately 9,600 respondents, which has regularly elicited measures of cognitive function since 2015. Collection of cognition measures took place before and during the pandemic, solely determined by a two-year cycle depending on when respondents joined the study. In addition, between March 10, 2020, and July 20, 2021, 8554 study members have participated in a COVID-19 tracking survey (29 waves total), regularly answering questions about their experiences during the pandemic, including symptoms and whether they have been infected. We tested whether cognitive change differed between respondents who experienced COVID-19 and those who did not.

Setting: The UAS is a longitudinal study of U.S. residents who have been recruited from probability-based samples of postal addresses. Respondents answer questions over the Internet once or twice a month. Respondents without prior Internet access have been provided with Internet enabled computer tablets.

Participants: U.S. residents 18 years of age or older.

Exposure: Self-reported coronavirus infection or diagnosis. COVID-19 risk for the UAS sample was the same as for the general U.S. population.

Main outcomes: Six cognitive tests (Numeracy; Number Series, Picture Vocabulary, Verbal Analogies; Serial Sevens; Financial Literacy). Two subjective cognition measures (Self-rated Memory and Memory Change).

Results: All six cognitive tests, measured before January 1, 2020, are significant predictors of infection status during the pandemic. The two subjective cognition measures show no significant association with infection. We replicate earlier cross-sectional findings of a negative association between COVID-19 infection and subsequent cognition. However, once accounting for baseline cognition, no significant associations are found for either the tests or the subjective measures. For three of the six cognitive tests the effects change signs.

Conclusions and relevance: We find no evidence for a negative association between COVID-19 infection and subsequent measures of cognitive functioning. The associations found in earlier studies may at least partly reflect reverse causation.

Keywords: cognitive functioning, longitudinal, COVID-19, surveys, pandemic