Background
Preliminary evidence has highlighted a possible association between severe COVID-19 and persistent cognitive deficits . Further research is required to confirm this association, determine whether cognitive deficits are related to clinical characteristics of the acute phase or mental health status at the time of assessment, and quantify the rate of recovery.
Methods
46 people who received intensive care for COVID-19 at Addenbrooke’s Hospital between March 10, 2020 and July 31, 2020 (16 on mechanical ventilation) underwent a detailed computerized cognitive assessment along with scales measuring anxiety , depression and post-traumatic stress disorder under supervised conditions with a mean follow-up up to 6.0 (± 2.1) months after acute illness.
Patient and matched control performances (N = 460) were transformed into standard deviation of expected scores, taking into account age and demographic factors using N = 66,008 normative data sets. Composites of overall accuracy and response time (G_SScore and G_RT) were calculated.
The linear model predicted acute severity composite score deficits, mental health status at assessment, and time since hospital admission. The pattern of task deficits was qualitatively compared to normal age-related decline and early-stage dementia.
Results
COVID-19 survivors were less accurate (G_SScore=-0.53SDs) and slower (G_RT=+0.89SDs) in their responses than expected compared to their matched controls.
Acute illness , but not chronic mental health, significantly predicted cognitive deviation from expected scores (G_SScore (p = 0.0037) and G_RT (p = 0.0366)). The most prominent task associations with COVID-19 were high cognition and processing speed, which was qualitatively distinct from the profiles of normal aging and dementia and similar in magnitude to the effects of aging between ages 50 and 70. A trend toward reduced deficits with time since illness (r∼=0.15) did not reach statistical significance.
Figure 1 Analysis of composite deviation of expected cognitive performance scores A. Analysis of DfE composite scores showed that COVID-19 survivors were, on average, less accurate and slower to respond than expected given their age and demographic profiles. The scale is standard deviation units relative to the control population. B. Left. Clinical characteristics of the acute phase, age, sex, and mental health and time since illness at the time of assessment showed strong correlations with clear natural clustering of acute clinical severity versus mental health scores in the moment of the cognitive evaluation. Color represents bivariate correlation strength where yellow = 1 and dark blue = -1. Good. Principal component analysis identified three components with eigenvalues greater than 1. Center. After varimax rotation, one overall component included heavy loadings of acute illness severity, a second component loaded more toward respiratory support features, and a third component included high loadings of depression, anxiety, and PTSD questionnaires. C. Acute clinical severity (component 1) showed statistically significant correlations with DfE composite scores that had a medium effect size. (X-axis is the clinical component score. Y-axis is the DfE score in SD units relative to the control population.)
Interpretation Cognitive deficits after severe COVID-19 are more strongly related to the severity of the acute illness , persist for a long time in the chronic phase, and recover slowly, if at all, with a characteristic profile that highlights more cognitive functions. high and processing speed. |
Research in context
Evidence before this study
A PubMed search for articles using the terms ’COVID-19’, ’chronic’ and ’cognitive impairment’ returns 85 results between 2020 and 2022, reflecting growing concern that people may suffer persistent cognitive problems after SARS-CoV-2 infection. However, most of these studies have relied on subjective reports of cognitive problems or brief paper-and-pencil rating scales that lack sensitivity to mild deficits and precision with respect to the cognitive domains affected.
Added value of this study
Using precision computerized cognitive assessment tools, we observed that 46 COVID-19 patients matched for age, gender, education and first language, 6 to 10 months after admission for care at Addenbrookes Hospital perform worse than controls in terms of cognition. Critically, the scale of their cognitive deficits was correlated with the severity of acute illness recorded during the hospital stay, but not with fatigue or mental health status at the time of cognitive assessment.
Implications of all available evidence
These results suggest that patients who have recovered from severe COVID-19 may require longer-term support for cognitive deficits that persist in the chronic phase. More research is required to understand the basis for these deficits. Future work will focus on mapping these cognitive deficits to underlying neural pathologies and inflammatory biomarkers, and longitudinally tracing recovery to the chronic phase.
Final message In summary, severe COVID-19 disease is associated with significant objectively measurable cognitive deficits that persist into the chronic phase. The scale of deficits correlates with clinical severity during the acute phase as opposed to mental health status at the time of assessment, shows at best a slow recovery trajectory, and the multivariate profile of deficits is consistent. with greater cognitive dysfunction as opposed to accelerated aging or dementia. |
