Cognitive Impairment Increases With COVID-19 Infection Severity


Impairment of cognitive function is a growing, concerning effect of "long COVID."

The risk of cognitive deficit after COVID-19 infection increased with illness severity.

As COVID-19 cases continue to decrease and treatment options improve, public attention is gradually shifting toward life after infection. Specifically, “long COVID,” the post-acute lingering symptoms, have come into focus.

Cognitive and mental health symptoms are of growing concern, with recovered COVID-19 patients reporting fatigue, brain fog, memory problems, trouble sleeping, anxiety, and post-traumatic stress disorder (PTSD) months after infection. One study, published in eClinicalMedicine, examined the association between severe COVID-19 and persistent cognitive deficits.

The investigators examined data from 46 recovered COVID-19 patients who required hospitalization during their infection. The study participants were admitted to Addenbrooke’s Hospital, past of the Cambridge University Hospitals NHS Foundation Trust, between March 10-July 31, 2020. Patient severity ranged from requiring in-hospital care to intensive care unit admission, with 16 of the 46 put on mechanical ventilation.

The participants underwent detailed computerized cognitive assessments measuring anxiety, depression, and PTSD at an average of 6 months after acute infection. Using the Cognitron platform, they completed tests measuring memory, attention, and reasoning. The patients and a matched cohort (n = 66008) were adjusted for age and demographic factors.

The patients who survived severe COVID-19 infection were less accurate and slower in their responses than the matched cohort. Acute illness, not chronic mental health, was a significantly accurate predictor of cognitive deviation from expected scores.

Overall, cognitive deficits after a COVID-19 infection were most correlated with illness severity. Even mild cases, however, could lead to persistent cognitive symptoms. The survivors scored especially poorly on verbal analogical reasoning and processing speed, findings consistent with observations of decreased brain glucose consumption within the frontoparietal network of the brain after COVID-19 infection.

Cognitive impairment after severe COVID-19 infection could be the equivalent to losing 10 IQ points, the study found, a deficit similar to that observed between 50 and 70 years of age. The results showed that these effects are detectable over 6 months after COVID-19 infection, and any recovery is very slow.

“Around 40000 people have been through intensive care with COVID-19 in England alone and many more will have been very sick, but not admitted to hospital,” said Adam Hampshire, PhD, of the Imperial College London’s department of brain sciences and the study’s first author. “This means there is a large number of people out there still experiencing problems with cognition many months later. We urgently need to look at what can be done to help these people.”

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