A new study has shown that between 59% to 65% of patients hospitalised through COVID-19 infection show clinically significant cognitive impairments 4 months after discharge. This is a small study (29 patients and 100 healthy controls) and needs to be confirmed with a larger sample. This work is published in the peer-reviewed journal European Neuropsychopharmacology**.

The researchers, from Copenhagen University Hospital in Denmark, followed 29 patients who had been hospitalised (in the respiratory department) by COVID. 4 months after their discharge, they underwent a series of tests, including cognitive tests: these tests, measuring verbal learning and memory, working memory, verbal fluency, processing speed, and executive function, showed a clinically significant impairment in cognitive performance, in comparison to a matched control group. This impairment was most pronounced in verbal learning and mental flexibility. Patients who had been hospitalised withCOVIDshowed an average globalcognition score of 67, whereas healthy age- and education matched control participants had an average score of 75.

Lead researcher Professor Kamilla Miskowiak said:

“This is the first study we know of which characterises the frequency and pattern of cognitive impairments after hospitalisation with COVID-19. We found that 59-65% of patients had clinically significant problems within learning, memory and mental flexibility and that this was related to poorer work function and quality of life. We need to be cautious expressing the results; it’s a small study, and the cognitive impairment in COVID patients is measured against a control group matched for age and education levels, rather than against previous performance (in e.g. a longitudinal study). Nevertheless, the patients in the study and the control group are very well characterised and the observed differences were of large effect sizes so the main findings seem robust. Based on this, critical care doctors and psychologists at the University Hospital have now included follow-up cognitive tests in standard post-COVID care.

The cognitive difficulties correlated with higher d-dimer levels, which is a marker of blood clots in the lungs, during the infection. They also correlated with the degree of lung dysfunction 4 months after hospital discharge. This may indicate that oxygen supply to the brain could have been compromised during the infection, but this needs to be confirmed.

We need to emphasise again the importance of not catching COVID-19 in the first place and the necessity of preventative measures such as social distancing and vaccination”.

Commenting, the Editor of European Neuropsychopharmacology, Professor Eduard Vieta (Barcelona) said:

“European Neuropsychopharmacology is pleased to publish Professor Miskowiak and coworkers’ report showing cognitive impairments in patients who had been hospitalized with COVID-19 infection. Although it is a small study, it is the first to show the relevance of such cognitive dysfunctions and their impact on daily life. The study does not address the potential occurrence of cognitive impairment in patients with mild -to-moderate COVID-19 (those who were not hospitalized), but given the global spread of the pandemic, it is extremely relevant for a substantial portion of the world’s population. The study also suggests that cognition and intellectual abilities should be further studied, especially in the context of Post-Acute COVID-19 Syndrome”.

Source: European College of Neuropsychopharmacology (ECNP)

Full bibliographic information

Paper details: Cognitive impairments four months after COVID-19 hospital discharge: Pattern, severity and association with illness variables

European Neuropsychopharmacology Volume 46, May 2021, Pages 39-48