Over half of long COVID patients experience cognitive slowing

For the study, researchers analyzed data from 270 patients who had been diagnosed with long COVID at two different clinics, one in Germany and the other in the United Kingdom. In the first cohort, there were 194 patients with long COVID, and in the second cohort, there were 76 patients.

The mean time from COVID-19 diagnosis among the patients was 326 days, and 20% had been hospitalized during their infection. All participants completed the study between May 2021 and July 2023.

During the study, participants completed two web-based cognitive tasks: the Simple Reaction Time (SRT) task and the Number Vigilance Test (NVT), which is a visual sustained attention task. Then, their results were compared to two control groups. One control group was COVID-19 patients who did not have long COVID, and the other was patients who had never had COVID.

Overall, the researchers found that participants with long COVID had significantly slower reaction times than participants in the control groups. While the average reaction time in the control groups was 0.34 seconds, participants with long COVID had a reaction time of 0.49 seconds. Over half of participants with long COVID (53.5%) had a reaction time that was two standard deviations slower than the control mean.

Long COVID patients also took significantly longer to react to targets on the NVT compared to those in the control groups. This slower time was also maintained across the entire test and could not be explained by participants trading speed for accuracy.

Long COVID patients who had not been hospitalized also showed substantial cognitive slowing when compared to non-hospitalized COVID-19 patients. "This indicates that the cognitive slowing observed in post-COVID-19 conditions was not merely due to the acute illness of COVID-19," the researchers wrote.

According to Sijia Zhao, the study's lead author from the University of Oxford, the study is the first to identify an objective cognitive marker for long COVID. "Importantly, this marker can be reliably and easily measured using a 30-second web-based task, so it has potential to be a marker to track the progress of rehabilitation of long COVID," the researchers said.

However, the researchers also acknowledged several limitations of the study, including a lack of comprehensive neuropsychological assessments for participants and the fact that cognitive symptoms were not present in all long COVID patients.

Going forward, additional research should incorporate more comprehensive neuropsychological tests and include a larger, more diverse patient cohort. (George, MedPage Today, 2/1; Soucheray, CIDRAP, 1/29; de Souza, News Medical, 1/29; Zhao et al., eClinicalMedicine, 1/25)

According to an  analysis  published in JAMA Internal Medicine, six factors could significantly increase your risk of developing long COVID — and one factor could protect you.