Story at a glance
- The CDC estimates 1 in 5 people who had a COVID-19 infection may have long COVID, or symptoms that persist after infection has passed.
- A new study suggests that people with long COVID have lower brain oxygen levels.
- The results also suggest that people with long COVID may suffer from cognitive dysfunction.
Researchers find evidence that people who had a previous COVID-19 infection have lower brain oxygen levels, in a new paper published in Brain, Behavior, & Immunity – Health.
The authors combined results from two parallel studies that suggest symptomatic COVID-19 history has a significant impact on cognitive functioning and may be explained by lower oxygen levels in the brain.
One of the studies was based in a laboratory where researchers compared cognitive function on computer tasks and oxygen saturation in the prefrontal cortex of the brain. Of the 120 participants, all were vaccinated and 52 had a prior COVID-19 infection. The computer tasks measured executive function, decision making and reaction time.
The researchers found that previous infection most affected executive functioning, like memory and focus. For this group, there was also lower oxygen in the right side of the frontal cortex, where they would have expected oxygen levels to increase during the tasks.
The studies bring new understanding on how long COVID may develop. “We are the first to show reduced oxygen uptake in the brain during a cognitive task in the months following a symptomatic COVID-19 infection,” says Peter Hall, who is lead author and researcher in the School of Public Health Sciences at the University of Waterloo, in a press release. “This is important because a lack of sufficient oxygen supply is thought to be one of the mechanisms by which COVID-19 may cause cognitive impairment.”
The other study involved two waves of surveys conducted in Canada between September 2021 and March 2022. The survey asked about symptomatic COVID-19 and self-reported symptoms six months later of cognitive dysfunction, depressive symptoms, anxiety symptoms or agitation.
Participants in this study with a past case of symptomatic COVID-19 self-reported cognitive issues and psychiatric symptoms like depression and anxiety months after a coronavirus infection.
The authors think that the cognitive dysfunction is linked to the psychiatric symptoms. “It appears that, regardless of gender and other demographic factors, COVID-19 infection at baseline is correlated with increased problems with emotion regulation six months later: depression, anxiety and agitation. In some cases, we are talking about symptom levels that are at or above recommended as cut-off scores for psychiatric diagnoses,” Hall says in the press release.
The Centers for Disease Control and Prevention estimates that 1 in 5 Americans who had COVID-19 may have long COVID. Worldwide, an estimated 65 million people may be suffering from the syndrome.
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