Reaction time slower among those with long COVID

CHICAGO – Rates of reaction times were slower among individuals who had long COVID compared with healthy counterparts, a researcher showed in a poster presentation at the 2022 American Neurological Association meeting.

“What we found is that compared to healthy controls who don't have long COVID symptoms — and in fact, only six of them had COVID-19 ever — people with long COVID-19 worked slower to start off with and slower at the end [of the trial],” William Hayward, MD, PhD, an NIH clinical fellow, told Healio.

Hayward and colleagues assessed reaction time and procedural memory among 197 participants (94 with long COVID, 103 healthy) to determine if participants could learn and consolidate a procedural memory skill assessment.

All participants underwent a reaction time test, then a procedural memory test, followed by another reaction time test before completing a baseline questionnaire.

“Then we tested them again 24 hours later, roughly, all done online,” Hayward said. “And 24 hours later, [the results] still weren't as good. But they showed the same pattern of consolidation.”

According to Hayward, reaction times were slower among the long COVID group, but learning rates were the same among both groups.

“So [participants with long COVID] learned just as well, which is great,” he said. “But what's peculiar to us is that they weren't as good to begin with, and they never became as good as healthy controls at this simple task.”

In addition, even though the reaction time among participants with long COVID was slower, it was not much slower than in healthy controls.

“They're slower,” he said. “However, it's about 40 milliseconds. Statistically, it’s really a big deal, because they have about 10 trials per person, and that's a big number. But it's 40 milliseconds.”

Hayward said that he was reassured by the similar learning times between the two groups.

“But we need to learn, why are they slower to begin with? And, really, is this related to this concept of brain fog? Because, obviously, that was my big question,” Hayward said. “What is brain fog? Is it procedural? This suggests to me that it's somehow related to the ability to get things out quickly. It's something related to speed, but not learning, which is good.”