And many “long-haulers,” or COVID-19 patients who have continued showing symptoms for months after the initial infection passed, report neurological problems such as confusion and difficulty concentrating (or brain fog), as well as headaches, extreme fatigue, mood changes, insomnia and loss of taste and/or smell.

Indeed, the CDC recently warned that it takes longer to recover from COVID-19 than the 10- to 14-day quarantine window that has been touted throughout the pandemic. In fact, one in five young adults under 34 was not back to their usual health up to three weeks after testing positive. And 35% of surveyed U.S. adults overall had not returned to their normal state of health when interviewed two to three weeks after testing.

Now a study of 60 COVID-19 patients published in Lancet this week finds that 55% of them were still displaying such neurological symptoms during follow-up visits three months later. And when doctors compared brain scans of these 60 COVID patients with those of a control group who had not been infected, they found that the brains of the COVID patients showed structural changes that correlated with memory loss and smell loss.