COVID-19 May Have Long-Term Effects on the Brain

COVID-19 has proven capable of affecting nearly every part of the body—including the brain. A study of 1.28 million people who had the disease, published Aug. 17 in the Lancet Psychiatry, sheds light on the often complex, and sometimes long-term, impacts of COVID-19 on the minds of kids and adults.

Analyzing data from patients in the U.S. and several other countries, researchers found that within the first two months of getting COVID-19, people were more likely to experience anxiety and depression than people who got a different type of respiratory infection. And for up to two years after, people remained at greater risk for conditions such as brain fog, psychosis, seizures, and dementia.

Long COVID—marked by at least one symptom that lingers for months after COVID-19—is a growing problem worldwide. Earlier research from the U.S. Centers for Disease Control and Prevention (CDC) estimates that roughly one in five people in the U.S. who gets COVID-19 develops it. This week’s study helps researchers further understand the manifestations of Long COVID.

The results “highlight the need for more research to understand why this happens after COVID-19, and what can be done to prevent these disorders from occurring, or treat them when they do,” said Maxime Taquet, the study’s lead author and a senior research fellow at the University of Oxford, in a statement.

Researchers found that the risks of poor neurological or psychiatric outcomes after infection with Delta were higher than the risks after infection with the original variant—and about the same as the risks after Omicron. The effects also varied by age group. Older adults ages 65 and up who had COVID-19 experienced brain fog, dementia, and psychotic disorders at a higher rate compared to adults of the same age who had other respiratory infections.

Read More: You Could Have Long COVID and Not Even Know It

Among COVID-19 patients in this age group, 450 cases of dementia were found per 10,000 people, compared to 330 cases per 10,000 people who had other respiratory infections. Brain fog occurred at a higher rate, too: there were 1,540 cases per 10,000 people infected with COVID-19, compared to 1,230 cases per 10,000 people with other infections.

The results were less dramatic for younger groups. There was little difference in dementia risk for people 64 years and younger who had either COVID-19 or another respiratory infection. For brain fog, there were 640 cases per 10,000 people who had COVID-19, compared to 550 cases per 10,000 people who had different respiratory infections.

Although children had a lower overall risk of poor brain outcomes compared to adults, they were still twice as likely to develop epilepsy or seizures within two years of being infected with COVID-19 (260 cases in 10,000) compared to children who had other respiratory infections. And while the risk of kids being diagnosed with a psychotic disorder remained low, the study authors did see an increase among children who had COVID-19 (18 in 10,000) compared to kids who had other respiratory infections (6.3 in 10,000).

Meanwhile, the risk of anxiety and depression wasn’t any greater for children who had COVID-19 than for those who had other respiratory infections. While mood and anxiety disorders were shown to peak during SARS-CoV-2 infections, these risks returned to a baseline after two months, after which the risk of anxiety and depression actually decreased among all ages studied.

“It is good news that the excess of depression and anxiety diagnoses after COVID-19 is short-lived, and that it is not observed in children,” said study author Paul Harrison, a professor in Oxford’s psychiatry department, in a statement. “However, it is worrying that some other disorders, such as dementia and seizures, continue to be more likely diagnosed after COVID-19, even two years later.”