People who died of severe COVID-19 had brain tissue similar to that of people who were at least 71 years old, prompting Harvard Medical School researchers to recommend that recovered COVID-19 patients seek neurological follow-up care.

The new study adds molecular-level findings to the growing body of evidence that severe and long COVID add to thinking problems sometimes referred to as “brain fog.”

“Ours is the first study to show that COVID-19 is associated with the molecular signatures of brain aging,” author Maria Mavrikaki, PhD, an instructor of pathology at Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School, said in a news release. “We found striking similarities between the brains of patients with COVID-19 and aged individuals.”

Researchers looked at 54 brain tissue samples from people ages 22 to 85. Samples from people who died of severe COVID-19 were compared to brain tissue of people of the same age and gender who did not have a history of neurological or psychiatric disease. Another comparison was made of a person who had both severe COVID and Alzheimer’s disease to a patient who had Alzheimer’s but not COVID-19. A third evaluation set was of samples from people with and without COVID-19 who had a history of intensive care or ventilator treatment. 

“While we did not find evidence that the SARS-CoV-2 virus was present in the brain tissue at the time of death, we discovered inflammatory patterns associated with COVID-19,” said co-author Jonathan Lee, PhD, a postdoctoral research fellow at BIDMC and Harvard Medical School. “This suggests that this inflammation may contribute to the aging-like effects observed in the brains of patients with COVID-19 and long COVID.”

The study was published in the journal Nature Aging this month.

“Given our findings, we advocate for neurological follow-up of individuals who recovered from COVID-19 and suggest potential clinical value in modifying risk factors to reduce the risk or delay the development of aging-related neurological pathologies and cognitive decline,” the researchers wrote.