And patients with altered mental function had significantly worse medical outcomes, according to the study, published on Monday in Annals of Clinical and Translational Neurology. The study looked at the records of the first 509 coronavirus patients hospitalized, from March 5 to April 6, at 10 hospitals in the Northwestern Medicine health system in the Chicago area.

These patients stayed three times as long in the hospital as patients without altered mental function.

After they were discharged, only 32 percent of the patients with altered mental function were able to handle routine daily activities like cooking and paying bills, said Dr. Igor Koralnik, the senior author of the study and chief of neuro-infectious disease and global neurology at Northwestern Medicine. In contrast, 89 percent of patients without altered mental function were able to manage such activities without assistance.