So, it comes as no surprise to ICU physicians that the virus can cause delirium. What has been surprising is seeing it on such a large scale and also affecting younger patients. He said COVID-19 makes for a perfect storm to cause delirium. Salem added any fever or infection can also cause delirium, even for patients who are treated at home. However, with other illnesses, this is an indication that dementia or some other neurological complication can affect patients long term.