The doctor says he’s OK to work, but his behavior says otherwise–what can we do?

Q: “An employee drank heavily after work and at his home, and fell down a flight of stairs. It took him a couple of days to go to the doctor, where he was found to have swelling in his brain. He has now returned to work with no restrictions from his doctor, but he is exhibiting mentally challenged behavior. What are our options? I am asking our office supervisor at that location to document everything for the time being.” – Patricia, Wisconsin