Anne-Marie, when it became apparant that my husband would not be able to return to work in the foreseeable future after his 1st surgery and radiation, he applied for SSDI.He did not have to meet with anyone personally, but I filled out tons of paperwork[and so did his Docs.] and spent many hours on the phone with our SS case worker. The mental test part may have to do with your son's previous medical history, depresion, etc. Good luck and don't give up. Amy