How Long

Doctor Joke:

An agitated patient was stomping around the psychiatrist’s office, running his hands through his hair, almost in tears.
"Doctor, my memory’s gone. Gone! I can’t remember my wife’s name. Can’t remember my children’s names. Can’t remember what kind of car I drive. Can’t remember where I work. It was all I could do to find my way here."
"Calm down. How long have you been like this?"
"Like what?"