The categories
Psychiatrist can be as intense or casual as you'd like. Keep things competitive by playing the team version, adding two psychiatrist and keeping score or play the free-for-all version.
Intensity
Keep things casual by playing in one big group, with just one psychiatrist. You can use a three minute time-limit per round or just let the rounds go as long as it takes to diagnose the symptom. Both are fun ways to play.