Well... at least the way I see it.... especially being someone who has severe ADHD, and who is medicated and talks to a therapist weekly.... as long as you're not being CRAZY offensive about medications, real-life struggles of patients, etc, and giving guests "Xanax cocktails" or "Valium chip cookies", I wouldn't worry. Honestly, even if you did, I wouldn't be offended, but that's just me. Doctors can be intimidating and are scary. Mean nurses are scary. Homicidal patients ARE scary, regardless of affliction. Terrible treatments from the past are scary and send chills up your spine. That's Halloween. Part of the fun is not being your 100% politically correct self during this fabulous time of year. You're given free reign to laugh and honor the dark side of life... so why not?
It's almost like saying, "Well, I know someone who has experienced death, so it's not really appropriate to have a coffin, or skeletons, or ghosts". Or... "I know a Wiccan, so gallows or a prop of a witch burnt at the stake must be REALLY offensive and wrong... so I'll change my theme to accommodate society". Nuh-uh, honeybee. Do what you WANT. This is YOUR day, just as much as it's everyone else's.
If you're still worried, I would keep it vintage, dark , and give it a 50 year grace and political correctness period. Think pre-1970s, so electro-shock, straight jackets, vintage sexy/scary nurses, vintage medical instruments, etc are all fair game to me. The mental health field ain't what it used to be... what better way to forgive and forget than to have some fun with this theme on Halloween? The day when you're allowed to be your SCARY self?
Acknowledge the TRUE horrors of the past that happened in the real world of mental health during every month that isn't October... but it's Halloween time. As long as you stay away from medications, etc.... I can't see any way that someone would (or SHOULD, truly) be offended, unless they WANT to be offended. I've been to some very popular haunted houses that have carried some controversial themes such as a work-camp-esque, World War II/1950s theme, but did so tastefully... It's almost as if they are paying homage in a very strange, weird (it's HALLOWEEN) way to the horrors of the past, and reminding us of how far we've come from them. Like "Oh crap, that happened... let's never let those horrible things happen again". It's like an unconventional memorial. That's what Halloween is. Letting the darkness of life shine through for a short while, instead of stifling it away like society likes to try and make us do.
Allow yourself to HAVE FUN.
*Sorry for the essay. I just hate to see people's inner demons shoved deep down inside when this is the time to let 'em rip, baby!