Ways to treat depression, raise happiness would be nice. I've really never found a good way to raise happiness from 0 other than spamming tons of items, and the centre seems to be the obvious place to do so.
Also, rehab seems to take 3 days no matter what, and it seems like having an A rank drug councilor should make the process go faster, while having an E rank or no one at all should make it go slower or flat out fail.
Other than that, maybe a way to remove certain negative mental traits like Twisted, Merciless, Pessimist, Yandere, etc.
On a slightly off topic note, do former drug addicts already have a built in relapse chance? Because it seems like they should be more likely to start their addiction again, or abuse some other substance.