"Risperidone, sold under the brand name Risperdal among others, is an antipsychotic.[2] It is used to treat schizophrenia, bipolar disorder, and irritability associated with autism"
I'm not saying that means it's a good idea, but I guess that explains why.
I've tried two anti-psychotics and found both experiences horrifying.
I just noticed, rereading this, that it seems like quite a jump to say, "Schizophrenia...Bipolar... annnnd irritability associated with autism. They're a grumpy bunch, they are."