Some say psychiatry is new scinece. Well, I wanna ask, is oncolgy older? Is endocrinology, cardiovascular surgery, or microbiology older? My grandfather didn't know what is a cell, nor the word biology really means, or that there can be a treatment for his difficulty in breathing. Yet, since 4000 B.C. and people knows that the poppy plant causes euphoria and used it as treatment for some psychological problems.
So it is accepted, since 4000 B.C. that something taken orally can change the mental state, while at this time, in the 21st century, some doctors still don't think that some well prepared chemicals in best research centres in the world today can have some effect on the psyche.