Well, it's science if you consider the patient to be the subject of an experiment. But the point I was trying to make is - they don't directly measure serotonin or anything else in the brain. They can't see thoughts through a machine or measure 'chemical balance', whatever that is. They leave it to correlation - give drug, report result given by patient. It's like nutritional science, but even worse, because at least with nutritional science you can measure blood sugar or cholesterol. Psychology involves the outside world - relationships, financial security, social stresses, physical health, etc. Habits of mind. Traumas. So much more.