Leukotomy (Neurosurgery)
This is horrific and is only ever used when there is quite literally no choice for whatever reason. Basically, your prefrontal cortex is screwed up by means of knife. On last counting, the UK performs (or performed) an average of 15 leukotomies a year. The procedure often leads to a massive change in personality and that's the most benign effect. It is the ultimate, most effective method of controlling symptoms, but at a huge price. As I said, this procedure is only ever carried out when there is no choice.
"[A] surgical procedure in which the nerve pathways in a lobe or lobes of the brain are severed from those in other areas. The procedure formerly was used as a radical therapeutic measure to help grossly disturbed patients with schizophrenia, bipolar disorder, and other mental illnesses. Lobotomy was introduced in 1935 by two Portuguese neurophysicians, António Egas Moniz and Almeida Lima. The practice was soon widely adopted, largely because there were few other viable therapeutic measures at the time for quieting chronically agitated, delusional, self-destructive, or violent patients." - Encyclopædia Britannica