Used to treat mental health issues from schizophrenia to depression, the lobotomy was popularized in the 1940s. The surgery severed the connection between the frontal lobes to the rest of the brain. The frontal lobes are engaged when we exercise will power and think abstractly or creatively, and it was thought mental illness was caused by a faulty connection between the frontal lobes and the rest of the brain. Tens of thousands of patients underwent the surgery in North America, including John F. Kennedy’s sister Rosemary, who was lobotomized at 23 to treat her rebelliousness. While the results of lobotomies varied widely, many suffered devastating consequences. Rosemary Kennedy, for example, was left unable to speak or control bodily functions. In the 1950s, anti-psychotic medicines came on the market and largely replaced the lobotomy, though the last one was performed in 1967.