Research has not yet established the side effects of long-term ketamine therapy, but older studies of recreational users offer some insight on heavy, extended dosing. Celia Morgan, now a psychopharmacology professor at the University of Exeter, in England, led a 2010 study that followed 120 recreational ketamine users for a year. Even infrequent users—those who used, on average, roughly three times a month—scored higher on a delusional-thought scale than ex–ketamine users, people who took other drugs, and people who didn’t use drugs at all. Those who averaged 20 uses a month scored even higher. People believed that they were the sole recipients of secret messages, or that society and people around them were especially attuned to them. The psychological profile of a frequent ketamine user, Morgan and her team concluded, was someone who had “profound” impairments in short- and long-term memory and was “distinctly dissociated in their day-to-day existence.” Morgan’s study was not designed to determine whether people who are more likely to be delusional are also more likely to recreationally use ketamine, but Morgan told me that stopping the drug, in most cases, will dramatically reduce these side effects.
What Ketamine Does to the Human Brain
