According to a new study published in the journal Schizophrenia Bulletin, marijuana can cause short-term paranoia in people who use it. The paranoia is specifically caused by marijuana’s main active ingredient THC (tetrahydrocannabinol).
Daniel Freeman, professor of clinical psychology at the University of Oxford in England and study leader, stated: “The study very convincingly shows that cannabis [marijuana] can cause short-term paranoia in some people.”
He also said: “But more importantly it shines a light on the way our mind encourages paranoia. Paranoia is likely to occur when we are worried, think negatively about ourselves, and experience unsettling changes in our perceptions.”
The researchers recruited 121 subjects between the ages of 2 and 50 who had previously used marijuana. One third of them were injected with a placebo while the remaining two thirds were injected with THC. The dose of tetrahydrocannabinol was equal to that of a single joint or marijuana cigarette.
Following the injections, 50 percent who had been injected with marijuana reported paranoid thoughts as opposed to only 30 percent of those who had been given a placebo. The investigative team thus concluded that the tetrahydrocannabinol was the cause of the “increased paranoia in one in five” of the subjects injected with the drug. Additionally, their paranoia lessened as the tetrahydrocannabinol left the bloodstream.
Freeman and his team also discovered that psychological elements such as anxiety, low self-esteem, worrying and experiencing numerous upsetting “changes in perception” brought on by tetrahydrocannabinol added to the paranoia.
The drug’s active ingredient also was responsible for several additional psychological effects including anxiety, bad mood, negative self-perception, “poorer short-term memory”, worry and numerous alterations in perception. For example, subjects often thought that colors were abnormally bright, sounds were louder and their sense of time was affected as well.
Freeman noted: “The study provides a great deal more information about the immediate effects of cannabis, but it did not investigate clinically severe disorder. The results don’t necessarily have any implications for policing, the criminal justice system, or legislation.”
He concluded: “It tells us about the little-discussed paranoid-type fears that run through the minds of so many people from time to time. The implication is that reducing time spent ruminating, being more confident in ourselves, and not catastrophizing when unusual perceptual disturbances occur will in all likelihood lessen paranoia.”