Study: Link between Psychosis and Marijuana Goes Both Ways in Teenagers
Marijuana use in teenagers may be linked to the development of psychotic symptoms, but the reverse may also be true: psychosis in adolescents may be linked to later pot use, according to a new Dutch study.
"We have focused mainly on temporal order; is it the chicken or the egg? As the study shows, it is a bidirectional relationship," wrote the study's lead author Merel Griffith-Lendering, a doctoral candidate at Leiden University in The Netherlands, in an email to Reuters Health.
Researchers in the study suggest that people with underlying psychosis may be "self-medicating" by smoking pot in an effort to diminish symptoms or improve mood. However, more research suggests that marijuana use may tweak the brain - especially the developing brain - in significant and detrimental ways, which could ultimately lead to psychosis.
In the new study, the authors followed over 2,100 Dutch teens, asking them questions about their mental health when they were 14, 16, and 19. The teens were quizzed about their pot use over the years and tested for "psychosis vulnerability," which included questions about their social relationships and feelings of loneliness, attention, and thought problems (for example, "seeing things that other people do not see").
Variables like alcohol and tobacco use, as well as their parents' mental health and families' socioeconomic status, were removed so as not to influence the results.
"What is interesting in this study is that both processes are going on at the same time," said Dr. Gregory Seeger, medical director for addiction services at Rochester General Hospital in upstate New York, according to Reuters.
Seeger said that researchers have been especially concerned about what tetrahydrocannabinol (THC), the active property in pot, could do to a teenager's growing brain.
"That's a very vulnerable period of time for brain development," and individuals with a family history of schizophrenia and psychosis seem to be more sensitive to the toxic effects of THC, he added.
A 2010 study of 3,800 Australian teenagers found that those who used marijuana were twice as likely to develop psychosis compared to teens who never smoked pot.