The physical side effects of using marijuana or cigarettes at a young age are frequently discussed. But what about the impact they have on teenagers’ mental health? A new study has found that for teenagers who smoke either cannabis or cigarettes on a regular basis are at an in increased risk of developing psychotic symptoms.
According to the researchers who conducted the study “Individuals who use cannabis regularly have a 2- to 3-fold increased risk of a psychotic outcome.” This study follows previous research into the link between tobacco and psychosis, which showed there was a strong correlation between the two.
The study looked at 3,328 teenagers, who were asked to answer questions about their tobacco and cannabis use at six separate points between the ages of 14 and 19. When looking at the results, the researchers found that teenagers who smoked cigarettes at a young age were at a 4.3% increased risk of suffering from psychosis before the age of 18.
For those who used cannabis the risk was 3.2% higher than non users. Even more worryingly, they found that the teenagers who used marijuana later into their teenage years were at an 11.9% increased risk of a psychotic episode before the age of 18.
The researchers also took into account other factors which are known to contribute to the likelihood of developing psychosis. For example, factors like family history of schizophrenia, social class, alcohol use, substance abuse or bulling were all considered when analyzing the figures to ensure the results were fair. Although the link between cigarettes and psychosis seemed to decrease when taking these factors into account, the effects seen from cannabis use remained clear.
Nehal Vadhan, psychologist at Zucker Hillside Hospital in Glen Oaks, New York who was not involved in the study, said that the accuracy of the study can be seen in the “very rigorous” methods and measurements, a high proportion of female participants — “which is not always common” — and longitudinal measurement, where the researchers do not look at data from “a single slice in time but over a period of four or five years.”
However, he added that this study doesn’t take into account any possible predisposition to psychosis. He said “Psychologists classify some people as having attenuated psychotic syndrome.” Adding that these people can have symptoms such as “visual illusions as opposed to hallucinations” or “magical thinking or overvalued ideation that don’t quite reach the level of delusion,”
The researchers also noted that one weakness in the study is that it doesn’t take into account the behaviour of marijuana users. “Most cannabis users smoke cannabis in combination with tobacco,” wrote the study authors. “Therefore, we cannot rule out whether the associations observed between the cannabis use class and psychotic experiences are exacerbated by the combined use of cannabis and cigarettes.”