Rates of marijuana use continue to rise, and legalization will only further increase its use. Studies suggest that continual adolescent marijuana use increases risk of subclinical psychotic symptoms (e.g. paranoia and hallucinations), that persist even after a year of abstinence
Despite the increasing prevalence of medicinal and recreational marijuana use, its consequences on physical and mental health are controversial and highly debated. Of particular interest is the association between adolescent marijuana use and the risk of psychotic symptoms, including paranoia, hallucinations, and bizarre behaviour. To date, studies have suggested that marijuana use increases the risk of acute psychotic episodes and subclinical psychotic symptoms. However, whether this increase in risk is short-lived or long-term demands further investigation. Moreover, there is an ongoing debate regarding whether the association between adolescent marijuana use and psychotic symptoms is causal or merely a result of confounding factors. Therefore, continual research is required to better understand the consequences of regular marijuana use on human health.
A study published in the American Journal of Psychiatry investigated whether adolescent marijuana use is associated with an increase in subclinical psychotic symptoms that persist even during periods of abstinence. In the study, 1,009 boys were recruited from the 1st and 7th grade in 1987 and 1988. The younger group was interviewed every 6 months for 4 years, followed by 9 yearly assessments. Similarly, the older group of boys were assessed every 6 months for 30 months, and then yearly for 10 years. During each assessment, a Substance Use Questionnaire assessed marijuana use, a Youth Self Report assessed subclinical psychotic symptoms, including paranoia, hallucinations and bizarre thinking, and finally the Substance Use Questionnaire assessed the use of other substances that may interfere with the results, including alcohol, tobacco and other illicit drugs. When examining specific subclinical psychotic symptoms, they found that current and prior use of marijuana was significantly associated with paranoia, both before and after controlling for confounding factors. In contrast, only prior marijuana use was significantly associated with increased hallucinations after controlling for confounding factors. Finally, neither current nor prior marijuana use was associated with bizarre thinking. Overall, prior to accounting for confounding factors, researchers concluded that current and prior marijuana use significantly increased total subclinical psychotic symptoms. However, when confounding factors were taken into consideration, only previous history of marijuana use was significantly associated with an increased risk of subclinical psychotic symptoms. The results further indicated that despite a year of abstinence, the subclinical psychotic symptoms did not disappear. Finally, the authors were also able to demonstrate that an increase in subclinical psychotic symptoms did not increase the likelihood of engaging in regular marijuana use.
In conclusion, the study found that regular adolescent marijuana use increased the risk of psychotic symptoms including paranoia and hallucinations. These symptoms of paranoia and hallucinations persisted despite abstaining from marijuana for a year. This is of concern because chronic subclinical psychotic symptoms in adolescents increase their risk of developing psychotic disorders by young adulthood. In addition, the increasing pressure on the government to legalize marijuana can put adolescents at greater risk for developing subclinical psychotic symptoms and potentially result in psychotic disorders in the future.
Written By: Haisam Shah