Marijuana is the most commonly used illicit drug, although several states have legalized it for medicinal as well as recreational use. There are approximately 6,600 new users each day with 6% of new users under the age of 18. Thirty-six percent of youths report using marijuana in the previous year with 6% reporting daily or near-daily use. Because of this it’s important to study potential repercussions as well as benefits. While cannabis use may be beneficial for some illnesses, it also comes with risks. A new study looked at teen marijuana use to see if it predicted eventual symptoms of hypomania.
The study, led by Steven Marwaha of Warwick Medical School, Coventry, UK, looked at data from 3,370 participants to see if there may be a connection between cannabis use and future episodes of hypomania. They cited research that found that adolescent use of cannabis predicted future episodes of psychosis and a slight association with depression and anxiety.
The participants in this study were part of a longitudinal study called the Avon Longitudinal Study of Parents and Children (ALSPAC) following children born between April 1, 1991 and December 31, 1992. The original study ultimately yielded results on 14,701 children.
Cannabis use was measured when the children were 17 years-old. Of those who reported marijuana use, researchers sent a follow-up questionnaire when the participants reached 22-23 years of age. The participants were then given an assessment for measuring hypomanic behavior called the Hypomania Checklist Questionnaire (HCL-32), a 32-question self-report survey on lifetime experience of manic symptoms.
Participants were also asked about frequency of cannabis use, family risk factors, history of physical or sexual abuse, alcohol use and use of other illicit substances by the age of 17. They were also questioned on any potential symptoms of psychosis, depression and anxiety.
In the study, 3,370 participants reported symptoms of hypomania by age 22-23. Marijuana use before the age of 17 was significantly associated with subsequent hypomania by the age of 22-23. The effect was greater for those who reported frequent use as opposed to any use. These results were independent of other factors like other drug use, alcohol use and symptoms of either psychosis, depression or anxiety.
Of those surveyed, almost 5% of men and almost 2% of women reported at least weekly cannabis use. Men were more likely to show subsequent hypomania than women, likely because of higher use.
Childhood physical or sexual abuse was also indirectly linked to an increased likelihood of cannabis use and subsequent symptoms of hypomania. Childhood trauma has been previously linked with subsequent bipolar disorder. It is hypothesized that cannabis use may be an additional link in childhood trauma leading to a later diagnosis of bipolar disorder.
There are some limitations to this study. In some cases symptoms of hypomania may have preceded cannabis use and there may have been other pre-existing conditions linking marijuana use with subsequent hypomanic symptoms. These results are preliminary and will need to be confirmed with future research.
Image credit: Chuck Grimmett