Study casts doubt on the link between cannabis use and anxiety disorders

A new longitudinal study suggests the link between cannabis use and anxiety is weaker than previously believed.

Cannabis is the most widely used illicit substance globally. Several studies have made note of the association between cannabis use and anxiety disorders. These studies indicated high cannabis use among those with anxiety, and a large number of anxiety disorders among those who use cannabis.

However, past studies have resulted in mixed findings. In a 15-year-long study, daily cannabis use was associated with an increased risk for developing an anxiety disorder; on the other hand, another study suggested that relief from stress and anxiety may be a main reason for cannabis use.

The new study, led by Daniel Feingold of the Sheba Medical Center and published in European Neuropsychopharmacology, aimed to determine the directionality of the supposed association between cannabis use and anxiety disorders. The study focused on determining whether people with anxiety disorders were more likely to use cannabis, or whether people who used cannabis were more likely to develop anxiety disorders.

The study followed two groups of people: one group who used cannabis at the baseline (and the onset of anxiety at the follow up) and another group who had anxiety orders at the baseline (and the initiation of cannabis use at the follow up).

The researchers used data from the National Epidemiologic Survey on Alcohol and Related Conditions. The first portion of the study was conducted in 2001 with 43,093 participants, all over the age of 18 years old. Three years later, researchers conducted a follow up; approximately 87% of the original participants responded.

The study used survey questions to assess cannabis use and anxiety disorders in the participants. The analysis of the survey was twofold for each group (cannabis baseline and anxiety baseline). The first type of analysis was not adjusted for any other variables. The second type of analysis was adjusted for socio-demographic values, alcohol use disorders, and additional psychiatric disorders. These variables were chosen because they tend to be associated with anxiety disorders.

For the cannabis baseline group, heavy cannabis use was originally associated with later social anxiety; however, in the fully adjusted model, this was association was not supported. For the anxiety baseline group, the analysis revealed that existing anxiety disorders were not associated with future cannabis use. This result was surprising because it had been widely believed that the main reason for cannabis use is general stress relief.

“Our finding point out that despite repeated findings on the cross-sectional association between cannabis use and anxiety disorders, the longitudinal association between the two is not as strong, perhaps suggesting that the this association may be mediated by other factors,” Feingold and his colleagues wrote in the study.

The study found that those with panic disorders, a specific classification of anxiety disorders, were more likely to use cannabis later in life. The researchers concluded that this association is an area for further study.

“Future investigation should further explore the association between cannabis use and succeeding social anxiety as well as the inverse association between panic disorder and future initiation of cannabis use,” the researchers said.