Research published in The American Journal of Psychiatry finds that during a period of increasing cannabis use in the U.S., the prevalence of cannabis use disorder is disproportionally increasing among veterans with psychiatric disorders, especially those with more severe psychiatric disorders.

The research team, led by Ofir Livne, M.D., M.P.H., assistant professor of clinical psychiatry, Columbia University / New York State Psychiatric Institute, used Veterans Health Administration (VHA) electronic health records over two periods (2005-2014 and 2016-2019) to identify trends in cannabis use disorder among patients with and without psychiatric disorders. They looked at data on veterans with depressive, anxiety, PTSD, bipolar, and psychotic spectrum disorders compared to veterans without mental health disorders.

According to the research, cannabis use disorder more than doubled among all VHA patients from 2005-2019, and there were greater increases in cannabis use disorder diagnoses in veterans with psychiatric disorders compared to those without. The greatest increases were seen among those with bipolar and psychotic-spectrum disorders.

Increases in cannabis use disorder prevalence were also disproportionately higher among younger veterans (under 35 years old) between 2205 and 2014 and older veterans (over 64 years old) between 2016 and 2019.

Several factors may contribute to the increasing risk of cannabis use disorder among people with psychiatric disorders, the researchers suggest, including the increasing legalization and access to marijuana, changing public attitudes, and increasingly potent cannabis products. A recent survey found that nearly half of U.S. adults believed cannabis use is beneficial for stress, anxiety, or depression.

With this greater availability, "patients with bipolar or psychotic-spectrum disorders may be using cannabis in an attempt to self-medicate, even though evidence suggests that this is inadvisable," the authors note. Individuals with comorbid cannabis use disorder and psychiatric disorders are at increased risk of functional impairments and other harms.

The authors conclude that the study highlights the need to systematically monitor risky cannabis use among vulnerable populations, such as those with psychiatric disorders, and to develop preventive and harm-reduction strategies.