The association between cannabis use and psychiatric comorbidity in people with personality disorders: A population-based longitudinal study

Cannabis Use, Cannabis Use Disorder, and Comorbid Psychiatric Illness: A Narrative Review

BACKGROUND

The landscape of attitudes, legal status and patterns of use of cannabis is rapidly changing in the United States and elsewhere. Therefore, the primary aim of this narrative review is to provide a concise overview of the literature on the comorbidity of cannabis use and cannabis use disorder (CUD) with other substance use and psychiatric disorders, and to use this information to accurately guide future directions for the field.

METHODS

A literature review of PubMed was conducted for studies relating to cannabis use, CUD, and a co-occurring psychiatric disorder. To provide an overview of representative data, the literature review focused on national-level, population-based work from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and National Survey on Drug Use and Health (NSDUH) surveys. Considering rapidly changing cannabis laws, recent (past five-year) studies were addressed.

RESULTS

A strong body of literature shows associations between cannabis use and CUD with other drug use, psychosis, mood disorders, anxiety disorders, and personality disorders. The strongest evidence of a potential causal relationship exists between cannabis use and psychotic disorders. While some evidence shows potential directionality between cannabis use and mood and anxiety disorders, results are inconsistent. Studies have established higher rates of CUD among those with personality disorders, but little about the specifics of this relationship is understood.

CONCLUSIONS

Although the general population in the United States increasingly perceives cannabis to be a harmless substance, empirical evidence shows that cannabis use is associated both with CUD and comorbid psychiatric illness. However, there is mixed evidence regarding the role of cannabis in the etiology, course, and prognosis of a co-occurring disorder across all categories of psychiatric disorders. Future research should expand on the existing body of literature with representative, longitudinal data, in order to better understand the acute and long-term effects of cannabis on comorbid psychiatric illness.

Cannabinoids and the endocannabinoid system in anxiety, depression, and dysregulation of emotion in humans

PURPOSE OF REVIEW

This review is to summarize most recent evidence published in the last 18 months on medical and recreational use of cannabis and cannabinoids in relation to anxiety, depression (unipolar and bipolar), and dysregulation of emotions as part of posttraumatic stress disorders (PTSD) and emotionally instable personality disorders. It also covers the investigation of endocannabinoids as potential biomarkers in these conditions. This is important with increasing medicinal use of cannabinoids and growing social tolerance towards recreational cannabis use.

RECENT FINDINGS

There is some recent evidence suggesting cannabinoids, cannabidiol or cannabidiol-enriched cannabis preparations have anxiolytic properties. In addition, depression may be worsened by cannabis use, however, randomized controlled trials (RCT) are lacking. New evidence also suggests that cannabidiol or cannabidiol-enriched cannabis use for PTSD and emotion regulation can induce hyporesponse to fear and stress. Further, several lines of evidence point to the endocannabinoid system as a key player in some of the reviewed disorders, in particular anxiety and PTSD.

SUMMARY

The most recent evidence for a therapeutic use of cannabinoids in the reviewed conditions is weak and lacking well designed RCTs. However, there is some indication of the role of the endocannabinoid system in these conditions that warrant further studies.