The association between cannabis use and psychiatric comorbidity in people with personality disorders : A population-based longitudinal study
Nadav Shalita, Jürgen Rehmb, Shaul Lev-Ran
Psychiatry Research, 2019, 278, 70–77
A B S T R A C T
Both personality disorders (PD) and cannabis use are highly comorbid with various psychiatric disorders. While previous research indicates specific interactions between cannabis use and schizotypal PD associated with schizophrenia, research into cannabis use among individuals with other PDs and the development of several additional psychiatric disorders is scarce. We explored the prevalence and incidence of psychiatric disorders among individuals with PDs who use cannabis, and whether individuals with PDs who use cannabis are at increased risk for developing psychiatric disorders compared to cannabis users without a PD. Finally, we examined the interaction effect between cannabis use and personality disorders on comorbid psychiatric disorders. Data from 34,653 participants in waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were analyzed. Our findings indicate that individuals with PDs who used cannabis were at increased odds for developing substance use disorders (including opioid use disorder), but not other comorbid psychiatric disorders, at 3-year follow up. No significant interaction effects were generally found between cannabis use and PD. These findings suggest that aside from specific substance use disorders, individuals with PDs are not at an increased risk for developing other psychiatric disorders following cannabis use.
Keywords : Cannabis, Personality disorders, NESARC
The association between personality disorders (PD) and other psychiatric comorbidity is firmly established (Khan et al., 2005; Tyrer et al., 2015). Different personality disorders have been shown to have variable associations with specific psychiatric comorbidities, e.g. schizotypal PD is strongly associated with bipolar disorder and several anxiety disorders (Pulay et al., 2009), while antisocial PD is strongly associated with substance use disorders and ADHD, as well as anxiety disorders (Compton et al., 2005; Goodwin and Hamilton, 2003).
The association between cannabis use and psychiatric disorders is also well-established, though causal associations were demonstrated by only a handful of studies. Nevertheless, there is substantial evidence of a statistical association between cannabis use and the development of schizophrenia or other psychoses, with the highest risk among the most frequent users, and there is moderate evidence for a statistical association between regular cannabis use and increased incidence of social anxiety disorder, depressive disorders, and increased suicidality measures (Gobbi et al., 2019; The National Academies of Sciences Engineering and Medicine, 2017)
There are consistent findings showing that substance use and substance use disorders (SUDs) are more prevalent in individuals diagnosed with a personality disorder (Hasin and Kilcoyne, 2012), and that this association is independent of sociodemographic background and psychiatric comorbidity. Several specific personality traits are associated with a higher prevalence of substance use, and these traits are variably accentuated in different personality disorders (Belcher et al., 2014).
Cannabis use is highly prevalent in the general population (UNDOC, 2018), and previous studies have shown that in several personality disorders, the odds of a Cannabis Use Disorder were up to eight-fold higher than in the general population (Hasin et al., 2016). To date, there is a paucity of data regarding the association between cannabis use and development of psychiatric disorders among individuals
In this study we analyze data from a large, nationally representative sample, with a 3-year follow-up. We aim to determine the association between cannabis use and prevalence and incidence of psychiatric disorders among individuals with PDs. Given that individuals with PDs are at increased risk for comorbid psychiatric disorders and Cannabis Use Disorders, we hypothesized that cannabis use, particularly frequent use, would be associated with increased prevalence and incidence of psychiatric disorders in this population.