A growing body of research indicates a genetic connection between cannabis use disorder (CanUD), cannabis consumption, and various psychiatric disorders. Recent data from the National Survey on Drug Use and Health revealed that in the United States, 52.5 million individuals aged 12 and older reported using cannabis in the past year. Among those, 16.3 million met the criteria for cannabis use disorder.
As cannabis legalization spreads, understanding the relationships among cannabis use, CanUD, and mental health issues becomes increasingly important. Previous studies employing genetic methods have suggested that CanUD is associated with a higher likelihood of developing other substance use disorders, a relationship that often runs both ways.
CanUD is commonly found alongside several psychiatric conditions, including anxiety disorders, major depressive disorder (MDD), post-traumatic stress disorder (PTSD), anorexia nervosa (AN), schizophrenia (SCZ), bipolar disorder (BPD), and attention deficit hyperactivity disorder (ADHD). A systematic review encompassing eight studies indicated that individuals with CanUD were over three times more likely to experience MDD and nearly three times more likely to suffer from anxiety.
The relationship between cannabis use and PTSD is particularly complex. While cannabis is approved for PTSD treatment in some states, a systematic review of 45 studies revealed mixed results regarding whether cannabis use predicts the onset of PTSD or vice versa. This ambiguity raises questions about the efficacy of cannabis as a treatment for a condition it may also exacerbate.
Research has also indicated a notable prevalence of CanUD among individuals with eating disorders. A meta-analysis showed a 6% prevalence of CanUD in individuals with AN, while 14% reported cannabis use. Despite cannabis’s known appetite-stimulating effects, its link with lower body mass index complicates this relationship and calls for further investigation.
Individuals with BPD and SCZ show significantly higher rates of cannabis use and CanUD. Studies indicate that 30% of BPD patients and 26.2% of those with SCZ also experience CanUD. Furthermore, genetic epidemiology and genome-wide association studies (GWAS) suggest positive genetic correlations between SCZ and both CanUD and general cannabis use, with evidence of a bidirectional causal relationship.
The genetic correlation between cannabis use and CanUD is significant, with findings indicating a 50% overlap in genetic variance. However, cannabis use and CanUD differ in their genetic associations with other traits, including AN, MDD, SCZ, anxiety, and PTSD subtypes.
To further explore these relationships, researchers conducted genetic correlation analyses, focusing on personality traits such as neuroticism and extraversion alongside psychiatric disorders. The analysis found that CanUD had strong positive genetic correlations with ADHD, MDD, and SCZ, while cannabis use showed varying degrees of correlation with these traits.
Local genetic correlation analyses revealed specific genomic regions where CanUD shared genetic variance with ADHD, MDD, PTSD, BPD, and anxiety, indicating distinct genetic influences at play. Multi-trait colocalization analysis identified particular variants, such as GULOP*rs11783093, significantly associated with both CanUD and SCZ.
Mendelian randomization analyses offered insights into causal relationships, revealing that CanUD is a risk factor for multiple psychiatric disorders, particularly SCZ and ADHD. Conversely, traits like MDD and BPD were found to increase the likelihood of CanUD. While cannabis use showed some causal effects on ADHD, it did not have significant direct relationships with other psychiatric conditions.
Genomic structural equation modeling suggested a three-factor model of psychiatric traits, highlighting the interrelations between PTSD, anxiety, MDD in one factor, and AN, SCZ, and BPD in another, with CanUD and ADHD forming a separate category.
The findings from this research underscore the intricate genetic relationships between cannabis use, cannabis use disorder, and various psychiatric conditions, illustrating the need for further exploration to clarify their interconnectedness. These insights could inform treatment approaches and public health strategies as cannabis use becomes more prevalent in society.
English 
Spanish 
German 
Czech