Home Health & Wellness Study Reveals Genetic Links Between Cannabis Use Disorder and Other Substance Use Disorders

Study Reveals Genetic Links Between Cannabis Use Disorder and Other Substance Use Disorders

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A groundbreaking study has uncovered significant genetic links between cannabis use disorder (CanUD) and various other substance use disorders (SUDs). The study, which used cutting-edge genomic data and analysis tools, shows how complicated the genetic makeup and link between causes are in CanUD and disorders connected to opioids, alcohol, and tobacco.

With the increasing legalisation and accessibility of cannabis, the prevalence of cannabis use disorder has risen, affecting approximately 20% of cannabis users. CanUD is known to have substantial negative health impacts, including associations with lung cancer, cognitive impairment, and other mental disorders. This study aimed to explore the genetic underpinnings of CanUD and its connections to other SUDs to better understand the public health implications.

The findings were published in the journal Molecular Psychiatry.

The research team employed a multi-faceted approach to analyse the genetic relationships between CanUD, lifetime cannabis use, and other substance use traits. Some important methods used were global and local genetic correlations. Linkage disequilibrium score regression was used to find global genetic correlations, and LAVA was used to look at local genetic correlations and find the specific genomic regions that were involved in these correlations.

Genomic structural equation modelling (GenomicSEM) was used to look at the genetic structure and connections between different SUDs and substance use traits.

The researchers also used Mendelian randomisation (MR) analyses to find links between genetic risks for CanUD and other SUDs and traits related to substance use.

The study found significant positive genetic correlations between CanUD and other SUDs. The most notable correlations were observed with opioid use disorder (OUD), problematic alcohol use (PAU), and smoking initiation. These correlations were not only global but also evident in specific genomic regions, suggesting shared genetic influences across these disorders.

One important finding of the study is that there is a strong genetic link between CanUD and opioid use disorder (OUD). The correlation coefficient (rg) for this link is 0.863, which means it is very strong.

Additionally, a significant genetic correlation was observed between CanUD and problematic alcohol use (PAU), with an rg of 0.681. Both CanUD and cannabis use also exhibited strong genetic correlations with smoking initiation, highlighting shared genetic factors that influence the initiation of tobacco use.

The study also revealed that CanUD and cannabis use exhibit different genetic relationships with other substance use traits. For instance, the Fagerström Test for Nicotine Dependence revealed that CanUD and cannabis use did not have a significant genetic correlation with nicotine dependence.

The GenomicSEM analyses provided further insights into the genetic structure underlying these relationships. The best-fitting model was a four-factor solution, where CanUD, OUD, PAU, and smoking initiation loaded strongly onto one factor. This factor represented a common genetic predisposition to multiple SUDs. Other factors included heavy tobacco smoking traits, alcohol-specific traits, and lifetime ever-use traits (including cannabis use).

MR analyses confirmed significant causal effects of CanUD on all analysed traits. The most robust causal relationships were between CanUD and OUD, PAU, and smoking initiation. Bidirectional causality was observed between CanUD and these traits, suggesting that not only does CanUD increase the risk of developing other SUDs, but other SUDs can also increase the risk of developing CanUD.

For cannabis use, the study identified bidirectional relationships with PAU, smoking initiation, and drinks per week (DPW). Cannabis use was found to increase the risk of developing OUD, albeit to a lesser extent compared to CanUD.

The findings underscore the substantial public health implications of CanUD and cannabis use. As cannabis becomes more accessible due to legalisation, the risk of developing other SUDs may increase, exacerbating the associated health and social harms. These results highlight the need for public health strategies that address the interconnected nature of substance use disorders.

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