Gene Mutations For Addiction Apply to Cannabis As Well
Any substance or activity can slip from enjoyable into addiction, but if you have these gene mutations, it’s more likely that you will make that slide.
Cannabis is one of the most commonly used psychoactive substances in developed countries. This is partly due to medicinal properties that alleviate symptoms of depression, PTSD, chronic pain, among other conditions; but also a result of recreational use. Individuals with certain gene mutations are vulnerable to an abuse problem with cannabis.
Unfortunately, it is estimated that about 10% of individuals using cannabis meet the criteria for lifetime dependence. Like other addictions, cannabis use disorder can come with mental health struggles. This may not be surprising when we take into consideration the situation with substances of abuse. Opioids, for example are a common painkiller that patients use instead of cannabis. It plays a critical role in helping patients function in their daily life, but certain individuals will end up addicted as they develop opioid use disorder.
Is Addiction in the Genes?
You’ve heard it before, I’m sure. Addiction runs in families; there’s a genetic component to substance abuse. And if you are addicted to one thing, say cigarettes, does this make you susceptible to other forms of substance abuse?
Molecular genetics is the discipline that deals with answering such questions. They perform genome-wide association studies (GWASs) in an effort to reveal genetic patterns and signatures for various disorders. So far seven GWASs were conducted and only two identified specific genes that were mutated for individuals that had cannabis use disorder. The disorder is defined by several criteria: loss of control of use, inability to fulfil social roles, continued use even when negative health (physical, emotional, psychological) outcomes arise.
Gene Mutations for People with Addiction
The first study identified three separate regions of the genome for cannabis dependence in European-Americans and African-Americans. Human genes are encoded within combinations of four letters. These letters (nucleotides A, T,C, G) constitute the DNA alphabet.
This study found variations in individuals who developed cannabis dependence, called single nucleotide polymorphisms, or SNPs, located on chromosomes 3, 8 and 10. These gene mutations can have negative consequences.
The authors sought to answer the question of whether these SNPs were associated with any mental disorders. These include the potential for shared genetic risk for a mental health disorder and addiction. They found that schizophrenia is associated with variability in the same gene on chromosome 8. Chromosome 8 is the chromosome for for cannabis dependence, however, different SNPs are present in schizophrenia than cannabis dependence. Therefore, it is inconclusive whether there is any genetic predisposition for developing schizophrenia from cannabis dependence.
What the Studies Say About Genes and Cannabis Dependence
The most recent GWAS, published earlier this year, found another region of genetic variability (within chromosome-10) relating to cannabis dependence. Researchers looked at over 2000 people who met the criteria for cannabis dependence and compared them with over 6000 people who did not. The control group also used cannabis throughout their lives.
Multiple SNPs have been identified within this genomic region, and seven of the SNPs occurred in the genes expressed in brain tissue. Additionally, these SNPs are predicted to alter the assembly of proteins the cell uses to read the genetic code (“transcription factors”) several of which show brain-related expressions.
Results and moving forward:
As a result, expression of other genes in the brain may become altered, which further increases the complexity of the events caused by these SNPs. Interestingly, the identified genetic variability associated with cannabis dependence is found to be associated with nicotine dependence, but not alcohol dependence.
The highest value of this study is: the SNPs identified are located in genes expressed in brain regions. These brain regions play a major role in the development of addictive behaviors (particularly in executive control and attention bias). Further identification of genetic risk factors associated with cannabis dependence will help decipher the genetic etiology of cannabis use disorders. This will help identify individuals at greater risk of developing them.
The next crucial step will be to enable personalization of pharmacotherapy among the affected individuals.