Genetics

The probability of an individual developing an addiction depends somewhat on their environment and genetics.

The Environmental Component

By environment, we mean the frequency and dosage of opioid use, personal experiences (trauma), and prevalence of drug use by peer groups. Higher doses of opioids that are taken over longer periods of time are more likely to lead to the biochemical changes that result in addiction. Additionally, having close friends that regularly take opioids increases an individual’s risk of developing an addiction as well. Due to this, drug addiction treatments include both a medication and community component. For instance, medications like methadone are used to treat the biochemical side, and community groups such as narcotics anonymous are used to help on the community side. 

The Genetic Component

The genetic component is a bit more complicated as there are genetic markers that seem to be associated with increased likelihood of someone developing an opioid use disorder. A genetic marker is a particular allele that is associated with a specific condition. Thus, there is a component of addiction that is heritable across generations.

To be able to determine this genetic component of opioid addiction, a genome wide association study (GWAS) is commonly used. This study first gathers two groups of people, one group would have opioid use disorder and the other would not. For every person involved in the GWAS, we need a large proportion of their genome in order to see if there are any alleles or gene sequences that tend to be shared amongst the opioid use disorder group. If there is an overlap, there is a possibility that those alleles contribute to opioid addiction.

Genome Wide Association Study for Opioid Addiction

The opioid receptor mu 1 (OPRM1) gene found on chromosome 6 has been shown to have a single nucleotide change that corresponds to a 10% increase in opioid use disorder rate. Individuals who have the nucleotide adenine at position 118 seem to have that 10% increased chance of developing opioid addiction. There are actually other versions of the OPRM1 gene that seem to be linked to a higher chance of developing opioid use disorder that are actively being examined under biomedical research.