Opioid Addiction and Genetic Factors

    Opioid addiction can be categorized as a chronic mental illness that may cause individuals with this disorder to go through periods of relapse and remission throughout their whole life.  This article goes into information about the biological mechanisms of opioid addiction and its receptors.  The opioid epidemic has become a nationwide issue and many suggestions have been made to help treat this illness.  A few medications- methadone, buprenorphine, and naloxone- have been show to have different effects on opioid receptors in the brain.  These medications may help but it is proven that with this the relapse and remission cycle is still highly active with it.  When people try opioids for the first time, for whatever reason that might be, they often experience a euphoric feeling that some individuals want more of.  They want to keep chasing that euphoria or it might alleviate all the pain they have been having so they keep using opioids to the point of losing control over their intake.  What is going on in the brain is that the receptors that are hit with the opioids get adjusted to the drug thus leading to a tolerance build-up.  The tolerance build-up creates a snowball effect because the body will then develop withdrawal symptoms if the individual stops using.  The symptoms can include severe muscle aches, bone pain, tearing, runny nose, diarrhea, abdominal cramping, anxiety, sweating, and agitation.   These symptoms are one of the core parts of opioid addiction and are the main reason for relapse.  Another main part of this article was the genetic susceptibility to addiction.  Twin, family, and adoption studies have proven that there are huge genetic influences on drug addiction proving that addiction is heritable.   It was shown from all these studies that children of addicts had higher rates of psychopathology.  The genetics of parents alone are not the sole cause of addiction as a whole. Actual behavior patterns of an individual such as impulsivity can make a person more likely to develop an addiction.

      It was found that there are molecular mechanisms from opioid-induced tolerance and dependence that play a role in opioid addiction as a whole.  The mechanisms involve the upregulation of cyclic AMP/protein kinase A and cAMP response element-binding signaling.  Along with this mechanism the cravings for drugs, lack of self-control, and strong response to drug-associated stimuli can be associated with cellular and molecular changes of the glutamatergic projection in the prefrontal cortex and the basal ganglia region.  This all means that there are processes in the brain on the cellular level that can be the main driving cause of the burning wildfire which is addiction.  This article goes into more depth about the types of opioid receptors and how this all works.    Many genes have been found that are associated with addiction in the genome.  This article shows information about heroin addiction and how genes can be classified into two systems: the dopaminergic system and the MOR system.  This table gives an organized view of the genes related to opioid addiction.  

      

https://www.mdpi.com/1422-0067/20/17/4294

https://www.sciencedirect.com/topics/medicine-and-dentistry/upregulation

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/glutamatergic