Genetics Do Influence Addiction: Yes, Our Brains Are Different
A University of Michigan study recently published in the Proceedings of the National Academy of Sciences suggests that genetic markers may play a role in whether someone develops an addiction or not. That is, genetic factors which vary from one person to the next.
Results revealed were the first of their kind – that the propensity for addiction in animals (in this case, rats) is definitively linked with differences in gene expressions for specific molecules in the brain. Also, is was discovered that DNA genetic markers can predispose a person to both addiction and relapse.
Pleasure receptors and differing genetic markers
Researchers examined the brains of rats for the genetic instructions which comprise a pleasure receptor, known as D2. This receptor allows receipt of dopamine signals – and also cocaine – to brain cells. Rats more prone to addiction had reduced levels of D2 instructions in the brain when compared to other rats.
In addition, rats prone to addiction where also more likely to have a specific genetic marker on their DNA – an epigenetic tag. This marker prevented brain cells from reading the gene for D2 receptors.
However, after becoming addicted to cocaine, rats prone to addiction revealed the same levels of D2 as the other rats. When cocaine was removed, these rats were also more prone to relapse into addictive behavior if they had that special epigenetic tag. One could speculate that the rats were, in a sense, self-medicating.
The rat’s comparison group didn’t show addiction signs, or relapse after abstinence was initiated. As it turns out, these rats had lower levels of instructions for making a molecule which is known to contribute to addiction. They also tended to have an epigenetic mark which prevented their brains from reading that gene. This is likely what protected them from addiction.
Shelly Flagel, Ph.D., authored the new study. Flagel:
“Because we had access to these rats that were bred for certain traits, and were able to control for environmental factors, such as the amount of drug exposure, we could assess differences in the brain both before and after the rats became addicted. By studying their gene expression and epigenetics, as well as their response to drug availability and drug-related cues, we can link these differences in the brain to addiction-like behaviors, such as relapse. This allows us to hone in on the biology of addiction even further.”
This knowledge on genetic markers could be used to assist understanding of human addiction, as well. The more evidence we have about addiction’s biological and genetic roots, the more knowledge we can wield regarding treatment options and public policy on drug abuse.
~ G. Nathalee Serrels, M.A., Psychology
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