A new study published in September shows that there may be a connection between an ancient retrovirus present in some human DNA and a predisposition for addiction. The study, which was conducted by scientists at Oxford University and the National-Kapodistrian University of Athens, looked at the HK2 retrovirus and found that those who injected illegal drugs were two to three times more likely to have DNA from the retrovirus in their blood.
Is Addiction Caused by a Virus?
A retrovirus is a virus that uses human cells to multiply itself. Instead of being encoded in human DNA, it is encoded in RNA, which means that once it takes over a cell, it can impose its own DNA and use it to replicate. HIV and certain lymphomas are examples of retroviruses and the impact, often serious, that they can have on an individual. The HK2 retrovirus in some people’s genes has not been thought to cause any active disease or really do much of anything but remain as a remnant of an ancient disease.
It is interesting to note where the retrovirus resides in the genetic code. It resides on a gene that is responsible for the body’s response to and regulation of dopamine levels. While all humans release small amounts of dopamine during healthy pleasurable activities like eating good food or hugging someone you love, some people whose dopamine levels are not well regulated may seek out drugs or alcohol to give them a high and help them release more dopamine.
The kind of connection shown in the study does not prove that the retrovirus caused people to become addicted to drugs, but it does suggest that something about the retrovirus caused the association between the two. Perhaps the five to 10 percent of people whose blood contains the virus are in some way more prone to becoming addicted to illegal drugs than others. Study researchers also found that HK2 can manipulate the genes close to it, which could also contribute to addiction in some way.
To make the study more conclusive, different populations were studied, including those who had used injected drugs and gotten a disease like Hepatitis C or HIV, and those who had the same diseases but had not gotten them by injecting drugs. The results were consistent across both groups, which showed a strong correlation between addiction and the retrovirus.
What Does This Correlation Mean for Addiction?
If an ancient virus influences or causes a predisposition toward addiction, this new information could have a huge impact on how addiction is perceived. While the language surrounding addiction has changed to reflect the complexities of how it happens, there is still a stigma associated with addiction for many people today.
The more researchers discover about the genetics of addiction, the more it seems impossible to blame the addicted person for a failure of willpower or some defect of character. Studies like this that show a genetic component of addiction, even if causation can’t be definitively proven, tend to diminish the stigma of addiction and allow the focus to shift to treating the disease.