About the Depression Gene and Biological Associations with Depression

Header image courtesy of KQED Science.

The debate of whether some mental illnesses, such as anxiety and depression, are the product of genetic or environmental factors is starting to feel age-old. With critics and skeptics on both sides, it feels as if no one has a solid answer on how to properly prevent and treat them; only differing hypotheses on what will, potentially, work the best.  

As conversations about mental illness become more widespread, so does the research and interest in the psychiatric community. One point of interest over the years has been “the depression gene,” which has long been thought to be associated with the onset of depression. Through summarizing an article by David Rettew, a child psychiatrist at the University of Vermont, titled “The Rise and Fall of the Depression Gene,” I am going to touch on the following points:

  • How researchers first became interested in “candidate genes”
  • The depression gene and its association with depression
  • What new research on candidate genes tells us about the depression gene

Let me start by throwing it back to “candidate genes,” which were a popular topic of discussion among scientists and psychiatrists in the early 2000s. In a landmark 2003 study, “Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene,” published in Science, researchers found that both biological and environmental factors played significant roles in the onset of depression.

a person on a bench slouches with their head in their hands in a fit of despair
A number of factors are thought to correlate with the onset of depression. Image courtesy of The Daily Pennsylvanian.

According to the study, not only do they both play a role in the development of one of the most prevalent mental illnesses in the United States, but they depend on each other. These researchers discovered that people with different genes  responded to stressful situations differently, and those with candidate genes, like the depression gene, ended up with — you guessed it — depression.

Therefore, much of the depression research in the 2000s and 2010s; thousands of articles; began to focus on the depression gene, or SLC6A4. While skepticism certainly existed, other hypotheses for the development of depression weren’t widely accepted in the scientific community. As of March, that may all change.

“No Support for Historical Candidate Gene or Candidate Gene-by-Interaction Hypotheses for Major Depression Across Multiple Large Samples,” published in The American Journal of Psychiatry, refuted claims that any singular genes played a role in the onset of depression. In other words, there’s no reason to dub SLC6A4 “the depression gene,” because the presence of that gene alone, in conjunction with a traumatic event or any other environmental situation, couldn’t possibly be the cause of depression.

a therapist speaks to a man on a white couch about depression
Talk to a therapist today to help rid yourself of negative emotions toward an addict. Image courtesy of Joseph W. LaFleur.

As of now, it seems that there’s no conclusive scientific evidence that a depression gene even exists. According to David Rettew, child psychiatrist at the University of Vermont, the publication of this study could mean a couple of things. But first and foremost, what it does not mean is that genetics has nothing to do with the development of depression. There’s not enough scientific evidence to support this claim — genetics could still be a factor, but it’s more probable that various genes would be involved, rather than just one.

This study could signify publication bias in psychiatric research. With so many candidate genes to test, one of them was bound to correlate to the onset of depression. Regardless of what led scientists to believe in the existence of the depression gene, one thing is for certain: the development of depression doesn’t result from a single gene or environmental factor. Moving forward, we have to be careful to trust oversimplified explanations of a complex mental illness.    

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