If you’re at all tuned into health news, you know just how common it is to hear about a specific gene being discovered as a risk factor for a certain disease. But this new study on so-called “depression genes” will make you think twice about such grand claims in the future.
While past research has suggested that there are genes that make you more likely to develop depression, a large new study published in the American Journal of Psychiatry has found just the opposite: Researchers looked at data from 620,000 individuals and found the 18 most-studied genes in relation to depression were no more associated with the disorder than genes chosen at random.
How could the previous studies have gotten it so wrong? These were “false positives,” say the study authors from the University of Colorado Boulder, and the idea that specific genes play a significant role in depression, called “candidate gene hypotheses,” should be scrapped altogether.
But senior author Matthew Keller, Ph.D., associate professor of psychology and neuroscience at CU Boulder notes that this doesn’t mean depression is completely unrelated to your genes. It’s just a heck of a lot more complicated than that.
"We are not saying that depression is not heritable at all. It is,” he says. “What we are saying is that depression is influenced by many, many variants, and individually each of those has a miniscule effect."
Research suggesting specific genes make you more susceptible to depression has been ongoing for the past few decades. For example, scientists have previously argued that people who have a gene called SLC6A4, one of the 18 assessed in the new CU Boulder study, were significantly more at risk of depression.
But the CU Boulder researchers, in the largest and most comprehensive study of its kind, set out to confirm whether any of the 18 genes or gene variants were truly associated with depression without the influence of environmental factors, such as childhood trauma. And they were shocked by the results: Using genetic data from 23andMe, UK Biobank, and the Psychiatric Genomics Consortium, the authors found that none of these 18 genes were more linked to depression than “any random gene out there,” said Keller.
While the authors emphasize their findings don’t mean all research on the genetic aspects of depression should stop, they note that it’s not as simple as identifying specific “depression genes.” Keller hopes this landmark study puts an end to further research on the so-called candidate-gene hypotheses. "It's like in 'The Emperor Wears No Clothes.' There's just nothing there," said Keller.
The authors hope this leaves consumers with a key takeaway about scientific studies:
"Any time someone claims to have identified the gene that 'causes' a complex trait is a time to be skeptical," said Border.
Until we have a better understanding of how genes play into depression, there are some identified risk factors you should know about. You’re more likely to develop depression if:
- You’ve been through traumatic or stressful events, such as abuse, death of a loved one, financial struggles, or difficult relationships
- You have a history of other mental health disorders, like anxiety or post-traumatic stress disorder.
- You have serious or chronic illness or chronic pain, such as cancer.
- You abuse alcohol or drugs.
- You’ve used certain medications, like sleeping pills.
- You’re lesbian, gay, bisexual, or transgender in an unsupportive situation.
- You have blood relatives with a history of depression or other serious mental disorders.