Scientists disprove gene/stress link to depression
by Kelly Crowe, CBC News
April 9, 2017

In 2003 it was a breakthrough the first evidence of a direct genetic link between stress and depression. The discovery made headlines. Since then, the original paper has been cited more than 4,000 times, with at least 100 research groups following up on that work.

But it wasn't true. That's the blunt conclusion after an international group of scientists pooled their data looking for that celebrated genetic link between serotonin, a neurotransmitter, and stress-related depression.

The original finding suggested that people born with a short variant of a gene for transporting serotonin were at a higher risk of depression if their lives became stressful. It was a tempting hypothesis, that people with the short gene couldn't get serotonin in their brains fast enough when they were exposed to trauma, leaving them more vulnerable to depression.

At Washington University in St. Louis, statistical geneticist Rob Culverhouse rounded up all of the scientists who had researched this hypothesis and convinced most of them to participate in a gigantic group project.

In a series of international conference calls spanning time zones that had some working into the night and others getting up before dawn, the more than 98 scientists wrangled their data into a harmonized form so that they could compare statistical apples to apples.

And then, in a spectacular example of failure to replicate a scientific finding, when they did the final analysis, they couldn't find a link between the serotonin genes, depression, and stress.

How did the original scientists get it wrong?

"We think their results reflected their data, but anytime you sample something you can get an unusual result," Culverhouse told us. "That's why it's so important to have true replication studies. Findings that are true will be replicated."

Culverhouse expects scientists will one day find a genetic/environmental link with depression. It's just not this one. "There is still a mechanism out there to be found, and we're more likely to find it if we stop looking here."


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