Study reverses thinking on genetic links to stress, depression

April 4, 2017
Credit: CC0 Public Domain

New research findings often garner great attention. But when other scientists follow up and fail to replicate the findings? Not so much.

In fact, a recent study published in PLOS One indicates that only about half of scientific discoveries will be replicated and stand the test of time. So perhaps it shouldn't come as a surprise that new research led by Washington University School of Medicine in St. Louis shows that an influential 2003 study about the interaction of , environment and depression may have missed the mark.

Since its publication in Science, that original paper has been cited by other researchers more than 4,000 times, and some 100 other studies have been published about links between a -related gene, and depression risk. It indicated that people with a particular variant of the were not as well-equipped to deal with stressful life events and, when encountering significant stress, were more likely to develop depression.

Such conclusions were widely accepted, mainly because antidepressant drugs called selective serotonin reuptake inhibitors (SSRIs) help relieve depression for a significant percentage of clinically depressed individuals, so many researchers thought it logical that differences in a gene affecting serotonin might be linked to depression risk.

But in this new study, the Washington University researchers looked again at data from the many studies that delved into the issue since the original publication in 2003, analyzing information from more than 40,000 people, and found that the previously reported connection between the serotonin gene, depression and stress wasn't evident. The new results are published April 4 in the journal Molecular Psychiatry.

When new research findings are published, the results often get a great deal of attention, but when other scientists follow up to replicate those findings, we usually don't hear very much. Now, a team of researchers, led by scientists at Washington University School of Medicine in St. Louis, has taken another look at a gene that was identified in 2003 as increasing the risk for depression in people who experienced severe stress. This new study, in contrast to the first one, has found that variations in the gene have no impact on depression. Jim Dryden has more... Credit: Washington University BioMed Radio

"Our goal was to get everyone who had gathered data about this relationship to come together and take another look, with each research team using the same tools to analyze data the same way," said the study's first author, Robert C. Culverhouse, PhD, an assistant professor of medicine and of biostatistics. "We all ran exactly the same statistical analyses, and after combining all the results, we found no evidence that this gene alters the impact stress has on depression."

Over the years, dozens of research groups had studied DNA and life experiences involving stress and depression in the more than 40,000 people revisited in this study. Some previous research indicated that those with the gene variant were more likely to develop depression when stressed, while others didn't see a connection. So for almost two decades, scientists have debated the issue, and thousands of hours of research have been conducted. By getting all these groups to work together to reanalyze the data, this study should put the questions to rest, according to the researchers.

"The idea that differences in the serotonin gene could make people more prone to depression when stressed was a very reasonable hypothesis," said senior investigator Laura Jean Bierut, MD, the Alumni Endowed Professor of Psychiatry at Washington University. "But when all of the groups came together and looked at the data the same way, we came to a consensus. We still know that stress is related to depression, and we know that genetics is related to depression, but we now know that this particular gene is not."

Culverhouse noted that finally, when it comes to this gene and its connection to stress and depression, the scientific method has done its job.

"Experts have been arguing about this for years," he said. "But ultimately the question has to be not what the experts think but what the evidence tells us. We're convinced the evidence finally has given us an answer: This serotonin gene does not have a substantial impact on depression, either directly or by modifying the relationship between and depression."

With this serotonin gene variant removed from the field of potential risk factors for depression, Culverhouse and Bierut said researchers now can focus on other gene-environment interactions that could influence the onset of .

Explore further: Genetics in depression: What's known, what's next

More information: Culverhouse, RC, et al. Collaborative meta-analysis finds no evidence of a strong interaction between stress and 5-HTTLPR genotype contributing to the development of depression. Molecular Psychiatry. April 4, 2017. DOI: 10.1038/MP.2017.44

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KBK
not rated yet Apr 04, 2017
Of course we have to look at not just the studies, but who funded them.

In studies that affect the fundamental landscape that stretches between medical prognosis, advice, lore, and a coming 'standard' in potential answers..vs that of pharmaceutical companies and what they stand to gain..one must ALWAYS look VERY closely on the subject of WHO exactly funded WHAT research, and WHAT the outcome of the 'research' means for the financial bottom line of the various parties that are involved.

Never take it at face value, look for triple layered corporate aspects (they'll do what it takes to set the ground rules - in ways you can't easily find) buried in the depths of all medical work that comes out of the deeply capitalist and incorporated medical (and research!) INDUSTRY that is the rolling insane human disaster called 'medicine' in the USA.

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