Blockbuster Discovery turns out to be based on False Positives

Two decades ago, researchers found that a certain gene, SLC6A4, might influence a person’s risk of depression as a less active form of the gene was more common among 454 people who had mood disorders than in 570 who did not. SLC6A4 seemed like a great candidate: It’s responsible for getting a chemical called serotonin into brain cells, and serotonin had already been linked to mood and depression.

However, a new study analysing data from large population-based and case-control samples did not find any clear evidence for SLC6A4 or any of the other 17 candidate genes commonly linked to depression to have any significant association with depression phenotypes or any polymorphism-by-environment moderator effects. The results suggest that early hypotheses about depression candidate genes were incorrect and that the large number of associations reported in the depression candidate gene literature are likely to be false positives.

This points to a fundamental problem in the academic world where scientists are often rewarded for being productive in making new discoveries rather than being right, for building ever upward instead of checking the foundations.

We’re told that science self-corrects, but what the candidate-gene literature demonstrates is that it often self-corrects very slowly, and very wastefully, even when the writing has been on the wall for a very long time

Marcus Munafò, University of Bristol. Source: The Atlantic