In a new study, researcher Martin Plöderl calls into question the conclusions of a meta-analysis of tryptophan levels in depression. That study’s conclusions were that tryptophan (a proxy for serotonin) was lower in those with depression. But using a more rigorous statistical method, Plöderl concluded that this was not actually the case. He argues that the original results may have been skewed by false positives from small preliminary studies, since a much larger and more powerful study found that tryptophan levels are unrelated to depression.
Reanalysis of Tryptophan Study “Raises Doubts” about Depression Connection
The reanalysis finds that the data supports the null finding—that tryptophan (a proxy for serotonin) is not related to depression.