Recent studies by the Duke team have used metabolomics tools to map biochemical pathways implicated in depression and have begun to distinguish which patients respond to treatment with an SSRI or placebo based on their metabolic profiles. These studies have pointed to several metabolites on the tryptophan metabolic pathway as potential contributing factors to whether patients respond to antidepressants.
Tryptophan is metabolized in different ways. One pathway leads to serotonin and subsequently to melatonin and an array of melatonin-like chemicals called methoxyindoles produced in the pineal gland. In the current study, the researchers analyzed levels of metabolites within branches of the tryptophan pathway and correlated changes with treatment outcomes.
Seventy-five patients with major depressive disorder were randomized to take sertraline (Zoloft) or placebo in the double-blind trial. After one week and four weeks of taking the SSRI or placebo, the researchers measured improvement in symptoms of depression to determine response to treatment, and blood samples were taken and analyzed using a metabolomics platform build to measure neurotransmitters.
The researchers observed that 60 percent of patients taking the SSRI responded to the treatment, and 50 percent of those taking placebo also responded. Several metabolic changes in the tryptophan pathway leading to melatonin and methoxyindoles were seen in patients taking the SSRI who responded to the treatment; these changes were not found in those who did not respond to the antidepressant.
The results suggest that serotonin metabolism in the pineal gland may play a role in the underlying cause of depression and its treatment outcomes, based on the biochemical changes that were seen to be associated with improvements in depression.
"This study revealed that the pineal gland is involved in mechanisms of recovery from a depr
|Contact: Rachel Harrison|
Duke University Medical Center