Much Touted “Depression Risk Gene” May Not Add to Risk After All
A range of factors led to the wide acclaim of a 2003 study suggesting a possible gene-environment interaction contributing to depression risk. This study had far-reaching influence on the field, including proposals by some researchers to market a gene test to the public, claiming to be able to predict a person's risk for depression. However, despite considerable resources being invested in research building upon the 2003 study, attempts to replicate its findings—a key step in the scientific process—had inconsistent results.
Akinso: A certain gene long thought to increase a person's risk for major depression actually may have no effect according to a study funded by the National Institute of Mental Health. NIMH senior investigator Dr. Kathleen Merikangas, says the study, published in a recent issue of the Journal of the American Medical Association, challenges a widely accepted approach to studying risk factors for depression.
Merikangas: When we put together the gene, serotonin gene, with stressful life events we did not find that people who had this particular gene were at increase risk for depression in the presents of life events.
Akinso: Serotonin is one of several chemical messengers in the brain, which help brains cells communicate with on another. Among, other functions, serotonin is involved with regulating mood. In the study, which included re-analyzing data on 14,250 participants in 14 studies, the presumed high-risk version of the serotonin transporter gene did not show a relationship to increased risk for major depression, alone or in interaction with stressful life events. Dr. Merikangas explains that researchers are still in the early stages of understanding how genes and environment interact to increase the risk for depression.
Merikangas: When we're trying to study the effective genes on complex human disorders such as depression that it's not going to be easy to simplify the way that we conceive of environmental exposure and these genes and producing these disorders then it's unlikely that there's going to be one single gene that is going to either elevate or protect against certain disorders in the presents of environmental exposures. We need to understand more about both the genetic architecture of complex diseases as well as how environmental factors are related to the risk of particular diseases.
Akinso: Most mental disorders are thought to be caused by a combination of many genetic risk factors interacting with environment triggers. However the exact combinations continue to present significant challenges to research. For more information about this study, visit www.nimh.nih.gov. This is Wally Akinso at the National Institutes of Health, Bethesda, Maryland.
About This Audio Report
Reporter: Wally Akinso
Sound Bite: Dr. Kathleen Merikangas
Topic: Depression, gene