But a new University of Colorado Boulder study assessing genetic and survey data from 620,000 individuals found that the 18 most highly-studied candidate genes for depression are actually no more associated with it than randomly chosen genes.
The previous studies were incorrect -- or "false positives" -- and the scientific community should abandon what are known as "candidate gene hypotheses," the authors conclude.
Study - Efforts - Gene - Handful - Genes
"This study confirms that efforts to find a single gene or handful of genes which determine depression are doomed to fail," said lead author Richard Border, a graduate student and researcher at the Institute for Behavioral Genetics.
Adds senior author Matthew Keller, an associate professor of Psychology and Neuroscience:
Depression - Depression - Variants - Miniscule - Effect
"We are not saying that depression is not heritable at all. It is. What we are saying is that depression is influenced by many many variants, and individually each of those has a miniscule effect."
For the study, published in the American Journal of Psychiatry, the authors looked at 18 genes which have appeared at least 10 times in depression-focused studies.
Gene - SLC6A4 - Transport - Serotonin - Research
Among them was a gene called SLC6A4, involved in the transport of the neurochemical serotonin. Research dating back 20 years suggests that people with a certain "short" version of the gene are at significantly greater risk of depression, particularly when exposed to early life trauma.
The researchers also looked at genes involved in the production of brain-derived neurotrophic factor (BDNF) a protein involved in nerve formation, and the neurotransmitter dopamine.
Using - Survey - Data - Individuals - UK
Using genetic and survey data gathered from individuals via the UK Biobank, 23andMe, and the Psychiatric Genomics Consortium, they set out to see if any of the genes, or gene variants, were associated with depression either alone or when combined with...
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