Scientists in the United States said they had found a gene that appears to play a key role in the onset of depression, a finding that could unlock new avenues for drug engineers.
A gene called MKP-1 was identified by Yale University investigators after comparing the genetic codes of 21 deceased people who had been diagnosed with depression with those of 18 otherwise healthy individuals.
MKP-1 plays the role of an off switch over a cascade of brain chemicals called MAPK that are crucial to the survival and function of neurons, according to the paper, which appears in the journal Nature Medicine.
"This could be a primary cause [of], or at least a major contributing factor to, the signalling abnormalities that lead to depression," said the study's lead author, Ronald Duman, a professor of psychiatry and pharmacology.
The scientists created "knockout" mice whose MKP-1 had been deactivated to explore the hunch that altering MAPK levels played a role in depression.
Mice without MKP-1 were happily resilient to stress. But stressed mice with the gene developed depression-like symptoms which were then eased by using anti-depression drugs, they found.
Depression, like many other mood disorders, is believe to have multiple causes, including genetic, for its symptoms vary widely among individuals.
As many as 40 percent of depressed patients do not respond to drugs, which are mainly based on boosting uptake of a brain chemical called serotinin.
Almost one in six Americans are afflicted by depression in any given year, and the disorder costs the US economy 100 billion dollars annually, according to figures quoted in the study.
The finding "identifies MKP-1 as a potential target for a novel class of therapeutic agents, particularly for treatment-resistant depression," Yale said in a press release.