Depression is a common mental disorder characterised by depressed mood, loss of interest or pleasure, feelings of guilt or low self-worth.

Although it’s among the leading causes of disability worldwide, scientists have been so far unable to pin down the cause of the condition. More over, as many as 40 percent of depressed patients do not respond to currently available medications.

Now, researchers at Yale University who found the depression-triggering gene said their discovery would lead to the development of new drugs for this condition which affects about 121 million people worldwide.

For their study, published in the journal Nature Medicine, researchers led by Professor Ronald S Duman carried out whole genome scans on tissue samples from 21 deceased individuals who had been diagnosed with depression.

Then they were compared with the gene expression levels of 18 other individuals who had not been diagnosed with depression. They found that one gene called MKP-1 was increased more than two-fold in the brain tissues of depressed individuals.