The paper, which has just been published in the British Journal of Psychiatry, has found more than a fifth of the population has a genetic predisposition to depression, in response to a series of stressful life events.
Brain Sciences UNSW represents researchers from the University of New South Wales (UNSW) and its affiliated research institutes and teaching hospitals including the Prince of Wales Medical Research Institute, Black Dog Institute, Garvan Institute of Medical Research, St Vincent's Hospital and Prince of Wales Hospital.
The researchers based their findings on DNA samples of a group of 127 people who have been monitored for over 25 years for depression onset and major life events. 42 percent met criteria for lifetime major depression.
"We have been following a group of school teachers who graduated in 1978," said the lead author of the paper, UNSW Associate Professor of Psychiatry Kay Wilhelm, who is based at St Vincent's Hospital in Sydney. "We've been catching up with them every five years since, to see if there has been any onset of depression and if there have been any major life events."
"There is an 80 percent chance that those with the genetic predisposition will become depressed, if there are three or more negative life events in a year," said the geneticist on the paper, Professor Peter Schofield, who is Director of the Prince of Wales Medical Research Institute (POWMRI).
"This contrasts with some people who have genetic resilience against depression," said Professor Schofield. "Even in similar situations, there's only a 30 percent chance of them becoming depressed."
There are three different genetic types in the population.