Researchers at Leicester University may have come closer to the development of a pill that will beat stress.
Scientists have worked out the brain chemistry that turns a healthy dose of fear into overwhelming anxiety or depression.
The pill would be different from anti-depressants, which are prescribed after a person's health deteriorates, reports the Daily Mail.
The research was inspired by the observation that while most of us experience traumatic events from bereavements to broken hearts, only some people descend into depression or other stress-associated psychiatric disorders.
Experiments flagged up a protein called neuropsin, which is made in the amygdala, the brain's "fear centre".
In times of stress, the brain makes more neuropsin and this triggers a series of chemical reactions that culminate in a "fear gene" being switched on - and feelings of anxiety.
"Studies in mice revealed that upon feeling stressed, they stayed away from zones in a maze where they felt unsafe," said Robert Pawlak, from the University of Leicester who led the UK team.
"These were open and illuminated spaces they avoid when they are anxious.
"However, when the proteins produced by the amygdala were blocked the mice did not exhibit the same trait.
"The behavioural consequences of stress were no longer present.
"We conclude that the activity of neuropsin and its partners may determine vulnerability to stress," added Pawlak.
Although the experiments were in mice, the researchers are optimistic that the protein also affects how the human brain copes with life's troubles.
The study is detailed in the journal Nature.