A study indicates that a gene may make a difference between bouncing back from a traumatic loss or sinking into depression.

The study focused on two forms of a gene called Five-HTT. Adults with a short form were more prone to depression after serious life events than were adults with a long form.

A researcher says the long form seems better able to control the brain chemical serotonin. Serotonin previously has been found to have an effect on mental state, antidepressant drugs such as Prozac work by increasing serotonin levels.

The international study looked at people in New Zealand. Researchers were at King's College London and the University of Wisconsin, Madison.

The study is in the journal Science.