Whether their optimism deserves the credit is not clear. And the broader questions of whether optimism is something that can be "taught" - and if it's even a good idea to try - are up in the air.
The findings do argue for helping teenagers to better manage their sometimes dramatic reactions to life's ups-and-downs.
For their study, published in the journal Paediatrics, Dr Patton and his colleagues followed 5,634 Australian students who were between the ages of 12 and 14 at the outset.
Positive-thinking teens were less likely to report depression symptoms at the study's start.
About 15% of the teens with the highest level of optimism also scored high enough on a standard questionnaire to suggest at least mild depression. That compared with 59% of boys and 76% of girls with "very low" optimism levels who showed signs of depression.
More importantly, the researchers say, the most optimistic teens were half as likely to report new depression symptoms one year later, compared with their least-positive peers.
The researchers looked at whether the highly optimistic teens had had fewer stressful life events in the past year - things like the death or serious illness of a family member, or a relationship break-up.
That was not the case, Patton said. Nor did optimistic kids seem to react to major stressors any better; such experiences were linked to an increased risk of new depression symptoms in all teenagers, regardless of their optimism levels.
Does it really work?
Not everyone is sold on the power of positive thinking. A researcher not involved in the study expressed doubts about the significance of the findings.
It's not surprising, said James C. Coyne, that kids deemed very low in optimism would frequently have depression symptoms.
And even if optimism itself is protective, it probably is not all that "changeable," Coyne said.
Optimism, he said, can be seen as a product of a person's basic personality and current circumstances - rich people typically have more reason for a bright outlook than poor people, for instance.
A number of studies of adults have linked optimism to physical health benefits, like a lower risk of heart disease. But Coyne said that those associations are modest, and seem largely connected to optimists' often healthier lifestyles.
Do you think being optimistic reall works to fight depression?