EVANSTON, Ill. --- A new Northwestern University and UCLA study has found for the first time that young people who are high on the personality trait of neuroticism are highly likely to develop both anxiety and depression disorders.

"Neuroticism was an especially strong predictor of the particularly pernicious state of developing both anxiety and depressive disorders," said Richard Zinbarg, lead author of the study and professor of psychology in the Weinberg College of Arts and Sciences at Northwestern.

Earlier research has shown that neuroticism is associated with substance abuse, mood and anxiety disorders but hadn't tested whether these associations are comparable in strength.

But the Northwestern and UCLA study found for the first time that neuroticism predicts mood and anxiety disorders more strongly.

"It's been my professional dream to be able to prevent the development of anxiety disorders and depression in people who would have otherwise experienced them," said Zinbarg, director of clinical psychology at Northwestern. "We have pretty good treatments once people have already started suffering from them. We do a lot less on prevention."

Researchers who study personality traits largely agree that of the five major dimensions of personality, neuroticism is the trait most relevant for developing nearly all forms of psychopathology. The other four personality traits are extraversion, agreeableness, conscientiousness and openness.

The study included 547 participants recruited as high school juniors at two Chicago and Los Angeles high schools. The study results, Zinbarg said, point the way toward a relatively cost-effective and broad-based program of prevention.

High schools students, he said, could be given a questionnaire on neuroticism -- either via paper and pencil or administered online -- that determines their standing on that personality trait.

"We can identify those kids that we should be targeting -- that's the first implication," Zinbarg said.

The goal would be to design a prevention that would not only prevent depression or anxiety disorders but reduce risks for both, given that they've got a common risk factor.

"It should be possible to reduce simultaneously, through a single intervention, the risk for anxiety as well as for depression and help people cope much better," Zinbarg said.

The results also shed light on a theoretical controversy about neuroticism and its definition.

"Some, including me, believe that neuroticism is somewhat specific," Zinbarg said. "The theorists in this camp believe that neuroticism makes people more susceptible to the negative emotions -- anxiety, depression, irritability, anger."

Others believe that neuroticism heightens susceptibility to emotions in general, including those that are positive. In that view, neuroticism would be as much a predictor of disorders of excess, like gambling or substance use, as of disorders that involve inhibition and pain.

The Northwestern and UCLA team did study substance use and found that neuroticism was not as strong a predictor of substance use disorders as anxiety disorders and depression.

"The study's results strongly suggest that neuroticism is more sensitive to threat than emotional reactivity writ large," Zinbarg said.