Extreme depression and anxiety affects up to 15 per cent of preschoolers, and such children tend to have mothers with the same affliction, according to a study by Montreal researchers.

The five-year survey also found that a bad temper at the age of five months was the most important clue that a child might develop depression or anxiety.

The results were published in the latest edition of The Journal of Child Psychology and Psychiatry.

University of Montreal professor Sylvana M. Cote was one of the scientists who conducted annual evaluations of 1,758 Quebec pre-schoolers from five months to five years of age.

"One thing about depression and anxiety is that contrary to other problems that are more externalized like aggression and hyperactivity, those children tend to disappear. People don't notice them," said Cote.

The study found that having a chronically-depressed mother was the second most important predictor of depression and anxiety in children, after bad temperament.

"Our study is the first to show that infant temperament and lifetime maternal depression can lead to a high trajectory of depressive and anxiety problems before school entry," said Cote.


While the signs of depression aren't as obvious in children under a year-and-a-half, Cote says the symptoms increase over time.

"For instance being fearful, being worried, being sad -- and those are normal in face of stressors," said Cote.

She recommends that health professional treat high-risk children early to head off future problems.

These children should be treated from infancy along with their parents, say researchers.


A team of researchers from the University of Montreal, Universit� Laval and McGill University took part in the study.

France's national medical research agency, Carnegie Mellon University in the U.S. and University College Dublin in Ireland were also involved.