The study of over 21,000 families over four years' time also suggests that children whose parents both seem depressed are at particularly high risk, Health news reported.

The research was conducted through the use of home interviews of families where both parents lived in the same house as their children. Children in the study ranged from ages 5 to 17.

Each interview was based upon self-report by either the mom or dad, who answered a series of questions.

These included questions about depression symptoms in both parents, as well as how much trouble kids had getting along with the parents or other kids and behaving at home and at school.

The researchers found that 1 in 10 of the children - 11 percent - with depressed dads showed signs of behavioural or emotional problems.

But when mom was the depressed parent, the number rose to 1 in 5 of children - 19 percent - of children who showed signs of behavioural or emotional problems. The number rises to 25 percent - or 1 in 4 - when both parents are depressed.

Teenagers aged 12 to 17 with depressed dads, males, whites and those who lived with smokers, had even higher levels of apparent depression.

The researchers suggest that their data reveal the need for pediatricians to be more aware of the presence of depression not just in moms, but also in dads.

Because the research was a survey, it could not determine a causal relationship. Therefore, it may be that depressed parents might make their children depressed, or that depressed kids might make their parents more depressed.

There isn't clear evidence that treating depression in parents will cut down on their kid's problems, the researchers said, but "recognizing it when it's there and seeking out treatment for it is the best possible approach we can have."

The researchers suggest that it may be helpful if schools and primary care doctors especially pediatricians - should be on the lookout for depression in dads, not just moms.