Parents' behaviour when their child complained of a headache also seemed to play a major role.

Their responses had a particularly strong effect on the frequency of symptoms in girls: reinforcing parental responses raised their risk of recurrent headaches by 25 percent.

The sexes also differed with respect to the frequency of headache. Twice as many girls as boys had their symptoms at least once a week.

The children's age, however, seemed to have no more than a minor effect on headache manifestations.

These findings appeared in the current issue of the Deutsches Arzteblatt International.