[A longitudinal study of the relationship between support reciprocity and mental health among elementary and high school students].

At both the beginning and the end of a school year, 124 sixth-year elementary school students and 242 first-year high school students completed questionnaires regarding mutual support in friendships and stress responses. For elementary school students, support reciprocity did not correlate significantly with stress responses at either the beginning or end of the school year. For high school students, support reciprocity related significantly to stress responses at the end of the year but not at the beginning. These results suggest that the relationship between support reciprocity and mental health is influenced by the developing relationship between two people as well as the state of each individual's development at the time of mutual support.