 to lower self-esteem in children (3). It was also suggested that person-focused but not process-focused praise leads children to avoid challenges in school (7). Furthermore, praise for behavior (process) was better than praise for personal qualities in terms of the effect on the self-esteem of children (2). Taken together, praise for behavior may be important in preventing depressive symptoms in adolescents, but it is still unknown which behaviors of children should be praised.
A negative correlation between prosocial behavior and depressive symptoms has been noted (8). Further, since prosocial behavior predicted future decreased depressive symptoms in adolescents (9), praise for prosocial behavior is a candidate preventive strategy against depressive symptoms in adolescents. However, no study has investigated the association between recognition of being praised for prosocial behavior and depressive symptoms in adolescents. Furthermore, no study has examined whether being praised for prosocial behavior has a preventive effect on depressive symptoms in adolescents. We hypothesized that being praised for prosocial behavior would be longitudinally associated with decreased depressive symptoms in adolescents. This study aimed to examine the longitudinal relationship between being praised for prosocial behaviors and depressive symptoms using a large-scale cohort of adolescents sampled from the general population.
Study Design and Survey Participants
The purpose of this study was to test the hypothesis that being praised for prosocial behavior would be longitudinally associated with decreased depressive symptoms in adolescents. We adopted 10–24 years as the definition of the age of adolescence according to the recent review (10), thus called the study participants as early adolescents. This study used data from the Tokyo Teen Cohort study (TTC), a prospective population-based cohort study that is currently underway and aims to investigate the developmental trajectory of adolescents (11). Children born between September 2002 and August 2004 in three local governments in Tokyo (Setagaya, Mitaka, and Chofu) were randomly extracted using the Basic Resident Register. Of the 10,234 pairs of children and their primary caregivers who were asked to participate, 4,478 pairs agreed to cooperate in the baseline survey (the 1st wave of data collection) at the age of 10 years. An oversampling method was used with the goal of having 3,000 pairs remain in the 2nd wave survey (11). Given the low follow-up rate of low-income families, all 620 pairs whose annual household incomes was lower than five million yen were asked to participate in the 2nd wave survey. Of the remaining 3,858 pairs, 2,551 were randomly asked to participate in the 2nd wave. A total of 3,172 pairs were asked to participate in the longitudinal cohort study, resulting in 3,007 pairs participating in the second wave of data collection at the age of 12 years (follow-up rate was 94.8%).
In each of the 1st and 2nd waves of data collection, trained investigators visited the participants' home twice and interviewed children and their primary caregivers. At the first visit, the investigators explained the research to both the child and the primary caregiver, obtained written consent, and asked them to complete the self-report questionnaire by the second visit. At the second visit, the child and the primary caregiver separately answered a self-report questionnaire containing sensitive content and sealed it immediately after completion. All questionnaires and data were collected anonymously. At this visit, the investigators also administered face-to-face psychological tests to the child.
TTC is a joint study of three institutions (Tokyo Metropolitan Institute of Medical Science, the University of Tokyo, and the Graduate University for Advanced Studies) and has been approved by the ethics committees of the three institutions.
The children answered self-report questionnaires including items on experiences of being praised, depressive symptoms and other variables, such as the number of 