e prosocial behavior itself, then lead to decrease of depressive symptoms. In any case, the present study further added that the recognition of being praised for prosocial behavior might decrease depressive symptoms more than the prosocial behavior itself.
This result would not necessarily be contrary to a previous study which showed that prosocial behavior served as a protective factor against depressive symptoms in adolescents (9) because the previous study did not assess being praised for prosocial behavior. It should also be noted that the previous study targeted a social minority (Latino immigrants to the United States) with a mean age of 14.5 years, so it was not entirely consistent with the population of interest in this study.
There are several strengths of this study. First, this study revealed a longitudinal relationship between recognition of being praised for prosocial behavior and depressive symptoms with the 2 year follow-up period. Second, since this study used a large-scale (n = 3,007) general population sample of adolescents, a certain generalizability of the results would be assured. This is significant because it provides suggestions for intervention methods for adolescents, who are at high risk of developing depression. Third, the follow-up rate was very high (94.8%). Fourth, we conducted the analyses while including several confounders, such as depressive symptoms at baseline, estimated IQ, and number of siblings.
There are several limitations to this study related to the fact that we assessed praise for prosocial behavior by asking the children. First, we cannot determine whether the children were actually praised. There may be children who did not describe the experience of being praised for prosocial behaviors in the questionnaire but actually had an experience of being praised for such behaviors. However, on the other hand, we could assess the importance of children's recognition of being praised for their prosocial behavior in preventing depression, which would conversely be a strength of this study. Second, since the participants were 10 year-old children, a recall bias should be noted for their responses. Third, we could not investigate parenting styles or parental habit to praise which could be important factors in how children experience praise. Fourth, since the study participants were sampled only in Japan, the generalizability to other countries is questionable. Similar investigation in other countries is needed in the further research.
Clinical implications can be derived from the results of this study. With regard to preventing depressive symptoms, caregivers and professionals in relation with adolescents should consider praising prosocial behaviors when they see them. In addition, we should devise ways to praise so that children receive the message that they have been praised for their prosocial behavior. In future research, the objective assessment of praise for prosocial behavior should be considered as well as subjective assessment. Additionally, an intervention study is required to examine the effect of praising children for prosocial behaviors on preventing depressive symptoms.
Being praised for prosocial behavior rather than objective prosocial behavior at 10 years of age predicted lower depressive symptoms 2 years later. Further study is required to examine the effect of praising children for prosocial behaviors on preventing their depressive symptoms.
Data Availability Statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
The studies involving human participants were reviewed and approved by Tokyo Metropolitan Institute of Medical Science (12–35), the University of Tokyo (10057), and SOKENDAI (Graduate University for Advanced Studies) (2012002). Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.
DN, NT, SA, MM, and TK designed the work. DN and NT conducted statistical analyses and wrote the draft of the manuscript. SA, KE, SY, AN, MH-H, 