Objectives:
Assessment of predictive value of the occurrence of depressive symptoms during adolescence. For this purpose,the life history of untreated adolescents screened for the presence of depressive symptoms was assessed twice, at intervals of fifteen years, including an assessment of their health history, their family-related, occupational, material and social situation. The comparison of the fate of depressive adolescents with the fate of their non-depressive peers was aimed at answering the question about the influence of adolescent depression on health in adulthood.

Methods:
In 1985, a random sample of 1,035 people – students aged 15 and 17 – was examined for a screening diagnosis of adolescent depression. The Krakow Depression Inventory (KID) questionnaires version for 15-year-olds (“IOB1”) and for 17-year-olds (“IOC1”) were used. After 15 years, data on 238 people (23%) were obtained. In 2015, responses were obtained from 101 people (9.8% of those surveyed in 1985).

Results:
An analysis of the results of a 30-year prospective study of the relationship between depressiveness in adolescence, in untreated adolescents, and the health and functioning in adulthood indicates that, contrary to predictions, the appearance of depression in this phase of development cannot be treated as a predictor of mental disorders later in life.

Conclusions:
Long-term observation in our prospective study supports the hypothesis of a developmental character of adolescent depression.