There has recently been an intense debate about the increased rate of bipolar disorders (BPD) in children and adolescents observed in clinical settings. Thus, there is great interest in child and adolescent symptoms of hypomania and whether these symptoms subsequently will develop into BPD. More knowledge about early signs could give insight into the development of the disorder. There are also concerns that hypomanic symptoms in adolescence indicate excess risk of other health conditions. It has been reported that patients with mood disorders have a high consumption of prescription drugs in different ATC classes. The primary objective of this thesis was to better understand the mental health outcome of adolescents with hypomania spectrum symptoms and to identify early risk factors for adult bipolar disorder among adolescents with mood disorders. In order to widen the scope and investigate health outcome of mood disorder in general psychopharmacological outcomes were included. A community sample of adolescents (N=2 300) in the town of Uppsala, Sweden, was screened for depressive symptoms. Both participants with positive screening and matched controls (in total 631) were diagnostically interviewed. Ninety participants reported hypomania spectrum episodes, while another 197 fulfilled the criteria for major depressive disorder (MDD) without a history of a hypomania spectrum episode. A follow-up after 15 years included a blinded diagnostic interview, a self-assessment of personality disorders, and national register data on prescription drugs and health services use. Adolescent mood symptoms, non-mood disorders, and family characteristics were assessed. Univariate and multivariate analyses were used. The results indicate that the phenomenology of the hypomania spectrum episodes during childhood and adolescence per se does not predict adult bipolar disorder. However, having both affective symptoms during adolescence and a family history of bipolar disorder increases the risk of developing bipolar disorders in adulthood. Disruptive disorder in childhood or adolescence as well as family histories of BPD emerged as significant risk factors that differentiated between the future development of BPD and MDD. Adolescents with hypomania spectrum episodes and adolescents with MDD do not differ substantially in health outcomes in adulthood. Both groups are at increased risk for subsequent mental health problems, high consumption of prescription drugs, and high health care use, compared with the control group. The high rates of prescription drugs in many ATC classes found among the former depressed females seem to indicate a series of co-morbid somatic illnesses. Thus, it is important to identify and treat children and adolescents with mood disorders, and carefully follow the continuing course. Characteristics such as disruptive disorders and family history warrant particular attention.