The main objective of this study was to examine the prevalence of major depressive disorder (MDD) among adolescents in a city of 200,000 inhabitants using a psychiatric diagnostic tool. We also looked into how possible internal/external factors may influence prevalence and examined the comorbidity between MDD and other psychiatric disorders. The study population included 1,238 adolescents in their final year of secondary education in Sabadell (Barcelona, Spain). A prospective observational study in two phases: (a) Initial population-based screening using the Beck Depression Inventory (BDI), and (b) Diagnosis using the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) with participants who, according to screening, exhibited significant depressive symptoms. The Child Behavior Check-list (CBCL) and the State-Trait Anxiety Inventory for Children (STAIC) were also used in the second phase of the study, which, together with K-SADS, enabled us to examine the comorbidity of MDD with other disorders. According to the initial screening, 7.92% of participants exhibited significant depressive symptoms. The results of the diagnostic interviews showed a prevalence of 1.29% adolescents with MDD. Prevalence was higher in girls (1.92%) than in boys 0.34%) (p=0.002) and at age 16 or over in both genders (p<0.001). 50% of participants with MDD presented comorbidity with other psychiatric pathologies. The low prevalence of MDD observed does not justify generalised screening in adolescents attending school, except in cases of individuals with significant depressive symptoms.
Key words: Depression, major depressive, disorder, adolescence, prevalence, screening, comorbidity.