BACKGROUND:Respiratory allergic symptoms impact on social life and school activities, influencing the patient's mood states. We evaluated the relationships between allergic respiratory diseases and depressive/anxious mood in a large sample of Italian middle school students, using the partial directed acyclic graph (P-DAG).METHODS:We studied 1283 subjects aged 10-13. A health respiratory questionnaire including questions relevant to socioeconomic status (HCI) and a test for depression and anxiety were administered. All subjects performed spirometry and skin prick tests.RESULTS:A causal role of rhinitis on depression was found: the likelihood of being depressed increased from 11.2 to 17.7%, when rhinitis was present. Moreover, a direct effect of low HCI on depressive mood was shown (p < 0.0001) as well as the correlation between anxiety and depression (p < 0.0001). Gender was not a direct causal factor for depressive mood, but their relation was mediated through anxious mood. Anxiety appeared to have a stronger association with depression than gender. Allergic sensitization was significantly related to both asthma and rhinitis (p < 0.0001, respectively). Asthma and rhinitis were also directly associated (p < 0.0001). Conversely, asthma was not directly associated with depressive mood, but their relation was mediated through rhinitis. Body mass index (BMI) and impaired lung function (IPF) were not associated with the other variables.CONCLUSIONS:The use of this novel approach to analyzing the dynamic relationships allowed us to find a causal role of rhinitis on depressive state. Moreover, anxious condition and low socioeconomic status contributed to induce depressive mood.