Background: The literature reports a significant association between various mental disorders and asthma, in particular depression and/or anxiety, with some more robust data regarding anxiety disorders. However, the nature of this association remains largely unclear.
Objectives: (1) To test the hypothesis of a specific association of anxiety and depressive disorder (according to the DSM-IV) with asthma and (2) to test the bidirectional hypothesis of causality between asthma and psychiatric disorders.