Thus one possible hypothesis is that the ADH variant contributes to the development of both conduct disorder and AD in the sense of a shared etiology. Another explanation is that the association finding originates from one of the two disorders, and that the association with the other disorder is simply the result of comorbidity. If the association arises from conduct disorder, the association would only be expected in patients with this disorder. Unfortunately, we were unable to test these alternative hypotheses by stratifying our sample for co-morbid conduct disorder. Further studies are required to disentangle this issue.
