Criminal policy is interested in general but enough precious definition of what should be understood under term mental disorder. That is why the new penal law from 2009, which will come in force on 1.1. 2010, determines in its paragraph 123 in relatively concrete way, which mental disorders are covered by the definition of mental disorder.
Further the key term in § 123 is not mental disease, but mental disorder. Nevertheless the last findings of psychiatry and psychology signalise our limited knowledges concernig mental health, so that we have to be prepared for possible change of particular terms of mental disorder in the future.