The trial is designed as a multicenter randomized controlled, parallel group study. Patients are randomized into 1 of 2 treatment arms with 14-week duration: one arm with initial intervention by structured skills training groups by weekly sessions or one with control condition (treatment as usual). Then after 15 weeks patients in the control condition arm are switched to the active intervention by 14 weeks of structured group therapy. All patients are assessed for defined outcomes after six months.