Treating depressive disorders: who responds, who does not respond, and who do we need to study?

Numerous studies show that pharmacotherapy and psychotherapy are efficacious and effective in treating depression. Even though that is true for many people, there are some who do not respond to these therapies, whether it is because they possess characteristics that make them resistant to treatment or because the treatment is not acceptable to them. Also, there are other populations for whom research has yet to determine if guideline-level treatment is effective. People with comorbid Axis I disorders, certain minority groups, and children have been under-represented in treatment research. Future research should focus on treatment-resistant depression and special populations that have been understudied.