How pharmacology can aid in the diagnosis of mental disorders.

The precise diagnosis of mental disorders constitutes a formidable problem. Mental disorders are currently diagnosed based on clinical symptoms, which are often subjective. Various drug classes, traditionally referred to as "antidepressants," "antipsychotics" and "mood stabilizers" are then used empirically to treat affected patients. The previous decade has witnessed an increasing extension of the use of drug classes beyond their traditional indications (e.g., "antidepressants" in the treatment of anxiety disorders). Therefore, we would like to initiate a discussion in the pharmacological and psychiatric research communities on an alternative classification of mental disorders: Instead of using the traditional categorical classification of mental disorders physicians should rather diagnose symptoms (e.g., anhedonia) without bias to a traditional categorization (e.g., depression). The appropriate most effective drugs are then selected based on these symptoms. Depending on the responsiveness of the patient towards a given drug X, the disease should be classified, e.g., as drug X-responsive disease. This approach will also help us elucidate the still poorly understood molecular mechanisms underlying mental disorders, i.e., drugs can also be viewed and used as molecular diagnostic tools. In several fields of medicine, drugs are already used as molecular diagnostic tools. Thus, there is already precedence for the concept proposed here for mental disorders.