Could the underestimation of bipolarity obstruct the search for novel antidepressant drugs?

INTRODUCTION: Despite the clinical and social relevance of depression, and the availability of numerous antidepressants and non-pharmacological interventions, response rates remain unsatisfactory and novel therapeutic targets are being explored. AREAS COVERED: This review starts with a brief overview of the evolution of the current antidepressant drug scenario and ends with a focus on the potential influence of the underestimation of bipolarity on the exploration of novel antidepressant drugs. EXPERT OPINION: The field of antidepressant drug development has suffered from a relative decline recently and, with the exception of agomelatine, innovative non-monoaminergic antidepressants have yet to be developed. The need for more effective compounds is evident. Clinicians and researchers should pay greater attention to the impact of bipolarity in depression. The ultimate goal of this review is not to discourage the use of antidepressants but rather to encourage judicious prescriptions, and also to solicit a better collaboration between clinicians and preclinical researchers so that more reliable diagnostic criteria can be adopted.