Many patients seen in clinical practice have a mood disorder not well described by the existing diagnostic categories. Formally, they would be called “not otherwise specified” but this creates a huge single category for many patients that belies the richness and complexity of their symptoms.

Review the existing information regarding the bipolar spectrum concept and reflect about its importance and utility.

Nonsystematic review of the literature – scientific publications from Pubmed and Psychiatry Textbooks.

The “bipolar spectrum disorder”, designating those patients who fall in the middle of the mood spectrum between the classic unipolar and type I bipolar extremes, would represent recurrent severe depression, but with a family history of bipolar disorder or antidepressant-induced mania or a number of other features of bipolarity in addiction to depressive symptoms, course, or treatment response. The presence of hyperthymic or cyclothymic mood temperaments has also been suggested as part of this bipolar spectrum concept. Several arguments can be found supporting the existence of this spectrum. A validated bipolar spectrum concept will allow a decrease in the diagnostic underestimation of bipolar disease and a more differentiated investigation and treatment model. Bipolar spectrum concepts will help identify those patients to whom antidepressants are not the best therapeutic approach, in relation to mood stabilizers and/or neuroleptics.

The bipolar spectrum concept has considerable supporting evidence and utility, theoretical as well as practical. Its development and diagnostic acceptance shall allow new discriminated investigation and better patient outcomes.

The authors have not supplied their declaration of competing interest.