[Manic-depressive psychosis - bipolar disorder - an affective spectrum: a change of paradigms].

A key role of cyclicity or polarity in the development of mood disorders is examined in the light of historical analysis of the concepts of these disorders. A critical analysis of the current trends in the study of bipolar spectrum disorders (suggestions on a new definition of hypomania, broadening of the diagnostic boundaries of bipolar disorders in the field that have not been regarded previously as pathological ones or in connection with bipolar disorders, supporting evidence for conceptual continuum between bipolar and unipolar disorders) is presented. Further studies in this field are warranted.