The continuum/spectrum concept of mood disorders: is mixed depression the basic link?
BACKGROUND
Mixed states, i.e., opposite polarity symptoms in the same mood episode, question the bipolar/unipolar splitting of mood disorders, and support a spectrum view. Study aim was assessing the distribution of intradepressive hypomanic symptoms between bipolar-II (BP-II) and major depressive disorder (MDD) depressions, and testing a dose-response relationship between number of intradepressive hypomanic symptoms and bipolar family history. No bi-modality, and a dose-response relationship, would not support a categorical distinction.


METHODS
Consecutive 389 BP-II and 261 MDD depressed outpatients were interviewed by the structured clinical interview for DSM-IV, hypomania interview guide, and family history screen, by a mood specialist psychiatrist, in a private practice. Intradepressive hypomanic symptoms were systematically assessed. Mixed depression was defined as the combination of depression and three or more intradepressive hypomanic symptoms, a validated definition.


RESULTS
BP-II, versus MDD, had significantly more intradepressive hypomanic symptoms. The distribution of intradepressive hypomanic symptoms between BP-II and MDD was not bi-modal but normal-like, and a dose-response relationship was found between the number of intradepressive hypomanic symptoms and bipolar family history.


CONCLUSIONS
Study findings question the categorical division of BP-II and MDD, and may support the spectrum view of mood disorders.
Benazzi
Franco
F
Hecker Psychiatry Research Center, Forli, Italy. FrancoBenazzi@FBenazzi.it
D000328:Adult; D000367:Age Factors; D000928:Antidepressive Agents / Q000009:adverse effects / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics / Q000523:psychology; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007406:Interview, Psychological; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics / Q000523:psychology; D012008:Recurrence; D012307:Risk Factors
D000928:Antidepressive Agents