Is There a Continuity between Bipolar and Depressive Disorders?

Abstract

Background: Recent studies questioned the current categorical split of mood disorders into bipolar disorders (BP) and depressive disorders (MDD). Methods: Medline database search of papers from the last 10 years on the categorical-dimensional classification of mood disorders. Various combinations of the following key words were used: mood disorders, bipolar, unipolar, major depressive disorder, spectrum, category/categorical, classification, continuity. Only English language clinical papers were included, review papers were excluded, similar papers selected by quality. The number of papers found was 1,141. The number of papers selected was 109. Results: The continuity/spectrum between BP (mainly BP-II) and MDD was supported by the following findings:(1) high frequency of mixed states (mixed mania, mixed hypomania, mixed depression, i.e. co-occurring depression and noneuphoric manic/hypomanic symptoms) because opposite polarity symptoms in the same episode do not support a hypomania/mania-depression splitting; (2) MDD was the most common mood disorder in BP probands’ relatives; (3) no bimodal distribution of distinguishing symptoms between BP and MDD; (4) bipolar signs not uncommon in MDD; (5) many MDD shifting to BP; (6) many lifetime manic/hypomanic symptoms in MDD; (7) correlation between lifetime manic/hypomanic symptoms and MDD symptoms; (8) hypomania factors in MDD; (9) MDD often recurrent; (10) similar cognitive style.The categorical distinction between BP (mainly BP-I) and MDD was supported by the following findings: (1) BP more common in BP probands’ relatives; (2) lower age at BP onset; (3) females as common as males in BP-I, more common than males in MDD; (4) BP-I depression more atypical and retarded, MDD depression more sleepless and agitated; (5) BP more recurrent. Conclusions: Focusing on mood spectrum’s extremes (BP-I vs. MDD), a categorical distinction seems supported. Focusing on midway disorders (BP-II and MDD plus bipolar signs), a continuity/spectrum seems supported. Results seem to support both a categorical and a dimensional view of mood disorders.

Pediatric Bipolar Disorder Versus Severe Mood Dysregulation: Risk for Manic Episodes on Follow-Up

“…Recent data demonstrate convincingly that DSM-IV diagnoses may not necessarily be pathophysiologically distinct: there is considerable genetic overlap between BD and schizophrenia 27 and between BD and MDD. 28 As noted, BD and SMD appear to share pathophysiological mechanisms, making it possible that the SMD phenotype will ultimately be placed on a pathophysiological spectrum between BD and MDD and/or other depressive syndromes. Accordingly, we found that depressive episodes were significantly more common in the BD group; a possible post hoc explanation for this finding is that, consistent with previous data, 10 SMD may be linked with depressive phenotypes not characterized by episodicity, such as dysthymia.…”

Differential Association of Circadian Genes with Mood Disorders: CRY1 and NPAS2 are Associated with Unipolar Major Depression and CLOCK and VIP with Bipolar Disorder

“…Moreover, a proportion of patients with MDD can develop manic or hypomanic episodes and become bipolar in the future (Akiskal et al, 1995) or even fit into de concept of 'bipolar spectrum' without showing obvious manic symptomatic polarity (Akiskal and Pinto, 2000). In addition, some clinical data support a unitary conceptualization of MD (Benazzi, 2007;Cassano et al, 2004). However, they differ in several clinical, pathophysiological, and therapeutic features (Ghaemi et al, 2004;Yatham et al, 1997) and independent loci have been reported to be associated with one or other diagnosis (Kato, 2007).…”

The Road to Recovery from Depression – Don’t Drive Today with Yesterday’s Map

“…Clinical differentiation of such morbidity requires a shift from the current psychometric model (where severity is determined by the number of symptoms and not by intensity or quality) to a clinimetric model [14,15,16], which may allow to define the progression, extent and severity of depressive illness. Finally, emerging evidence from the studies concerned with bipolar disorders [17,18,19,20,21] call for a reassessment of the current categorical split of mood disorders. Benazzi [18] has suggested that, focusing on mood spectrum’s extremes, a categorical distinction seems to be supported.…”

“…Finally, emerging evidence from the studies concerned with bipolar disorders [17,18,19,20,21] call for a reassessment of the current categorical split of mood disorders. Benazzi [18] has suggested that, focusing on mood spectrum’s extremes, a categorical distinction seems to be supported. Focusing on midway disorders (e.g.…”