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[Unipolar-bipolar distinction. The genetic arguments].
M A Crocq1, J P Macher, F Duval
1Centre Hospitalier Spécialisé, Rouffach.
L'Encephale
|January 1, 1992
Summary
Mood disorder classifications now distinguish between bipolar and unipolar types, primarily supported by family studies. Research indicates bipolar disorders are more prevalent in relatives of bipolar patients, suggesting genetic links.
Area of Science:
- Psychiatry
- Genetics
- Mood Disorders
Context:
- Recent classifications like DSM III and ICD 10 emphasize the bipolar-unipolar distinction in mood disorders.
- This distinction, supported by family studies, has gained wide consensus.
- Early work by Kleist, Leonhard, Perris, and Angst laid the groundwork for this classification.
Purpose:
- To review the evidence supporting the bipolar-unipolar distinction in mood disorders.
- To explore various genetic approaches, including family, twin, adoption, and linkage studies.
- To discuss the genetic overlap and potential polygenic environmental factors influencing mood disorder polarity.
Summary:
- Family studies show bipolar mood disorders are twice as prevalent in first-degree relatives of bipolar probands compared to unipolar probands.
- While family studies suggest distinct yet overlapping genetic factors for unipolar and bipolar disorders, twin and adoption studies are less conclusive.
- Recent genomic linkage studies have not definitively validated the bipolar-unipolar distinction, though they hint at a major gene locus in a subset of bipolar pedigrees.
Impact:
- The findings reinforce the validity of the bipolar-unipolar distinction, crucial for accurate diagnosis and treatment strategies.
- Highlights the complex genetic architecture of mood disorders, involving both specific and shared genetic influences.
- Suggests that while major genes may play a role in some cases, polygenic and environmental factors likely contribute significantly to the overall development and polarity of mood disorders.