Conversion from unipolar depression to bipolar depression

BACKGROUND Clinicians, both psychiatrists and non-psychiatrists, underdiagnose bipolar disorder in a substantial proportion of depressed patients. Correct diagnosis is important since the prescription of antidepressants without mood stabilizers may precipitate a switch to mania. In patients presenting with depression, what are the odds they will turn out to really be bipolar? There are few long-term studies looking at the conversion rates from unipolar to bipolar depression. The conversion rates vary across subpopulations of depression. In out-patient depressed patients new-onset bipolar was found in up to 20% of individuals. In depressed adolescents the conversion from unipolar to bipolar ranges from 19% to 37% in follow-up studies. Most depression studies in the 1980s involved patients with the average age in the middle 30s, which would underestimate conversion rates.