The newest data from meta-analyses indicate that traditional antidepressants that are effective in unipolar depression are not effective in bipolar depression.
Some patient groups, especially those with very early onset depression and mixed depression, are at increased risk of switching into mania and making a suicide attempt while taking antidepressants.
This is the conventional wisdom on antidepressants in bipolar disorder.
It used to be felt that they were almost always harmful, and some experts still feel that way (especially Nassir Ghaemi) but more recent studies find that the incidence of mood destabilization (more rapid or more severe mood cycling) in bipolar patients treated with antidepressants is less than had been thought. Perhaps in only 10% (or so) patients with bipolar is there mood destabilization.
On the other hand, it does appear that for many people with bipolar disorder (particularly bipolar type 1) antidepressants are not more effective than placebo. So, if a medication has a low incidence of making things worse, and little evidence that it makes things better, why take it?
Not all bip0lar is the same, and we now think of bipolar and unipolar as a continuum that ranges from bipolar type 1 with frequent mania all the way to unipolar depression with minimal mood variation from day to day… with most people fitting somewhere in that continuum.
For those at one end of the spectrum (bipolar 1 with frequent mania) antidepressants are a bad idea. They are not likely to help and quite likely to make things worse. This is particularly true with the MDI pattern of mood cycling.
On the other hand, for patients closer to the depressive end of the spectrum, bipolar type 2 with rare hypomanias and a DMI pattern, these medications may be helpful.
It remains true that some patients (particularly some patients with bipolar disorder type 2) appear to benefit from the SSRI’s, especially for certain symptoms of anxiety, which are very common in patients with bipolar 2.