I also responded to this in the other thread you're referring to just a few minutes ago, so I apologize if this is repeating info.

Some antipsychotics, particularly Abilify and Seroquel, have antidepressant qualities at low doses. They are typically used to augment, or add on to, an existing antidepressant. They are being prescribed not only in Bipolar disorder, but also in people with a pure Major Depression. As you raise the dosages of these meds, the effect goes from antidepressant to more of an antimanic. I'm not sure when the antipsychotic benefits kick in.

Hope this helps.