Bipolar depression is not unipolar depression with mood swings. The algorithm is different, the risks are different, and the trap most new PMHNPs fall into — adding an SSRI to a patient labeled depressed who is actually bipolar — can flip a stable patient into mania within weeks. This Deep Dive walks through the 2026 first-line algorithm: when to reach for lurasidone versus quetiapine, the role of cariprazine and lumateperone, why lithium and lamotrigine still belong on the list, and the exact decision tree for patients who failed the first agent. We also cover the screening miss that causes most "treatment-resistant depression" referrals — patients with bipolar II who got missed in a 25-minute intake — and the three questions that catch them every time. Based on the full guide at psychnpfellowship.com/bipolar-depression-treatment-algorithm-pmhnp-2 ...