Treatment of Tardive Dyskinesia with High Dose Vitamin B6 Associated with Depression

Tardive dyskinesia (TD) is a movement disorder associated with dopamine receptor blocking medications. Recommended treatments for TD include discontinuing the causative agent, adding vesicular monoamine transporter 2 (VMAT2) inhibitors, or adding vitamin B6. We present a 66-year-old Caucasian male with bipolar I disorder who developed TD while on lithium and quetiapine, having been euthymic on this regimen for three years. He was initially treated with 1200 mg B6 daily, which failed to improve his TD and was associated with a depressive episode. He switched to valbenazine 40 mg daily, which improved his TD and concurrently his mood, but months later, the TD symptoms worsened again. Our case adds to the literature by demonstrating that some patients with TD will not respond to vitamin B6. To our knowledge, ours is the first case suggesting the association of high-dose vitamin B6 with depression. This case also demonstrates that response to valbenazine may not last, and further studies are needed.