CEQUEL-FA: Comparative evaluation of quetiapine plus lamotrigine vs quetiapine monotherapy, and folic acid vs placebo

People with bipolar depression often endure years of debilitating low mood because existing treatments work poorly or cause side effects. This trial directly tests whether combining two drugs—quetiapine and lamotrigine—works better than quetiapine alone, and whether adding folic acid, a cheap vitamin, boosts symptom relief. Why this matters: Bipolar depression accounts for most of the disability in bipolar disorder, yet treatment options remain limited. Doctors currently lack high-quality evidence to guide combination therapy, leaving many patients cycling through ineffective regimens. The trial fills that gap by providing head-to-head data from a randomised clinical trial. If the combination proves superior, clinicians could immediately prescribe a new, evidence-based regimen using drugs already available on the NHS. If folic acid helps, it would offer a safe, low-cost addition with no new side effects. Either result would give patients and doctors clearer choices, reducing the trial-and-error period that prolongs suffering. The impact is direct: better symptom control, fewer relapses, and improved daily functioning for people living with bipolar depression.