Dr. Keller has made fundamental contributions to standardized, verifiable methods for assessing time to recovery, relapse, recurrence and chronicity of episodes of mood and anxiety disorders. A major advance was the Longitudinal Interval Follow-Up Evaluation (LIFE), which prospectively assesses psychopathology over time and has been used in over 1,000 research programs internationally.

Dr. Keller serves as Executive Psychiatrist-in-Chief at the seven Brown-affiliated hospitals. He and his colleagues have long-term studies underway involving over 950 adults with mood disorders, a project that has been going on for over 30 years. They are also conducting studies with over 1,200 adults with anxiety disorders, and with over 400 children and adolescents with bipolar disorder. He directs multi-institutional clinical trials investigating the safety and efficacy of antidepressant agents and psychotherapy with bipolar and unipolar illness and several multi-site studies of treatments of chronic and recurrent depression.