In a small study from Helen Mayberg and colleagues at Emory University, depressed participants were randomized to either a medication or CBT, and underwent PET scans before treatment.

Then the scans were analyzed to see if they were predictive of treatment response. The goal was to find a biomarker in order to determine in advance who will respond better to which type of treatment.

However, as The Neurocritic points out, often people respond to a combination of both psychotherapy...