How psychotherapy changes the brain--the contribution of functional neuroimaging.

A thorough investigation of the neural effects of psychotherapy is needed in order to provide a neurobiological foundation for widely used treatment protocols. This paper reviews functional neuroimaging studies on psychotherapy effects and their methodological background, including the development of symptom provocation techniques. Studies of cognitive behavioural therapy (CBT) effects in obsessive-compulsive disorder (OCD) were consistent in showing decreased metabolism in the right caudate nucleus. Cognitive behavioural therapy in phobia resulted in decreased activity in limbic and paralimbic areas. Interestingly, similar effects were observed after successful intervention with selective serotonin reuptake inhibitors (SSRI) in both diseases, indicating commonalities in the biological mechanisms of psycho- and pharmacotherapy. These findings are discussed in the context of current neurobiological models of anxiety disorders. Findings in depression, where both decreases and increases in prefrontal metabolism after treatment and considerable differences between pharmacological and psychological interventions were reported, seem still too heterogeneous to allow for an integrative account, but point to important differences between the mechanisms through which these interventions attain their clinical effects. Further studies with larger patient numbers, use of standardised imaging protocols across studies, and ideally integration with molecular imaging are needed to clarify the remaining contradictions. This effort is worthwhile because functional imaging can then be potentially used to monitor treatment effects and aid in the choice of the optimal therapy. Finally, recent advances in the functional imaging of hypnosis and the application of neurofeedback are evaluated for their potential use in the development of psychotherapy protocols that use the direct modulation of brain activity as a way of improving symptoms.