Monday, August 16, 2010

Functional Neural Correlates of Mindfulness Meditations in Comparison with Psychotherapy, Pharmacotherapy, and Placebo Effect

In a recent issue of Acta Neuropsychiatrica, Chiesa and colleagues, a group of researchers in Italy, published a review article of neuro-imaging studies. They were interested in comparing neural correlates of mindfulness meditation with those of psychotherapy, pharmacotherapy (e.g., antidepressants), and placebo. The main areas of the brain the researchers focused on were the prefrontal cortex, the anterior cingulate cortex, and the amygdala.

I found the placebo piece of the review particularly interesting as there’s a huge research literature showing placebo effects are powerful enough to be a treatment in themselves. Like psychotherapy, it’s hard to create an adequate placebo substitute for something like meditation, especially as people know more about it today than they did decades ago when this research began.

The authors’ findings suggest that mindfulness meditation may help facilitate a greater flexibility in emotion regulation, and an improved ability to step back from negative mood states by engaging the frontal cortex (higher order functions) in order to dampen amygdala activation (emotion response, especially fear). The authors also found there’s a great deal of overlap in the brain structures activated by mindfulness meditation, psychotherapy, pharmacotherapy, and placebo effects.

They make a preliminary suggestion that mindfulness meditation, psychotherapy, and placebo act through “top down” regulation (i.e., through other processes), whereas antidepressants have a “bottom-up” effect (i.e., more directly). For example, they suggest mindfulness meditation may regulate the amygdala through frontal brain areas whereas antidepressants target the amygdala directly. I found this curious, as Irving Kirsch and others have recently suggested that much of the benefit from antidepressants is through placebo or expectancy effects (here's a short review of this debate). I am not trained as a neuroscientist nor am I an expert in this area of research, so I won’t directly challenge the authors’ conclusions. Nonetheless, I was left uncertain how much of the notion of grouping meditation, psychotherapy, and placebos into one category, and antidepressants in another, is based more on theory than on data.

Nonetheless, I think the authors did a nice job of trying to organize and summarize a growing but somewhat disparate body of research. Additionally, they’ve raised some important questions for other researchers to begin to explore in a more systematic manner. As I blogged about last week, Fletcher and colleagues (2010) recently suggested ways in which a neuroscientific understanding of mindfulness may be refined. This is a really exciting avenue of study, but I agree with the latter authors in that what researchers should really focus on is building our understanding of the neurological underpinnings of mindfulness and meditation in a very deliberate and step-by-step approach.

Full Citation:

Chiesa, A., Brambilla, P., & Serretti, A. (2010). Functional neural correlates of mindfulness meditations in comparison with psychotherapy, pharmacotherapy and placebo effect. Is there a link? Acta Neuropsychiatrica, 22(3), 104-117.

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