Sir, I wish to comment on the paper ‘Increase in prefrontal cortical volume following cognitive behavioural therapy (CBT) in patients with chronic fatigue syndrome (CFS)’ (De Lange et al., 2008). The authors compared the grey matter volume (GMV) of 22 patients with CFS before and after treatment with CBT, and with 22 healthy controls who were assessed at a similar time interval but received no treatment. The patient sample at baseline had a 5% smaller GMV as compared to healthy controls. In patients, GMV at baseline was correlated with slow information processing speed and physical activity. At follow-up, in the patient group, mean GMV increased with 0.7% from 669.4 to 674.1 ml. This increase in GMV was correlated with changes in cognitive speed. On the basis of this result, the authors conclude ‘that the cerebral atrophy associated with CFS is partially reversed after effective CBT’. In the Netherlands, a press release of the author’s institution even states ‘CBT brings about structural changes in brains of patients’ (Radboud University, 2008). The question arises whether the study results indeed support such far reaching conclusions.
Two critical points need to be taken into consideration. First, the authors did not include a control group of patients receiving no treatment or a different treatment. Therefore, the increase in GMV cannot be attributed to the CBT treatment given. It is possible that the natural course of and fluctuations in the illness are responsible for this result. In addition, it might be possible that other treatments than CBT would have resulted in the same, or even better, results. Second, even if the results were indeed to be attributed to changes in lifestyle brought about by CBT, several questions still remain. To name a few, first, the increase in volume of <1% is very modest. Therefore, the question is whether, although statistically significant, this small increase is also of clinical significance. Second, if CBT brings about changes in lifestyle, and these changes are responsible for small improvements in the patients’ brain and activity levels, are these changes structural and related to the primary disease process? An alternative interpretation is that changing the lifestyle of patients, influences their quality of life, activity patterns and GMV, while the underlying disease process is not influenced.
Another critical remark relates to the fact that the authors in their paper do not mention the proportion of absolute increase in GMV of 0.7%, but rather report that the initial between-group difference between patients and healthy controls decreases with 12%. For readers, it is important to realize that the measure of change reported by the authors is influenced by the absolute size of the between-group difference: the smaller, and therefore less relevant, this difference is, the larger the reported proportion becomes, thereby making less relevant results looking more impressive.
The above considerations lead to the conclusion, that the author’s results, although interesting, do not support the far reaching conclusions regarding the power of CBT.
You can read the rest of this comment here: http://brain.oxfordjournals.org/content/132/6/e110.long
Comment in: Change in grey matter volume cannot be assumed to be due to cognitive behavioural therapy. [Brain. 2009]
Comment on: Increase in prefrontal cortical volume following cognitive behavioural therapy in patients with chronic fatigue syndrome. [Brain. 2008]
Source: Bramsen I. Can CBT substantially change grey matter volume in chronic fatigue syndrome? Brain. 2009 Jun;132(Pt 6):e110; author reply e111. doi: 10.1093/brain/awn207. Epub 2008 Aug 29. http://brain.oxfordjournals.org/content/132/6/e110.long (Full article)