I’m not a neuroscientist, clinician, or medical scientist. But a recent article on Scientific American piqued my interest. The SciAm article is reporting on a study published online in the journal Brain, and is suggesting that activation of brain glial cells is associated with sufferers of chronic lower back pain (CLBP). There’s a couple of items that are worth discussing in both the report, and the published study itself.

First up, the SciAm article reports that the study imaged 19 sufferers of CLBP and 25 healthy age/sex-matched controls. However due to exclusions, the study actually only imaged nine matched pairs: nine CLBP sufferers, and eight controls (one of the controls was matched twice). This could just be a misinterpretation of the study by the SciAm author, but does nevertheless give a flase sense of confidence that would only be found by reading the study.

So why the restrictions? The authors of the study required all eligible participants (the original 44) to be genotyped for the Ala147Thr TSPO (translocator protein) polymorphism, as this polymoprhism affects binding affinity for the radioligand they used to highlight glial activation in the PET-MRI (¹¹C-PBR28). So, those with a low binding affinity were excluded from the study.

This appears to me to be a quite important exclusion. I can understand that there are measurement issues with the radioligand used, and as I said, I’m not a clinician/radiologist, but if you need to exclude over half of your pool of eligible subjects to make the test work, what effect does that have on the results? There’s no discussion on the subjects that were excluded, so how can we infer/generalise these results, especially when the author is quoted in the report as stating

… Seeing that glial activation really happens in patients will provide the rationale to justify a more aggressive exploration of this therapeutic route …

This post is continued here …