|"My name is Gladiator"|
I've talked about S100B previously on this blog in relation to autism (see here) including some of the possible whys and wherefores. Very briefly, S100B - S100 calcium binding protein B - is a protein primarily secreted by glial cells which seems to be involved in various important functions including those in relation to synaptic plasticity and the innate immune response among others. S100B levels have also been examined in relation to brain injury, although some uncertainty seems to persist about their value here .
With schizophrenia in mind, there is a growing research base suggestive of some role for S100B in the condition (see here). Not all the evidence has universally pointed to a connection between protein and condition, bearing in mind the similar issue of heterogeneity and 'spectrums' being discussed in schizophrenia circles as they have in autism circles (albeit with caveats).
The Aleksovska paper reported that based on their analysis of the combined literature (using the PRISMA guidance) "S100B in peripheral blood was significantly increased in schizophrenia patients, with an almost double level in cases than controls". Results drawn from 20 studies which survived their filtering (all case-control reports) also indicated: "no evidence of difference in subgroups regarding detection of S100B in plasma or serum, medication status, stage of the disease, ethnicity, selection of cases and controls and source of controls". Interestingly too, the authors make reference to the "the traditional reductionist assessments based on single-pathways analyses and categorical diagnoses" used in schizophrenia as not being all that useful. They call their alternative 'Systems Medicine'. I would say however that they're describing something like RDoC (see here).
What's more to say on this area of schizophrenia research? Well, further investigations on the reason(s) for elevated S100B might be a good starting point including that related to glial cell activation in relation to schizophrenia . But... and it is an important point, investigations also need to consider the variety of other factors which might account for elevated levels of S100B and are comorbid to psychiatric symptoms such as weight and insulin resistance , potentially all the more pertinent in light of the findings from van Beveren and colleagues  discussed in a recent post (see here).
Music to close. Cue the 70's detectives... Sabotage.
 Aleksovska K. et al. Systematic Review and Meta-Analysis of Circulating S100B Blood Levels in Schizophrenia. PLoS One. 2014 Sep 9;9(9):e106342.
 Hansen-Schwartz J. & Bouchelouche PN. Use of biomarker S100B for traumatic brain damage in the emergency department may change observation strategy. Dan Med J. 2014 Sep;61(9):A4894.
 Rothermundt M. et al. Glial cell activation in a subgroup of patients with schizophrenia indicated by increased S100B serum concentrations and elevated myo-inositol. Prog Neuropsychopharmacol Biol Psychiatry. 2007 Mar 30;31(2):361-4.
 Steiner J. et al. Elevated S100B levels in schizophrenia are associated with insulin resistance. Mol Psychiatry. 2010 Jan;15(1):3-4.
 van Beveren NJ. et al. Evidence for disturbed insulin and growth hormone signaling as potential risk factors in the development of schizophrenia. Transl Psychiatry. 2014 Aug 26;4:e430.
Aleksovska K, Leoncini E, Bonassi S, Cesario A, Boccia S, & Frustaci A (2014). Systematic Review and Meta-Analysis of Circulating S100B Blood Levels in Schizophrenia. PloS one, 9 (9) PMID: 25202915