"C-Reactive Protein as a Peripheral Biomarker in Schizophrenia"

The results of the 'updated systematic review' published by Guillaume Fond and colleagues [1] looking at the "relationships between elevated blood C-reactive protein (CRP) levels and schizophrenia (SZ) onset risk, illness characteristics and treatments, cognition and physical health" provides the blogging fodder today.

Fond (a name not unfamiliar to all-things schizophrenia) et al dip into a topic with more than its fair share of research 'uncertainty' (see here and see here for examples) on whether or not C-reactive protein (CRP), a marker of systemic inflammation, shows a connection to schizophrenia. On this particular research occasion, no new data is added to the debate, but rather authors looked at the collected peer-reviewed data (up to November 2017) to see if any 'general opinions' could be discerned from the collected works.

Results: based on over 50 studies included in their review, authors concluded that it was 'reasonable' to assume that high-sensitivity CRP (hs-CRP) may be a marker for 'schizophrenia onset risk'. The caveat to that statement is that CRP is probably not something 'schizophrenia-specific' in terms of elevations of CRP being indicative of a inflammatory state. So increased hs-CRP may well be a risk factor for "increased positive symptoms, cognitive impairment, hypovitaminosis D, microbiota disturbances, cardiovascular and metabolic syndrome risk in SZ subjects, and increased nicotine dependence in SZ smokers."

I'm pretty happy with the Fond results and interpretation as they stand. They suggest that CRP probably does show some sort of connection to schizophrenia and onward, points to an immune system connection to at least some cases (see here and see here). At the same time, they also imply that certain other observations around schizophrenia - such as a link with certain physical health issues (see here) and/or vitamin D deficiency (see here) - probably also contribute to the elevations of CRP noted in relation to cases of schizophrenia. They also imply that moves to reduce levels of CRP in relation to schizophrenia may well have various other 'knock-on' effects on those other risk factors associated with the condition/diagnosis. This 'double hit' effect could be quite useful.

And with that last sentence in mind, and accepting that consistently high levels of CRP are probably good for no-one, the next question: what can we do about elevated CRP levels in relation to schizophrenia and further, the immune system issues also being co-expressed? Lots, is my impression; perhaps also learning from other labels where immune function (and dysfunction) has been noted [2] and intervention is similarly indicated.

And there's more to come from this authorship group on this blog soon...

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[1] Fond G. et al. C-Reactive Protein as a Peripheral Biomarker in Schizophrenia. An Updated Systematic Review. Front. Psychiatry. 2018. Aug 23.

[2] Marchezan J. et al. Immunological Dysfunction in Autism Spectrum Disorder: A Potential Target for Therapy. Neuroimmunomodulation. 2018 Sep 5:1-20.

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