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Neuroscientists from University of Florida investigate plasma proteins’ influence on peripheral and central inflammation in depression.

Peripheral blood C-reactive protein (CRP) is a biomarker used clinically to measure systemic inflammation. Patients with major depressive disorder (MDD) show increased amounts of CRP. Increased peripheral blood CRP in MDD has been associated with altered reward circuitry, which has to do with the neural structures responsible for desires, motivation, associative learning including positive reinforcement and classical conditioning, positive emotions, and more. This has also been associated with increased brain glutamate, an excitatory neurotransmitter in the vertebrate nervous system, related to symptoms of anhedonia, which affects a person’s ability to feel pleasure.

The relationship between peripheral CRP and other peripheral and central markers of inflammation in depressed patients has not been established prior to this study.

Plasma and CSF was collected from medically stable, currently unmedicated adult outpatients with MDD, and a strong correlation was found between plasma and CSF CRP. In turn, CSF CRP correlated with CSF cytokine receptors/antagonists. Clusters of CSF inflammatory markers were associated with high plasma CRP and correlated with depressive symptom severity. These correlation findings were found in the sample as a whole and particularly females.

“CRP appears to be a peripheral biomarker that reflects peripheral and central inflammation and seems well-suited for guiding immunotherapies targeting TNF and IL-6 in patients with MDD.”

Read the full text in PubMed.