Inflammatory marker levels linked to mood state in BD patients
MedWire News: Results from a Norwegian study suggest that levels of certain inflammatory markers are associated with mood state in patients with bipolar disorder (BD).
"Several lines of evidence have implicated inflammatory abnormalities in BD," observe Sigrun Hope (University of Oslo) and colleagues in the Journal of Psychiatric Research.
But they add it is unclear whether such abnormalities are associated with mood state and affective symptom severity in BD patients.
To investigate further, the team studied 112 BD patients, 153 patients with schizophrenia, and 239 mentally healthy controls.
The Young Mania Rating Scale and the Inventory of Depressive Symptomatology were used to assess affective symptoms among the BD and schizophrenia patients, and they were divided into groups based on depressed, neutral, and elevated mood.
Blood samples were collected from all of the participants and examined for levels of the immune markers tumor necrosis factor receptor 1 (TNF-R1), interleukin 1 receptor antagonist (IL-1Ra), IL-6, high sensitive C-reactive protein (hsCRP), osteoprotegerin (OPG), and von Willebrand factor (vWf).
The researchers found that in the BD patients, those in a depressed state (n=58) had significantly lower levels of TNF-R1, IL-1Ra, OPG, and IL-6 than those in a neutral (n=26) or elevated mood state (n=17), at 0.98 versus 1.03 and 1.24 ng/ml, 0.53 versus 0.65 and 0.80 ng/ml, 2.57 versus 3.24 and 3.69 ng/ml, and 0.26 versus 0.77 and 0.36 pg/ml, respectively.
Levels of TNF-R1 were positively correlated with elevated mood scores in the BD patients, while scores for sad mood were negatively correlated with OPG, IL-1Ra, and IL-6 levels.
Compared with controls, BD patients in a neutral mood state had significantly higher levels of OPG (2.25 vs 3.24 ng/ml) and IL-6 (0.30 vs 0.77 pg/ml), and those in an elevated mood state had higher levels of TNF-R1 (0.95 vs 1.24 ng/ml) and vWf (87% vs 126%).
There were no significant associations between affective symptoms or mood states and immune marker levels in schizophrenia patients.
Hope and team conclude: "The present results suggest that low levels of inflammatory markers are associated with depressive mood, and high levels with elevated mood in BD, and not in schizophrenia.
"This indicates that variation in these markers of immune activation and inflammation is related to core psychopathology of BD."
They add: "Further studies on the underlying mechanisms of the immune system in affective phenotypes are needed."
By Mark Cowen