Inflammation in the Affective Disorders

July 12, 2010 · Posted in Comorbidities, Risk Factors 

Bipolar children exhibit more inflammation than healthy children, according to a paper presented by Pandey, Dwivedi, and Pavuluri from the University of Illinois at the American College of Neuropsychopharmacology in December 2009.

In “Pro-inflammatory cytokines in plasma of patients with pediatric bipolar disorder,” the researchers described their study in which 21 normal controls were compared with 22 children with pediatric bipolar disorder who were unmedicated for a period of at least two weeks. The level of the inflammatory cytokine interleukin-1b (IL-1b) was significantly higher in the pediatric bipolar patients compared with controls, and levels of TNF alpha, another inflammatory marker, were significantly higher as well. Not only is this evidence of increased inflammatory processes in pediatric bipolar disorder, but TNF alpha is associated with activation of transcription factors and the initiation of preprogrammed cell death, or apoptosis.

Natalie Rasgon of Stanford University studied neurotrophins and inflammatory markers in women with bipolar disorder. She found that women with bipolar disorder compared with controls had higher levels of C-reactive protein (CRP, a marker of inflammation) although BDNF and inflammatory markers TNF, beta-1 and interleukin-2 did not differ significantly from controls. She did find a negative correlation between BDNF concentrations and depression scores on the Montgomery-Asberg Depression Rating Scale (MADRS), again replicating the findings from multiple studies that show lower BDNF levels are associated with greater severity of depression.

Inflammation compounds the medical problems faced by people with affective disorders.  Both markers of inflammation and also insulin resistance (which can lead to Type 2 diabetes) are altered in women with bipolar disorder compared with controls. CRP was highly correlated with body mass index (BMI) and all biomarkers of insulin resistance in women with bipolar disorder while, in the control group, CRP correlated only with BMI. Interleukin-2 was significantly correlated with insulin area under the curve in women with bipolar disorder, but not in controls.

Editors Note: Increases in inflammation may not only be a marker for patients with affective disorders (along with decreases in BDNF and other neurotrophic factors), but cytokines and other factors may also explain some symptoms (such as fatigue) and contribute to other pathological processes which can disrupt normal neuronal functioning.

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