Peripheral inflammation during abnormal mood states in bipolar I disorder

Area of Science:

• Neuroscience
• Psychiatry
• Immunology

Background:

• Bipolar disorder (BD) is linked to significant morbidity and mortality, often associated with cardiovascular disease.
• Peripheral inflammatory markers are frequently reported in BD, potentially connecting these comorbidities.
• The episodic nature of inflammation in BD, whether mood-dependent or chronic, remains unclear.

Purpose of the Study:

• To investigate the relationship between mood states and peripheral inflammatory markers in bipolar disorder.
• To compare cytokine levels in individuals with BD across mania, depression, and normal mood states versus healthy controls.
• To explore potential neuroimaging correlates of inflammation using T1ρ imaging.

Main Methods:

• Compared inflammatory cytokine concentrations, including tumor necrosis factor alpha (TNF-α), in 37 BD participants (across 3 mood states) and 29 healthy controls.
• Assessed cytokine levels in relation to T1ρ imaging in specific brain regions in a subsample.
• Utilized case-control design comparing BD participants in different mood states.

Main Results:

• No significant differences in overall cytokine concentrations between BD participants and controls.
• Elevated levels of TNF-α, its soluble receptors, and other pro-inflammatory cytokines (IL-1β, IL-6, IL-10, IL-18, IL-4, IFN-γ) were observed in BD during abnormal mood states (mania and depression) compared to normal mood.
• Cytokine levels did not correlate with T1ρ imaging signals in selected brain regions.

Conclusions:

• Inflammatory marker activation is associated with abnormal mood states in bipolar disorder.
• Findings suggest that inflammation in BD may be episodic and linked to mood state fluctuations.
• Longitudinal studies are necessary to confirm these results and understand the temporal dynamics of inflammation in mood disorders.