Association Between Elevated Body Mass Index, Inflammation, and Cognitive Performance in Individuals With Bipolar
Marzieh Majd1,2,3, Jennifer Nicoloro-SantaBarbara1,3, Maura De Laney1
1Department of Psychiatry, Brigham and Women's Hospital, Boston, Massachusetts, USA.
Bipolar Disorders
|May 15, 2026
Summary
Higher Body Mass Index (BMI) is linked to poorer cognitive function in bipolar disorder (BD) and the general population. Inflammation, particularly Interleukin-6 (IL-6), may partially explain this association.
Area of Science:
- Neuroscience
- Psychiatry
- Immunology
Background:
- Cognitive impairment is a significant issue in bipolar disorder (BD).
- Obesity, indicated by Body Mass Index (BMI), is prevalent in BD and may impact cognitive function.
- Peripheral inflammation is implicated in various psychiatric and neurological conditions.
Purpose of the Study:
- To examine the relationship between Body Mass Index (BMI), peripheral inflammation, and cognitive performance in individuals with bipolar disorder (BD) and healthy controls (HCs).
- To investigate the potential mediating role of inflammation in the association between BMI and cognitive function.
Main Methods:
- 127 participants (79 BD, 48 HCs) completed the MATRICS Consensus Cognitive Battery.
- Blood levels of C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-α were measured.
- Regression and mediation analyses were performed to assess associations and mediating effects.
Main Results:
- Individuals with BD exhibited higher inflammation levels compared to HCs.
- Increased BMI was associated with worse global cognitive performance across the entire sample and within the BD group.
- Higher inflammation was linked to poorer global cognition in the total sample, but this effect was not significant in the BD group alone.
- Interleukin-6 (IL-6) partially mediated the relationship between BMI and cognitive performance in the overall sample.
Conclusions:
- Body Mass Index (BMI) may be a relevant biomarker and therapeutic target for cognitive deficits associated with obesity in both BD and the general population.
- Interleukin-6 (IL-6) may play a role in the link between BMI and cognitive impairment, suggesting potential intervention pathways.
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