The Relationship Between Inflammation and Mental Sluggishness

Ellie Teng ‘21

Red engraving brain illustration in top view isolated on blue background
Red engraving brain illustration in top view isolated on blue background

Mental sluggishness or ‘brain fog’ is often comorbid with inflammation, the body’s response to  an illness. Previous research has shown the negative impact of inflammation on the brain’s alert state. Although it is still unclear as to how inflammation impacts specific processes of the brain, a study conducted by researchers at the University of Birmingham evaluated the impact of mild acute inflammation on the cognitive functions of visual attention. 

The results of this study involved a region of the brain that was responsible for visual attention. In a blind study, a group of 20 young male subjects received a salmonella typhoid vaccine that caused temporary inflammation with fewer side effects. They performed attention tests and underwent brain activity measurements. The subjects also received a placebo and took the same attention tests. Assessment tests categorized three separate attention processes in different parts of the brain: alerting, orienting, and executive control. “Alerting” involved reaching and maintaining an alert state, “orienting” involved selecting and prioritizing useful sensory information, and “executive control” involved determining what to pay attention to when available pieces of information came into conflict with each other. The results from these tests showed that inflammation could affect the brain’s alertness. The vaccine causing temporary inflammation imitated the transient low-grade inflammation caused by fat cells. 

While inflammation affected brain activity related to alertness, it did not affect other attention processes. Researchers determined that mild inflammation may enhance mental fatigue or cognitive stress due to increased efforts for performing normally effortless tasks. Future studies will be able to expand upon the results from this study, and new treatments could be developed to combat conditions related to chronic inflammation or abnormal brain activity such as obesity, kidney disease, arthritis, or Alzheimer’s disease.


  1. L. Balter, et al., Selective effects of acute low-grade inflammation on human visual attention. Neuroimage 202, 1-10 (2019). doi:
  2. Image retrieved from: 

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