Inflammation is a critical element of the body’s immune response that involves the activity of immune cells, cell-signaling proteins, and pro-inflammatory factors. Chronic inflammation, which occurs on the cellular level in response to toxins or other stressors, is implicated in the development of many chronic illnesses, including cancer, cardiovascular disease, and diabetes. Findings from a new study indicate that inflammation may be a factor in the “brain fog” that commonly accompanies chronic illness.

The double-blinded placebo-controlled study involved 20 young men (average age, 24 years) who were injected with either a typhoid vaccine or saline. The purpose of the vaccine was to induce mild, transient inflammation, which was confirmed by the participants' blood levels of interleukin-6, a pro-inflammatory molecule.

Six hours after the participants received their injection, three measures of their brain activity – alerting, orienting, and executive control – were assessed via electroencephalogram (EEG). The EEG results indicated that the participants' capacity for staying alert in preparation for a task was diminished post-vaccine but their other brain activities were unaffected. These findings point to a causal link between inflammation and diminished brain function and may explain why people who suffer from chronic disease often complain of difficulty concentrating or carrying out tasks.

Interestingly, other studies have used methods similar to those used in this study to show that inflammation plays a causal role in depression. To learn more about the role of inflammation in depression, check out the FMF topic page on depression. Read the whole article or skip to the section on inflammation.

• Link to study abstract.

• Link to FMF overview article about depression.