Rethinking Brain Inflammation: A New Era of Research
The impact of brain inflammation on both the body and the mind has received serious recognition in only the last decade, when researchers started investigating the high rates of depression and anxiety in patients with chronic inflammatory conditions.
What is inflammation?
Inflammation is a condition where the immune system’s white blood cells and the chemicals that they produce accumulate in the body. It can be a reaction to an infection or injury, and it helps protect against invaders like bacteria or viruses. It can be acute (short lived) like when you catch a cold and have a sore, inflamed throat. In some cases, it can become chronic (lasting a long time), like with some types of arthritis. Sometimes, inflammation happens because the immune system becomes unregulated and flares up when it is not needed. And in some illnesses, the immune system can even get confused and attack healthy parts of the body, which is called auto-immunity.
Classically, we expect inflammation to show with swelling, redness, pain, and warmth of a part of the body (as with an infected cut), or whole body effects like fever (as with the flu). However, some forms of chronic inflammation can be harder to detect, requiring blood testing or imaging. Some inflammatory conditions need more specialized detection methods, while others can’t even be measured on commonly available tests.
Here are some conditions we now know are related to chronic inflammation:
- Heart disease
- Alzheimer’s disease
- Rheumatoid arthritis
- Many types of cancer
We are always discovering new ways that inflammation contributes to many diseases.
What happens when inflammation affects the brain?
Inflammatory processes in the brain can affect how we think, act, feel, and move, often seemingly out of the blue.
For the purposes of the Unhide™ Project, we will define brain inflammation as a condition where cells from the immune system and/or their chemical products become abnormally active in areas of the brain and alter brain function.
Whether triggered by an infection or occurring as part of an autoimmune response (or both), brain inflammation can cause an eclectic mix of neurological and psychological symptoms and complications, from depression and anxiety to obsessive compulsive and movement disorders.
Using MRI (shown here), researchers examined how rheumatoid arthritis inflammation changes the brain.
In order to best treat these patients, doctors would ideally identify clues left by infection or an autoimmune response (like auto-antibodies directed at brain tissue). Unfortunately, sometimes it can be difficult to identify these triggers.
Explore this website to learn more about what causes brain inflammation, how it presents, common comorbidities, and how to diagnose and treat infection-related and autoimmune brain inflammation.
Pioneering Research in this Area
Autoimmune Diseases and Severe Infection as Risk Factors for Mood Disorders, a study published in JAMA Psychiatry in 2013, laid the groundwork to establish the connection between immune dysfunction and mental health. Researchers looked at over 91,000 Danish citizens diagnosed with a mood disorder (depression, bipolar disorder) and found that being hospitalized for an infection increased the risk of a later mood disorder by 62%. A prior hospital contact due to an autoimmune disease increased the risk of a mood disorder by 45%. They estimated that 12.1% of mood disorders would be prevented if the hospitalizations related to infections never happened.
The same team found that two or more severe infections in childhood, particularly where hospitalizations were required, had increased risk of developing mental health issues including anorexia. The correlation of repeat infections and subsequent mood issues created an even greater risk than being diagnosed with an autoimmune disease. For instance, if a child is hospitalized for pneumonia, is treated and heals, but continues to relapse with two or more bacterial or viral infections into adulthood, they are at a greater risk of mood disorder in adulthood.
An inflammatory link between many central nervous system disorders and their mental health components has been recognized. These include lupus, Alzheimer’s, Parkinson’s, psoriasis, autism spectrum disorder, and multiple sclerosis (MS).
Since 2020, COVID-19’s ability to kill through cytokine storm and disable through lingering brain fog has focused the scientific community’s attention on the importance of unchecked inflammation. What we are learning is throwing open doors to understanding post-infectious brain inflammation. Yet there is still much we don’t understand.
With better understanding of brain inflammation, doctors, parents, and patients alike can more appropriately manage conditions that manifest with seemingly disparate symptoms, and which frequently appear following infection or other immune triggers.