Most people don’t worry about an abscessed tooth, a viral infection, concussion, or a tick bite causing the body to develop a chronic illness. However, for some people, these events trigger inflammatory or autoimmune processes which can impact the brain, even much further down the line in a person’s life.
The role of infection (and reinfection) in brain inflammation
Infection has been linked to disorders that are characterized by chronic brain inflammation and may be a trigger for autoimmune dysfunction. Re-infection in these cases often causes the development or worsening of neuropsychiatric symptoms.
In fact, psychiatric symptoms that seemingly appear overnight—clinically called “acute- or abrupt-onset”—are thought to be part of a post-infectious response in which a previous infection has paved a path for cytokines and other inflammatory substances to make their way into the brain.
Infections associated with chronic brain inflammation and altered immune system function:
- Streptococcal bacteria (Sydenham chorea, Pediatric Autoimmune) Neuropsychiatric Syndrome Associated with Streptococcus- PANDAS)
- Mononucleosis (multiple sclerosis, chronic fatigue)
- Tick bite (Lyme disease)
- COVID-19 (brain fog, post COVID psychosis)
- urinary tract infection (UTI) (delirium)
- dental bacteria (including an abscessed tooth), periodontal disease, and gingivitis (Parkinson’s, Alzheimers, depression)
- Viral or bacterial infections (ME/CFS, POTS, Nacrolepsy, PANS)
Mechanism of infection in chronic brain inflammation
One theory underlying chronic brain inflammation is when the body’s response to infection leads to sustained cytokine release. (Cytokines are small proteins that control activity of the immune system.)
This in turn leads to the production of distress signals that damage the endothelial cells forming the blood brain barrier (BBB). When immune cells migrate across the BBB, brain tissue becomes vulnerable to further damage from inflammatory processes.
References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466892/
https://www.frontiersin.org/articles/10.3389/fneur.2022.819636/full
https://www.nature.com/articles/s41591-022-01766-7
https://www.karger.com/Article/FullText/511552#:~:text=Summary%3A%20Brain%20microvascular%20endothelial%20cells,transporter%2C%20and%20extracellular%20matrix%20proteins.
