Researchers have found signs of ongoing inflammation in the brains of athletes still experiencing concussion symptoms months or years after their injury, according to a new study published in Journal of Neuroinflammation.
The findings suggest the concussion triggered chronic neuroinflammation that may be contributing to their persistent symptoms.
Key Facts:
- The study examined athletes who were still experiencing significant concussion symptoms preventing sports participation and normal work/school/social functioning at least 6 months after injury.
- Cerebrospinal fluid samples were analyzed for levels of 27 inflammatory proteins.
- 8 inflammatory proteins were significantly increased compared to healthy controls, indicating neuroinflammation.
- Athletes reported many severe symptoms and over 40% showed cognitive impairment on testing.
- Findings suggest the concussion triggered an inflammatory process still ongoing months/years later that may exacerbate injury.
- Anti-inflammatory treatments may help athletes recover from long-lasting concussion effects.
Source: Journal of Neuroinflammation (17 Aug 2023)
Signs of Chronic Brain Inflammation in Athletes With Lingering Concussion Symptoms
Sports-related concussions, also known as mild traumatic brain injuries (mTBIs), are caused by impacts that shake the brain inside the skull.
While most athletes recover within weeks, an increasing number go on to develop persistent post-concussion symptoms (PPCS) like headaches, fatigue, depression, memory problems, and difficulty concentrating that can last for months or years after the concussion.
Researchers believe concussions cause initial injury to brain cells through stretching and shearing of axons and that secondary neuroinflammatory processes kickstarted by the injury may continue long-term and exacerbate damage.
Previous studies have found signs of inflammation acutely after concussion, but little research has looked at whether inflammation persists chronically in athletes with PPCS.
In this study, researchers analyzed cerebrospinal fluid from 24 athletes with PPCS lasting over 6 months after concussion for levels of inflammatory proteins.
They also had athletes complete concussion symptom scales and cognitive testing. Their cerebrospinal fluid levels of inflammatory markers were compared to 12 healthy athletic control subjects.
Chronic Inflammation Observed in Athletes With Lasting Concussion Effects
The athletes with persistent concussion symptoms had experienced a median of 5 previous concussions and their last injury occurred a median of 17 months prior to the study.
They reported an average of 19 different concussion symptoms that were rated high in severity. Additionally, 10 of the 24 athletes showed cognitive impairment on testing.
Analysis of their cerebrospinal fluid found 8 out of 25 measured inflammatory proteins were significantly increased compared to controls. This included cytokines like IL-2, TNF-α, IL-15, TNF-β, and VEGF and chemokines like Eotaxin, IP-10, and TARC.
The researchers conclude these findings provide evidence of ongoing neuroinflammation months or even years after the athletes’ last concussions.
They propose the chronic inflammatory process may be exacerbating the brain injury and contributing to the athletes’ persisting symptoms and cognitive problems.
Connection Between Chronic Inflammation and Concussion Recovery
Previous studies have also found signs of prolonged inflammation following concussion, including one that showed concussion patients have elevated blood inflammatory markers for a year after injury.
PET imaging studies have also revealed increased activation of microglia and astrocytes—immune cells in the brain—in football players years after retirement suggesting chronic neuroinflammation.
Animal research has demonstrated single and repeated concussions cause ongoing neuroinflammation for weeks to months afterwards.
And experimental drugs that reduce inflammation have been shown to lessen brain damage and cognitive deficits from concussions in mice.
Together, these studies indicate concussions trigger inflammatory processes that may persist long-term in some patients and drive further neuronal damage.
Though it hasn’t been definitively proven, dampening down this chronic inflammation has potential as a therapeutic approach to improve outcomes in patients with lasting concussion symptoms.
Anti-Inflammatories: A Possible Treatment for Persisting Concussion Effects?
Currently, treatment for concussion is limited to rest, gradually increasing physical and cognitive activity, and managing specific symptoms. But there are no treatments that directly target ongoing pathobiology like inflammation to promote healing in the brain.
The authors of the current study conclude that since neuroinflammation may be contributing to lasting concussion effects, treatments aimed at resolving inflammation warrant further research.
Non-steroidal anti-inflammatory drugs (NSAIDs) are medications with anti-inflammatory effects that could be trialed, but they also come with side effects and risks if used long-term.
Other options like anti-inflammatory nutraceuticals may provide a safer approach for dampening chronic inflammation.
While this area needs more research, these findings provide hope that directly targeting lingering inflammatory processes with pharmaceuticals or natural agents could help resolve concussion symptoms and potentially facilitate recovery in athletes struggling with the lingering effects of head injuries.
Takeaways on the Link Between Concussion, Inflammation, and Lingering Symptoms
This study provides evidence of ongoing neuroinflammation months to years after concussion in athletes with persisting post-concussive symptoms.
8 inflammatory proteins were significantly elevated in the cerebrospinal fluid of concussed athletes compared to healthy controls.
The findings suggest the initial concussion triggered chronic inflammation still present long after the event that may exacerbate injury.
Previous research indicates ongoing inflammation can drive secondary damage and worsen outcomes after concussion.
Anti-inflammatory treatments may hold promise for improving recovery in those with lingering effects, but clinical trials are needed.
While return to normal activities is still the mainstay of concussion treatment, anti-inflammatory therapies could provide much-needed help for patients who don’t fully recover.
References
- Study: Cerebrospinalfluid levels of neuroinflammatory biomarkers are increased in athletes with persistent post-concussive symptoms following sports-related concussion
- Authors: Anna Gard et al. (2023)
