Dietary Impact on Chronic Traumatic Encephalopathy in Contact Sports Athletes

Chronic Traumatic Encephalopathy

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative condition affecting individuals who participate in high impact sports that risk exposure to repetitive brain injury. These sports include boxing, American football, rugby, and soccer, all of which have substantial risk of exposure to brain injuries. In addition to professional sports, cases of CTE have been identified in military personnel who have been exposed to multiple explosive blasts during combat or other situations. CTE is not a result of the accumulation of prior brain trauma, but rather a progression of neuronal dysfunction and death triggered by repetitive head trauma, from sub-concussive blows to the head where the participant may be asymptomatic (does not present any symptoms), to moderate concussion, to severe traumatic brain injury (TBI). (Yi, Padalino, Montenegro, Cantu, & Chin, 2013)

An individual who experiences mild TBI or concussion may show symptoms such as dizziness, fatigue, headaches, irritability, mental fogginess and impairment of sight and concentration. This is caused by the strain put on the brain tissue after the collision between the skull and the brain itself during impact, however majority of cognitive and physical deficits typically resolve after days, weeks or months of rest depending on the severity of the impact. (Stern, et al., 2011)

Symptoms of concussion are widely known these days throughout sport, and precautions are taken when an individual shows any signs of these symptoms, however as mentioned, CTE progression can occur even when an individual suffers a mild head impact and shows no signs of concussion. The likelihood of a contact sports player developing CTE is proportional to the number of years they have competed within their sport, due to longer exposure to the possibility of suffering head impacts.

The clinical symptoms of CTE are like that of mild TBI or concussion, however they usually begin within 8-10 years after experiencing repetitive brain injuries. Symptoms of early stage CTE include aggression, depression, impulsivity, short-term memory loss and suicidality. Due to the progressive nature of the disease, symptoms can worsen in later stages of its development to include dementia, speech abnormalities and parkinsonism. (McKee, et al., 2009)

Figure 1: Common symptoms associated with CTE.

Neuropathology of CTE

CTE occurs through a build-up of hyperphosphorylated tau protein over time. Tau is typically a highly soluble protein found mostly in neurons (Noble et al., 2013).

Tau is a shortened name for the microtubule-associated protein tau (MAPT). The build-ups take the form of tangles and abnormal neurites, typically starting in the perivascular area of the sulci in the cerebral cortex and in time spreading throughout the cortex unevenly. Tau’s job under normal circumstances is to facilitate microtubule stabilisation in cells, but in the case of CTE tau becomes over phosphorylated leading them to remove themselves from microtubules and relocate to the cell body and proximal dendrites where they aggregate into neurofibrillary tangles (NFTs) (Katsumoto Atsuko, 2019). A presumed sequence of p-tau pathology progression has been developed based on provisional criteria for CTE, accompanied by the presence of macroscopic changes, neuroinflammation and the 43 kDa TAR DNA-binding protein (TDP-43) at each stage (McKee AC, 2015).

Figure 2: Progression of tau protein to aggregated neurofibrillary tangles.

Figure 3: The proposed stages of CTE development I, II, III and IV.

The Importance of Neuroinflammation in CTE

TBI causes neuroinflammation by activating resident glia (microglia and astrocytes), releasing inflammatory mediators within the brain, and attracting peripheral immune cells called leukocytes (Lozano et al., 2015). Microglia are the brain's primary resident immune cells, thought to develop from macrophage/monocytes in the bone marrow early in embryogenesis (Schwulst et al., 2013). Peripheral macrophages can also invade the brain and differentiate into microglia in response to TBI (Ginhoux, Lim, and Hoeffel, 2013). Microglia play an important part in neuroinflammation because they are the first line of defence when an injury occurs (Blaylock, Maroon, and Joseph, 2012). Microglia can create excessive proinflammatory mediators, which increase brain damage, impede brain repair, and prevent neurological functional recovery (Loane and Kumar, 2016). Neuroinflammation because of TBI can be both negative and positive. An early treatment that can modify inflammation, prevent subsequent damaging chain reactions, and improve recovery should be implemented.

Novel Treatment

Chronic disease is driven by inflammation (Sears, 2015). Understanding the impact of an anti-inflammatory diet on inflammation can propel the diet from a source of calories to being at the forefront of gene-silencing technologies (Sears, 2015). Simple carbohydrates ('sugars') are consistently related with adverse global cognition, whereas complex carbs are associated with successful brain ageing and increased memory in both the short and long term (Muth and Park, 2021). Diets like the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) both rich in plant-based foods, lean proteins, and healthy fats have demonstrated associations with reduced cognitive decline and better cognitive function in long term studies (Ekstrand et al., 2021).

Saturated fatty acid consumption correlates with lower memory and learning scores, but omega-3 intake correlates positively with memory scores. When there are strong task demands, protein ingestion improves executive function and working memory (Muth and Park, 2021). A good diet promotes brain health and function, whereas poor nutrition impairs it. Diet research can help inform dietary recommendations, improving mental health and healthy brain ageing.

Our innovative treatment approach involves creating dietary plans for athletes with a preventive focus on potential future CTE. By incorporating anti-inflammatory foods early on, we aim to mitigate symptoms and potentially reduce the incidence of CTE among athletes.