Nutrition selection for the high-level athlete:
Utilizing genetics and brain injury pathways
to promote protective neurological effects in
athletes at the University of Guelph
Daniel MacDonald (0753150)
NUTR4360
April 14th, 2017
Introduction
The future of sports, and the future of young athletes depends on finding a solution to the
problem of concussions and its long-term impacts on health. In the past 10 years, Chronic
Traumatic Encephalopathy (CTE) and its long-term health impacts on former athletes has
become a major concern for parents and players of sport worldwide. Increased media coverage
of concussion related deaths as well as increased reporting of injuries by former athletes is
pushing parents and youth away from sports. The sports most associated with contact such as
football and rugby are significantly impacted. Concussive and sub-concussive blows sustained
during play have been linked to numerous instances of early onset Alzheimer’s disease,
dementia, depression and death on a scale never before seen1. The rate of occurrence of these
progressive injuries has been reported as high as 20-times greater than in an age matched
population1. Chronic traumatic encephalopathy, or “punch drunk syndrome” is a progressive
brain degenerative neurological condition that is characterized by the deposition of large
quantities of paired helical filament tau proteins (PHF-tau) into large neurofibrillary tangles,
neurophil neurites and astrocytic tangles1,2,6. This deposition mainly occurs in the brain in the
frontal lobe, temporal lobe, basial ganglia and the brainstem as well as in the connective circuitry
that link these sections of the brain6. This buildup of PHF-tau (specifically 3R and 4R variety) in
these connections is associated with the progressive cognitive, mood and motor decline of
CTE2,6. Furthermore, the increased presence of PHF-tau has been postulated to increase excess
glutamate in the brain1,3,5,6. The extracellular glutamate (primary sources are microglia and
astrocytes) lead to influx of massive quantities of calcium, which in turn leads to neuronal cell
death through the production of ROS, increased oxidative stress, secretion of cytokines and other
pro-inflammatory factors which promotes further glutamate cascading and in turn progressive
neural degeneration1. These immunoexcitotoxic effects are characterized physiologically in the
brain by the presence of cerebral and mammillary body atrophy, ventricular dilation in the first
and third ventricle, decreased white matter integrity and cavum septum pellucidum (persistence
of embryological fluid filled space in leaflets)4,6. In general, early symptoms of CTE present
themselves through memory problems and confusion, depression, low behavioral control,
increased agitation and aggression6,7. As the disease progresses, individuals may be subject to
decreased cognitive abilities (speech, mood control), motor disturbances, Parkinsonism and
dementia1,6. There is little known about the specific pathway for CTE development which
indicates that preventative solutions are extremely scarce. There is an starting point for
preventative research which includes the study of the correlation between CTE and the genes
ApoE (specifically ApoE e4) and Transactive response DNA-binding protein 43 (TNP-43)1,6,7.
Studies suggest that individuals with the ApoEe4 genotype are subject to more severe
neurological outcomes in both early and late stages of life than the wild-type, as well as poorer
recovery from TBIs as compared to the non-carriers1,6,7,8. Molecular analysis has shown a
possible correlation between repeated TBI and increased toxicity of TDP-43, which is associated
with frontotemporal dementia as well as ALS (amyotrophic lateral sclerosis). TDP-43 neurites,
neuronal, glial and intranuclear inclusions present early in CTE9,10. As the disease progresses the
TDP-43 immunoreactivity increases leading to increased accumulation of TDP-43 markers
across the brain which include hippocampus, amygdala, cerebral cortex, medial temporal lobe,
basal ganglia and the brainstem9,10. This increasing deposition and subsequent degeneration is
associated with the behavior and personality changes seen in CTE9.
Rationale
In the U.S. alone there are between 1.6 and 3.8 million reported concussions annually,
and CTE symptoms have been shown in individuals with singular instances of TBI, so there is a
need for research and preventative solutions. Past studies in the analysis of traumatic brain
injuries and omega 3 interactions have demonstrated in vivo and using animal models a strong
correlation with protective and even regenerative properties. If we look at current published work
by Bhardwaj, McMillan and Geser, TDP-43 autoregulation is controlled by TDBPR which is
located in the 3’ coding region of TDP-4311,18,21. Autoregulation becomes unstable after
concussive impact occurs, which leads miscoding in this region and subsequent mRNA
instability11. Resulting overexpression of TDP-43 and the associated aggressive toxic effect seen
in CTE patients. This excitotoxic effect was reduced in invitro models post concussive blows
with the supplementation of Omega 311,13,14. Currently, research has already shown a link
between Alzheimer’s disease and Eicospanetaenoic Acid (EPA) and Docosahexaenoic Acid
(DHA) implementation, EPA models of protection is thought to occur through the inhibition of
conversion of linoleic acid to arachondic acid (AA) limiting the rate production of inflammatory
mediums such as prostaglandins, leukotrienes and thromboxanes16,17. DHA implementation is
proposed to increase density of dendritic spines, synaptic proteins, and reduce amyloid-Beta
plaque and reduce tau levels through reduce phosphorylation and conformational changes.
DHA’s primary mechanism for neuroprotection has been correlated to increased its derivation of
neuroprotectin D1(NDP1) which promotes membrane fluidity, regulates apoptosis and modulate
inflammation and its mediators16,17. ApoE gene variation and n-3 Fatty acid interaction has been
correlated with higher cognitive prevention against Alzheimers disease, dementia and general
cognitive decline, which suggests a possible ApoE alleleotype interaction that affects
effectiveness of supplementation and protective effects11,17. ApoEe4 variant is associate with
increased risk of TBI degeneration, and n-3 FA supplementation may reduce risk of cognitive
decline11,17. Furthermore, in-vivo studies suggest that post-injury Omega 3 consumption could
serve to increases neurite density and length as compared to a control, which may indicate
possible solutions for neurite death in CTE and other neurological disorders that have similar
suggested pathways such as Alzheimer’s Disease and dementia15. The National Football League
is the largest contact sports organization on the planet. The introduction of a possible solution to
the most problematic health issue arising in the sport would be significant and would help to
ensure the future of the league. As further research uncovers the problems associated with
repetitive concussive blows, combined with our proposed Fatty Acid supplementation solution,
the future for football across the globe remains viable and lucrative. In addition to finding the
key to concussions, the link between cognitive degeneration and other neurological disorders
such as Alzheimer’s and dementia could be solved through fatty acid supplementation. What is
required is an organization willing to support fulsome high quality focused research
Main Hypothesis and Objectives
Due to current data suggesting a link between reducing neural degeneration in dementia
patients with EPA and DHA supplementation, and considering the suggested CTE pathways that
result in axonal and neuronal degeneration. It is hypothesized that the introduction of n-3 fatty
acid supplementation pre-concussive blows may reduce the degree of cognitive injury. It is also
suggested that in post-concussive states, Omega-3 fatty acid supplementation may help to stop
further cognitive degeneration that is associated with CTE.
Objective 1: To determine if Omega-3 supplementation is related to Fatty Acid levels in the
midbrain in contact-sport athletes.
In studies relying on the ingestion of Omega-3’s through fish consumption, 10 of 11 showed
significant and non-significant protective effects11,28. In an elderly population group, individuals
supplemented with DHA-EPA combination, 60% of the entire population showed improvement
in cognitive functioning. In the non-dementia population, an increase of 75% was noted11,26.
Studies analyzing a group of pre-dementia risk patients, found that DHA-EPA supplementation
was critical with pre-dementia diagnosis in reducing extent of cognitive impairment11,26.
Furthermore, the introduction of Omega-3 post-traumatic brain injury has been correlated with
an increase in mitochondrial creatine kinase (uMtCK) that returns the enzyme to normal
homeostatic levels13. This increase in uMtCK is responsible for maintaining calcium homeostasis
and energy regulation of calcium pumps13. As stated previously, increased calcium influx into
the brain results in neuronal cell death13.
Methods
Male contact-sport athletes with no prior head injuries from the University of Guelph will
be selected participate in randomized controlled trial. The independent variable will be the
supplementation of Omega-3 fatty acids, where half of participants will be randomly selected to
receive a daily dosage of 1.5g of an EPA/DHA supplement in a ratio of 2:127. The other half of
participants will receive a daily placebo, and will serve as the study control group.
Supplementation will begin one month prior to the start of each participant’s sporting season,
and discontinue once the season has concluded for a total duration of approximately five months.
The dependent variable is midbrain fatty acid levels, which will be measured prior to the
beginning of supplementation, and will then be re-measured post-sporting season for each
participant. To measure midbrain fatty acid levels, a volumetric resolution MRI will be used.
Fatty acid levels in the supplement group will be compared between the Omega-3 group and the
placebo group. A two-tailed T-test will be used to determine if midbrain fatty acid levels are
significantly greater in the Omega-3 group.
Based on previous research conducted and reviewed by Huang, Contreras, Rapport and
Mitchell et al, on the availability of Omega-3’s to pass into the midbrain through the blood brain
barrier by way of protein and lipid transportation, it is anticipated that Omega-3 supplementation
will increase fatty acid levels in the midbrain. With this study, issues that may arise pertain to the
adherence of the athletes to consistently ingesting the Omega-3 supplements or placebos. This
will be addressed through supervised administration. Additionally, other supplementation use
(specifically with regards to antioxidants) will be suspended by participants in this study, as
results could be altered by these substances. Athletes utilizing drugs that may increase cognitive
performance, or alter chemical pathways significantly, such as anti-depressants or Adderall will
not be admitted to the study.
Objective 2: Determine the association between the presence of gene variants in TDP-43
associated proteins and ApoE genotypic variations and cognitive impairment due to
concussive and sub-concussive blows and if Omega-3’s will mitigate cognitive impairment.
As outlined in the introduction to our research, there is a clear association between the
autoregulation of TNP-43 and cognitive decline. The microtubule-associated protein tau (MAPT)
gene, tags with a H1 and H2 haplotype18,22. H1 haplotype is correlated with 4 different taupathic
pathways and the A/A form is protective of atrophy as compared to H2 allele carriers. H2 is
associated with reduced brain weight, reduced glucose metabolism and increased neurofibrillary
tangles18,22. Previous studies propose that the H1 haplotype correlates with increased risk of
tauopathies, and in turn H2 is correlated with in increased Temporal degeneration from TDP-43
excitooxicity18,22. Sortilin related gene variants (rs646776) was correlated to have a 2-fold
increase in risk for TDP-43 pathology relating to tauopathy18. This correlation is presumed to
occur due to reduced Fatty acid levels in the midbrain as well as decrease in progranulin levels
that correlate with increased accumulation of neutrophils and inflammatory factors (McMillan,
He). Granulin Precursor variation (rs5848) correlated to 3.2 times risk increase in TDP-related
neuron degeneration18, and also correlates with reduced FA. GRN associated mutations have
been correlated with myelin changes, microglial activation and gliola (neuronal loss) especially
in the midbrain18,20,21. It is hypothesized that individuals that carry SNP variants in the Granular
Precusor (GNP) gene (rs5848), Soritilin (SORT1) variant rs646776 and Microtubule-associated
protein tau (MAPT) and its risk conferring allele A/A gene (rs8070723) will correlate to higher
incidences of tau-related neuronal degeneration and subsequently higher incidences of CTE
related cognitive decline11,18,20. Individuals carrying the apolipoprotein E gene (ApoE) variant
epsilon 4 has been associated with increased susceptibility16,29. Individuals that carry the ApoEe4
genotype have been suggested to be incompatible with the protective affects of Omega-3
supplementation against TBI and its related effects, which has been associated with decreased
FA transport across the blood brain barrier16,29,30. Additionally, DHA supplementation may have
atherogenic affects in individuals with ApoEe4, as an increase in LDL cholesterol was associated
with the gene variant post-supplementation16,25.
Methods
Male contact-sport athletes with no prior head injuries from the University of Guelph will
be selected participate in randomized controlled trial. The independent variable will be the
supplementation of Omega-3 fatty acids, where half of participants will be randomly selected to
receive a daily dosage of 1.5g of an EPA/DHA supplement in a ratio of 2:127. The other half of
participants will receive a daily placebo, and will serve as the study control. Supplementation
will begin one month prior to the start of each participant’s sporting season, and discontinue once
the season has concluded for a total duration of approximately five months. Only participants
sustaining concussive or sub-concussive blows, tracked using a JOLT sensor31, will be included
in this study. The dependent variable will be the presence of gene variants in the TDP-43
associated genes SORT1 (rs646776), GNP (rs5848), MAPT (rs8070723) as well at ApoE
genome variant episolon-4. MassARRAY Assay design software will be used to assess the
presence of gene variants according to methods outlined by McMillan et al18. The presence of
gene variants will be compared between the Omega-3 group and the placebo group to determine
if omega-3 supplementation mitigates cognitive impairment in athletes with concussive or subconcussive blows. A t-tailed t-test will be used to determine the presence of a significant effect.
Based on previous research outlined in the McMillan, Wider and Gass studies have demonstrated
that cognitive impairment after the introduction of Omega-3 supplementation in individuals with
these gene variants will be reduced18,20,22. The issues that may affect results are adherence to
supplementation, which will be addressed through supervised administration. Additionally, other
supplementation use (specifically with regards to antioxidants) will be suspended by participants
in this study, as results could be altered by these substances. Athletes utilizing drugs that may
increase cognitive performance, or alter chemical pathways significantly, such as antidepressants or Adderall will not be admitted to the study
Conclusion
In conclusion, current data and previous studies suggest that the implementation of Omega-3
supplements in pre and post traumatic brain injury states may experience improved cognitive
protection and quicker recovery post injury. The introduction of Omega-3 supplements are
proposed to increase fatty acid levels across the brain (in this case study, specifically in the
midbrain). The association between Omega-3 supplementation and gene variants associated with
TDP-43 and ApoE, with regards to concussive and sub-concussive blows, is proposed to
demonstrate significant preventative effects on in individuals carrying these gene variants. The
expected outcomes of the trials suggest that the link between EPA and DHA supplementation
will result in greater protection pre and post concussive episodes. The genotypic variation of
TDP-43 and ApoE that codes to greater cognitive impairment post TBI episodes will offer
greater protection and recovery than the control group. The potential outcomes of this study will
provide an approach to assist in the reduction in the number of current and former football
players that suffer from CTE and other dementia related diseases. The supplementation of EPA
and DHA in younger high-collision sport athletes should reduce the intensity of concussive
episodes, which may enable a quicker return to play and reduced negative long-term health
effects. Additionally, further studies of Omega-3 supplementation in related dementia and
neurocognitive impairment illnesses such as Alzheimer’s and ALS may produce a viable option
for reduced cognitive impairment and decline in susceptible individuals
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