For the past few years, Chronic traumatic encephalopathy more commonly known as
CTE has been a hot topic in the news surrounding athletes and the military. In the 1920s
the first studies connected chronic neurodegeneration with mild traumatic brain injuries
(mTBI). In the late 1920s, group of symptoms that resulted from a mTBI were categorized
and labeled punch drunk. These would later be used to describe some neurodegenerative
disorders including CTE. Decades later, in 1973, a study was done on the brains of 15 retired
boxers. They found that unique abnormalities would demonstrate brain cell loss and would
later be considered CTE.
CTE is a progressive neurodegenerative disease, which means over time the nervous system
stops working or dies. It is associated with repetitive mild traumatic brain trauma (rmTBI),
especially in sports and military service. During mTBI the brain undergoes deformation that
elongates and injurs parts of the cell body and small blood vessels. Dr. Froecking talked about
the window of vulnerability following the first mTBI. Another brain injury or blow to the head
could lead to a traumatic brain injury. Also, rmTBI could lead to the accumulation of abnormal
tau that could overwhelm the clean-up crew in the brain. These could lead to inflammation or
microhemorrhages.
Microscopically, CTE is characterized by the accumulation of a certain protein called tau in a
unique pattern in neurons, which is common among many different neurodegenerative diseases.
However, the location of the layers of the brain distinguishes the different neurodegenerative
diseases. The abnormal accumulation of tau leads to something called neurofibrils tangles (NFT),
which are a collection or aggregation of the mutated tau. The accumulation of NFT in regions of
the brain, specifically the temporal lobe and brainstem leads to atrophy or cell death. Atrophy in
these brain regions could account for wh CTE is associated with behavioral and personality
changes and cognitive impairments. From a macroscopic level, CTE is connected to the
enlargement and discoloration of brain cells CTE is hard to diagnose because symptoms appear
after a long period that can range from several years to several decades. The initial symptoms
are insidious, for example, they could experience irritability impulsivity, aggression, depression,
short-term memory loss, and heightened suicidality. Symptoms progress very slowly and can
include cognitive defects and dementia. Another major issue regarding diagnosing is that it can
only be accurately diagnosed by an autopsy post-mortem. Many promising studies are going on
to allow for a diagnosis while alive. For example, PET scanners and biomarkers could allow
researchers and doctors to diagnose and monitor CTE.
The progression of CTE is classified into four stages. Stage one is a mild case and stage four is
severe case. In stage one there is mild enlargement and some NFTs. But in stage four there is a
significant decrease in brain weight, global atrophy and enlargement, discoloration, severe loss
of brain cells, and widespread clusters of NFTs. It is still unclear whether all cases progress at
similar rates or whether CTE persists indefinitely. However, it is known that CTE is associated
with the development of other neurodegenerative diseases. For example, Alzheimer's disease (AD),
Lewy body disease (LBD), Frontotemporal lobar degeneration (FTLD), and Motor neuron
disease (MND). The average age of death of subjects with CTE is younger than those with AD,
suggesting that these comorbidities are not just simply age-related. The presence of comorbid
progression of CTE suggests that rmTBI and the accumulation of tau NFTs provoke the other
abnormalities involved in neurodegeneration.
Many sports are associated with CTE such as boxing, American football, ice hockey, soccer, rugby,
and wrestling. Also, veterans and people who are victims of assault or abuse are at risk for CTE.
Since it is only diagnosed through autopsy it is hard to know the prevalence. Some of the American
football players who were identified with CTE had records of reported and repeated concussions
but others did not. Among American football players, the stage of CTE at death significantly
correlates with the age of death, the number of years playing football, and the number of years
after retirement from football. mTBI is a common wound among those who served in the military.
Blast-induced neurotrauma put military personnel at risk. In a study of veterans brains, of those
with CTE most were veterans, some saw combat, were exposed to explosive devices, and were
diagnosed with Post Traumatic Stress Disorder.
Right now the best therapies are the prevention of the initial trauma and the continued education
regarding proper detection of minor traumatic head injuries. This demonstrates the importance of
Dr. Foecking’s research into the treatment of rmTBI by the injection of testosterone and
nanoparticles.
Resources
https://alzres.biomedcentral.com/articles/10.1186/alzrt234
https://www.espn.com/nfl/story/_/id/39417850/how-fears-cte-football-exceeded-scientific-certainty
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