Neurology: Longitudinal changes in cognitive function and brain structure in professional boxers and mixed martial arts athletes after a truce

Repetitive head impact (RHI), common in combat sports, is considered a serious risk factor for several long-term neurological disorders, including chronic encephalopathy (CTE), cognitive and behavioral impairment, and post-traumatic parkinsonism
.
RHI is associated with widespread cognitive changes in professional boxers, who experience RHI in both approved matches and daily training, and RHI may increase their risk of
developing neurodegenerative diseases.
As fighters move from an active combat state to an inactive combat state at a relatively young age (early 30s), it is unclear whether the cognitive changes noted after cessation of exposure to RHI will progress, remain stable, or recover.

Understanding the clinical trajectory in the cohort of well-characterized fighters during this transition period may have direct implications for several other groups in our society with RHIS, such as other contact sports athletes and veterans
with multiple blast exposures.

A study published in Neurology compared longitudinal changes
in cognitive function and brain structure in male fighters who transitioned to an inactive combat state without further exposure to repeated head impacts (RHI) with continuous exposure to RHI and remained active in a combative state.

Participants were
recruited from the Professional Boxers Brain Health Study.
At point 1 (TP1), all fighters are active and continuously exposed to the RHI
.
At point 2 (TP2), a boxer is considered "transitional" if he or she has not had an approved professional boxing match and has not engaged in martial arts in the
past two years.
If boxers continue to train and compete, they are considered "active"
.
All of the fighters underwent cognitive tests and 3T magnetic resonance imaging (MRI)
at both TPS.
Our group of fighters (50%) received blood samples to characterize neurofilament light (NFL) levels
for both TPS.
Linear mixed-effects models were applied to study the potentially different longitudinal trajectories (interaction effects between population and time) on cognitive function indicators, NFL levels, and local thickness indicators (derived from structural magnetic resonance)
of transitional and active combat aircraft.

After the warrior stops RHI exposure, cognitive function and brain thickness measurements may stabilize, and NFL levels in the blood may decrease
.
This study may be a starting point
for identifying potential predictors of individuals at higher risk for long-term neurological disorders associated with RHI.

Literature source:

Zhuang X, Bennett L, Nandy R, Cordes D, Bernick C, Ritter A.
Longitudinal Changes in Cognitive Functioning and Brain Structure in Professional Boxers and Mixed Martial Artists After They Stop Fighting [published online ahead of print, 2022 Sep 14].
Neurology.
2022; 10.
1212/WNL.
0000000000201158.
doi:10.
1212/WNL.
0000000000201158