Rates and Outcomes of Concussion Affected by Intensity Hits and Family History of Dementia 

Susceptibility to concussion may have a genetic component, and intensity of head impacts may better predict future consequences (eg, chronic traumatic encephalopathy [CTE]) better than years of play or number of hits to the head. 

In a study of active boxers and mixed martial arts (MMA) fighters (n=198, 100% identified as men in study report) who had a family history of dementia had more symptomatic concussions over their careers (P<0.05). Symptoms included higher incidences of depression (P<0.01) and impulsivity (P<0.01). 

Another study matched data from current football players for head impact characteristics to football-playing brain donors (n=656) and correlated the pathology in their brains on autopsy with those characteristics. Cumulative rotational (AUC=0.765, P<.001) and linear (AUC= 0.758, P<.001) forces more strongly correlated with the presence and severity of CTE compared with years of play (AUC=0.716) and frequency of head impacts. Years of play and head impacts were similar accurately predicting presence and severity of CTE (AUC=0.698, P=.25).

In the study of boxers and MMA fighters, number of concussions was from self-reports, depression was measured with the Patient Health Questionnaire (PHQ)-9 scores and impulsivity with the Barratt Impulsiveness Scale Version 11 (BIS-11) scores. Statistical significance was evaluated after adjusting for age, sex, education, and number of professional fights.

In brain pathology study, donors were mean age 60, and 69% had findings of CTE. The expected force and frequency of head impacts for each year of play at a specific level and position was calculated from data in the published literature reported helmet accelerometer recordings hit frequency and linear/rotational forces. Data regarding how long, at what position, and at what level (youth through professional) the brain donors played came from interviews with their next of kin.

These studies were presented at the Alzheimer's Association International Conference held July 31-August 4, 2022 (AAIC2022) in San Diego, CA and online.