The scientists gathered data on 3,439 ex-professional football players, average age 57 years, who had played during at least five seasons from 1959 to 1988 for the National Football League. They searched through all the death certificates, specifically looking out for deaths caused by ALS, Parkinson's disease and Alzheimer's disease. When the study was ongoing, 10% of the ex-footballers had died.
The team discovered that professional football players:
- had triple the risk of death caused by diseases that destroy or damage brain cells compared to other people
- had four a times greater risk of dying from ALS or Alzheimer's disease
- had about the same risk of death from Parkinson's disease as the rest of the population
In the USA this sport is known as "Football". In the UK and much of the rest of the world, it is known as "American Football". The term "Football" in the UK means "Soccer" in the USA
Did a footballer's position affect his risk of death?Everett J. Lehman, MS, and team also set out to find out whether different positions played by footballers impacted on their risk of death from brain damaging diseases. They divided the players into two groups:
- The speed group - those in speed (non-line) positions, such as fullbacks, running backs, quarterbacks, halfbacks, wide receivers, tight ends, defensive backs, safeties and linebackers
- The non-speed group - those in non-speed (line) positions, such as defensive and offensive linemen
Everett J. Lehman said:
"These results are consistent with recent studies that suggest an increased risk of neurodegenerative disease among football players. Although our study looked at causes of death from Alzheimer's disease and ALS as shown on death certificates, research now suggests that chronic traumatic encephalopathy (CTE) may have been the true primary or secondary factor in some of these deaths.
A brain autopsy is necessary to diagnose CTE and distinguish it from Alzheimer's or ALS. While CTE is a separate diagnosis, the symptoms are often similar to those found in Alzheimer's, Parkinson's and ALS, and can occur as the result of multiple concussions."
The authors pointed out one limitation in their study; the small number of deaths they assessed.
What are neurodegenerative diseases?Neurodegenerative diseases include those with a progressive loss of function or structure of neurons, including their death. Examples include:
- Alzheimer's disease - a progressive neurologic brain disease which leads to irreversible loss of neurons and cognitive abilities, including memory and reasoning.
- Parkinson's disease - a progressive nervous system disorder that disrupts the patient's ability to move properly, including how they write, speak, walk, and use their hands. Signs and symptoms develop gradually over time, and may begin with very slight tremors in one hand. Patients also develop stiffness and find it progressively harder to carry out movements as quickly as they used to (bradykinesia). Muscles become weaker. The person's posture often changes.
- Amyotrophic lateral sclerosis (ALS) - also known as Lou Gehrig's Disease or motor neuron disease. This is a progressive neurodegenerative disease that destroys the nerve cells in the spinal cord and brain. Motor neurons reach from the brain to the spinal cord, and from there to all our muscles. The progressive deterioration of the motor neurons eventually causes death. The death of motor neurons leads to the loss of muscle control. In the later stages of the disease, patients become completely paralyzed.
Head injury risk linked to playing professional and amateur footballBoth professional and amateur football players have a higher risk of sustaining head and/or brain injuries than other people. Experts believe that head and brain injuries are major risk factors for neurodegenerative diseases.
Researchers from the Walter Reed National Military Medical Center in Washington, DC, found that collegiate football players have a much higher risk of sustaining head injuries and concussion than the rest of the population.
A two-year study carried out by scientists from Purdue University indicated that concussions among high school football players are probably caused by several hits over time, rather than one single blow to the head.
Written by Christian Nordqvist