No Evidence of Early-Onset Dementia in Retired Contact Sport Athletes

Concerns are growing that professional sports players may develop degenerative disorders of the brain, such as chronic traumatic encephalopathy (CTE), later in life.  We have previously focused on the specific risk associated with heading footballs in editions 203 (here) and 244 (here) of BC Disease News. In this article, we discuss additional research on CTE and contact sports, which has been undertaken a team at the University of Buffalo.

Symptoms of CTE usually begin many years after the onset of head impacts, and can include changes to mood and behavior, including aggression, depression, diminished impulse control and paranoia. As the disease progresses, patients may also experience memory loss, confusion, impaired judgement, and, eventually, progressive dementia. 

Currently, the disease can only be diagnosed after death. 

CTE is believed to be caused by repeated concussions. It is also proposed that CTE can be caused by regular, less intense, impacts to the head that are not significant enough to cause concussion, such as heading a football. 

Most athletes with CTE damage exhibit early-onset dementia, although some evidence suggests that it may be possible to have CTE damage without clinical symptoms[i].

In a recent study, the Buffalo researchers compared 21 retired National Football League (NFL) and National Hockey League (NHL) players with non-contact sport athletes. Comparison between groups is necessary to determine whether an effect is more prevalent in one group than in another and previous studies have been limited by a lack of comparison.

The data collected has been published in 4 papers. These have provided analysis of cognitive changes[ii], executive function[iii], brain imaging[iv] and a general overview.[v] 

Overall, the study found no evidence of early-onset dementia in the retired NFL and NHL players. As discussed above, research suggests that most CTE sufferers would have onset dementia symptoms.

A comparison of features associated with cognitive function, such as memory, attention and visual spatial orientation, did not reveal any significant differences between the contact sport athletes and the control participants.  Mild cognitive impairment was slightly more common in the contact sport athletes, but prevalence was normal for the age, education level and body mass index of the participants. Any difference between the groups was not statistically significant. 

When asked to assess their own health and functioning, the retired athletes reported impaired executive function. However, reports were inconsistent with the objective assessments carried out by the research team.  The athletes were more anxious and more likely to report unusual beliefs and experiences.

Advanced brain imaging also showed no differences between brain tissue injuries sustained by participants in both groups. 

The researchers concluded that, contrary to the opinion of certain experts, it should not be assumed that CTE is inevitable in professional athletes. However, this was a small-scale study, so larger-scale testing is needed to validate findings.


[i] Study of 21 retired NFL and NHL players doesn’t find evidence of early onset dementia.  Science Daily, 7 August 2018. (Accessed 5 September 2018)

[ii]  Baker, J. G. et al. An Exploratory Study of Mild Cognitive Impairment of Retired Professional Contact Sport Athletes. J Head Trauma Rehabil (2018). doi:10.1097/HTR.0000000000000420 (Accessed 5 September 2018)

[iii]  Willer, B. S. et al. Evaluation of Executive Function and Mental Health in Retired Contact Sport Athletes. J Head Trauma Rehabil (2018). doi:10.1097/HTR.0000000000000423 (Accessed 5 September 2018)

[iv] Zivadinov, R. et al. Multimodal Imaging of Retired Professional Contact Sport Athletes Does Not Provide Evidence of Structural and Functional Brain Damage. J Head Trauma Rehabil (2018). doi:10.1097/HTR.0000000000000422 (Accessed 5 September 2018)

[v] Willer, B., Zivadinov, R., Haider, M. N., Miecznikowski, J. C. & Leddy, J. J. A Preliminary Study of Early-Onset Dementia of Former Professional Football and Hockey Players. The Journal of Head Trauma Rehabilitation Publish Ahead of Print, (2018). (Accessed 5 September 2018)