Former NFL players report Mild Cognitive Impairment, dementia at higher rates than national average for their age

By Conor Gormally. This article was initially published in our Concussion Update newsletter; please consider subscribing.

Samual Walton et al. investigated the prevalence of Mild Cognitive Impairment (MCI) and dementia in former NFL players ages 50+ in research published in Medicine & Science in Sports & Exercise. The authors found significant disparities in the rate of self-reported MCI and dementia diagnoses between the study participants (who had spent at least one year in the NFL) and national incidence estimates. Alarmingly, almost 23% of participants aged 50-60 reported MCI, which is so rare in that age range among the general population that there is no national trend data for it. 

However, when accounting for concussion history, only a history of 10+ concussions (compared to 0 concussions) was definitively associated with increased prevalence of MCI and dementia (vs. 1-2, 3-5, and 6-9 concussions). “Other predictors of MCI and dementia were depression, anxiety, sleep apnea, and pain—each of which may be potentially modifiable with targeted treatments or therapies.”

Walton et al. contacted 15,025 former NFL players and received 1784 responses, 922 of which were included in the study. Participants filled out a survey self-reporting demographic information, medical diagnoses, and concussion history. The authors used 50 as the cutoff age because of the lack of a precedent for neurodegenerative diseases and MCI to occur before those ages. 

Shockingly, a larger percentage reported 10 or more concussions (27.2%), than the combined percentage of athletes who reported 0 or 1-2 concussions (26.9%). Almost a quarter of athletes reported diagnoses of MCI (23.8%), while 8.9% reported a dementia diagnosis. The authors break down prevalence by age group below in a chart (below):

(Source) Mild Cognitive Impairment and Dementia Reported by Former Professional Football Players over 50 yr of Age: An NFL-LONG Study. Medicine & Science in Sports & Exercise54(3):424-431, March 2022.

(Source) Mild Cognitive Impairment and Dementia Reported by Former Professional Football Players over 50 yr of Age: An NFL-LONG Study. Medicine & Science in Sports & Exercise54(3):424-431, March 2022.

The authors found that a lifetime history of 10+ concussions was associated with a higher prevalence of MCI and dementia (compared to no concussions). While MCI and dementia were more prevalent among those with 1-2, 3-5, and 6-9 concussions compared to those with 0 concussions, this association was not strong enough to be statistically significant. These results suggest that the association of behavioral and physiological changes (like MCI and dementia) with repetitive concussion may not be linear, instead increasing dramatically at certain thresholds. Their results lead the authors to posit that the thresholds these changes occur at may be higher than previous studies have suggested. Many studies aggregate multiple concussions into a ‘3+’ or ‘5+’ bucket, which doesn’t allow for the same level of granularity when assessing risk of repeated concussions.

They also found that higher pain intensity was associated with increased prevalence of MCI and dementia, though the mechanism for this is unclear. The authors mention two potential causes behind this relationship. First, the pain may be caused by underlying systemic inflammation, which could factor into long-term development of these conditions. Second, psychological distress due to living with chronic pain may cause depression and anxiety, which are also strongly associated with MCI and dementia prevalence.

The greatest disparities in MCI and dementia prevalence were in the youngest age groups for which national trend data was available (60-64 for MCI and 65-69 for dementia), though prevalence disparities decreased with increasing age. Walton et al. note that increased awareness of cognitive & memory issues for football players may make them more likely to seek out diagnoses and care than the general population, which is a limitation of the self-reported survey methodology.

Despite the study’s focus on concussions, “Self-reported depression and/or anxiety had the strongest association with MCI and dementia in this study,” with the authors noting that lifetime depression diagnosis is associated with a 1.7 to 2.9 times higher risk of developing a dementia-related illness. Modifiable factors like depression, anxiety, sleep apnea, and pain are all potential targets for therapies that may reduce the risk of developing these conditions. The study’s limitations include relative sample size and generalizability concerns, and biases related to self-reporting.