NFL players are at greater risk of developing cognitive problems and mental health issues


Longer NFL careers and certain playing positions appear to each spell greater long-term risk for serious cognitive problems such as confusion, memory deficits, depression and anxiety in former football players, according to a new report published Aug. 30 in The American Journal of Sports Medicine.

The study is believed to be the first to explore the interplay between career length, position and cognitive and mental health outcomes among professional football players.

The analysis — based on a survey of nearly 3,500 former NFL players — was conducted by investigators at the Harvard T.H. Chan School of Public Health and Harvard Medical School as part of the ongoing Football Players Health Study at Harvard University.

The study results show that players who experienced concussions had elevated risk for serious cognitive problems, depression and anxiety, which persisted over time, as long as 20 years following injury.

The investigators caution that their analysis relied on players’ memories of experiencing concussion rather than on diagnosis at the time of injury.

And the findings do not mean that everyone with concussion will necessarily experience cognitive or mental health problems, they add.

Contrary to previous reports, the new research did not find a link between starting football at a young age and cognitive problems in adulthood.

On one level, the researchers say, many of their findings make intuitive sense and confirm what some might have already suspected:

The longer players remain in the game, the more likely they are to suffer a head injury, which increases the risk for neurocognitive problems.

It also affirms that certain positions are more prone to concussions and, therefore, players in them face greater risk for experiencing the downstream of effects of head injury.

Nonetheless, the researchers said, the analysis is the first to document and quantify the risk that stems from lengthier careers and certain high-impact positions.

Specifically, the analysis showed that players who reported the most concussion symptoms had 22-fold risk of reporting serious long-term cognitive problems and six times the risk of having symptoms of depression and anxiety, compared with those who reported the fewest symptoms.

“Our findings confirm what some have suspected — a consistently and persistently elevated risk for men who play longer and who play in certain positions,” said study lead investigator Andrea Roberts, a research scientist at the Harvard T.H. Chan School of Public Health.

“Our results underscore the importance of preventing concussions, vigilant monitoring of those who suffer them and finding new ways to mitigate the damage from head injury.”

For the study, former players, average age 53, were asked about the number of seasons played in the NFL, their positions and any history of blows to the head or neck followed by symptoms of concussion such as dizziness, confusion, vision problems, loss of consciousness, nausea, headaches and seizures, among other symptoms. Based on the number and severity of symptoms, players were given a concussion score.

Overall, one in eight players (12 percent) reported signs of serious cognitive problems.

By comparison, about 2 percent of people in the general population in the United States report such problems.

Age made no difference in the interplay between concussion and cognitive problems, the study showed.

Those under age 52 reported serious cognitive problems at a similar rate as the rest (13 percent), a finding that suggests neurocognitive decline was likely not a function of mere aging. Alarmingly, that risk remained magnified even in those 45 and younger. Indeed, 30 percent of players 45 and younger who had the most concussions reported serious cognitive problems.

To gauge whether the number of seasons played and position type were linked to depression, anxiety and cognitive problems, the researchers used standard questionnaires commonly used to screen for the presence of such disorders.

The researchers compared the proportion of players with serious cognitive problems among individuals with various career lengths – one season, two to four seasons, five to six seasons, seven to nine seasons and 10 seasons or more.

Overall, those with the longest careers – 10 seasons or more – were twice as likely to report severe cognitive problems compared with players who’d played a single season – 12.6 percent in the 10-plus season group reported signs of severe cognitive problems, compared with 5.8 percent in the single-season category.

The risk crept up proportionally with the number of seasons played, growing progressively higher as the number of years increased. Every five seasons of play carried a nearly 20 percent increase in risk for serious cognitive problems.

Which position one played also mattered. To evaluate the risk-position link, the researchers divided players into three groups based on the average concussion symptoms per year that players reported in each position.

Kickers, punters and quarterbacks had the fewest symptoms per year, followed by wide receivers, defensive backs, linemen and tight ends. The groups with the highest number of symptoms included running backs, linebackers and special teams.

Those in the group with the most concussion symptoms had twice the risk for serious cognitive problems – 15 percent of those in this group had cognitive difficulties – compared with those reporting the fewest concussion symptoms (6 percent).

Those with the most concussions also had a nearly 50 percent greater risk for depression and anxiety, compared with those playing in the group with the fewest concussion symptoms.

One in four in the first group had symptoms indicative of depression, compared with 15 percent of players reporting problems in the latter one, while 27 percent had signs of anxiety, compared with 16 percent in the group with the fewest concussions.

Those who played in the mid-range group had a 75 percent higher risk of cognitive problems and a 40 percent elevation in risk for depression and anxiety, compared with players in the group with the fewest symptoms.

Nearly one in four players reported symptoms of anxiety (26 percent) and depression (24 percent), and nearly one in five (18 percent) reported symptoms of both conditions.

Career length influenced risk for depression, with every five seasons boosting the risk by 9 percent. The number of seasons, however, was not linked to greater anxiety risk.

The age at which an individual started playing organized football did not affect risk. Indeed, outcomes were similar between those who began playing the game before age 12 and those who began later.

The findings, however, pertain solely to former NFL players and not necessarily to the general population, the researchers caution.

The question of when a child should start playing organized football remains very much open, and should be made by each individual family, the researchers said.

Risultati immagini per NFL players are at greater risk

The study is believed to be the first to explore the interplay between career length, position and cognitive and mental health outcomes among professional football players. The image is in the public domain.

“The overarching goal of the Football Players Health Study is to unravel risk factors and disease mechanisms and to inform interventions that preserve and optimize player health and wellness,” said study senior author Marc Weisskopf, the Cecil K. and Philip Drinker Professor of Environmental Epidemiology and Physiology at the Harvard T.H. Chan School of Public Health.

“These latest findings confirm much of what we know but they add much needed granularity and specificity to risk magnitude by career length and position.”

“Clearly, not everyone who sustains a concussion is destined for cognitive trouble, but the results of the research highlight just how critical it is to continue to find ways to prevent head injuries from occurring in the first place because of the many downstream and long-lasting effects on physical, cognitive and mental health,” said Ross Zafonte, the Earle P. and Ida S. Charlton Professor of Physical Medicine and Rehabilitation and head of the Department of Physical Medicine and Rehabilitation at Harvard Medical School. Zafonte is also principal investigator of the Football Players Health Study.

Funding: The research was supported by National Football League Players Association (NFLPA).

Over the last 20 years, there has been increasing concern both about the acute injury effects as well as the long‐term consequences to athletes participating in high‐impact contact sports.1 

These are not new concerns. Incidental case reports of acute traumatic injuries resulting in significant incapacitation and even deaths had been reported for over 50 years.

More recently, chronic or late‐onset significant morbidity associated with participation in high‐impact sports has become of increasing concern, as reports of significant neurodegenerative diseases occurring in former prominent athletes, particularly related to those who played professional American style football (ASF), have made news in both the scientific as well as the lay press.2 

Other chronic conditions, including musculoskeletal, cardiovascular, sleep disorders and behavioral mental health conditions have also been reported.34 

However, for the most part, the published literature falls short in providing sufficient data to make informed judgments to quantify the magnitude of the risks associated with ASF for any of these conditions.

This has the unfortunate effect of placing a burden on former players, potential players, and their families, as well as other stakeholders to make potentially lifestyle and health‐related decisions without adequate facts.

It should be noted that this manuscript is designed to describe a strategic programmatic response to a research need and a series of studies under a large umbrella rather than a single study.

In an effort to better document the potential long‐term consequences of participation in ASF, the National Football League Players Association (NFLPA) in 2014 put forward a nationally advertised major Request for Proposals to study the health and welfare status of retired professional ASF players.

The proposal asked for studies to assess and develop potential new preventive, diagnostic, and therapeutic interventions that would mitigate potential long‐term consequences of participation in the sport.

In response, Harvard University developed the Football Players Health Study (FPHS), which was designed as a multidisciplinary investigative team approach to address these issues.

This effort was formally funded in 2014. 

The goal of the Football Players Health Study at Harvard University (FPHS) is to further understand the benefits and risks of participation in ASF, identify those risks that are potentially reversible or preventable, and develop interventions or approaches to improve the broad array of issues impacting the health and wellbeing of former ASF players.

From the onset, it was clear that the success of this program would be dependent on understanding and being committed to the concept of ongoing engagement with the population of interest in a participatory approach throughout the research process.5 

We initially conducted a number of focused meetings with representatives of the NFLPA as well as former ASF players from a variety of other player associations.

These sessions provided input into prioritizing clinically meaningful targets for assessment, intervention, and potential functional improvements.

Follow‐up meetings led to working groups of Harvard University faculty who came together to design a comprehensive set of studies, as indicated below, around the theme of “the whole player, the whole life.”

Issues considered included, but were not limited to, identifying factors that could mitigate risk of having an injury; understanding consequences of injury as well as other factors associated with participating in the sport at the professional level on short and long‐term health impacts; and, to the degree possible, understanding the long‐term consequences for both physical and social impacts of having participated in the sport.

In addition, we proposed to explore potential new approaches to therapeutics to lessen long‐term consequences of the unique exposures and putative injuries to which players are exposed.

Not the least of our objectives was to determine the magnitude of the risk rates of a wide variety of outcomes.

Such data would give all stakeholders better estimates for making potentially life‐changing decisions regarding participating in ASF.

Because of the complex nature of player‐team relationships, a group of bioethics and legal scholars formed an additional unique component of our studies to explore and address the ethical and legal implications of the way professional ASF is organized.

Finally, a significant component of our efforts is to keep the former players informed of our progress.

This has been done through both a series of former player advisor group meetings and social media efforts to both inform former players on the progress of the studies and encourage participation in the ongoing efforts.

This paper describes the components of the FPHS studies undertaken and completed thus far, as well as those studies currently underway or planned for the near future. We present our initiatives herein as a potential paradigm of one way to proceed.

We fully acknowledge that our approach is not the only way, but believe that what we have learned may be useful to others, particularly in regard to trying to make professional sports meet the needs of multiple stakeholders ranging from players to owners, to fans, and possibly even to parents making decisions for their children.


We initially established two important Advisory groups. The first was made up of former NFL players who represented a spectrum of regional areas of the US, positions played, and different age groups.

These former players provided essential insight into the concerns and questions that were most germane to the former player groups.

The second was a group of local physician/scientists representing the range of research domains believed to be important to consider. Both groups have continued to evaluate and provide input into the research designs undertaken.

The range of studies can be divided into three broad categories (Figure 1).

Within each of these categories, there are a number of substudies, some of which have been completed, some which are ongoing, and some which are still in the planning or early implementation stages. In addition, an important component is communication and return of results to the participating former players and other stakeholders.

Figure 1Open in figure viewerPowerPointRange of studies undertaken, ongoing, and planned [Color figure can be viewed at]

Former player studies

A major effort of the FPHS focuses on studies of former NFL players with the goal of assessing risk factors associated with participating in professional ASF and the putative long‐term consequences to their health and wellbeing.

This plan requires a coordinated set of studies. Initially, we needed to assess components related to the exposures that are or have been a necessary part of the game. Further, we are attempting to quantitate the current physical, social, and neurocognitive state of former players, and testing within nested case‐control subgroups newer diagnostic techniques and remote assessment tools. Eventually, we would hope to introduce potential new therapeutic modalities that may enhance the lives of former players after they leave the game.

Cohort questionnaire studies

Beginning in 2014, we sought to enlist the participation of an as large as possible cohort of former ASF players who had participated in the NFL (or former American Football League). Our criterion for enrollment was “formerly played professional football at any point from 1960 to present.”

“Formerly played” was defined as having received compensation as a player from an NFL team.

The year 1960 was chosen because by that time the transition from the soft, leather helmet to the hard, plastic helmet had been established throughout the league.

The eligibility to join the cohort is a dynamic one in which younger players are invited and encouraged to enroll as they declare themselves retired.

In addition, as subsequent substudies identify former players who had not enrolled in the initial round of cohort data collection, they are invited to provide baseline data.

To determine the topics to include in the initial standardized questionnaire, we held focus group meetings with both former players and research advisors.

We first identified the parameters that would permit us to measure some of the characteristics of “exposure” in professional football (eg, position played, years of play, nature of some of the injuries during active playing years, essential demographics, etc).

We also identified a number of health‐related domains of concern, for which we believed, by using well‐validated questions, we could establish baseline health status for the proposed cohort.

Because a significant portion of the eligible cohort had either a home address or an email address, but not both, we needed to assess the potential difference in response patterns that might occur using one rather than both methods for contact.

We selected approximately 500 former players at random who had both home addresses and emails to assess the response rate and degree of completion of the various components of the questionnaire.

We determined that the response patterns and degree of completeness were no different between administering the questionnaire by email (REDCapC) vs Scantronc paper questionnaires, and thus both methods were used for those for whom we had appropriate contact information.

The original main sources for defining former players were lists provided by the NFL Players Association, supplemented by NFL Profootball Reference.1 

Additional sources, many overlapping, included a number of philanthropic associations formed by former player groups, wives of current and former players, and other regional and local groups.

These groups were asked to communicate with their members and to inform them of the study.2Figure 2 describes the sources and number of former players for whom we initially believed we had obtained a contact address.

Initially, we estimated that approximately 20 000 individuals played for one or more of the approximately 30 teams over the years starting in 1960.

Of these, we estimated that approximately 4000 had died before the beginning of the follow‐up period. I

n February 2015, at the time of our first effort to contact the former players, and over the initial 3 years of follow‐up, we were able to confirm 14 538 individuals who met the criteria as former active players.

Other members of the initially constructed lists had included coaches, management staff, and others who were not active players.

We were able to confirm anticipated valid home addresses for approximately 12 713 players. In addition, we had available potential email addresses for 8542.

Using combined mailings for both paper questionnaires and web‐based methods, we estimated that 13 403 former players with appropriate years played eligibility received our questionnaire in one or both forms (only the first method used to respond was counted). At present, the cohort is made up of 3785 former players who have completed our initial questionnaire.

Newly retired players are continuing to enroll and plans exist to follow them over time.

Figure 2Open in figure viewerPowerPointFlow chart of former player contacts [Color figure can be viewed at]


The Football Players Health Study at Harvard University is a broad and ambitious research and translation program that attempts to securely capture data from all aspects of former ASF players’ lives.

We anticipate that such data will help to quantify the potential long‐term risks associated with ASF.

As more pathophysiologic data and risk quantification are obtained, we anticipate the information will be useful to drive more informed player decision‐making.

We would also anticipate that results will lead to appropriate interventions as these men age, and thus enhanced health and wellbeing outcomes.

Media Contacts: 
Ekaterina Pesheva – Harvard
Image Source:
The image is in the public domain.

Original Research: Closed access
“Exposure to American Football and Neuropsychiatric Health in Former National Football League Players: Findings From the Football Players Health Study”. Andrea L. Roberts, Alvaro Pascual-Leone, Frank E. Speizer, Ross D. Zafonte, Aaron L. Baggish, Herman Taylor, Lee M. Nadler, Ann Connor, Rachel Grashow, Alexandra M. Stillman, Dean A. Marengi, Marc G. Weisskopf, Theodore K. Courtney.
American Journal of Sports Medicine. doi:10.1177/0363546519868989


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