Study examines NFL players' brain health

Cognitive deficits and depression more common among retired players than in general population


By Jeff Carlton and Shelly Kirkland

A study examining the neuropsychological status of former National Football League players has found that cognitive deficits and depression are more common among retired players than in the general population.

Dr. John Hart Jr. (left) and Dr. Munro Cullum
Dr. John Hart Jr. (left) and Dr. Munro Cullum

But researchers from UT Dallas’ Center for BrainHealth and UT Southwestern Medical Center say their study, published in January’s JAMA Neurology, also is significant for what it did not find: evidence of cognitive impairment in the majority of ex-players.

“Many former NFL players who took part in our study, even those with extensive concussion histories, are healthy and cognitively normal,” said Dr. John Hart Jr., Medical Science Director at the Center for BrainHealth and Professor of Neurology and Neurotherapeutics and Psychiatry at UT Southwestern. “In 60 percent of our participants – most of whom had sustained prior concussions – we found no cognitive problems, no mood problems, and no structural brain abnormalities. Many former NFL players think that because they played football or had concussions, they are certain to face severe neurological consequences, but that is not always the case.”

Dr. Hart, who is the study’s lead author and Director of the BrainHealth Institute for Athletes, said the investigation is the largest comprehensive study of former NFL players that involves the use of neuropsychological testing, neurological assessments, and neuroimaging.

Former Dallas Cowboys fullback Daryl Johnston, who participated in the study and helped recruit other players to take part, said: “Having played 11 years in the NFL and taken countless hits, I’ve heard about the struggles of the players who came before me and the challenges regarding their quality of life. Former players can find out if there is an issue, and if you catch it early or late, there are things you can do to improve your condition. The brain is regenerative for life, and we can restore faculties that just a few years ago were thought to be lost forever.”

Since 2010, 34 ex-NFL players with a mean age of nearly 62 underwent detailed neurological and neuropsychological assessments measuring aspects of intelligence, cognitive flexibility, processing speed, language skills, memory, and mood. Researchers also gathered detailed retrospective histories of mental status and concussion experiences, and examined motor and sensory functions, gait, and reflexes. Twenty-six of the ex-players also underwent detailed diffusion tensor MRI brain scans. All but two of the 34 players reported having experienced at least one concussion, with 13 as the highest reported number.

NFL Players Brain Study
The illustration above represents a composite brain scan of retired NFL players involved in the study. The blue areas show where disrupted white matter was found in the brain.

Also noteworthy was that, for the first time, researchers identified a correlation between cognitive impairment and cerebral white-matter abnormalities. Among the players who were found to have cognitive deficits or depression, researchers found damage in the brains’ white matter, connective tissue that allows information to travel from brain cell to brain cell. There also were associated brain blood flow changes in those who developed cognitive impairments, providing clues to the active brain changes resulting in deficits.

Some of the players do have cognitive impairment. Four were diagnosed with fixed cognitive deficits, eight with mild cognitive impairment, and two with dementia. When compared to healthy, age-matched control subjects, the former football players generally had more difficulty on neuropsychological tests that dealt with naming, word finding, and visual and verbal episodic memory.

About 24 percent of the players were diagnosed with depression, including six who never before had been diagnosed or treated. The rate of depression in an age-matched general population is about 10 percent to 15 percent, said neuropsychologist Dr. Munro Cullum, the study’s senior author and a Professor of Psychiatry and Neurology and Neurotherapeutics at UT Southwestern.

The findings could have implications beyond the football field, particularly in the areas of aging and Alzheimer’s disease, Dr. Cullum said.

“There still is so much we don’t know about concussions and later life function, nor do we know who is vulnerable to cognitive problems later in life,” Dr. Cullum said. “Severe and moderate head injuries have been identified as a potential risk factor for Alzheimer’s. We’re still learning about concussions.”

Other UTSW researchers on the study included Dr. Kyle Womack, who holds an appointment at UT Dallas and also is an Assistant Professor of Neurology and Neurotherapeutics and Psychiatry at UT Southwestern; and Dr. Hanzhang Lu, Associate Professor of Psychiatry and Radiology in the Advanced Imaging Research Center at UT Southwestern.

The study was supported by the BrainHealth Institute for Athletes at the Center for BrainHealth.



Dr. Cullum holds the Pam Blumenthal Distinguished Professorship in Clinical Psychology.

Dr. Lu is a TI Scholar in Advanced Imaging Technologies.