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. 2017 Feb 15;34(4):772-780.
doi: 10.1089/neu.2016.4536. Epub 2016 Aug 11.

Olfactory Function and Associated Clinical Correlates in Former National Football League Players

Michael L Alosco  1 , Johnny Jarnagin  2 , Yorghos Tripodis  3 , Michael Platt  4 , Brett Martin  2   5 , Christine E Chaisson  2   6 , Christine M Baugh  1   7 , Nathan G Fritts  2 , Robert C Cantu  8 , Robert A Stern  1   8   9
Affiliations

Olfactory Function and Associated Clinical Correlates in Former National Football League Players

Michael L Alosco et al. J Neurotrauma. .

Abstract

Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. Olfactory dysfunction is a frequent early sequelae of neurodegenerative diseases (e.g., Alzheimer's disease), and RHI is associated with the neurodegenerative disease, chronic traumatic encephalopathy (CTE). We examined olfaction, and its association with clinical measures, in former National Football League (NFL) players. Ninety-five former NFL players (ages 40-69) and 28 same-age controls completed a neuropsychological and neuropsychiatric evaluation as part of a National Institutes of Health-funded study. The Brief Smell Identification Test (B-SIT) assessed olfaction. Principal component analysis generated a four-factor structure of the clinical measures: behavioral/mood, psychomotor speed/executive function, and verbal and visual memory. Former NFL players had worse B-SIT scores relative to controls (p = 0.0096). A B-SIT cutoff of 11 had the greatest accuracy (c-statistic = 0.61) and specificity (79%) for discriminating former NFL players from controls. In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction.

Keywords: American football; National Football League; chronic traumatic encephalopathy; olfaction; repetitive head impacts.

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Conflict of interest statement

R.A.S. has received research funding from Avid Radiopharmaceuticals, Inc. (Philadelphia, PA). He is a member of the Mackey-White Committee of the NFL Players Association. He is a paid consultant to Amarantus BioScience Holdings, Inc. (San Francisco, CA), Avanir Pharmaceuticals, Inc. (Aliso Viejo, CA), and Biogen (Cambridge, MA). He receives royalties for published neuropsychological tests from Psychological Assessment Resources, Inc. (Lutz, FL), as well as compensation from expert legal opinion. R.C.C. is a paid consultant to the NFL Head Neck and Spine Committee, NOCSAE, Concussion Legacy Foundation, royalties from book publications, and compensation from expert legal opinion. C.B. has research funding from the National Collegiate Athletic Association and the National Football League Players’ Association. For the remaining authors, no competing financial interests exist.

Figures

<b>FIG. 1.</b>
FIG. 1.
Mean differences in B-SIT total score between the former NFL players and same-age controls. y-axis are B-SIT raw total scores and higher scores reflect better performance. x-axis included the former NFL players (N = 95) and same-age controls (N = 28). The difference between the former NFL players and age-matched controls is statistically significant (p = 0.0096). B-SIT, Brief Smell Identification Test; NFL, National Football League.
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