Concussions and Subsequent Brain Disease: Sometimes Yes, Sometimes No

The two studies below, both published in Neurology in March 2015, show that the earlier the boy starts tackle football play, the more likely the same football player as a grown man is to get late-life cognitive problems (including dementia).

On the other hand, even though Parkinsonism with dementia has been well described in boxers as dementia pugilistica, a study of prior head trauma and Parkinson disease did not show an association of head injury and risk of standard Parkinson's disease.


Age of first exposure to football and later-life cognitive impairment in former NFL players

Julie M. Stamm, BS, Alexandra P. Bourlas, MA, Christine M. Baugh, MPH, Nathan G. Fritts, BA, Daniel H. Daneshvar, MA, Brett M. Martin, MS, Michael D. McClean, ScD, Yorghos Tripodis, PhD and Robert A. Stern, PhD

doi: 10.1212/WNL.0000000000001358

Neurology March 17, 2015 vol. 84 no. 11 1114-1120


Objective: To determine the relationship between exposure to repeated head impacts through tackle football prior to age 12, during a key period of brain development, and later-life executive function, memory, and estimated verbal IQ.

Methods: Forty-two former National Football League (NFL) players ages 40–69 from the Diagnosing and Evaluating Traumatic Encephalopathy using Clinical Tests (DETECT) study were matched by age and divided into 2 groups based on their age of first exposure (AFE) to tackle football: AFE <12 and AFE ≥12. Participants completed the Wisconsin Card Sort Test (WCST), Neuropsychological Assessment Battery List Learning test (NAB-LL), and Wide Range Achievement Test, 4th edition (WRAT-4) Reading subtest as part of a larger neuropsychological testing battery.

Results: Former NFL players in the AFE <12 group performed significantly worse than the AFE ≥12 group on all measures of the WCST, NAB-LL, and WRAT-4 Reading tests after controlling for total number of years of football played and age at the time of evaluation, indicating executive dysfunction, memory impairment, and lower estimated verbal IQ.

Conclusions: There is an association between participation in tackle football prior to age 12 and greater later-life cognitive impairment measured using objective neuropsychological tests. These findings suggest that incurring repeated head impacts during a critical neurodevelopmental period may increase the risk of later-life cognitive impairment. If replicated with larger samples and longitudinal designs, these findings may have implications for safety recommendations for youth sports.


Head injury and risk for Parkinson disease

Results from a Danish case-control study

Line Kenborg, MSc, PhD, Kathrine Rugbjerg, MSc, PhD, Pei-Chen Lee, PhD, Line Ravnskjær, BSc, Jane Christensen, MSc, Beate Ritz, MD, PhD and Christina F. Lassen, MD, PhD

doi: 10.1212/WNL.0000000000001362

Neurology March 17, 2015 vol. 84 no. 11 1098-1103


Objective: To examine the association between head injuries throughout life and the risk for Parkinson disease (PD) in an interview-based case-control study.

Methods: We identified 1,705 patients diagnosed with PD at 10 neurologic centers in Denmark in 1996–2009 and verified their diagnoses in medical records. Patients were matched to 1,785 controls randomly selected from the Danish Central Population Register on sex and year of birth. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression.

Results: We observed no association between any head injury before first cardinal symptom and PD (OR 1.02; 95% CI 0.88, 1.19). Examination of number of head injuries (1: OR 1.02; 95% CI 0.87, 1.20; ≥2: OR 1.03; 95% CI 0.72, 1.47) or hospitalization for a head injury (OR 0.89; 95% CI 0.70, 1.12) did not show an association with PD. For 954 study subjects with at least one head injury, there was no evidence of an association between loss of consciousness (OR 0.89; 95% CI 0.67, 1.17), duration of loss of consciousness (≤1 minute: OR 0.93; 95% CI 0.58, 1.49; 1–5 minutes: OR 0.74; 95% CI 0.51, 1.08; ≥5 minutes: OR 0.81; 95% CI 0.53, 1.24), or amnesia (OR 1.31; 95% CI 0.88, 1.95) and risk for PD. Application of a lag time of 10 years between head injury and first cardinal symptom resulted in similar risk estimates.

Conclusions: The results do not support the hypothesis that head injury increases the risk for PD.

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