Tau‐PET in retired contact sport athletes

Abstract Background Long term effects of concussions and sub‐concussions in athletes can include delayed neurodegeneration as seen in Alzheimer’s disease (AD) and chronic traumatic encephalopathy (CTE). The PET tracer [18F]AV1451 has high affinity and selectivity for paired helical filament‐tau in vivo, the pathological form of tau in CTE and AD. The aim of this study was to assess the effect of tau‐PET binding on brain atrophy in former contact sports athletes and evaluate differences between subjects with and without tau‐PET binding. Method 31 retired athletes (age:53±15; sex: 29M, 2F; concussions/athlete: 7±6) negative for AD (CSF: p‐tau <68 pg/mL and ATI >0.8 and/or normal range of plasma p‐tau181) and 54 normal controls (age: 50±13) were included. All athletes completed MRI, [18F]AV1451 tau‐PET, the Sport Concussion Assessment tool 2 (SCAT2) and the Personality Assessment Inventory (PAI) depression and anxiety scales. Tau‐PET standardized uptake value ratios (SUVR) images were created using cerebellar gray matter (GM); tau‐PET positivity was set to ≥1.30 SUVR. Normal control MRI scans were used to create age/intracranial volume corrected GM volume maps. Result GM volumes were significantly lower in tau‐PET positive voxels in retired athletes ≥40 y.o. (N = 25; ‐0.48±0.40 vs. ‐0.42±0.41; p = .02) and there was a trend for lower GM volumes in tau‐PET positive voxels across athletes of all ages (N = 30; ‐0.40±0.42 vs. ‐0.35±0.41; p = .09), compared to tau‐PET negative voxels. Mean tau‐PET SUVR values in the cortical GM were used to divide retired athletes into tau‐PET positive (N = 20; SUVR ≥1.30) and negative (N = 11; SUVR <1.30) groups. The tau‐PET positive group did not differ in age (52±16 vs. 56±12; p = .4) or concussion number (9±7 vs. 7±5; p = 1.0) from the tau‐PET negative group; the tau‐PET positive group had significantly higher SCAT2 symptom severity (28.26±25.15 vs. 8.89±12.67; p = .01), PAI anxiety t‐scores (49.90±11.25 vs. 42.55±4.13; p = .01), and a trend for higher PAI depression t‐scores (54.75±16.58 vs. 47.09±8.08; p = .095), compared to the tau‐PET negative group. Conclusion Tau‐PET may be useful for identifying those at risk for delayed neurodegeneration. Older athletes showed relatively greater brain atrophy in tau‐PET positive regions, suggesting that detection of tau‐PET at a younger age may enable interventions to prevent future degeneration.