Traumatic Brain Injury and Firearm Use and Risk of Progressive Supranuclear Palsy Among Veterans

Abstract

Background: Progressive supranuclear palsy (PSP) is a tauopathy that has a multifactorial etiology. Numerous studies that have investigated lead exposure and traumatic brain injury (TBI) as risk factors for other tauopathies, such as Alzheimer's disease, but not for PSP.Objective: We sought to investigate the role of firearm usage, as a possible indicator of lead exposure, and TBI as risk factors for PSP in a population of military veterans.Methods: We included participants from a larger case-control study who reported previous military service. Our sample included 67 PSP cases and 68 controls. Participants were administered a questionnaire to characterize firearm use in the military and occurrence of TBI.Results: Cases were significantly less educated than controls. In unadjusted analyses, the proportion of PSP cases (80.6%) and controls (64.7%) who reported use of firearms as part of their military job was positively associated with PSP, odds ratio (OR) 2.2 (95% CI: 1–5.0). There were no significant case-control differences in mean service duration. There was only a weak association with history of TBI, OR 1.6 (95% CI: 0.8–3.4). In multivariate models, firearm usage (OR 3.7, 95% CI: 1.5, 9.8) remained significantly associated with PSP.Conclusions: Our findings show a positive association between firearm usage and PSP and an inverse association between education and PSP. The former suggests a possible etiologic role of lead. Further studies are needed to confirm the potential etiologic effects of metals on PSP.The study was registered in clinicaltrials.gov. ClinicalTrials.gov Identifier: NCT00431301.

Frontrunner in Translation: Progressive Supranuclear Palsy

“…Though pesticide, organic solvents, and metal exposures, assessed by an industrial hygienist and toxicologist, as well as living in or close to a rural area were significantly associated with PSP in univariate analyses, these factors were, however, not statistically significant in the multivariate analysis (67), which could be in part related to the relatively small study size. Note the possible contributory role of metal exposure found in the PSP cluster in Northern France (66) and the association between firearm use in veterans and PSP found in the ENGENE-PSP case-control study (70).…”

Environmental Risk Factors for Progressive Supranuclear Palsy

“…Head trauma was not associated with the development of PSP. 52,54 Although one case-control study did not reach statistical significance, they found a higher occurrence of TBI in PSP cases (38.8%) than in controls (27.9%). 54 Small case-control studies, consisting of 50 to 79 cases, did not find an association between PSP and smoking habits.…”

“…52,54 Although one case-control study did not reach statistical significance, they found a higher occurrence of TBI in PSP cases (38.8%) than in controls (27.9%). 54 Small case-control studies, consisting of 50 to 79 cases, did not find an association between PSP and smoking habits. 48,52,89 In the ENGENE-PSP study, a higher number of smoking pack-years were associated with PSP cases (OR = 1.15; 95% CI = 1.05-1.27; p = 0.001) in the univariate analysis but did not reach statistical significance in the multivariate analysis (OR = 1.10; 95% CI = 0.99-1.22; p = 0.08).…”

“…There was an association between firearm exposure during military service and PSP (OR 2.2; 95% CI = 1.0-5.0; p = 0.04), suggesting a possible association of lead with PSP. 54 Notably, metal exposure might be associated with the occurrence of PSP in a report of 92 PSP patients in a cluster occurring in Wattrelos and Leers, France (Figure 1). These regions were contaminated by textile-dyeing and leather tanning plants in which arsenic, a potential neurotoxin, was found in the soil.…”

“…ment was a risk factor for PSP (Table 2). 35,48,51,54 The report that high educational background was a risk factor for PSP was based on the results of a case-control study with a small sample size. 52 Furthermore, the opposite finding was shown by the same researchers.…”