Traumatic brain injury in later life increases risk for Parkinson disease

Abstract

Objective Traumatic brain injury (TBI) is thought to be a risk factor for Parkinson’s disease (PD) but results are conflicting. Many studies do not account for confounding or reverse-causation. We sought to address these concerns by quantifying risk of PD after TBI compared to non-TBI trauma (NTT, defined as fractures). Methods Using inpatient/emergency department (ED) ICD-9 code data for California hospitals from 2005–2006, we identified patients age ≥55 with TBI (n=52,393) or NTT (n=113,406) and without baseline PD or dementia who survived hospitalization. Using Kaplan-Meier estimates and Cox proportional hazards models (adjusted for age, sex, race/ethnicity, income, comorbidities, healthcare use, trauma severity), we estimated risk of PD after TBI during follow-up ending in 2011. We also assessed interaction with mechanism of injury (fall vs. non-fall) and effect of TBI-severity (mild vs. moderate/severe) and TBI-frequency (1 TBI vs. >1 TBI). Results TBI patients were significantly more likely to be diagnosed with PD compared to NTT patients (1.7% versus 1.1%, p<0.001, adjusted hazard ratio (HR) 1.44, 95% CI 1.31–1.58). Risk of PD was similar for TBI sustained via falls versus non-falls (interaction p=0.6). Assessment by TBI-severity (mild TBI HR 1.24, 95% CI 1.04–1.48; moderate/severe TBI HR 1.50, 95% CI 1.35–1.66) and TBI-frequency (1 TBI HR 1.45, 95% CI 1.30–1.60; >1 TBI HR 1.87, 95% CI 1.58–2.21) revealed a dose-response. Interpretation Among patients age ≥55 presenting to inpatient/ED settings with trauma, TBI is associated with a 44% increased risk of developing PD over 5–7 years that is unlikely due to confounding or reverse-causation.

Traumatic brain injury in the prodromal period of Parkinson's disease: A large epidemiological study using medicare data

“…We identified TBI using the Centers for Disease Control and Prevention (CDC) criteria using the following ICD-9 diagnosis codes, as in other studies: 800.0–801.9; 803.0–804.9; 850.0–854.1; and 959.01 10,18 . Severity of TBI was categorized based on the CDC: mild (includes concussion) versus moderate/severe 19–21 .…”

Tau Oligomers Derived from Traumatic Brain Injury Cause Cognitive Impairment and Accelerate Onset of Pathology in Htau Mice

“…In many patients, even mild TBI is a chronic disease that contributes to neurological, neuropsychological, and behavioral deficits for years post-injury. 7 Additionally, TBI is a significant risk factor for subsequent development of dementia, [8][9][10] even in patients with no post-traumatic cognitive impairments. 11 TBI causes neuronal injury through processes that begin on impact and continue for days to months or years post-injury.…”

How close are we to revealing the etiology of Parkinson's disease?

“…Other etiologies underlying parkinsonisms, like tauopathies or other neurodegenerative disorders, are not considered here. Among exogenous lesions, traumatic brain injury in later life has been shown to increase the risk for PD [5] and the role of infections in the etiology of PD has been discussed recently [6].…”