Mild TBI and risk of Parkinson Disease:
A chronic effects of neurotrauma consortium study
Gardner RC,
Byers AL, Barnes DE, Li Y, Boscardin J, Yaffe K. Neurology. 2018. [Epub Ahead of Print].
Take Home Message: A military veteran with a prior traumatic brain injury
(TBI; 0.6%) is >56% more likely to develop Parkinson’s disease than a
veteran without a prior TBI (0.3%).
Recently, there has
been attention on the association of traumatic brain injury (TBI) with
progressive neurodegenerative diseases; such as, Parkinson’s disease. However,
the association between mild TBI and Parkinson’s remains unclear. Therefore,
the authors used 3 nationwide Veterans Health Administration databases
(Comprehensive TBI Evaluation, National Patient Care Databases, Vital Status
File Database) of inpatients and outpatients seen between 2002-2014 to
determine the risk of developing Parkinson’s disease following a TBI. Authors
age-matched 162,935 patients (~48 years of age) with TBI diagnosis without
dementia, Parkinson’s disease, or secondary parkinsonism at baseline to a
random sample of patients without any of the aforementioned conditions. The
authors defined TBI exposure as a diagnosis of TBI after a comprehensive
neurological assessment or by at least one inpatient or outpatient TBI
diagnosis from a list of ICD-9 codes. Parkinson’s disease was defined as any
inpatient or outpatient diagnosis of ICD-9 332.0 at least 1 year after TBI. The
average follow-up was ~5 years. The authors found that a veteran with a prior
TBI (0.6%) is >56% more likely to develop Parkinson’s disease than a veteran
without a prior TBI (0.3%). This finding was consistent even after accounting
for factors such as medical comorbidities (diabetes, hypertension,
cerebrovascular disease) and psychiatric disorders (anxiety, post-traumatic
stress, drug/alcohol use). Furthermore, this finding was consistent among
people with mild or moderate-severe TBI.
The authors identified
a relationship between TBI and the development of Parkinson’s disease over the
next 12 years. This finding has substantial public health implications for our
active military and veteran populations. Additionally, the authors accounted
for numerous demographic variables; hence, this association of TBI and
Parkinson’s disease may also be an implication for increased risk of
Parkinson’s disease in the civilian and athletic populations following a TBI.
Still, we must keep in mind that association does not imply causation. Furthermore,
less than 1% of veterans developed Parkinson’s disease. Hence, TBI increases
the risk of Parkinson’s disease but the absolute risk is small; however, if one
develops Parkinson’s it can have a profound impact. It is important for
clinicians to talk to patients about the elevated risk of Parkinson’s disease
among people with a TBI, but also discuss the overall incidence rate of the
disease and its potential implications. Medical professionals must also stay
vigilant with being knowledgeable about risk factors for TBI and poor long-term
outcomes and how to modify risk factors for TBIs.
Questions for Discussion: Do you
work with a military population? If so, how are military personnel and veterans
educated about his/her TBI?
Written by: Jane McDevitt
Reviewed by: Jeffrey