# Traumatic Brain Injury in Parkinson’s Disease: A Longitudinal Study

> **NIH VA I01** · VA SAN DIEGO HEALTHCARE SYSTEM · 2023 · —

## Abstract

Parkinson's disease (PD) and Traumatic Brain Injury (TBI) are highly prevalent conditions in the United
States and a major cause of disability, particularly among our nation’s Veterans. Emerging evidence suggests
that mild or moderate TBI is a critical risk factor for later developing PD. Yet, little is known about the impact
of mild or moderate TBI on symptoms in PD. Specifically, there is a vital need to better understand the
relationship between mild-moderate TBI and neuropsychological functioning, quality of life, and
neuropathology in PD. Preliminary work from our group has indicated that a history of remote mild-moderate
TBI is associated with greater cognitive deficits (d’ = .77) and decline (d’ = 1.54), elevated neuropsychiatric
symptoms (d’ = .55), decreased motor function (d’ = .71), poor quality of life (d’ = .62), as well as reduced
brain volumes (d’s = .61-1.1) in PD. However, due to the preliminary nature of these findings, further research
is needed to 1) confirm these results in a larger, descriptive sample; 2) examine symptoms with a
comprehensive, standardized battery, including those symptoms that may be impacted by PD and/or TBI; 3)
determine the longitudinal impact of mild-moderate TBI on long-term outcomes in PD; 4) assess the
neuropathological substrates that may underlie this comorbid condition; and 5) determine the relationship
between critical biomarkers and neuropsychological symptoms as well as long-term clinical outcomes. Such
knowledge will advance our understanding of mild-moderate TBI impact in PD and will ultimately aid in the
treatment and management of these vulnerable individuals.
 The overall aim of this longitudinal study is to determine the impact of chronic (> 1 year since injury)
mild or moderate TBI on cognition, neuropsychiatric symptoms, quality of life, and neuropathology (i.e., brain
morphometry) in PD. We hypothesize that cognition (particularly executive function), neuropsychiatric
symptoms (e.g., depression, anxiety), motor function and quality of life will be significantly worse in PD
patients with a history of mild or moderate TBI (PD+TBI) compared to PD patients without a history of TBI
(PD-TBI). We also hypothesize that the PD+TBI group will demonstrate a greater decline in motor and non-
motor symptoms, as well as decrements in quality of life, over time (i.e., two years). Moreover, we predict
that brain volumes, specifically pathognomonic brain regions implicated in PD and/or TBI (i.e., fronto-striatal
regions) will be significantly reduced in the PD+TBI group compared to PD-TBI. We will examine the
relationship among these symptoms, quality of life, and relevant biomarkers in exploratory analyses.
 Ninety non-demented individuals with PD and a history of mild or moderate TBI (PD+TBI; n = 45) or
without a history of TBI (PD-TBI; n = 45) will be enrolled in the proposed study. Over-recruitment by 15% will
be instituted to account for subject attrition or unusable data, and to ensure an adequat...

## Key facts

- **NIH application ID:** 10662458
- **Project number:** 5I01CX001925-04
- **Recipient organization:** VA SAN DIEGO HEALTHCARE SYSTEM
- **Principal Investigator:** Dawn M. Schiehser
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2023
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2020-07-01 → 2024-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10662458

## Citation

> US National Institutes of Health, RePORTER application 10662458, Traumatic Brain Injury in Parkinson’s Disease: A Longitudinal Study (5I01CX001925-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10662458. Licensed CC0.

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