Summary: A study of 55,204 older veterans reveals a dangerous two-way association between traumatic brain injury (TBI) and several neurological disorders. Researchers found that older adults who sustained a TBI were three to four times more likely to have received a new diagnosis of epilepsy, stroke, dementia, or Parkinson’s disease in the prior year—conditions that commonly impair balance, coordination and mobility and therefore increase fall risk.
Conversely, experiencing a TBI was associated with a higher likelihood of subsequent neurological events: the study observed that a TBI doubled the later risk of stroke and epilepsy and increased new dementia diagnoses by about 24%. These findings highlight a critical clinical window for immediate fall-prevention assessment and intervention after any new neurological diagnosis.
Key Facts
- Bi-directional risk relationship: While previous work has shown that TBIs can accelerate neurodegenerative processes, this study demonstrates the reverse is also substantial: a new diagnosis of a neurological disease is itself a major risk factor for sustaining a subsequent TBI.
- Large older-veteran cohort: The analysis compared 13,801 veterans (average age 78) with a recent TBI to 41,403 age-matched veterans without TBI, using precise one-year windows before and after the injury or equivalent index date.
- Three- to four-fold elevations in prior-year diagnoses: After adjusting for baseline health factors—such as diabetes, smoking and cardiovascular history—those with TBI were roughly four times more likely to have had a recent epilepsy diagnosis and about three times more likely to have had recent diagnoses of stroke, dementia or Parkinson’s disease.
- Increased post-TBI disease risk: Following a TBI, veterans were approximately twice as likely to experience stroke or epilepsy compared with their pre-injury risk and showed a 24% higher rate of new dementia diagnoses within the year after injury.
- Immediate clinical implications: Because falls account for the majority of TBIs in older adults, the authors recommend prompt fall-risk screening and rapid referral to fall-prevention services—such as physical and occupational therapy—when older patients receive a new neurological diagnosis.
Source: AAN
For traumatic brain injury (TBI) and certain brain diseases, risks appear to operate in both directions, according to a study published on June 17, 2026, in Neurology.
Prior research has linked TBI to an elevated risk of stroke, dementia, epilepsy and Parkinson’s disease. This new study examined whether older veterans who recently sustained a TBI were more likely to have received any of those neurological diagnoses in the year before their injury compared with similarly aged veterans without a recent TBI.
The investigators found that older veterans with a recent TBI were three to four times more likely to have been diagnosed with one of the four conditions in the prior year than age-matched veterans without TBI. The study documents a strong association, although it does not prove causation between the neurological conditions and subsequent brain injury.
“These findings suggest the period immediately after a neurological diagnosis is a crucial time to prevent TBI,” said study author Carrie Peltz, PhD, of the San Francisco Veterans Affairs Health Care System. Neurological diseases commonly impair motor control, balance, gait, coordination and cognitive skills—factors that increase the likelihood of falls, which are the leading cause of TBI in older adults.
For the analysis, researchers reviewed medical records for 13,801 veterans with a recent TBI (mean age 78) and compared them with 41,403 age-matched veterans who did not have a TBI. They examined diagnoses in the one-year interval before and after the index event (or equivalent index date for controls) and excluded any individuals who had one of the four target conditions prior to that year-long window.
Across all four conditions, rates in the year before TBI were substantially higher among those who later experienced a TBI. For stroke the rate was 64 cases per 1,000 person-years in the TBI group versus 20 in controls; for dementia it was 58 versus 19; for epilepsy 14 versus 4; and for Parkinson’s disease 10 versus 3. After statistical adjustment for confounding variables, recent epilepsy was about four times more likely among the TBI group, while recent stroke, dementia and Parkinson’s were each about three times more likely.
The investigators also compared disease incidence after a TBI to the pre-injury baseline and found that post-TBI participants were roughly twice as likely to develop stroke or epilepsy and had a 24% higher likelihood of new-onset dementia. Parkinson’s disease did not show a measurable increase within the one-year follow-up—an outcome the authors suggest may reflect the longer time course typically required for Parkinson’s pathology to become clinically evident.
Peltz emphasized practical steps clinicians can take: screen older adults for fall risk at the time of a new neurological diagnosis and rapidly refer them to preventive services. Evidence-based measures include strength and balance training, home safety modifications (for example, installing grab bars and removing tripping hazards), and careful medication review to limit drugs that cause dizziness—interventions shown to reduce falls among older adults.
The study has limitations. Requiring medical records one year after TBI excluded people who died within that year from severe injury, and mild TBIs for which patients did not seek care were also not captured. Additionally, because the cohort comprised veterans, findings may not generalize to all older populations.
Funding: The study was supported by the U.S. Department of Defense.
Key Questions Answered:
A: These conditions impair the specific neurological systems required for safe movement and spatial awareness. Declines in motor control, balance, visual-spatial reasoning, coordination and rapid gait adjustments increase the chance of falls. Because mechanical falls are the leading cause of TBI in older adults, any disease that compromises balance and mobility becomes a direct risk factor for brain injury.
A: The study found that a TBI is associated with higher subsequent rates of several neurological conditions. After a TBI, individuals were about twice as likely to experience stroke or epilepsy compared with their pre-injury risk, and their risk of new-onset dementia rose by roughly 24%. The absence of a detectable short-term increase in Parkinson’s disease is likely related to the study’s one-year follow-up window, while Parkinson’s typically develops over longer periods.
A: Clinicians should treat the period following a neurological diagnosis as a high-risk time for falls and TBI. Immediate steps include fall-risk screening, prompt referral to physical and occupational therapy for strength and balance programs, arranging home safety assessments (such as adding grab bars and removing loose rugs), and conducting medication reviews to reduce drugs that increase dizziness or sedation.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by staff.
About this neurology research news
Author: Aleksa Atkinson
Source: AAN
Contact: Aleksa Atkinson – AAN
Image credit: Neuroscience News
Original Research: The research will be published in Neurology.