Traumatic Brain Injury in Older Adults: Epidemiology, Management, Outcomes

Older adults have the highest incidence of traumatic brain injury (TBI) of any age group in the United States and many countries worldwide, mostly caused by ground-level falls (Figure 1).^1,2 TBI is the most common fall-related injury among adults age 65 and older. Hospitalization rates for TBI are highest among older adults and increase exponentially with age, such that annual rates among adults age 75 years or older (321.4/100,000) are 3 times higher compared with rates among people who are 65 to 74 years of age (105.5/100,000).³

Risk factors for TBI among older adults include comorbid conditions (eg, cerebrovascular disease, depression),⁴ sedative hypnotic and opioid use,^5,6 and self-reported disability in activities of daily living.⁴ Factors known to increase fall risk, such as gait instability and cognitive impairment, likely increase risk for TBI, given that falls cause the majority of TBI in this population.² Furthermore, experiencing a single TBI increases risk for repetitive TBI almost fourfold among older adults.⁷ Older age, epilepsy, Parkinson disease, depression, atrial fibrillation, and Alzheimer disease and related dementias also increase risk for repetitive TBI.⁷

Relative to older adults without TBI, those who present to hospitals with TBI are more likely to be female and white, with a higher burden of comorbidities, including Alzheimer disease and related dementias, depression, diabetes, or heart disease.⁸ Higher comorbid burden results in decreased physiologic reserve, leaving older adults with TBI even more vulnerable to its effects. For example, an analysis of the combined TBI Practice-Based Evidence–TBI Model Systems National Database in a mixed-age sample showed that preexisting cardiac disease, diabetes, and hypertension were associated with poorer motor recovery over a 5-year follow-up.⁹ In addition, a recent analysis from the TRACK-TBI (Transforming Research and Clinical Knowledge in Traumatic Brain Injury [NCT02119182]) study found that hyperglycemia at presentation was associated with increased risk of poor cognitive outcome 1 year after mild TBI.¹⁰ These findings highlight the fact that unlike TBI in younger adults, TBI in older adults is usually part of a constellation of interrelated multimorbidities.

Clinical Management

Older adult TBI is different from TBI in younger people and therefore deserves an age-appropriate approach to management. Preexisting conditions, frailty, and disability are common and may confound the initial evaluation and diagnosis of TBI. Older adults with preexisting conditions continue to be excluded systematically from most large prospective TBI research cohorts and trials. As a result, there remains a dearth of evidence to guide complex medical decision-making in the older adult TBI multimorbidity population. The field lacks consensus on basic questions such as when to operate on an older adult with an intracranial hemorrhage who is taking antiplatelet agents, optimal intracranial pressure goals, and the length of time a person should be observed for neurologic improvement before the team recommends transitioning to comfort measures only.

In an effort to streamline clinical management, the American College of Surgery Trauma Quality Improvement Program (ACS TQIP) released Geriatric Trauma Guidelines in 2013 that cover many general principles borrowed from geriatric medicine.¹¹ These guidelines emphasize the importance of considering preexisting comorbidities, functional status, and frailty in older adults to guide prognostication. The guidelines also provide instructions for reversal of anticoagulation, a common complicating factor in this age group, as well as identification and mitigation of inappropriate drug prescribing according to the Beers criteria. ACS TQIP is preparing new TBI management guidelines that will include geriatric TBI–specific guidelines for the first time.

An important management area is prevention of repeat falls and repeat TBI in older adults presenting with TBI. Previous TBI is a known risk factor for repeat TBI, particularly among older adults, who may have preexisting risk factors for falls and in whom the TBI itself may produce new postconcussive symptoms that will exacerbate fall risk.⁷ The Centers for Disease Control and Prevention initiative “Stopping Elderly Accidents, Deaths, and Injuries” provides resources for providers, older adults, and caregivers about preventing falls with a focus on preventing injurious falls.

Outcomes

Older adults have the highest TBI-related death rates, primarily attributable to falls and suicides.¹² In 2019, there were 24,856 TBI-related deaths among adults age 65 and older in the US, representing nearly 40% of TBI-related deaths.¹² Older adults receive less intense management for TBI, which may result in increased in-hospital mortality. For example, a single-site study reported that older adults had less severe TBI and received less intense management compared with younger adults with TBI, yet they experienced higher in-hospital mortality.¹³ This is consistent with other reports that older adults receive less intense treatment after TBI, including a recent study of older adults treated for severe TBI that showed that despite meeting Brain Trauma Foundation criteria, only 18% underwent intracranial pressure monitoring.^14,15 Treatment decisions are based on multiple considerations, including injury severity, comorbid burden, and the desires of the patient and family. Nonetheless, there is evidence that provider assumptions about poor outcome in older people TBI can affect treatment intensity.² Although studies often focus on poor outcomes, it is important to remember that the majority of older adults survive even moderate to severe TBI.¹⁵ Thus, it is important to identify subgroups of older people most likely to achieve full recovery as well as to develop and test interventions to optimize recovery among this population.

In addition to increased risk of mortality, older adults experience slower cognitive and functional recovery after TBI compared with younger adults with similar injury severity.² Relative to older adults without TBI, those with TBI are at increased risk of neurologic^16,17 and psychologic disorders,¹⁸ which can complicate recovery. Furthermore, cognitive and physical deficits after TBI may interact synergistically to lead to loss of independence. For example, a recent study of Medicare administrative data showed that relative to similar older adults without TBI, those with TBI experienced shorter time to long-stay nursing home admission.¹⁹

Recent Advances in Diagnostic Biomarkers

Head CT remains the diagnostic test of choice to rule out intracranial trauma in older adults, but there have been several recent advances in blood-based diagnostic biomarkers for TBI that warrant discussion. In February 2018, the Food and Drug Administration authorized measurement of plasma glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal hydrolase isozyme L1 to aid clinicians in determining whether a head CT is warranted in adults presenting with suspected TBI.²⁰ In Europe, plasma S100b level has been incorporated into some TBI guidelines as a means to avoid obtaining a head CT in certain lower-risk older people.²¹

Only a handful of studies have investigated the accuracy of these emerging blood tests for diagnosing TBI in older adults. Both age and neurodegenerative disease are known to lead to baseline elevations in brain injury biomarkers. Evidence suggests that although some of these biomarkers may be highly sensitive in older adults, they will not reduce head CTs, given poor specificity (Table 1).^22-24 On the other hand, given that older adults with complicated mild TBI frequently are mistriaged (potentially because of complicating comorbid conditions or initially normal Glasgow Coma Scale score),²⁵ these biomarkers ultimately may prove useful as a means to rule in TBI more rapidly and optimize efficiency of triage and acute surgical management in older adults. More research in this fast-moving focus area, including the role of blood biomarkers for predicting outcome in geriatric TBI, is indicated.

Conclusion

Older adults are at increased risk of TBI, primarily because of increased fall risk; are often triaged inappropriately; and tend to have longer time from injury to care.¹⁵ Despite a perception that older adults have poor outcomes after TBI, the majority recover well. However, there has been little research focused on best practices for management and rehabilitation of TBI among older adults.