In the last century, population demographics in almost every developed country have changed substantially. Older adults (aged >=65 years) are now the fastest growing segment of the population in Canada.1 This trend is the result of low fertility rates, an increase in life expectancy, and aging baby boomers. In 2011, there were 5.0 million Canadians (14.4% of the population) older than 65 years, up from 2.4 million in 1981 (9.6%).2 Canada is not the only country witnessing a rise in the elderly population. In 2005, the older adult population reached 16% in the United Kingdom and 19.7% in Japan.3
The leading edge of the baby boomers have now reached 65 years of age. The prevalence of injuries and chronic health conditions in this aging cohort has significant implications for the health care system. One area of concern is the incidence and prevalence of traumatic brain injuries (TBIs) in older adults. According to data from the Canadian Institute for Health Information,4 children (aged 0-19 years) account for 30% of all head injury hospitalizations in Canada, followed closely by older adults (aged >=60 years) at 29%. On average, the majority of TBIs are sustained by males.5 According to the Centers for Disease Control and Prevention,6 the most common cause of TBI in older adults is due to falls (62%), followed by motor vehicle collisions (17%). Older adults are at an increased risk of falls for a number of reasons, including poor muscle tone, impaired vision, impaired balance and gait, and polypharmacy side effects.7
Traumatic brain injury is now the leading cause of injury death in older adults.8 Clinical research has demonstrated that TBI seriously hinders all health domains regardless of the initial injury severity. This article highlights the results from a scoping review of literature related to TBI sustained among older adults.
MATERIAL AND METHODS
Literature search strategy
A computer-assisted search of multiple databases (ie, PubMed/MEDLINE, CINAHL, ProQuest, and PsycINFO) was conducted for literature published between 1980 and September 2012. Specific subject headings related to older adults and TBI were used as the search terms for each database. Multiple key words were used and included "brain damage," "chronic"; "traumatic brain injury"; "acquired brain injury"; "concussion"; "head trauma"; "head injury"; "non-traumatic brain injury"; "aging"; "aged", or "aged 80 and over"; "old"; "senior"; "geriatric"; and "frail elderly, or elderly." Unpublished studies were not included, and the search was limited to articles written in English.
Study inclusion
Studies were included if they provided relevant information within the scope of our objective. Both quantitative and qualitative studies were included. In addition, both prospective and retrospective studies were included. Studies were included if at least 50% of the population included individuals with a TBI. Aging research indicates that there is no defining point when one is suddenly deemed to be old, thus defining who is an older adult becomes a challenge. According to the Canadian government, an "older adult"-used synonymously with the terms "senior" and "elder"-are individuals who are 65 years or older. However, for the purposes of maximizing the number of included studies that describe older adults, a single article was included that examined individuals 55 years or older; this article has been identified.
Data extraction
When an article was selected for full review, the following data were extracted: inclusion and exclusion criteria, sample size, details regarding the population studied (ie, type of injury, severity, source, sex, age, time since injury), outcome measures, and results. Data on the following 4 areas were pooled and summarized: post-TBI mortality, functional outcome, cognitive outcome, and psychosocial outcome. Articles evaluating similar subjects were summarized using tables and descriptive reviews.
RESULTS
Mortality
Many studies reported information on the rate of mortality among their sample of older adults post-TBI. In a recent meta-analysis on 24 studies, McIntyre et al9 reported that among individuals aged 60 years or older, who had sustained a TBI of any severity, the overall mortality rate was 38.3% (95% confidence interval [CI], 27.1-50.9). When comparing individuals in the old-old (>75 years) age bracket to the young-old (65-74 years) age bracket, the odds of mortality was 1.734 (95% CI, 1.311-2.292; P < .0001). When comparing individuals 65 years or older with those younger than 65 years, rates of mortality vary considerably, with older adults having higher rates among all 3 injury severity classifications up to 1 year postinjury (Table 1). Despite varying mortality rates among those young and old, the highest rates of mortality occur during the first 48 hours, regardless of age or injury severity.10 The influence of gender on mortality rates is currently understudied; consensus has not been reached as to whether mortality rates truly differ between older men and women post-TBI.11,12
Historically, research has consistently shown that the Glasgow Coma Scale (GCS), an indicator of injury severity, is an independent predictor of mortality post-TBI. In the same meta-analysis, McIntyre et al9 found that overall mortality rates among older adults for mild (GCS score = 13-15), moderate (GCS score = 9-12), and severe (GCS score = 3-8) head injuries were 12.3% (95% CI, 6.1-23.3), 34.3% (95% CI, 19.5-53.0), and 65.3% (95% CI, 53.1-75.9), respectively. In comparing injury severities, the authors report odds ratios of mortality for severe to mild and moderate to mild injuries at 12.69 (95% CI, 5.29-30.45; P < .0001) and 5.31 (95% CI, 3.41-8.29; P < .0001), respectively. Interestingly, the authors found no significant difference in the odds of death among older adults sustaining severe and moderate injuries (P = .116). Clearly, mortality increases significantly with increasing injury severity.
Research also suggests that chronic disease has a significant effect on one's ability to recover from a TBI. In Canada, a significant proportion of older adults have at least 1 chronic disease (71% of adults 60-79 years of age, 82% of adults >80 years of age). Furthermore, of those older than 80 years, 59% report having at least 2 comorbid chronic diseases.13 Preexisting hypertension, diabetes mellitus, and heart disease in older patients contribute to increased trauma mortality rates.12,14 The greatest mortalities post-TBI have occurred in conjunction with cancer, renal disease, liver disease, and heart and lung disease. Individuals with 3 or more preexisting diseases have been reported to have mortality rates that are 4 times higher than those with none.15
Functional outcome
In addition to examining mortality rates, researchers have reported on functional outcomes of older adults after a TBI. The Glasgow Outcome Scale is a common tool used to report functional outcomes post-TBI. Most studies conducted to date have examined functional outcomes up to 1 year postinjury. In a recent meta-analysis, McIntyre et al16 reviewed 11 studies published between 1986 and 2008. After pooling the Glasgow Outcome Scale scores for each injury severity, the authors reported rates for favorable (good recovery or moderate disability), unfavorable (severe disability or vegetative state), and fatal outcomes up to 1 year postinjury among older adults with TBI (Table 2). Compared with those 60 years or older, those younger than 60 years experienced significantly better rates of favorable outcome and lower rates of unfavorable or fatal outcomes with similar injury severity. This study further demonstrated that increasing age and decreasing GCS scores are independent predictors of poor functional outcome.
Other scales, including the Disability Rating Scale (DRS) and Functional Independence Measure (FIM), have been used to determine an individual's level of disability and burden of care, respectively, post-TBI. Three studies have examined changes in DRS scores among older adults and younger individuals on admission to and discharge from inpatient rehabilitation. Frankel et al8 reported that despite the same injury severity on admission, older adults (aged >55 years) only recovered at a rate of 0.25 DRS points per day compared with 0.33 DRS points per day for the younger age group (<55 years). Thus, while recovery among the older group occurred, the process was slower. These findings are similar to an earlier study by Cifu et al.17 Marquez de la Plata et al18 examined functional improvement over a longer period of time. The authors reported that while both their younger and older groups experienced functional improvement and a decline in DRS scores, after 5 years the older patients plateaued at 2.9 while the younger group achieved a score of 1.6, despite having worse injury severity scores on admission to rehabilitation. These results are congruent with the findings of both Mosenthal et al19 and Livingston et al20; FIM scores have also been studied. The FIM is a scale that measures one's level of disability (physical and cognitive) to determine his or her "burden of care." The scale has 18 questions, with a total score ranging 18 (minimum) to 128 (maximum). Table 3 summarizes studies publishing admission and follow-up (or modified FIM) scores among older and younger adults post-TBI. Among 4 key studies,8,17,19,20 it has been shown that older adults typically have worse FIM scores despite similar or less severe initial injury severities than younger individuals.
Several differences among age brackets have been noted regarding rates of nonneurological conditions experienced during acute care. Cifu et al17 compared nonneurological complications between younger and older TBI patients and found differences between older and younger patients in rates of respiratory failure (39% vs 26%), pneumonia (26% vs 15%), and urinary tract infections (48% vs 20%). Higher complication rates lead to significantly poorer functional outcomes.5 Following discharge from acute care rehabilitation, individuals may be faced with long-term health consequences as a result of their brain injury. Von Wild21 reported that among 626 older adults, 47% indicated that they experienced at least 1 significant health problem up to 1 year post-TBI. Health complaints included headaches (63%), dizziness (63%), impaired concentration (50%), immobility (23%), and vision, hearing, or olfactory impairments (5%-12%).21
Cognitive outcomes
Changes in cerebral architecture, vasculature, and neurochemistry help explain age-related changes in the brain. A reduction in both gray and white matter contributes to brain atrophy, subsequently exposing bridging veins. These veins are particularly vulnerable to trauma with resultant subdural hematomas. As neuronal fallout occurs with aging, the brain compensates by increasing the number of synaptic connections per neuron. Thus, a TBI may have a more significant effect on cognitive functioning in older adults who are less able to now compensate.
The literature on cognitive outcomes following TBI in older adults is limited. Much of the literature conducted to date has assessed attention, information processing, verbal learning, initiation speed, working memory, mental flexibility, verbal fluency, and/or response inhibition performance. Studies directly assessing older adults following a TBI have found cognitive impairments in delayed recall,22 abstract reasoning,23,24 and word fluency.23-27 Ashman et al28 also found differences in verbal memory and attention between older individuals with and without TBI. There is very little known about how cognitive outcomes differ by gender in the older TBI population.
Few studies27,29 have shown that older adults following a TBI perform comparatively worse on cognitive assessments than younger individuals and those without TBI. However, the amount of short-term cognitive decline as a factor of age or injury severity has not been elucidated at this time. There is more research that supports the notion that cognitive deficits exist over the long term, regardless of the age when the TBI was sustained. Many authors affirm that cognitive decline is not simply the result of normal aging but rather a product of accelerated cognitive decline from the original insult26,30-32
Neurological conditions are common in late adulthood. Approximately 85% of all individuals with dementia are older than 65 years. Therefore, it can be difficult to tease apart cognitive deficits as aging-related, TBI-related, or both. Dementia and TBI-related cognitive decline are often comorbid conditions in the oldest patients. Memory loss and poor executive functioning may actually mask deeper neurological issues associated with the TBI. Another complicating factor is that TBI is a risk factor for the development of Alzheimer disease and other dementias.33 Researchers have found that upon death, the brains of individuals who had sustained a TBI were remarkably similar to those suffering from dementia. The brains of individuals who had sustained a TBI contained tangled neurofibrillary fibers that were molecularly identical to brains of those with dementia.34 Thus, changes in the brain following a TBI may lower the threshold for the manifestation of Alzheimer disease.35
How post-TBI changes in the brain contribute to neurodegeneration and dementia is not well understood. There has been considerable focus in the last decade on the influence of a genetic polymorphism, apolioprotein E (apoE, protein; APOE gene). Multiple researchers have reported that TBI and possession of the APOE4 allele work in an additive manner in the development of Alzheimer disease. Thus, the APOE4 allele has become an important predictor for poor clinical outcome post-TBI.35,36 Further work is needed in this area to determine the relationship between genetic variance and cognitive function post-TBI.
Psychobehavioral outcomes
In the acute period of recovery following a TBI, there is considerable emphasis on physical improvement. However, over the long term, resolving psychological/behavioral issues often becomes the primary focus. Depression, anxiety, and other abnormal psychobehavioral presentations are common.37,38 Caregivers of older adults (aged >=50 years) have reported mood changes (eg, feelings of hopelessness and worthlessness) up to 13 months post-TBI.39 In another study, Deb and Burns40 reported that older adults reported irritability (37%) and sleep problems (37%) most often compared with young adults who reported poor memory (40%) and dependence (38%) as their greatest concerns.
Compared with age- and gender-matched controls without TBI, older adults with TBI have reported depression as a common psychological issue post-TBI, with rates between 11% and 35%.24,41 Examining anxiety, depression, and somatic concerns using the General Health Questionnaire,24 the Geriatric Depression Scale, and the Neurobehavioral Rating Scale,41 researchers report significantly worse scores for older adults (aged >=50 years) with TBI than those without TBI (P < .0001, P < .05, and P < .01, respectively).
Researchers have sought to determine whether there is an aging effect in developing psychological disorders post-TBI. Rapoport and Feinstein42 found that older adults (aged >=60 years) had less anxiety, depression, and somatic distress as determined by the General Health Questionnaire than younger adults (aged 16-59 years; P = .002). This finding was replicated in a later report using formal diagnoses of major depression (P < .01).43 Again, Deb and Burns40 reported that younger individuals (aged 18-65 years) reported higher rates of depression (16%) than older adults (aged >65 years) with TBI (11%), although this trend was not significant. Regardless, according to the General Health Questionnaire, the younger group (45%) had significantly higher rates of psychiatric caseness than the older group (21%; P < .01); thus, there appears to be an aging, protective effect in the development of depression and anxiety post-TBI. However, researchers caution against making firm conclusions, as these results could be due to differences in time to follow-up. Goldstein et al39 reported that many mood changes were not noticed until more than 1 year post-TBI, so there may be a delayed onset of psychobehavioral issues in the older adult population. Regardless, psychological and behavioral issues are important secondary conditions post-TBI. They require accurate diagnosis and appropriate treatment, given their known impact on disability and quality of life (QOL).
Social outcomes
The literature on social functioning post-TBI in the areas of vocational status, life satisfaction and QOL, family dynamics, spousal relationships, and caregiving is not well developed; these fields are further limited when examining only the older adult population. In examining vocational status, several researchers report that fewer older adults return to work post-TBI than do younger adults.44,45 For example, in a group of 366 preinjury workers, 1 year after the original insult, Dikmen et al46 reported that only 36% of individuals older than 50 years had gone back to work compared with 70% of those aged 41 to 50 years. This conclusion was confirmed by Testa et al,44 who also demonstrated that fewer individuals in the older group (50-89 years) returned to work than those in the younger group (16-49 years) up to 2 years postinjury. A decline in return-to-work rates is likely the result of increased neuropsychological and cognitive morbidity combined with individuals nearing the retirement age prior to or shortly after the time of injury.
Vocational status has been shown to be tightly linked to QOL47 and life satisfaction48 post-TBI. Thus, one would assume that older adults would have lower scores on QOL and life satisfaction assessment than younger adults; however, this is not the case. Authors have found no significant relationship between perceived QOL47 or life satisfaction48 and older age (>65 years) post-TBI.
There is considerable research on family functioning and relationships for young and middle-aged adults post-TBI. In contrast, with the older TBI population, we know relatively little about these social issues. In comparing older adults with TBI with those without TBI, Rapoport and Feinstein42 report that the former experience greater psychosocial distress according to the Rivermead Head Injury Follow-up Questionnaire. However, in comparing older adults (aged >60 years) with TBI with younger adults (aged 18-59 years) with TBI, the authors found that the older adults had less impairment in the areas of relationships, work, and domestic activities as evidenced by the Rivermead Head Injury Follow-up Questionnaire than the younger group (P < .0001). There are several reasons for this conclusion. Older adults may be retired and likely have adult children; thus, following a TBI, they are less likely to return to a high-stress/high-demands environment. In addition, many older adults already have physical ailments and conditions that can impose on their activities of daily life. They may have acquired coping skills prior to the TBI, which following the injury now allow them to adjust more easily.
Until 2005, there had been no study specifically on spousal relationships and partnerships post-TBI, as well as among older adults, although there has been extensive literature indicating that the experience of TBI in older adulthood is very different from that of younger adults. Overall, wives of men suffering TBI have reported marital changes post-TBI, including loneliness, isolation, insomnia, and role reversals,49 as well as less overt acts of sexual expression.50 In examining the stability and survival of relationships between spouses post-TBI, Wood and Yurdakul51 compared younger (aged <35 years) and older individuals (aged >35 years). The authors report that there were lower rates of marital dissolution in the older age groups and rates of divorce and separation were inversely proportional to the number of years in marriage. Unfortunately, only 11 of 131 participants were older than 60 years, so interpretation of these findings warrants caution. In a more recent study, Layman et al52 investigated changing aspects of a marital relationship among spouses (aged >50 years) where one had sustained a TBI. Overall, the authors found great variability among the older couples. Since many of the control couples also experienced similar social changes with age, Layman et al52 suggested that changes in partnership roles from TBI may be difficult to distinguish from changes due to natural aging.
Recent research suggests that, in terms of relationships post-TBI, the caregiver-spouse relationship has been the most commonly assessed. Caregiving is a common part of older spousal relationships, as one individual may become ill and requires greater assistance with everyday tasks. Caregiving among older adults can be very challenging and has historically been done by females.53 However, given that men are living longer, society as a whole is aging, and family and gender roles are broadening, there are more male caregivers than ever before. In a qualitative study, Russel54 found that older men caring for their wives with TBI validated them. Other studies have found that older caregivers report less distress55 and were more satisfied in their life than young caregivers.56 Despite these few conclusions, the paucity of research in caregiving among older adults, specifically with TBI, makes it difficult to draw any definitive conclusion regarding this area.
DISCUSSION
Limitations
There are significant gaps in the literature on the topic of TBI among older adults. At present, there is a lack of agreed-upon age for which adults can be defined as older. In addition to recruiting "older adults" without a clear definition of old, many studies do not recruit enough older adults to be able to make meaningful conclusions. Few researchers use multiple or logistic regression, or other statistical methods, to control for the effects of confounding variables (eg, educational background/general intelligence). Follow-up time after injury is extremely variable among studies and comparisons prove to be virtually impossible. A significant proportion of the research is conducted cross-sectionally and retrospectively. Memory and selection bias threaten the accuracy of data, whereas cross-sectional studies prevent the understanding of temporal associations between variables. Finally, many studies do not compare outcomes with a younger group or age- and gender-matched control group; thus, firm conclusions cannot be drawn, as there is no baseline from which to compare.
CONCLUSIONS
This scoping review explored various outcome domains for those who experience TBI in later life. Older adults with TBI have been shown to have higher mortality rates, and recovery is impacted by the presence of chronic disease and other comorbid conditions. Such findings can be used to identify the critical points of care, in terms of necessary services, for older adults post-TBI. Furthermore, the importance of chronic disease management and falls prevention is evident. Post-TBI, this group should be monitored more closely for anxiety, depression, and somatic concerns than those without to ensure psychological well-being and QOL. Despite a significant amount of mortality research among this population, there remains a gap in research regarding the impact of injury on one's social relationships and the impact of gender on the discussed outcomes. More knowledge on the recovery of older adults with TBI would allow for increased QOL for the individual and proper allocation of health care resources.
References