Populations worldwide started to enjoy significantly longer life expectancies starting in the 20th century due to improved medical care and economic/social development. According to the Health and Affair Forum on "The Life Expectancy and Health-Adjusted Life Expectancy of Koreans"11), the life expectancy at birth in Korea was 80.7 years (76.8 years for males and 82.92 years for females), and 29.4% of individuals over 65 years old still maintain careers21). Given this aging revolution, it is fitting that the number of neurocognitive studies on elderly populations has increased greatly in the past decade14). However, brain injury or other physical trauma in old aged patients has not been the subject of disability evaluations or other forensic studies. Some studies have evaluated morbidity and mortality associated with brain injury in old aged populations and suggested that higher rates of mortality in older patients as well as neurologic deficits, even mild ones, result in poor prognosis18,19). Significant prognostic factors could serve as a gold standard for disability evaluations to determine indemnification or compensation. However, characteristics of brain injury in old aged Koreans have not been extensively studied, and advanced age is only part of a negative prognosis5). Furthermore, poorer outcomes of old aged patients with brain injury are not yet sufficiently explained by physiological monitoring data. In particular, reduced vascular versatility is likely to contribute to this occurrence6).

Studies of adult patients who have suffered brain injury or stroke demonstrated how age and injury severity are likely to interact given that increased age enhances the impact of injury severity. When injury severity is not taken into account, age alone does not appear to significantly impact the outcomes of young to middle aged patients14). In another study of prognostic factors for adults with brain injury, higher levels of education were found to be associated with good prognosis regardless of Glasgow Comma Scale (GCS) scores10). Additionally, they suggested that younger individuals showed better memory retention with the exception of patients who sustained severe traumatic brain injury (TBI), but in the severe TBI group, the meaningful effect of demographic variables was not noted by the cause of influence of severe brain injury. A systematic review of prognostic factors impacting the ability to return to work after sustaining brain injury provided strong evidence that the length of inpatient care is a negative prognostic factor while other factors do not appear to have any effect or have a minimal relationship with the overall prognosis23).

In a disability evaluation to determine indemnification or compensation for a loss, disability severity is based on patient status including demographic variables such as age, gender, education level, and career; clinical variables including GCS scores, radiological findings, physiological data collected just after brain injury, neurocognitive test results, and other functional datum on a status at now under disability evaluation. However, patient age is typically not considered for disability evaluation because age-matched individuals are compared in these types of assessments, thereby taking into account the normal aging process, particularly for older patients. In the present study, we evaluated neurocognitive and functional outcomes according to demographic and clinical variables as prognostic factors, and compared outcomes between junior and senior elderly patients for assess the effect of age old patients with TBI.

Clinicians treating patients often make therapeutic decisions based on their assessment of prognosis. An accurate prognostic evaluation is important when selecting specific methods of treatment, deciding whether or not to discontinue treatment, and when counseling patients and relatives16). For disability evaluation to determine indemnification or compensation for a loss, widely accepted prognostic factors for TBI treatment could be a gold standard for making a decision acceptable and fair to all interested parties. However, there is wide variety of opinions and research findings about prognosis after TBI as well as great variability in the quality of research2). These include patient age, clinical findings indicating the severity of brain injury (e.g., the depth and duration of coma or other neurological abnormalities), and the results of investigative and imaging studies, particularly intracranial pressure and computed tomography scanning, which disclose the nature of the brain injury and its effects on intracranial dynamics. Even though there is little doubt regarding the importance of these features, there are still debates about the precise nature of their relationships and exactly how these different factors should be assessed, categorized, and utilized3).

The most widely used variables or demographic characteristics of patients with TBI are age, gender, race and culture, premorbid mental abilities, education level, and premorbid personality and social adjustment. In particular, older adult show less improvement 1 year after TBI than younger ones, have a greater number of complications including subdural hematomas, and are less likely to survive a severe injury14). Although advanced age at the onset of TBI is a severe risk factor, it does not significantly affect some areas of disability evaluation. Decrements or impairment of neurocognitive outcomes in old aged patients with TBI are evaluated in the context of normal neurocognitive aging processes by comparison to healthy individuals in the same age range. Consequently, clinician should concerned to not a onset age of TBI but a difference from a normal neurocognitive aging process of old aged patient with TBI when performing a disability evaluation.

In the present study, we compared junior elderly and senior elderly patient with TBI to explore the effects of normal aging. The age of 55-65 years may be a starting point of normal neurocognitive aging given that most neurocognitive functions of individuals this age are poorer than those of young adults. Results of the comparison between junior and senior elderly patients in the present study did not show significant differences among neurocognitive outcomes even for low MMSE scores. Almost all (92.6%) of the recruited patients were employed and would therefore need to undergo evaluation to determine how much compensation they would receive for their disability. Since premorbid unhealthy patients were excluded from our study, individuals undergoing disability evaluation were more active and healthy than most people of the same age. Furthermore, relationship between neurocognitive outcome and age were significant minimally, and verbal memory was affected or decreased by the onset age of TBI. Thus, though the evaluation of neurocognitive outcome was administrated and interpreted based on patient age or using age corrected norms, the onset age of TBI should be disregarded partially for old aged individuals.

Gender-related differences between the groups were identified for the low MMSE scores as well as the standard scores for confrontational naming and generative naming. Altogether, above 10% of the variance in neurocognitive functions was associated with gender, and male patients scored higher in these areas. Functional outcome using CDR showed similar results. The results of TBI outcomes are reported according to gender in only a small percentage of the published literature, but a quantitative review of those studies revealed that worse outcomes are observed in women after TBI7).

Standard MMSE scores corrected for age, gender, and education level did not show any significant difference. Thus, differences in low MMSE scores between genders was not a prognostic factor for recovery after TBI unlike gender difference in normal aging1,9). However, differences between genders in verbal abilities assessed by confrontational and generative naming could be considered a prognostic factor unlike a common sense about gender difference. Gender-associated differences and individual test performances in the context of neurocognitive differences between the genders must nevertheless be interpreted with caution14).

Next to age, the most widely accepted prognostic factor is education level. Higher levels of education are associated with greater cognitive functioning and decreased susceptibility to dementia24). But almost of criteria for dementia or dementia status in South Korea have not used statistically standardized comparison norms considering gender and education level. Low MMSE scores did not show any significant difference among educational levels, but significant differences in standard MMSE scores were observed, had significant trends with higher at education level, and old aged patients with higher education level showed lower standard score at same a low score. Furthermore, significant differences in attention, visuospatial functioning, and visual memory were observed according education level and almost of neurocognitive functions were affected by education level. Those results had replicated the prognostic value of education level about adult study10).

Another demographic factor did not show any congruently significant differences or relationship. The cause of visit (disability evaluation group versus disability evaluation appointed group after treatment) did now show significant difference each other, but explained some variances of visual memory performance. Adult patients that had undergone disability evaluation after TBI showed differences in neurocognitive outcomes according to the cause of visit, and showed lower performance than the treatment group (patients who were scheduled to undergo disability evaluation after recovering from TBI). This suggested that disability evaluation process has an effect on the test-taking attitude or will affect the attitude of the clinician administering the test or the patient actually taking the test intentionally or unintentionally20). Therefore, clinicians should not assume that old aged patients with TBI are "faking" their symptoms or injuries as adult patients with TBI, but assume that they could faking their performance in a test set available visual feedback.

An examination of head injury causes with respect to age demonstrated that there were an increased proportion of injuries secondary to falls and pedestrian accidents with advanced age. The primary etiology of TBI among old aged patients was falling. Certain age-related medical conditions may predispose individuals to falling. Cognitive impairment is also a significant risk factor for falls. This may be due to both decreased safety awareness and increased use of psychotropic medications13). In a prospective study of the Traumatic Coma Data Bank3), motor-vehicle accidents were the cause of injury in 55% of patients 15-25 years old whereas only about 5% suffered falls. In contrast, 45% of patients over 55 years old suffered falls and only about 15% were in motor-vehicle accidents. However, falling as a mode of injury did not appear to be an independent predictor of poor outcomes. Older patients have poor outcomes compared to younger individuals regardless of the cause of injury. However, in our study 87.5% of head injuries were caused by 'car accidents (33.2%)' or 'pedestrian accidents (54.3%)'. Subjects of our study had an occupation and had undergone disability evaluation or were appointed to do so. Therefore, the cause of head injury does not appear to be a suitable prognostic factor for the disability evaluation process of old aged patients with TBI.

Utilization of clinical prognostic factors such as the type of brain injury, GCS scores, or other characteristics is limited for old aged patients. The GCS was developed by Teasdale and Jennett22) in 1974 as an objective measure of the level of consciousness. Since then, a number of studies have confirmed a fairly high degree of inter- and intra-rater reliability of the GCS among observers with a wide variety of experience levels3). Classical clinical features with prognostic significance for patients with TBI include age, GCS scores, pupil reactivity, brainstem reflexes, and the presence of post-traumatic hypotension. Many patients today arrive at the hospital already intubated, paralyzed, and ventilated. An accurate estimation of changes in GCS scores during the initial hours after trauma is therefore often difficult to obtain. In a survey of patients with severe and moderate head injuries conducted by the European Brain Injury Consortium, the full GCS scores were only testable for 56% of patients upon admission to neurosurgery17). In our study, 64.8% of subjects had a loss of consciousness, 66.0% of subjects had comorbidity, but they did not showed any significant difference at neurocognitive outcomes. In 39.5% of subjects with operation, they had showed lower performance at confrontational naming, only than had not operated. Functional outcome of old aged patient with TBI were assessed by intensive interviews based on evaluated neurocognitive outcomes as CDR and lead to a final decision of disability evaluation compromising all of data acquired in evaluation process. In those final process, gender, LOC, standard score of MMSE, education and visuospatial function were adopted by critical marker.

The present study showed a relationship among demographic, clinical variables, neurocognitive outcomes, and functional outcomes as prognosis factors for old aged patients with TBI undergoing or directed to undergo disability evaluation after treatment. Gender, LOC, and education level were found have a significant impact on determining the prognosis of these individuals. Gender should also be carefully considered as a meaningful prognostic factor. Furthermore, onset age of old aged patients with TBI should be disregarded partially for old aged individual using age corrected norms. Unlike adult patients with TBI under disability evaluation, old aged patients with TBI had not affected by disability evaluation itself for compensation, but assume that they could faking their performance in a test set available visual feedback. In a previous study of adult patients with TBI10) comparisons were made according to TBI severity based on the GCS. For old aged individuals, comparison of GCS scores and other clinical variables was limited because the caregivers or guardians of these patients were also old aged and could not provide an accurate medical history. Therefore, further studies should be conducted to identify prognostic features based on the results of medical examinations such as CT scanning, information with important therapeutic implications for operative intervention, and indications for intracranial pressure monitoring would include for providing information concerning prognostic significance.