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Successful Aging of Individuals with Brain Injury
by Paul F. Aravich, Ph.D. and Anne McDonnell, OTR/L Successful aging is a goal for all creatures great and small. This is true for the lowly mayfly living one day and for the inspiring — if not scrawny — bristlecone pine tree living 4000 years. However, successful aging in people requires more than longevity: it requires the maintenance of physical, cognitive and social function (Rowe and Kahn 1997). The survivors of traumatic brain injury (TBI) are living longer than ever before. This article will distinguish successful aging from senescence. It will then identify 10 ways to promote successful aging in long-term survivors so that — within the constraints of their injuries — physical, cognitive and social function can be maintained. The number of older people has increased dramatically throughout most of the world. This has been accompanied by an expansion in the number of people aging with disabilities in general (Klingbeil et al., 2004), and with an increase in the number of people aging with TBI in particular. Various factors have contributed to this phenomenon, not least of which is a declining overall TBI death rate (Adekoya et al., 2002). Declining death rates have been accompanied by advances in long-term medical care, rehabilitation and social support making the prospects for successful aging an ever increasing reality for survivors. More information on the epidemiology of this aging phenomenon, the primary causes of death in aging survivors, and interventions that go beyond typical TBI services is desperately needed to maximize successful aging in this population. Only a few studies have looked at mortality rates and the primary causes of death in long-term TBI survivors (see Trudel et al., current issue). Mortality rates have been estimated to be nearly four times greater than those for people without TBI (Baguley et al., 2000). Even mild TBI is associated with a small but statistically significant reduction in long-term survival (Brown et al., 2004). Overall life expectancy may be reduced by 7 years in survivors, who are twice as likely to die as age, gender and ethnically matched controls; the best predictors of premature death were older age, lack of employment at the time of injury, and disability at the time of rehabilitation discharge (Harrison-Felix et al., 2004). The limited data available suggest that long-term survivors have increased death rates from circulatory and respiratory diseases, as well as 10
BRAIN INJURY PROFESSIONAL
from seizures and choking (Shavelle et al., 2001). Last but not least, TBI increases the risk of Alzheimer’s disease (Lye and Shores, 2000). Compared to seizures and choking, much less attention has focused on cardiovascular, respiratory and brain fitness in long-term survivors, despite the importance of each for successful aging. It follows that the promotion of successful aging in long-term survivors requires attention to factors that go beyond the brain injury itself. The promotion of successful aging in survivors distinguishes aging from senescence. Many people fear old age. Contrary to popular belief, aging is not a disease. In fact, it can be argued that aging starts at conception and then continues across various developmental life stages. Instead of aging, we fear senescence: a progressive loss in the ability to maintain fitness and defend against death (Williams, 1999). It has been argued that senescence is a relatively recent evolutionary phenomenon and that there are numerous “negligible senescers,” including oysters and insect queens (Finch and Austad, 2001). The causes of senescence are both biological and environmental. Biological factors include genetic predispositions, the lack of cell division via chromosomal telomere shortening, the loss of growth factors, programmed cell death known as apoptosis, endocrine changes, and free radical toxicity (see Finch and Austad, 2001). But nurture as well as nature determines survival: identical twin studies indicate that only 35% of the variance in human survival is genetically determined (Finch and Tanzi,1997). Hence, environmental and lifestyle factors play a more important role in successful aging than genetic factors. A good example is the queen of an ant colony: as a negligible senescer she does not show a progressive decline with age in most biological functions. Her only flaw is that she runs out of eggs, at which time extrinsic factors —namely, her sons — kill her (see Finch and Austad, 2001). Another example is the oysters that once dominated the Chesapeake Bay. As negligible senescers they are literally fountains of youth. Yet, this population was decimated by extrinsic factors, including over fishing and pollution (see Finch and Austad, 2001). More research is needed to identify the modifiable environmental and lifestyle factors that are unique to long-term survivors. This requires a leap beyond the simple