Amanda McIntyre MSc, Swati Mehta PhD, Rachel Anderson BSc, Robert Teasell MD FRCPC
The term “aging” is often used in the literature to describe how an adult progresses developmentally to an older state of being. However, the meaning of aging in the current context is used to describe individuals that have already reached the age of 65 years and are living out their remaining years according to Canada’s life expectancy estimate. Although the differences are subtle, the point is to highlight the aging process as normal physical, cognitive and psychosocial decline in later years, beyond the age of 65, and not simply a chronological progression. These normal functional declines are commonly referred to as senescence (Comfort 1964).
Traumatic brain injury (TBI) is a leading cause of death in the elderly and often has devastating long-term effects (Frankel et al. 2006). Not only does TBI have consequences for the individual, but also for the public health system and caregivers. Clinical research has demonstrated that TBI can seriously hinder physical, cognitive and psychosocial functioning, regardless of whether the head injury was mild, moderate or severe (National Institutes of Health 1998).
Statistics regarding TBI in Canada were collected by the Canadian Institute for Health Information. In the fiscal year 2003-2004, 29% of all head injury hospitalizations in Canada were elderly individuals (age 60+ years; Canadian Institute for Health Information 2006). This corresponds to 4,902 hospital admissions in older adults alone. The prevalence of head injury is alarming given that the elderly population made up only 12% of the total Canadian population in 2004. More alarming is that many head injuries go unreported by family physicians and outpatient healthcare settings, and more remain undiagnosed in individuals that do not seek medical help. In 2004, 1,368 individuals who had experienced a head injury died in the hospital as a result of their injuries, the majority of which were elderly (59%). The number of deaths reported in hospitals does not include individuals that died at the scene of an accident or shortly before arriving to the hospital; therefore, it is estimated that the number of fatalities is higher than reported (Canadian Institute for Health Information 2006).
Mechanism of Injury
In 2004 the predominant mode of injury for older Canadian adults was unintentional falls and represented 76% of all head injury admissions. Further, 82% of all injury related admissions of Canadian older adults were the result of a fall (Canadian Institute for Health Information 2006). Individuals who have fallen previously are at a high risk of subsequent falls (Teno et al. 1990). In 2004, the second and third leading causes of head injury in older Canadian adults were motor vehicle collisions and assaults at 17% and 1.1%, respectively (Canadian Institute for Health Information 2006). The rates due to motor vehicle collisions are particularly worrisome given that older adults drive considerably less than younger adults. The rate of death resulting from motor vehicle collisions in those 65 years and older was 13.2 per 100,000, yet for those aged 45 to 64 years, the rate was only 8.2 per 100,000 (Ramage-Morin 2008). Head injuries caused by falls produce a greater number of focal brain lesions than those produced by other mechanisms such as motor vehicle accidents (Alberico et al. 1987).
Head injury incidence by age and gender
In 2004, the average age of Canadian seniors sustaining a head injury was 75 years, and on average 57% of all admissions were males. This overrepresentation by males is observed in other age brackets for TBI as well (Zygun et al. 2005). However, American studies have shown that gender differences regarding TBI incidence disappear over the age of 65 (Tieves et al. 2005). Pentland et al. (1986) reported a slightly higher number of head injuries in women over 75 years of age, resulting mostly from falls, in part because of the large number of women in this age group.