Aging with Disability

 

Increased life expectancy 

Until recently, individuals with a disability seldom enjoyed the same life expectancy as their peers without disabilities.  Secondary medical conditions such as respiratory illness, renal failure, accidents, infections, and depression, coupled with a general lack of adequate primary medical care, prevented most persons from experiencing their true life expectancy.  Today, advances in medicine and rehabilitation have made the expectation of living to late life fairly reasonable for most persons, even those with a significant disability.  In fact, aging with a disability has been described as one of the most important new developments in rehabilitation.

 

Disability changes over the lifetime 

 

Research on aging with a disability has been ongoing for only about 15 years, but many new discoveries have already challenged previously accepted beliefs.  The single most important finding is that "chronic disability" is not at all static over the life span. Many, if not most, persons who live 20+ years with a disability or who are 40 years of age or older encounter substantial new medical, functional, and psycho-social problems that were neither expected nor planned for at an in earlier age.  Many of these changes are well underway by middle age; some are even underway by age 30 or as soon as 10 years after one acquires a disability.  While the exact causes of this "premature aging" are unknown, the following discussion shows that persons with disability do not age in a typical matter.

 

The phenomenon of aging. 

 

To the gerontologist, the term aging refers to the natural progression of biological, psychological and social functioning after the point of maximum development (Birren and Schaie, 1985).  The goal of aging research is to gain understanding and control of the genetic, environmental, health, and lifestyle variables that affect the processes of aging so that each person can live a quality life for the maximum number of years. Aging is not the same as being aged. Biological aging actually begins when a person is about 25 years of age.  By then, organ systems begin to lose 1% of their function per year. The significance of this is that research on aging must begin with people who are still in their 20's. Traditionally, gerontologists distinguish three kinds of aging:  biological, psychological and social.  Biological capacity peaks earliest, and then slowly begins to decline.  Despite this decline, physical illnesses do not show a rapid increase in prevalence until after age 70 because all organ systems have large reserve capacities.  Psychological maturity reaches a peak at about age 35 as measured by learning ability, intelligence, creativity and skilled performance.  Psychological aging declines at a slower rate than physical aging because people learn compensatory abilities.  Social maturity peaks last, about 55 years of age as measured by income, number of important social roles and career advancement.  Normally, individuals can maintain social roles well into their 70's and 80's.  Decades of studies on normal aging (such as the Baltimore Longitudinal Studies) have provided baseline data on physical, psychological and social aging that are helpful for gauging both normal and atypical aging patterns, such as among people with disability.

 

Medical problems 

 

Whereas typical aging is not accompanied by a high rate of medical and functional problems until after 70-75 years of age, people with disability show these higher rates 20-25 years sooner. People with disabilities also have 3 to 4 times the number of secondary health problems compared to their age-matched peers without disabilities. In fact,
 

  - Rates of respiratory illnesses are four times higher in persons with post-polio syndrome;

 - Diabetes is five to six times higher in many disability groups;

 - Cardiovascular disease is the second leading cause of death in persons with spinal cord injury;

-  Fractures are five times more common in persons aging with cerebral palsy, and

-  Osteoporosis affects nearly 70% of people with disability whose mobility is affected by disability.

Other problems with especially high rates include hypertension, pressure sores, high cholesterol, obesity, heart disease, diabetes, respiratory illness and osteoporosis Reasons for these conditions are not yet well understood; they are probably multi-factorial and act together.  A person acquiring a disability early in life may have reduced reserve capacity in one or more organ systems.  Combined with normal aging, more illnesses may then occur. 

 

Some problems may be linked to widespread changes in physiology.  For example, cholesterol levels of persons with spinal cord injury are abnormal at an early age (Bauman and Spungen, 1996) and persons with polio who develop post-polio syndrome have higher numbers with elevated cholesterol compared to persons with polio who stay ambulatory or compared to a nondisabled controls (Kemp and Campbell, 1993). 

 

Orthopedic problems that produce severe consequences for daily functioning and quality of life include bone loss, fractures, dislocations, rotator cuff injuries, scoliosis and over-use syndrome (Murphy et al., 1995;  Sie et al., 1992; Waters et al., 1995; Garland et al., 1993).  Orthopedic problems arise because of excess wear and tear (due to compensations for postural or ambulatory effects of disability, accidents, deconditioning and  metabolic conditions (e.g., osteoporosis).

 

Functional problems. 

 

The early onset of new functional problems impacts Activities of Daily Living (mobility, dressing, toileting, etc.), Instrumental Activities of Daily Living (IADLs) (shopping, transportation, money management, etc.), work and recreation.  Such changes are common to many, if not most, persons aging with disability, regardless of the original disability.  These problems often begin with loss of strength, endurance and range of motion, along with increased pain. This complex of symptoms may be the most characteristic age-associated functional change with age. 

 

This complex, together with decreased function constitute "post-polio syndrome," affecting up to 80% of people with a history of polio (Halstead, 1991) However, this complex also affects others and it is becoming increasingly likely that this may constitute a "post-disability syndrome" common among many impairment groups. For example, Gerhart et al., (1993) found that approximately one-third of persons aging with spinal cord injury in England underwent such changes.  Kemp and Thompson (1997) studied 150 persons from a United States Spinal Cord Injury Center and found that 26% of those who had durations of five years or more reported changes in function, most often beginning with excess fatigue. 

 

Similar results have been found in persons with cerebral palsy (Murphy et al., 1995) and rheumatoid arthritis (Campbell et al., 1998).  A recent study by Olsen and Hutchings (1998) demonstrated that the physical nature of a disability is the key factor in these changes.  In their study, persons aging with mental retardation had far fewer of these functional changes compared to persons aging with physical disabilities.

 

Employment seems to be a functional activity especially vulnerable to the effects of aging.  Because employment is such a valued and important activity, many persons aging with disability who experience problems with fatigue, pain and weakness try to maintain work roles above all else.  Our studies indicate that individuals decrease recreation, get more help with IADLs, and try to get more rest in order to preserve their work capacity. 

 

However, these efforts may not suffice.  In a recent study conducted at the Rehabilitation Research and Training Center on Aging with Disability at Rancho Los Amigos Medical Center, McNeal, Somerville, and Wilson (1996) found that over 50% of persons with polio had to adjust work roles, reduce effort and hours, or else retire altogether by the age of 50 because of these problems.  Over one-third of persons with spinal cord injury showed similar results;

however, the persons with spinal cord injury were 10 years younger on average than the persons with polio and they may eventually reach the same degree of change.

 

To summarize, as persons with disability begin to reach age 50, many show the kind of functional changes that would not be expected until age 70-75 in people without disabilities.  It is not yet clear whether this "aging gap" is independent of the medical problems discussed earlier or is somehow related to them.   However, what is clear is that service providers need to learn more about these recent discoveries in order to better plan and provide services.

 

Psychosocial changes 

 

Psychosocial changes are important not only because they affect individuals who are aging, but also involve their families.  Quality of life (QOL) is negatively affected by age-related changes in function and health.  Gerhart, et. al. (1993) found that persons with spinal cord injury who had decreased function rated their lives as less satisfying than persons who had not changed function. 

 

Krause (1990) had earlier shown that life satisfaction normally increases as one ages with a disability as long as major functional changes do not occur.  Similarly, Fuhrer et al., (1992) and Dijkers (1996) showed that life satisfaction was only slightly lower among persons with a disability compared to people without disabilities, and what differences did exist were due to health, mobility, work and social problems.  In addition to lower QOL, decline in health and functioning often result in psychological distress or depression. 

 

Overall rates of depressive disorder are 2-3 times higher among persons aging with disability compared to age-matched non-disabled persons (Fuhrer et al., 1993; McColl and Rosenthal, 1994; Kemp et al., 1997).  This finding is of major importance because depression itself is a disabling condition and in conjunction with a physical disability can cause excessive health, functional and family problems.  Contrary to popular belief though, depression is not a "natural" consequence of disability or age and does not correlate with the severity of impairment, or even with the level of disability (Fuhrer et al., 1993; Reinhardt, 1996; Tate,  et. al., 1994; McColl and Rosenthal, 1994).  However, it does correlate with difficulty coping with changes in health, function and social roles that accompany age. 

 

Kemp, Adams and Campbell et. al. (1997) found that among persons aging with polio, depression scores were higher only if individuals had more post-polio changes and/or had poor family cohesion.  Hansen et al., (1998) recently showed that poor coping in the form of using escape-avoidance techniques was related to poorer psychological outcomes.

 

The impact of health and functional changes on the family is equally important.  As changes in ability occur in the person with disability, families are usually the first one called upon to provide increased assistance.  However, this may not be something families are ready for or capable of doing.  Recent reports indicate that families experience worry and stress, including individuals with mental retardation (Heller and Factor, 1991) or physical disabilities (Holicky, 1996).  Richards and Shewchuck (1996) reported that spouses actually had higher average depression scores than the individuals who had a disability. 

 

McColl and Rosenthal (1994) found that family support was highly correlated with both depression (a negative correlation) and with life-satisfaction (a positive correlation) among persons aging with disability.  Therefore, quality of life, depression and personal assistance/caregiving issues are all related to and impacted by physical and functional changes affecting persons aging with disability.

 

Possible Causes. 

 

The age-related problems described above are not yet well understood.  We do not yet have sufficient data to know the eventual course of aging with a disability, how these changes may vary by such factors as gender or ethnicity, nor do we yet fully understand the causes of these problems.  At least five hypotheses have been proposed in the literature to explain these changes, and more than one may be correct.
 

1.  Accelerated biological aging processes.  Is there something inherent in disability that alters the course or rate of aging at the cellular or organ system level?

2. Wear and Tear.  Does living with a disability for a long period of time place increased stress on the body?

3. The era of onset.  Is the critical variable really when the person became  disabled?  People with disabilities of 20, 25, and 30 years duration received rehabilitation in a different era.  Medical and rehabilitation care, technology, and social factors have changed markedly over the years.  Are the problems observed today caused by the care that was given then?

4. Latent illness.  Does a major impairment like polio or cerebral palsy start a cascade of metabolic changes at culminate in a variety of illnesses that  were not diagnosed in earlier decades because people didn't live long enough to develop them?

5. Environmental causes.  Are excess disability and health problems due to living for years in an unaccommodating, disability-causing environment?

The RRTC on Aging with a Disability approach to the research program.  These are complex issues and testing hypotheses like these require sophisticated research designs and large samples, both of which we will provide.  Moreover, understanding the causes of these problems is not enough.  It is time to test interventions and to disseminate current information.

 

Our research has two goals: 

1) to conduct studies that further basic knowledge about the natural course of aging.

2) to test interventions designed to help alleviate the problems found in persons aging with disability. 

Our strategy for the first goal is to conduct the largest cross-disability longitudinal study of people aging with disability to date. To do this, we will use the 1,000+ person database we compiled from earlier research.  This database includes persons with cerebral palsy, polio, spinal cord injury, rheumatoid arthritis, stroke and also a control group without disability.