The syndrome of dementia is an irreversible decline in cognitive abilities that causes significant dysfunction. Like most syndromes, dementia can be caused by a number of diseases. In the nineteenth century, for example, a main cause of dementia was syphilis. As a result of dramatic increases in average human life expectancy, dementia is caused primarily by a number of neurological diseases associated with old age. Dementia is distinguished from pseudo-dementia because the latter is reversible—for example, depression, extreme stress, and infection can cause dementia but with treatment a return to a former cognitive state is likely (Oizilbash et al.). Dementia is also distinguished from normal age-related memory loss, which effects most people by about age seventy in the form of some slowing of cognitive skills and a deterioration in various aspects of memory. But senior moments of forgetfulness do not constitute dementia, which is a precipitous and disease-related decline resulting in remarkable disability. Since 1997, a degree of cognitive impairment that is greater than normal age-related decline but not yet diagnosable as dementia has been labeled mild cognitive impairment (MCI), with about one-third of those in this category converting to dementia each year. These cognitive conditions from normal age-related forgetfulness to dementia form a continuum. Specialized clinics that were once called Alzheimer's Centers are increasingly changing their name to Memory Disorders Centers in order to begin to treat patients at various points along the continuum prior to the onset of dementia.
Although dementia can have many causes, the primary cause of dementia in our aging societies is Alzheimer disease (AD). Approximately 60 percent of dementia in the American elderly and worldwide in industrialized nations is secondary to AD (U.S. General Accounting Office). This discussion will focus on so-called Alzheimer's dementia in order to illustrate ethical issues that pertain to all progressive dementias. One epidemiological study in the United States estimated that 47 percent of persons eighty-five years and older (the old-old) had probable AD, although this is a widely considered inflated (Evans et al). Epidemiologists differ in their estimates of late-life AD prevalence, but most studies agree roughly on the following: about 1 percent to 2 percent of older adults at age sixty have probable AD, and this percentage doubles every five years so that 3 percent are affected at age sixty-five, 6 percent at age seventy, 12 percent at age seventy-five, and 24 percent by age eighty. While some argue that those who live into their nineties without being affected by AD will usually never be affected by it, this is still speculative. According to a Swiss study, 10 percent of non-demented persons between the ages of eighty-five and eighty-eight become demented each year (Aevarsson). There are very few people in their late forties and early fifties who are diagnosed with AD. Without delaying or preventive interventions, the number of people with AD, in the United States alone, will increase to 14.3 million by 2050 (Evans et al). These numbers represent a new problem of major proportions and immense financial consequences for medicine, families, and society (Binstock et al).
There is a second very rare form of AD which is early onset that is clearly familial. About 3 percent ofAD cases are caused by rare autosomal dominant (or causative) single gene mutations, of which three are clearly defined. In these cases of familial AD, symptoms usually occur in the early forties or mid- to late-thirties, and death occurs within five years of diagnosis, in contrast to the more typical seven to eight years for ordinary late-onset disease (Post and Whitehouse).
Various stage theories of disease progression have been developed. However, in clinical practice, professionals speak roughly of three stages. In mild stage dementia, the newly diagnosed patient has significant cognitive losses resulting in disorientation and dysfunction, and often displays affective flatness and possibly depression. In moderate stage dementia, the patient forgets that he or she forgets, thereby gaining relief from insight into losses. Some patients will at this point adjust well emotionally to a life lived largely in the pure present, although some long-term memories are still in place. The recognition of loved ones is usually still possible. However, as many as one-third of patients in the moderate stage will struggle with emotional and behavior problems, including agitation, combativeness, paranoia, hallucinations, wandering, and depression. A small percentage becomes sexually disinhibited. The advanced stage of dementia includes a loss of all or nearly all ability to communicate by speech, inability to recognize loved ones in most cases, loss of ambulation without assistance, incontinence of bowel and/or bladder, and some weight loss due to swallowing difficulties. The advanced stage is generally considered terminal, with death occurring on average within two years. AD, however, is heterogeneous in its manifestations, and defies simplistic staging. For example, while most people with advanced AD will have no obvious ability to recognize loved ones, this is not always the case. In late December 2000, for example, the daughter of a man recently deceased sent an e-mail note to the AD networks around the world:
Hello Dear Friends: As many of you know, my father has been suffering from Alzheimer's disease for the past 4.5. years. It has been a long and often very hard road for him, for my mom, and for me too. However, as of 7 p.m. last night, my father no longer has to struggle with the disease that robbed him of every part of his being, except one. He never once stopped recognizing my mom and never, ever stopped reaching out to her and wanting to give her a kiss. No matter how many parts of his personality were lost, no matter how many hospital visits full of needles and catheters, no matter how many diapers, he always retained his kind, gentle sweetness and his European manners as a gentleman. In the end, things went very quickly for him. He simply closed his eyes and closed his mouth, indicating no more food or water.
The gentleman described above was in the advanced and therefore terminal stage of AD. Yet he retained the ability to recognize loved ones.
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