Health and disease in people over 85BMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b4715 (Published 23 December 2009) Cite this as: BMJ 2009;339:b4715
- Thomas Perls, associate professor of medicine
People aged 80 years and over are the world’s fastest growing age group.1 In the United States from July 2007 to July 2008 the over 85 age group grew by 3.5%, whereas the overall population grew by 0.73%.2 In the linked population based study (doi:10.1136/bmj.b4904), Collerton and colleagues point out that despite this unprecedented growth, relatively little is known about what is perceived by many to be a predominantly frail and disabled group.3 4 The authors recruited 53 of 64 general practices in Newcastle upon Tyne and North Tynside to send letters of invitation to all but their terminally ill patients who were born in 1921. Sociodemographic, medical, cognitive function, and physical function data were collected from personal visits and reviews of the medical records. In all, 1042 people (72%) agreed to participate (62% women, 38% men), 10% of whom were living in non-family care settings.
The authors found that despite high prevalence and complexity of age related diseases, these people had difficulty with a median of only three of 17 basic and instrumental activities of daily living. A fifth had no difficulty at all. They also found that 40% rated their health as excellent or very good compared with other people of the same age. Only 4% thought their health was poor.
Although the prevalence and multiplicity of various diseases is substantial in this age group, age related diseases such as ischaemic heart disease, heart failure, and cerebrovascular disease occurred at relatively low rates: 37%, 13%, and 25%, respectively. These rates are consistent with figures reported by the Framingham Heart Study and the Cardiovascular Health Study.5 Accordingly, Collerton and colleagues noted that the increased growth of the over 85 population mainly results from decreased age specific death rates at the oldest ages. These declines have been dramatic. For example, in people aged 65 and older in the US, deaths related to cardiovascular disease declined from 40% of deaths in 1980 to 30% in 2004.6 From 1999 to 2005, annual deaths in developed countries from cardiovascular disease declined from 6063 deaths to 4778 deaths per 100 000 people over 85, a decrease of 22% in six years.7 As mortality for middle age and older age groups continue to fall, and as large birth cohorts such as the “baby boomers” age (figure⇓), the increase in the over 80 age group from 2000 to 2050 will be dramatic. Furthermore, the over 80 group will make up an increasingly greater proportion both of the total population and those over 65 years in nearly all the countries shown. By virtue of the sheer numbers involved, the projected growth in the US, China, and India is particularly striking. Even the countries of Africa will see an impressive growth in people over 80.
Decreasing the risk for premature death from causes such as cardiovascular disease also allows other age related causes of death to become more prevalent. For example, from 1999 to 2005, deaths from Alzheimer’s disease in over 85 year olds in the US increased from 601 to 862 per 100 000 people—an increase of 30%.7 The Medical Research Council’s Cognitive Function and Ageing Study found that the incidence of dementia increases with age: 7.4 cases per 1000 person years at age 65-79 years to 68.5 cases per 1000 person years at age 85 and older.8
Does this increase in Alzheimer’s disease in the fastest growing segment of our population predict a looming disaster? Yes and no. Without the development of effective preventive measures, the sheer number of people aged 85 and over will probably result in millions more people developing the disease, and governments must prepare for this—from research into prevention and treatment to provision of care.9 A large proportion of older people do not develop Alzheimer’s disease, however, and its incidence may even plateau in the nonagenarian years.10 This muted incidence is probably the result of demographic selection, which results in the existence of select cohorts at the most extreme ages that have decreased risks for certain age related diseases and disabilities that are associated with premature death.11 The fact that demographic selection is a potent force at the oldest ages underlies the importance when studying this population of further segregating the oldest old into even older age groups when possible.
As Collerton and colleagues point out, the presence of age related diseases and functional impairment seem to be disconnected in the over 85 age group. Terry and colleagues saw this phenomenon with centenarians, and they speculated that disability, rather than disease, is the better predictor of mortality at these older ages, and that people who cope better with their disease(s), perhaps via enhanced functional reserve or adaptive capacity, are the survivors.12 Thus, the social and individual effect of various age related diseases may be attenuated in the over 85s. Functional status, rather than age alone, must be an important consideration in establishing goals of medical treatment in the very old. Understanding the genetic and modifiable underpinnings of how some people deal with disease better than others should be a priority.
Cite this as: BMJ 2009;339:b4715
Competing interests: None declared.
Provenance and peer review: Commissioned; not externally peer reviewed.