Background: The compression of morbidity hypothesis predicts that, in order to achieve their extreme old age, centenarians markedly delay or even escape diseases that would otherwise be lethal at younger ages. Phenotypic studies have not adequately characterized the prevalence and timing of age-related illnesses among those who achieve exceptional old age. Thus, we conducted a retrospective cohort study of centenarians to explore the timing of such diseases among centenarians.
Methods: Health history questionnaires were completed by 424 centenarians (aged 97-119 years) or their proxies. Lifetime (to-date) diagnoses of 10 major lethal illnesses (hypertension, heart disease, diabetes, stroke, nonskin cancer, skin cancer, osteoporosis, thyroid condition, Parkinson's disease, and chronic obstructive pulmonary disease) and one ocular disease (cataracts) that befall the elderly population, approximate age of diagnosis, level of alcohol and tobacco use, and presence or absence of cognitive impairment were assessed. Because of the retrospective nature of the study, the typically imprecise age of onset of cognitive impairment negated the ability to include age of onset of cognitive impairment in this aspect of the analyses.
Results: Examining the ages of onset for the 10 age-associated diseases and excluding cognitive impairment, we found that the centenarians fit into three morbidity profiles-Survivors, Delayers, and Escapers. 24% of male subjects and 43% of female subjects fit the Survivor profile, or those who had a diagnosis of an age-associated illness prior to the age of 80. Delayers were individuals who delayed the onset of age-associated illness until at least the age of 80, and 44% of male and 42% of female subjects fit this profile. Escapers were individuals who attained their 100th year of life without the diagnosis of common age-associated illnesses, and 32% of male and 15% of female subjects fit the Escaper profile. When examining only the most lethal diseases of the elderly population, heart disease, nonskin cancer, and stroke, we found that 87% of male and 83% of female subjects delayed or escaped these diseases. Subjects with and without cognitive impairment did not differ in terms of the profile to which they belonged.
Conclusions: These results suggest there may be multiple routes to achieving exceptional longevity and that there are sex differences according to which route is taken. These routes represent different phenotypes and thus likely different genotypes of centenarians. The identification of three types of centenarians, Survivors, Delayers, and Escapers, provides direction for future study into the factors that determine exceptional longevity.