Epidemiological studies of members of long-lived families are driving much of the interest in the genetics of longevity. While it is thought that genetic variations are much less important than lifestyle choices, they appear to become more influential in extreme old age, in the period of life when individuals are very damaged and frail. Investigating the root causes of such variations in human longevity is good science, but probably irrelevant to the future of longevity-enhancing medicine: effective therapies will repair damage and keep people young, indefinitely postponing the phase of life and loss of function in which genetic differences have any meaningful effect.
In this study, members of long-lived families are compared with age-matched individuals from families of ordinary longevity, and they are largely more healthy, as you'd expect. Aging is a global phenomenon of damage accumulation, and people who live longer tend to be less damaged and thus more healthy at a given age. Other studies have provided evidence for a genetic component to familial longevity, but note the spouse effect here however. That spouses marrying into long-lived families are also more healthy than the general population suggests that lifestyle choices continue to have a fairly strong influence on this data even in later ages:
The Long Life Family Study (LLFS) is a multicenter longitudinal study of exceptional survival among members of long-lived sibships (probands), their offspring, and spouses of either group. For these four "roles", we asked: Does membership in a long-lived family protect against disease? We used 2008-2010 Beneficiary Annual Summary Files from the Centers for Medicare & Medicaid Services (CMS) to compare prevalences of 17 conditions among 781 LLFS participants in Medicare with those of 3,227 non-LLFS matches from the general Medicare population.
Seven conditions were significantly less common among LLFS probands than their matches: Alzheimer's, hip fracture, diabetes, depression, prostate cancer, heart failure, and chronic kidney disease. Four diseases not strongly linked to mortality (arthritis, cataract, osteoporosis, glaucoma) were significantly more common for LLFS probands. Despite fewer people and less disease in those roles, LLFS offspring and LLFS spouses of either generation also had significantly lower risk for Alzheimer's, diabetes, and heart failure.
Common, severe mortality-associated diseases are less prevalent among LLFS probands and their offspring than in the general population of aging Americans. Quality-of-life-limiting diseases such as arthritis and cataract are more prevalent, potentially through more diagnosing of milder forms in otherwise healthy and active individuals. LLFS spouses are also relatively healthy. As the younger cohorts age into Medicare and develop more conditions, it will be important to see whether these tentative findings strengthen.