Since the 1950s the mortality rate among the oldest inhabitants
in the developed countries has declined dramatically causing a
four-fold increase in octogenarians, an eight-fold increase in
nonagenarians and a twenty-fold increase in centenarians. In order
to shed light on the ageing process among the extremely old, professor
Bernard Jeune and his colleagues of the Institute of Public Health,
Odense University, established The Danish 1905-Cohort Survey. The Survey is a longitudinal nation-wide study of all Danes born in 1905 irrespective of residence, health, mental, and physical status. Five percent of the 26,625 Danish nonagenarians are expected to live to be a hundred years old which will provide the Survey sufficient power to study a large number of predictive factors for loss of abilities and mortality among this highly selected population.
As a Ph.D. student at Odense University, Hanne Nybo studied functional status and predictors of mortality among 2,262 of the Danish nonagenarians. Her results are interesting and comforting news for old people. Significant predictors of mortality among both males and females were disability, cognitive impairment and low Body Mass Index. However, factors often found to predict mortality among middle-aged and the younger elderly such as marital status, low education, smoking and intake of alcohol, seem to loose their importance with age, as they did not influence mortality. It has earlier been shown that a moderate intake of alcohol has an U-shaped relation to mortality which is explained by the fact that alcohol has some beneficial effects, such as raising the level of HDL-cholesterol, lowering fibrinogen levels and inhibiting platelet aggregation. Among the Danish nonagenarians the relation between alcohol intake and mortality seems to be linear: the higher the consumption the lower the mortality! The intake of alcohol in the 1905-Cohort was moderate among most participants, however, as only 10% of the males and 3% of the females drank more than 14 drinks/week. Among the females almost half of the participants did not drink at all. This suggests that the linear and inverse relationship between alcohol intake and mortality might only represent the "left leg" of the U-shaped curve.
People surviving into their nineties may have characteristics - genetic and/or environmental - that protect them against the obvious toxicity of cigarette smoking and excess amounts of alcohol. Interventions meant to improve survival among the very old should therefore not focus on well-known risk factors such as quitting smoking, cutting down on alcohol consumption or reducing body weight.The old descendants of the vikings may still drink to their health!