“There is one, and only one, cause of death at older ages. And that is old age.” So said Leonard Hayflick, one of the most influential gerontologists of all time. But dying of old age isn’t just a case of peacefully losing the will to live – it is an accumulation of diseases and injuries different to those that tend to kill people at younger ages.
For a start, the oldest old have very low rates of chronic diseases such as cancer, heart disease and stroke. The trend is particularly apparent for cancer. The odds of developing it increase sharply as people age, but they fall from the age of 84, and plummet from 90 onwards. Only 4 per cent of centenarians die of cancer, compared with 40 per cent of people that die in their fifties and sixties.
Many centenarians even manage to ward off chronic diseases after indulging in a lifetime of serious health risks. Many people in the New England Centenarian Study experienced a century free of cancer or heart disease despite smoking as many as 60 cigarettes a day for 50 years. The same story applies to people from Japan’s longevity hotspot, Okinawa, where around half of the local supercentenarians had a history of smoking and one-third were regular alcohol drinkers. These people may well have genes that protect them from the dangers of carcinogens or the random mutations that crop up naturally when cells divide.
So what does kill off the oldest old? Pneumonia is the biggest culprit, with other respiratory infections, accidents and intestinal problems trailing behind. “Dying of old age involves total systems failure,” says Craig Willcox of the Okinawa Centenarian Study in Japan. “Centenarians avoid age-associated diseases, but you see a lot of systemic wear and tear. Almost all of them have had some problems with cataracts, they can’t hear very well and have osteoarthritis. Our most recently deceased centenarian in Okinawa caught a cold and died in her sleep.”
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