Death risk stopped rising after age 105

The risk of death for humans and most animals is described by a pattern known as the Gompertz distribution, which was formulated back in the 19th century. It states that the probability of death increases exponentially with age. However, in the 20th century, when the life expectancy of people in many countries increased significantly, it became clear that Gompertz’s law describes mortality statistics well only up to the age of 80, and after this point, the rate of decline of the old part of the population slows down.

As the number of very old people has increased recently, scientists have had the opportunity to build demographic models on large amounts of data. While scientists previously still believed that the risk of death continues to rise with age, albeit more slowly, recent research suggests that after a certain age, previously labeled 110, the risk reaches a plateau. In the new paper, the scientists confirmed this hypothesis using Italian long-livers as an example, and in doing so lowered the “borderline” age to 105.

Statisticians from several Roman universities and the University of California at Berkeley, with input from renowned European demographer James Vaupel, used data from Italy’s National Institute of Statistics on residents who were 105 years old or older at the start of the observation period, from 2009 to 2015. In total, the database contained records of 3,836 such people, of whom only 463 were men. During the observation period, 2,883 of them died.

The researchers noted that previous work by their colleagues had used data where all people over a certain age (e.g., 110) were assigned to a single cohort, while their work analyzed the data in more detail by year. For ages below 105, the authors used data from the Human Mortality Database (HMD – Human Mortality Database), which includes information on residents of many countries, including Italians.

Based on the collected data, the researchers built their model linking all-cause mortality to age, for people over 65. The resulting curve agreed well with Gompertz’s law up to age 80, but after that the probability of mortality began to decline and reached a plateau by age 105.

Risk of death (hazard) among Italian women born in 1904

According to the authors of the paper, their data suggest that the limit of human life expectancy has not been reached and will continue to move away with time. However, they do not give an explanation for this phenomenon in terms of modern theories of aging. To date, the oldest person whose age has been documented remains Jeanne Kalman, who died in 1997 at the age of 122.

Previously, mathematicians had suggested, based on the trend of increasing life expectancy from 1970 to 2010, that the maximum human age could be limited to 115 years. However, critics of the work, among them James Vaupel, said that in many countries the peak of life expectancy gains had not yet been reached.

Source: N+1