The Italian island of Sardinia recently lost its oldest citizen and the world's oldest man. But the Mediterranean island continues to have a population worth researching and analyzing because of the longevity of its residents.
Antonio Todde was just days away from his 113th birthday when he died earlier this month. He was born and bred in Sardinia and led a calm and hard-working life in the mountains. He was just one of the many centenarians living on the island who took part in a project called Akea, an epidemiological study by Sassari University of all the centenarians on the island.
Luca Deiana, professor of clinical biochemistry at Sassari University, is director of the study. He says the name Akea derives from the expression "a kent'annos," a traditional and widely used greeting in Sardinia that means approximately "health and life for 100 years."
The project was discussed and written up in 1996, says Professor Deiana. Data started to be collected in 1997 when Akea researchers traced 222 people who had celebrated their 100th birthday in 377 municipalities in Sardinia.
According to Professor Deiana, the survey was carried out on the entire territory of the island and three sources were used to validate age: the person's birth certificate from the municipality, their baptism certificate from church archives and the testimony of a first-degree relative.
According to Gianni Pes, one of the researchers on the team, the survey yielded two important findings. "The first is the extremely high number of centenarians," he said. "We found a prevalence of about 13.5 centenarians per 100,000 people and the second important result is the very unusual female to male ratio."
Mr. Pes says a female to male ratio of two to one was discovered on the island, a rare figure if compared to similar studies carried out elsewhere in the world where the ratio is much higher. In addition, the ratio dropped to one to one in the central part of Sardinia, in the province of Nuoro, home to the descendants of ancient Sardinians.
Of the centenarians traced, 141 were interviewed at their homes. Information was collected on basic demographics, health and nutritional aspects during the subjects' life. Recurrent diseases in family members were also recorded.
Research was then taken one step further in an effort to gain more knowledge about the genetic traits that can be associated with extreme longevity and successful aging. Mr. Pes said a very high proportion of centenarians - over 90 percent of those involved in the study - were willing to give a blood sample for further testing. "From about 129 centenarians, we took approximately 40 milliliters of blood and we were able to extract DNA for the genetic research but the genetic tests are on-going and we have only preliminary data," he said.
The blood has been used to test a number of candidate genes for longevity, said Mr. Pes. Until now, a similarity has only been found with one gene that is responsible for the production of lipoprotein in blood. A variant of this gene, the researcher says, is more prevalent in centenarians than in the normal population.
Mr. Pes believes there is no single explanation for longevity in Sardinia. He says genetic and environmental factors are undoubtedly involved, but the percentage to be attributed to each of these has still not been established.
Professor Deiana has a similar view. There's a chromosome heritage, therefore a genetic potential, Professor Deiana says. In addition, he says, there's the environmental conditions, that is, the fact that they live in a place where the food is very healthy, where water is excellent and not polluted. Where air is very clean and without any traces of gases and pollutants. These are life and environmental conditions, the professor says, that favor genetic potential.
Further analysis of the data and blood samples collected continues and Professor Deiana and his team hope to have more definitive genetic results on the reasons for the longevity of Sardinians by the end of the year.