Five genes were investigated, but only one had a tie-in to longevity.
The study was led by Bradley Wilcox, MD, of the Pacific Health Research Institute and Kuakini Medical Center.
In a news release, Willcox called the findings "very surprising and exciting."
Researchers looked at two groups of men who had data collected about their health in 1991-1993. The men were all of Japanese descent from the Hawaii Lifespan Study and at that time the average age was 78.
From this group, the researchers followed those who were still alive in 2007 (at least 95 years old) and considered them "longevity" cases. They compared these men to men from the group who had died before they turned 81 years old (considered "averaged-lived").
The participants were examined for their general health, biological characteristics, whether they had a history of cancer, diabetes , or cardiovascular related diseases, and how well they could function overall.
Researchers also studied the men's genetic makeup. One gene called FOXO3A caught the researchers' attention. Participants who were in better health had similarities on that gene.
Those similarities were also noticed 15 years later in the men who were healthier and lived longer than their co-participants. From that baseline group, researchers took 213 men who by 2007 had reached age 95 or older. The average age reached in 2007 was 98 years; some lived as long as 106. They became the longevity group.
The comparison group consisted of 402 men who died before reaching age 81.
The study showed the long-lived group was leaner (lower waist-to-hip ratio), had lower levels of blood fats (triglycerides), lower glucose and insulin levels, and greater prevalence of FOXO3A gene variation at baseline.
Members of the group that lived the longest also said they were in better health with less heart disease and cancer. They also appeared better able to walk, but had lower grip strength than the younger comparison group.
In their article, the researchers write that "up to 50% of the variation in human life span might be explained by genetic differences."
The FOXO3A gene is located on what researchers call the "insulin signaling pathway" and may be linked to how cells respond to stress.
In studies done with mice and roundworms, genes that are along the insulin signaling pathway seem to protect against obesity that can come with aging, stress on a cellular level, and life span.
The study was funded by the National Institute of Aging. It appears in September's issue of Proceedings of the National Academy of Sciences.
By Kelley Colihan
Reviewed by Louise Chang
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