To understand the study do read the whole piece, but here are the key conclusions:
“What allows people to work, and love, as they grow old? By the time the Grant Study men had entered retirement, Vaillant, who had then been following them for a quarter century, had identified seven major factors that predict healthy aging, both physically and psychologically.
Employing mature adaptations was one. The others were education, stable marriage, not smoking, not abusing alcohol, some exercise, and healthy weight. Of the 106 Harvard men who had five or six of these factors in their favor at age 50, half ended up at 80 as what Vaillant called “happy-well” and only 7.5 percent as “sad-sick.” Meanwhile, of the men who had three or fewer of the health factors at age 50, none ended up “happy-well” at 80. Even if they had been in adequate physical shape at 50, the men who had three or fewer protective factors were three times as likely to be dead at 80 as those with four or more factors.
Good sibling relationships seem especially powerful: 93 percent of the men who were thriving at age 65 had been close to a brother or sister when younger. In an interview in the March 2008 newsletter to the Grant Study subjects, Vaillant was asked, “What have you learned from the Grant Study men?” Vaillant’s response: “That the only thing that really matters in life are your relationships to other people.”