For older adults, having more or closer family members in one's social network decreases his or her likelihood of death, but having a larger or closer group of friends does not, finds a new study that will be presented at the 111th Annual Meeting of the American Sociological Association (ASA).

"We found that older individuals who had more family in their network, as well as older people who were closer with their family were less likely to die," said James Iveniuk, the lead author of the study and a post-doctoral researcher at the University of Toronto's Dalla Lana School of Public Health. "No such associations were observed for number of or closeness to friends."

Titled, "Social Relationships and Mortality in Older Adulthood," the study used nationally representative data from the 2005/2006 and 2010/2011 survey waves of the National Social Life, Health, and Aging Project (NSHAP), to investigate which aspects of social networks are most important for postponing mortality. Mortality of wave one respondents, who were 57 to 85-years old, was assessed at wave two.

In the first wave, these older adults were asked to list up to five of their closest confidants, describe in detail the nature of each relationship, and indicate how close they felt to each person. Excluding spouses, the average number of close confidants named was 2.91, and most older adults perceived high levels of support from their social contacts. Additionally, most respondents were married, in good physical health, and reported not being very lonely.

Iveniuk and co-author L. Philip Schumm, a senior biostatician at the University of Chicago, found that older adults who reported feeling "extremely close" on average to the non-spousal family members they listed as among their closest confidants had about a six percent risk of mortality within the next five years, compared to approximately a 14 percent risk of mortality among those who reported feeling "not very close" to the family members they listed.

Furthermore, the study found that respondents who listed more non-spousal family members in their network -- irrespective of closeness -- had lower odds of death compared to those who listed fewer family members. "Regardless of the emotional content of a connection, simply having a social relationship with another person may have benefits for longevity," Iveniuk said.

Iveniuk said he was surprised that feeling closer to one's family members and having more relatives as confidants decreased the risk of death for older adults, but that the same was not true of relationships with friends.

"Because you can choose your friends, you might, therefore, expect that relationships with friends would be more important for mortality, since you might be better able to customize your friend network to meet your specific needs," Iveniuk said. "But that account isn't supported by the data -- it is the people who in some sense you cannot choose, and who also have little choice about choosing you, who seem to provide the greatest benefit to longevity."

Besides comparing friendships to relationships with family members, the study examined the characteristics of social networks in general and their association with mortality. The four factors most consistently associated with reduced mortality risk were being married, larger network size, greater participation in social organizations, and feeling closer to one's confidants, which all mattered to about the same degree. Factors found to be less important included time with confidants, access to social support, and feelings of loneliness.

"I expected the association between participation in social organizations and mortality to diminish in size considerably once we controlled for other aspects of peoples' social worlds, but that didn't happen," Iveniuk said.

Interestingly, marriage was found to have positive effects on longevity, regardless of marital quality. "We observed no association between measures of support from the spouse and mortality, indicating that the presence of a marital bond may be more important for longevity than certain aspects of the bond itself," Iveniuk said.

Generally, Iveniuk said his findings underscore the substantial importance of familial relationships for longevity. "Going back to the very first sociological theorists, many different thinkers have noted that there is some kind of special significance that people attribute to family ties, leading people to stay close to and support people who wouldn't necessarily be individuals that they would associate with if they had the choice," Iveniuk said.