Social ties can influence peoples’ moods as well as their physical well-being, said Nicholas Christakis in a lecture Monday to Syracuse University students.

Named one of 2009’s most influential people by Time magazine, Christakis, a Harvard medical professor in the departments of health care policy, medicine and sociology, stressed the relationships between people, social networks and health as part of the eighth annual SU Center for Health and Behavior lecture, “Social Networks and Health.” The lecture took place in the Joyce Hergenhan Auditorium in the S.I. Newhouse School of Public Communications.

“I became obsessed with this topic,” Christakis said. “Social networks are these intricate things of beauty. They are so elaborate, complex and ubiquitous one has to ask a set of fundamental questions: what purpose do they serve, how do they work and how do they affect us?”

Christakis’ work as a hospice doctor with terminally ill patients in the South Side of Chicago was a catalyst for his research, he said. Christakis couldn’t help but notice how the illness of patients affected those around them, he said.

“Something happens to the patient, which affects her daughter, which affects her husband, which affects his friend,” Christakis said. “Something is spreading in the network from one person to another.”

In 2008, Christakis and collaborator James Fowler, a professor at the Center for Wireless and Population Health Systems at the University of California, San Diego, mapped the relationships of more than 12,000 people in a small Massachusetts city. Among their findings was the statistical correlation between body sizes within networks — thin people tend to be friends with thin people, and obese people tend to be friends with obese people, Christakis said.

“If your friend is obese, you have a 45 percent chance of being obese yourself,” Christakis said. “If your friend’s friend is obese, you have a 25 percent higher risk, and if your friend’s friend’s friend is obese, you have about a 10 percent higher risk.”

His research has also looked at the effects of neighborhoods on health, the environment’s affect on lifespan, the widowhood effect — dying of a broken heart — and the genetic basis for human behavior. Christakis believes his research has varied implications, including the potential for the creation of a new structure for social hierarchy, he said.

There are three possible explanations for clustering, or how social groups and networks form, he said. The three include induction, the social domino effect; homophily, the birds-of-a-feather link; and confounding, wherein something happens in the environment that makes people lose or gain weight at the same time.

Nazanin Khajoueenejad, a sophomore biology major, said the lecture was fascinating.

“I never correlated how my behavior affects others,” Khajoueenejad said.

She said she thinks the online relationships between people reflect the environment of a college campus.

Michael P. Carey, director of the Center for Health and Behavior, lauded Christakis for the broad reach of his research.

“Outstanding talk,” Carey began. “There’s a link between medicine, public health and happiness.”

Published on April 12, 2010 at 12:00 pm