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"Jack Stall"(Ashton Holmes) confronts a bully at school in New Line Cinemas thriller A History of Violence.

Targeted rejection, in which students — even those considered to be at the top of the teen social hierarchy — are personally shunned by a friend or singled our for taunting, can have measurable effects on the immune system that can increase risk for diabetes, mental illness, heart disease, stroke and some cancers later in life, according to new research.

"High social status in both humans and animals tends to protect against the negative health effects of chronic stress. However, social rejection — which can be a threat to social status — may be different from other types of stresses," TIME reported.

Michael Murphy of the University of British Columbia in Vancouver, Canada, set out to determine how social stress could affect immune response. Murphy examined 147 young women, ages 15 to 19, who scored high on an attitude test, showing a high risk of becoming depressed by having either a parent or a sibling with depression.

The researchers met with the teens every six months for 2.5 years, taking blood samples and interviewing participants to assess their moods in correlation with their social lives and exposure to rejection. The girls ranked their social status through visual symbols of their school's academic and social hierarchy.

The girls who had been recently targeted for rejection had higher levels of substances that lead to the production to two inflammatory proteins.

“These data demonstrate that exposure to a recent targeted rejection life event activates the molecular signaling pathways that regulate inflammation,” the authors wrote, noting that “if sustained, this heightened inflammatory signaling could have implications for life-span health.”

Social interaction and approval stimulate reward centres in the teenage brain, Dr. Louann Brizendine, a clinician at the University of California, San Francisco and author of the best-selling book "The Female Brain," told Edmonton Journal. Young adults typically venture out to form their own social circles beyond the family in their teen years.

Parents who have noticed that their teen has become depressed or isolated should consider sending them to a counselor or a family doctor, Brizendine told Edmonton Journal. “Society still holds parents responsible for teenagers, but teenagers don’t reach out in their moments of social isolation.”

Rachel Lowry is a reporter intern for the Deseret News. She has lived in London and is an English graduate from Brigham Young University. Contact her at rachel.lowry@gmail.com or visit www.rachellowry.blogspot.com.