doesn’t just boost your mood. According to new research, a
glass-half-full attitude also strengthens the immune system.
The study, which tracked changes in optimism and immune
response among first-year law students, found that as students
became more optimistic, they showed stronger cell-mediated
immunity, the flood of immune cells that respond to an
invasion by foreign viruses or bacteria. When optimism
dropped, so did cell-mediated immunity, LiveScience reported.
To probe the connection, Segerstrom recruited 124 incoming law
students and had them complete five questionnaires and
immunity checks over the course of a year. The questionnaires
measured students’ optimism by asking how closely they
identified with statements like “I will be less successful
than most of my classmates.”
To test immunity, the students had a dose of dead mumps virus
or candida yeast injected under the skin of the forearm. These
harmless cocktails trigger a cellular immune response,
resulting in a small bump at the injection site. By measuring
the bump, researchers can estimate the strength of the immune
As the students experienced classes, exams and internship
interviews, their optimism levels rose and fell. So did their
cell-mediated immunity. When optimism went up, so did the
cell-mediated immune response.