Research
Boost Immune System
Depression Alters Immune Systems By Decreasing Physical
Activity
11-30-1999
Women with mild to moderately severe depression show alterations
in their immune systems, according to researchers at Carnegie-Mellon
University and the University of Pittsburgh School of Medicine.
"We
also found that depression was associated with greater tobacco
and caffeine consumption, less physical activity, and poorer
sleep quality," said Gregory E. Miller, PhD, lead author
of the study.
The
researchers believe they have found a brain-behavior connection
that links the altered immune response of mildly to severely
depressed women outpatients to their typically low level
of physical activity. From 42 to 63 percent of the differences
in specific immune functions between depressed and non-depressed
study participants was related to physical activity, the
researchers found. They used the participants' production
of lymphocytes under stimulation by mitogens to measure
the impact of various depression-related factors on their
immune function.
The
study, appearing in the November/December issue of Psychosomatic
Medicine, presents the first published data to identify
a behavior that might be responsible for the immune system
alterations that occur in depressed women, the researchers
pointed out.
These
new findings have potentially wide future impact because
the observed immune differences between depressed and non-depressed
women could help to explain the higher rates of sickness
and death observed repeatedly among depressed individuals,
the scientists said.
The
Pittsburgh scientists worked with 32 non-hospitalized clinically
depressed women and 32 healthy non-depressed women matched
as controls. Miller and colleagues Sheldon Cohen, PhD and
Tracy B. Herbert, PhD, investigated a broad spectrum of
both endocrine and health practice pathways through which
depression might influence immune function.
The
possibility that depression might influence immune function
through the neuroendocrine system was tested by measuring
participants' levels of hormones such as norepinephrine,
cortisol, estradiol, epinephrine, and progesterone. Researchers
found, however, that hormone levels did not account for
differences in immune response between the groups of depressed
and non-depressed women.
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