Research
Boost Immune System
Moderate Aggression May Lead To Stronger Immune Systems
8-30-2000
University Park, Pa. -- Men who are moderately aggressive
have stronger immune systems, according to new study by
a team of researchers from Penn State and the University
of Nebraska.
"We
have observed this relationship in animal studies but this
is the first time that a connection has been made between
aggression and immunity in humans," according to Douglas
Granger, associate professor of biobehavioral health in
Penn State's College of Health and Human Development.
Granger,
Alan Booth, Distinguished Professor of Sociology and Human
Development and Family Studies at Penn State, and David
R. Johnson, professor of sociology at the University of
Nebraska, published their findings in "Human Aggression
and Enumerative Measures of Immunity," in the current
issue of Psychosomatic Medicine, the professional journal
for the American Psychosomatic Society.
"Our
study suggests that differences in people's aggressive behavior
influences how their immune systems are prepared to deal
with infections, viruses and bacteria," says Booth.
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Men who have been in occasional fights or been in
trouble with the law, either as an adult or youth, have immune systems
that may be ready to marshal a more rapid and intense response to
pathogens associated with disease or injury than do men who are seldom
aggressive, according to the researchers. "However, higher levels
of aggression do not convey additional immune benefits," says
Booth.
The researchers studied a sample of 4,415 men aged
30 to 48 years who were interviewed to determine their level of aggressive
behavior. The subjects then underwent medical examination to determine
their state of health. The researchers also took blood samples from
each subject. Those samples were then analyzed for different types
of white blood cells or lymphocytes.
"White blood cells are major players in the body's
immune system," explains Granger. Out of eight enumerative indicators
of immune activity studied, two specialized types of lymphocytes (CD4
cells and B cells) that determine the initiation, magnitude, and duration
of specific cellular immune responses were present in high concentrations
in the circulation of moderately aggressive men. The activity of these
particular lymphocytes, which includes antibody production and secretion
of intercellular signals that turn the immune response on or off has
considerable value for increasing the chances of survival in a pathologically
challenging environment, says Granger.
According to the study, individuals who reported engaging
in two aggressive acts were 30 percent more likely to be in the top
quartile of CD4 cell numbers than those reporting no aggressive acts,
after taking into account current health risks and problems that might
be stimulating the immune system. Men reporting five aggressive acts
were seven percent more likely to be in the top quartile than those
reporting three aggressive acts. Those with eight aggressive acts
were only four percent more likely to be in that category than those
reporting six aggressive acts. Increases in aggressive behavior did
not convey correspondingly higher odds of being in the top quartile.
A parallel pattern was observed for B lymphocytes.
Men reported on 12 different acts of aggression ranging
all the way from playing hooky twice a year or more to fights involving
weapons. Twenty-two percent reported no aggressive acts. Thirty-nine
percent reported, one to two aggressive acts, 27 percent indicated
three to five, and 12 percent recorded six or more aggressive acts.
"The strength of the finding is that we controlled
for all types of factors that could impact the subjects' immune systems,
such as whether the subjects smoked or consumed alcohol, their level
of health and their testosterone scores," says Booth. "While
testosterone was associated with aggressive behavior, it was not the
hormone that accounted for the higher immune cells found among aggressive
men."
The researchers explain that aggressiveness was seen
throughout history as being vital for gaining access to food, protecting
the young, battling predators, and fighting other communities over
resources and territory. Engaging in aggressive behavior, however,
has a high likelihood of leading to trauma, wounds, and exposure to
new diseases.
Foraging, hunting, and war may require travel far
from home. Isolated from nursing care and the protection of the home
community, individuals benefit if their immune system more effectively
recognizes and mobilizes its components to eliminate pathogens, says
Booth. In addition, individuals benefit if their immune system promotes
efficient recovery from disease, facilitates repair of tissue damage
wounds, and records immunologic history to be prepared to respond
more efficiently if subsequent reexposure occurs.
This story has been adapted from a news release issued
by Penn State, www.psu.edu.
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