Page 185 - Biobehavioral Resilence to Stress

162 Biobehavioral Resilience to Stress

expectancies were more likely to develop symptoms. Among these individu-
als, the disease itself progressed more rapidly.
Social support can exert positive and health-promoting effects on the

immune system. Conversely, social isolation is a major risk factor for mor-
bidity and mortality (House, Landis & Umberson, 1988). Kiecolt-Glaser,
Garner et al. (1984) found that the number of natural killer cells (a type of

lymphocyte) in the immune system and the efficiency with which these cells
destroyed diseased cells (such as tumor cells) were reduced in response to
stress (studying for and taking medical school exams). Furthermore, and most

importantly here, these effects were most dramatic in students who reported
greater loneliness. Similar results were found in an in-patient psychiatric set-
ting (Kiecolt-Glaser, Ricker et al., 1984). On the contrary, individuals who
have strong social networks (families, friends, social and religious affi liates,
coworkers) are generally better able to resist infection (Uchino, Cacioppo &
Kiecolt-Glaser, 1996). Immune response to a hepatitis vaccine inoculation
during a time of high stress (a three-day series of medical school exams)
was stronger among students who reported greater social support (Glaser
et al., 1992). Two recent studies by Cohen and colleagues have also dem-

onstrated this effect very convincingly. Individuals who have diverse social
networks and individuals who report the least amount of loneliness are least
susceptible to infection by viruses that cause colds, and also show the high-
est antibody responses to flu vaccinations (Cohen, Doyle, Skoner, Rabin &

Gwaltney, 1997; Pressman et al., 2005). Th ese findings have direct relevance

to resilience in extreme environments. For example, those who participate in
expeditions and scientific endeavors in the Antarctic must contend not only

with extreme weather, but also with physical isolation in cramped living con-
ditions. Individuals who live and work in such conditions oft en have reduced
cell-mediated immune responses (Mehta, Pierson, Cooley, Dubow & Lugg,
2000; Muller, Lugg & Quinn, 1995; Williams, Climie, Muller & Lugg, 1986).

Resilience Modifiers: Exercise and Other Interventions

Aerobic fitness is intimately tied to optimal physical and cognitive perfor-
mance. Numerous studies have reported a direct relationship between aero-
bic fitness and maintenance of cognitive abilities during the aging process.

Clarkson-Smith and Hartley (1989, 1990) found that physically active adults
performed better than their low-fit counterparts on tests of reaction time,

memory, and reasoning. In older adults, these diff erences are magnifi ed as
cognitive tasks become increasingly complex (Shay & Roth, 1992). More-
over, cognitive performance can be improved by improving aerobic fi tness.
Hawkins, Kramer, and Capaldi (1992) tested older adults (63–82 years) and
found that participation in a 10-week exercise program led to signifi cant

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