Loneliness, Like
Chronic Stress, Taxes the Immune System, Researchers Find
New
research links loneliness to a number of dysfunctional immune responses,
suggesting that being lonely has the potential to harm overall health.
Researchers
found that people who were more lonely showed signs of elevated latent herpes
virus reactivation and produced more inflammation-related proteins in response
to acute stress than did people who felt more socially connected.
Reactivation
of a latent herpes virus is known to be associated with stress, suggesting that
loneliness functions as a chronic stressor that triggers a poorly controlled
immune response.
"It
is clear from previous research that poor-quality relationships are linked to a
number of health problems, including premature mortality and all sorts of other
very serious health conditions. And people who are lonely clearly feel like
they are in poor-quality relationships," said Lisa Jaremka, a postdoctoral
fellow at the Institute for Behavioral Medicine Research at Ohio State
University and lead author of the research.
"One
reason this type of research is important is to understand how loneliness and
relationships broadly affect health. The more we understand about the process,
the more potential there is to counter those negative effects -- to perhaps
intervene. If we don't know the physiological processes, what are we going to
do to change them?"
The
results are based on a series of studies conducted with two populations: a
healthy group of overweight middle-aged adults and a group of breast cancer
survivors. The researchers measured loneliness in all studies using the UCLA
Loneliness Scale, a questionnaire that assesses perceptions of social isolation
and loneliness.
Jaremka
will present the research January 19 at the Society for Personality and Social
Psychology annual meeting in New Orleans.
The
researchers first sought to obtain a snapshot of immune system behavior related
to loneliness by gauging levels of antibodies in the blood that are produced
when herpes viruses are reactivated.
Participants
were 200 breast cancer survivors who were between two months and three years
past completion of cancer treatment with an average age of 51 years. Their
blood was analyzed for the presence of antibodies against Epstein-Barr virus
and cytomegalovirus.
Both
are herpes viruses that infect a majority of Americans. About half of
infections do not produce illness, but once a person is infected, the viruses
remain dormant in the body and can be reactivated, resulting in elevated
antibody levels, or titers -- again, often producing no symptoms but hinting at
regulatory problems in the cellular immune system.
Lonelier
participants had higher levels of antibodies against cytomegalovirus than did
less lonely participants, and those higher antibody levels were related to more
pain, depression and fatigue symptoms. No difference was seen in Epstein-Barr
virus antibody levels, possibly because this reactivation is linked to age and
many of these participants were somewhat older, meaning reactivation related to
loneliness would be difficult to detect, Jaremka said.
Previous
research has suggested that stress can promote reactivation of these viruses,
also resulting in elevated antibody titers.
"The
same processes involved in stress and reactivation of these viruses is probably
also relevant to the loneliness findings," Jaremka said. "Loneliness
has been thought of in many ways as a chronic stressor -- a socially painful
situation that can last for quite a long time."
In
an additional set of studies, the scientists sought to determine how loneliness
affected the production of proinflammatory proteins, or cytokines, in response
to stress. These studies were conducted with 144 women from the same group of
breast cancer survivors and a group of 134 overweight middle-aged and older
adults with no major health problems.
Baseline
blood samples were taken from all participants, who were then subjected to
stress -- they were asked to deliver an impromptu five-minute speech and
perform a mental arithmetic task in front of a video camera and three
panelists. Researchers followed by stimulating the participants' immune systems
with lipopolysaccharide, a compound found on bacterial cell walls that is known
to trigger an immune response.
In
both populations, those who were lonelier produced significantly higher levels
of a cytokine called interleukin-6, or IL-6, in response to acute stress than
did participants who were more socially connected. Levels of another cytokine,
tumor necrosis factor-alpha, also rose more dramatically in lonelier
participants than in less lonely participants, but the findings were
significant by statistical standards in only one study group, the healthy
adults.
In
the study with breast cancer survivors, researchers also tested for levels of
the cytokine interleukin 1-beta, which was produced at higher levels in
lonelier participants.
When
the scientists controlled for a number of factors, including sleep quality, age
and general health measures, the results were the same.
"We
saw consistency in the sense that more lonely people in both studies had more
inflammation than less lonely people," Jaremka said.
"It's
also important to remember the flip side, which is that people who feel very
socially connected are experiencing more positive outcomes," she said.
Story Source:
The
above story is reprinted from materials provided by Ohio State University, via Newswise. The
original article was written by Emily Caldwell.
