So:
friendship and socialising are good for your mental and physical health?
Not
always. Like everything in life, the picture is more complex than that.
Sometimes friends get each other into bad habits.
One
study in the late 1990s8 found that, contrary to expectation, among
205 HIV-positive men, lower levels of
loneliness predicted more rapid declines in CD4 counts. These CD4 declines did
not seem to have anything to do with medication adherence or sexual practices.
Significantly, they also were not correlated with negative emotions.
An
exception to the rule? No. A review of other studies of friendship and social
support9 by the same authors found that, quite consistently, people
who perceived themselves as having stronger links to friendship networks
actually progressed faster to AIDS – if they were asymptomatic. Once they
became sick, however, the opposite happened: supportive friends produced better
health outcomes and survival.
People
don’t seek friends in order to have a healthier lifestyle: they seek friendship
because it makes them happier. But if those friends are doing things that are
bad for your health, this can have the paradoxical effect that social
integration can make you ill. The authors found that strong friendship networks
tended to expose people to more temptation: they were more likely to take part
in high-risk sexual behaviour and “socially facilitated health-compromising behaviour”
such as drink and drugs.
Social
ties don’t always help in prevention either. This was noticed in a study of a
gay men’s prevention intervention that reported in 2004.10 Peer-led workshops
in San Francisco and New York were designed to get gay men talking about the
sexual risks they’d been taking and think of ways of reducing the risk.
Overall, the intervention did not produce a significant reduction in unsafe
sex, to the researchers’ disappointment. When they investigated why, they found
that the lower-risk gay men were tending to adopt the sexual practices of the
higher-risk men. Peer group influences were working – but in the wrong way.
The
way this works has been demonstrated in an extraordinary series of studies by
Nicholas Christakis and James Fowler of the Harvard School of Public Health.
The town of Framingham, Massachusetts, has given its name to a measure of heart
attack risk – your Framingham score – because a huge scientific study has been
ongoing since 1948, quantifying the risks associated with heart attacks in
three generations of New Englanders.
The
original records of the study included the details of study participants’ close
friends, colleagues and family members, compiled so that people who dropped out
of the study could be traced. This allowed Christakis and Fowler not only to
see if social integration predicted health behaviours, but also to see how
members of the social network influenced each other over time. If one person in
a closely connected group changed their behaviour, would others follow? How
fast did a health behaviour spread through a network?
They
investigated a troubling behavioural epidemic that has taken hold in the last
few decades, and threatens the health of people worldwide – obesity.11
They found that in 1948, 10% of the Framingham study group was obese. In 1985,
18% of the 12,067 people they investigated were obese; but the rate accelerated
fiercely and by 2005 40% of the population was obese.
A 2004 study of 90 people with HIV found that greater social support
related to better adherence, whereas higher depression scores related to
non-adherence.
Christakis
and Fowler found that obesity spread as if it was a virus, radiating out from
individuals. Clusters of people would become obese at the same time, and the
closer you were to someone who was obese, the more likely you were to become
obese yourself.
But
for the purposes of this article, the most striking finding is that the most
‘infectious’ people were close friends. Having an obese spouse increased your
chances of becoming obese by 37%, but having an obese friend increased the risk
by 60%.
This
‘infection rate’ ensured that thin people whose friends were obese soon became
very rare, and that obese people tended to be the most well-connected; there
were two large, closely connected networks of predominantly obese people in the
centre of the social network, and a lot of thin loners on the outside. Doesn’t
this sound like the studies of closely related genetic ‘clusters’ of HIV in
high-risk communities?
This
all seemed to be related to social norms of diet and physical appearance.
Interviewed in Wired Magazine earlier
this year, Nicholas Christakis said: “A bunch of people discovered fast food at
the same time. Then the network took over.”