The influence of social
relationships on risk for mortality is comparable with well-established
risk factors for mortality.
Humans
are naturally social. Yet, the modern way of life in industrialized
countries is greatly reducing the quantity and quality of
social relationships. Many people in these countries no longer
live in extended families or even near each other. Instead,
they often live on the other side of the country or even across
the world from their relatives. Many also delay getting married
and having children. Likewise, more and more people of all
ages in developed countries are living alone, and loneliness
is becoming increasingly common. In the UK, according to a
recent survey by the Mental Health Foundation, 10% of people
often feel lonely, a third have a close friend or relative
who they think is very lonely, and half think that people
are getting lonelier in general. Similarly, across the Atlantic,
over the past two decades there has been a three-fold increase
in the number of Americans who say they have no close confidants.
There is reason to believe that people are becoming more socially
isolated.
Some
experts think that social isolation is bad for human health.
They point to a 1988 review of five prospective studies (investigations
in which the characteristics of a population are determined
and then the population is followed to see whether any of
these characteristics are associated with specific outcomes)
that showed that people with fewer social relationships die
earlier on average than those with more social relationships.
But, even though many prospective studies of mortality (death)
have included measures of social relationships since that
first review, the idea that a lack of social relationships
is a risk factor for death is still not widely recognized
by health organizations and the public. In this study, therefore,
the researchers undertake a systematic review and meta-analysis
of the relevant literature to determine the extent to which
social relationships influence mortality risk and which aspects
of social relationships are most predictive of mortality.
A systematic review uses predefined criteria to identify all
the research on a given topic; a meta-analysis uses statistical
methods to combine the results of several studies.
WHAT
DID THE RESEARCHERS FIND
The
researchers identified 148 prospective studies that provided
data on individuals' mortality as a function of social relationships
and extracted an “effect size” from each study.
An effect size quantifies the size of a difference between
two groups—here, the difference in the likelihood of
death between groups that differ in terms of their social
relationships. The researchers then used a statistical method
called “random effects modeling” to calculate
the average effect size of the studies expressed as an odds
ratio (OR)—the ratio of the chances of an event happening
in one group to the chances of the same event happening in
the second group. They report that the average OR was 1.5.
That is, people with stronger social relationships had a 50%
increased likelihood of survival than those with weaker social
relationships. Put another way, an OR of 1.5 means that by
the time half of a hypothetical sample of 100 people has died,
there will be five more people alive with stronger social
relationships than people with weaker social relationships.
Importantly, the researchers also report that social relationships
were more predictive of the risk of death in studies that
considered complex measurements of social integration than
in studies that considered simple evaluations such as marital
status.
These
findings indicate that the influence of social relationships
on the risk of death are comparable with well-established
risk factors for mortality such as smoking and alcohol consumption
and exceed the influence of other risk factors such as physical
inactivity and obesity. Furthermore, the overall effect of
social relationships on mortality reported in this meta-analysis
might be an underestimate, because many of the studies used
simple single-item measures of social isolation rather than
a complex measurement. Although further research is needed
to determine exactly how social relationships can be used
to reduce mortality risk, physicians, health professionals,
educators, and the media should now acknowledge that social
relationships influence the health outcomes of adults and
should take social relationships as seriously as other risk
factors that affect mortality, the researchers conclude.
COMMENTS
AND CRITICISM by Sean
Wilson
As
an Exercise Scientist I was particularly curious by Holt-Lunstad’s
ranking of exercise in the least to strongest predictors
graph as depicted in her paper and was very keen to have
a look at this research given that the claims promulgated
by Pinker hinges on this evidence.
So
let’s now look at her data in summary, going from
the least powerful predictor to the strongest.OK? So clean
air, which is great, it doesn’t predict how long you
will live. Whether you have your hypertension treated is
good. Still not a strong predictor. Whether you’re
lean or overweight, you can stop feeling guilty about this,
because it’s only in third place. How much exercise
you get is next, still only a moderate predictor. Whether
you’ve had a cardiac event and you’re in rehab
and exercising, getting higher now. Whether you’ve
had a flu vaccine. Did anybody here know that having a flu
vaccine protects you more than doing exercise? Whether you
were drinking and quit, or whether you’re a moderate
drinker, whether you don’t smoke, or if you did, whether
you quit, and getting towards the top predictors are two
features of your social life. First, your close relationships.
These are the people that you can call on for a loan if
you need money suddenly, who will call the doctor if you’re
not feeling well or who will take you to the hospital, or
who will sit with you if you’re having an existential
crisis, if you’re in despair. Those people, that little
clutch of people are a strong predictor, if you have them,
of how long you’ll live. And then something that surprised
me, something that’s called social integration. This
means how much you interact with people as you move through
your day. How many people do you talk to? And these mean
both your weak and your strong bonds, so not just the people
you’re really close to, who mean a lot to you, but,
like, do you talk to the guy who every day makes you your
coffee? Do you talk to the postman? Do you talk to the woman
who walks by your house every day with her dog? Do you play
bridge or poker, have a book club? Those interactions are
one of the strongest predictors of how long you’ll
live.
One
of the big changes in exercise research over the last decade
or so is the development of, and refinement in how accurately
physical activity and exercise can be measured. In earlier
studies that assessed the effects of exercise on mortality,
the methods utilised to ascertain the data on the amount
of exercise performed was quite crude and was established
subjectively. In other words, those involved in such studies
were usually asked via a questionnaire how much exercise
and/or physical activity do they do everyday/in a week?
As you would appreciate data collected in this fashion is
unlikely to be very accurate. It would not therefore be
a true reflection of what participants were actually doing.
What
does this mean for the graph that Pinker used in her presentation
that I have been discussing. In short, a lot. The influence
and impact of exercise and physical activity on mortality
is far stronger than many acknowledge or give credit. Based
on more recent research that is able to accurately quantify
levels of physical activity and exercise, particularly MVPA,
much greater promotion, awareness and utilisation (and rightly
so) should be placed on one of the most powerful ways of
reducing your chances of premature death. Unfortunately,
this TED talk by Susan Pinker cites what is arguably outdated
15-year old exercise data that diminishes and misconstrues
– to a significantly large and impressionable audience
– the very strong inverse relationship that exists
between physical activity and mortality. This needs to be
called out, so here you go, I am calling this out as loudly
as I can.
