Depression can increase people’s mortality as
much as smoking, a new study
Researchers at King’s College London teamed up
with researchers in Norway to investigate whether depression and
anxiety are associated with increased mortality. The large-scale
study was carried out in Norway and involved 61,349 people. The
findings are published in the August issue of the British
Journal of Psychiatry. The study showed that depression is
associated with increased mortality. Moreover, depression is as
great a risk factor for mortality as smoking.
Writing in the British Journal of
Psychiatry, lead researcher Dr Arnstein Mykeltun and
colleagues said: “To illustrate the strength of the association
between depression and mortality, we compared it with the effect of
current smoking – an accepted risk factor for mortality and a
target for major public health initiatives.
“The odds ratios for mortality associated with
smoking and depression were comparable. This illustrates the
potential importance of depression as a risk factor for mortality –
however, the reasons for this require further consideration.”
The researchers found no association between
anxiety and mortality. However, when they studied patients who had
both anxiety and depression they found lower mortality.
Dr Mykeltun and colleagues described this
finding as “counter-intuitive” because having both anxiety and
depression is associated with poorer physical health and more
disability than having depression alone.
The researchers suggest that people who
experience anxiety may be more likely to seek help when they feel
unwell, be more likely to follow any treatment given to them, and
be less likely to indulge in risky behaviour that could put them at
risk of accidental death. “In other words, there may be an
evolutionary advantage of moderate levels of anxiety, a hypothesis
that requires further evaluation,” they said.
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Mykletun A, Bjerkeset O, Øverland S, Prince M, Dewey M and Stewart R (2009) Levels of anxiety and depression as predictors of mortality: the HUNT study, British Journal of Psychiatry, 195: 118-125