(Corrects spelling of Goodyer and misattribution of quote in
paras 15, 16)
* Depression affects 350 million people worldwide
* Biomarker means screening could find teenagers at risk
* Early intervention, treatment can limit mental illness
By Kate Kelland
LONDON, Feb 17 British brain scientists have
identified the first biomarker, or biological signpost, for
clinical depression and say it could help find boys in
particular who are at risk of developing the debilitating mental
In a study in the Proceedings of the National Academies of
Science (PNAS) journal, the team found that teenage boys who
have a combination of depressive symptoms and raised levels of
the stress hormone cortisol are up to 14 times more likely to
develop major depression than those who show neither trait.
The findings suggest teenagers could in future be screened
for such signals, and those at highest risk could be helped to
develop the kind of coping strategies and "brain fitness" to
help them avoid becoming depressive.
"We're very bad about looking after our mental health, and
yet the problems of mental health are extremely common," said
Barbara Sahakian, a Cambridge University professor of clinical
neuropsychology who worked on the study.
"Depression is one of the greatest global burdens of disease
- it's a much bigger problem than heart disease or cancer and
it's much more expensive."
Depression affects around 350 million people worldwide and
at its worst can blight patients' lives for decades, affecting
their relationships, work and ability to function. It can also
lead to suicide, which alone leads to a million deaths a year.
"Depression is a terrible illness," said Ian Goodyer, a
child and adolescent psychiatrist who led the research team.
"(And) we now have a very real way of identifying those teenage
boys most likely to develop clinical depression."
He said armed with such knowledge, doctors and other carers
could target prevention strategies at depression-vulnerable boys
and "hopefully help reduce their risk of serious episodes of
depression and their consequences in adult life".
According to the World Health Organisation, prevention
programmes - including boosting cognitive, problem-solving and
social skills in children - have been shown to reduce
depression, and earlier intervention is more effective.
Different factors are thought to influence the development
of depression, including genetics, brain chemistry, lifestyle
and upbringing. Key triggers for the condition can include
stressful life events, medical illness and alcohol abuse.
For their study, Goodyer's team measured levels of cortisol
in saliva from two large separate groups of teenagers. The first
group of 660 provided samples on four school mornings within a
week and then again 12 months later. A second group of 1,198
teenagers gave samples over three school mornings.
Using self-reports, collected over 12 months, of any
symptoms of depression - such as feeling sad or anxious - and
combining them with the cortisol results, the researchers then
divided the teenagers into four sub-groups ranging from those
with normal levels of cortisol and low symptoms of depression in
Group 1 through to those teenagers with more cortisol and high
symptoms of depression in Group 4.
Tracking the teenagers for three years, the team found that
those in Group 4 were on average seven times more likely than
those in Group 1, and two to three times more likely than in the
other two groups, to develop clinical depression.
Further analysis showed that boys in Group 4 were 14 times
more likely to develop clinical depression than those in Group
1, and two to four times more likely to develop it than either
of the other two groups.
Commenting on the findings, Oliver Howes at the Institute of
Psychiatry and the Maudsley Hospital at King's College London
noted that depression is "incredibly costly to society" and
cited a 2011 European College of Neuropsychopharmacology report
that said mood disorders cost Europe alone more than 110 billion
euros ($150 bln) a year.
"We desperately need ways to identify people at high risk of
depression early so we can potentially prevent its onset and
treat it early to reduce its burden. In this context, (this)
study... is a landmark in the field," he said.
($1 = 0.7307 euros)
(Editing by Jon Boyle)