A Northwestern Medicine scientist has developed the
first blood test to diagnose major depression in
teens, a breakthrough approach that allows an
objective diagnosis by measuring a specific set of
markers found in a patient's blood.
The current method of diagnosing depression is
subjective. It relies on the patient's ability to
recount his symptoms and the physician's ability and
training to interpret them.
Diagnosing teens is an urgent concern because they
are highly vulnerable to depression and difficult to
accurately diagnose due to normal mood changes
during this age period.
The test also is the first to identify subtypes of
depression. It distinguished between teens with
major depression and those with major depression
combined with anxiety disorder. This is the first
evidence that it's possible to diagnose subtypes of
depression from blood, raising the hope for
tailoring care to the different types.
"Right now depression is treated with a blunt
instrument," said Eva Redei, a professor of
psychiatry and behavioral sciences at Northwestern
University Feinberg School of Medicine and lead
investigator of the study, published in
Translational Psychiatry. "It's like treating type 1
diabetes and type 2 diabetes exactly the same way.
We need to do better for these kids."
"This is the first significant step for us to
understand which treatment will be most effective
for an individual patient," added Redei, also the
David Lawrence Stein Professor of Psychiatric
Diseases Affecting Children and Adolescents. "Without
an objective diagnosis, it's very difficult to make
that assessment. The early diagnosis and specific
classification of early major depression could lead
to a larger repertoire of more effective treatments
and enhanced individualized care."
The estimated rates of major depressive disorder
jump from 2 to 4 percent in pre-adolescent children
to 10 to 20 percent by late adolescence. Early onset
of major depression in teens has a poorer prognosis
than when it starts in adulthood. Untreated teens
with this disease experience increases in substance
abuse, social maladjustment, physical illness and
suicide. Their normal development is derailed, and
the disease persists into adulthood.
The depressed teens in the study were patients of
Kathleen Pajer, M.D., a co-first author of the study,
and her colleagues from the Research Institute of
Nationwide Children's Hospital in Columbus, Ohio.
Pajer is now head of Dalhousie University's division
of child and adolescent psychiatry in Nova Scotia,
The study subjects included 14 adolescents with
major depression who had not been clinically treated
and 14 non-depressed adolescents, all between 15 to
19 years old. The depressed and control subjects
were matched by sex and race.
Redei's lab tested the adolescents' blood for 26
genetic blood markers she had identified in previous
research. She discovered 11 of the markers were able
to differentiate between depressed and non-depressed
adolescents. In addition, 18 of the 26 markers
distinguished between patients that had only major
depression and those who had major depression
combined with anxiety disorder.
The blood analysis was done by Brian Andrus from
Redei's lab, the other co-first author of the study,
who was blind to the diagnoses of the subjects.
"These 11 genes are probably the tip of the iceberg
because depression is a complex illness," Redei said.
"But it's an entree into a much bigger phenomenon
that has to be explored. It clearly indicates we can
diagnose from blood and create a blood diagnosis
test for depression."
Redei first isolated and identified the genetic
blood markers for depression and anxiety based on
decades of research with severely depressed and
anxious rats. The rats mirror many behavioral and
physiological abnormalities found in patients with
major depression and anxiety.
Further indicating the challenge in working with
depressed adolescents, none of the teens who were
diagnosed with depression opted for treatment.
"Everybody, including parents, are wary of
treatment, and there remains a social stigma around
depression, which in the peer-pressured world of
teenagers is even more devastating," Redei said.
"Once you can objectively diagnose depression as you
would hypertension or diabetes, the stigma will
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