|Extreme Irritability: Is It Childhood Bipolar
Brain’s electrical signals provide clues.
Results of a new study may help improve the diagnosis and treatment
of two debilitating childhood mental disorders — pediatric
bipolar disorder (BD) and a syndrome called severe mood dysregulation
(SMD). When the brain’s electrical signals were measured during
mildly frustrating situations, researchers from the National Institute
of Mental Health (NIMH), of the National Institutes of Health,
found a very different pattern in children with SMD, compared with
children who had BD. The results indicate that different brain
mechanisms may lead to irritability in children with SMD, suggesting
that they may have an illness other than BD and may require different
“These aren’t children with the occasional bad moods you see in
most kids. They’re typically very ill, with symptoms that interfere
with their lives in major ways. Establishing clear diagnostic criteria
is an essential step toward making sure they get the help they
need,” said NIMH Director Thomas R. Insel, M.D.
Children have a comparatively low rate of BD, but the rate increases
with age, to approximately 1 percent among adolescents. About 3
percent of pre-adolescent and adolescent youth are estimated to
have SMD. Mood-stabilizing and antipsychotic medications are used
to treat children with BD, although the data on their effectiveness
are limited and several studies are underway. Since SMD was only
recently defined, there are no systematic studies on its treatment,
and children with SMD are often treated as if they have BD.
Defining pediatric BD is a major issue in child psychiatry, because
the disorder tends to be severe in this age group and the rate
of diagnosed cases is rising. Until recent years, most studies
of BD were conducted in adults. Some researchers maintain that
pediatric BD should be defined more broadly to include children
with SMD, an assertion countered by the new finding. Results of
the study were published in the February 2007 issue of the American
Journal of Psychiatry.
The classic definition of BD (http://www.nimh.nih.gov/publicat/bipolarupdate.cfm)
includes extreme, sustained mood swings that range from over-excited,
elated moods and irritability — the manic phase of the disorder — to
depression. In contrast, children with SMD are extremely irritable
and hyperactive, but do not have clear-cut manic episodes.
One component of irritability is the tendency to get acutely frustrated
when a goal is not met. Thus, through electroencephalograms (EEGs),
the researchers could observe the brain's electrical signals that
occurred during frustration while children with either disorder
performed simple tasks.
The new study shows that clinicians some day could use biological
measurements, such as EEGs, to help make psychiatric diagnoses,
in combination with clinical symptoms. Currently, clinicians diagnose
mental illnesses based on symptoms alone. The difficulty of diagnosing
BD in children is compounded by the frequent co-occurrence of one
or more other mental disorders.
“We’re approaching the day when we’ll be able to use neuroscience
techniques to improve psychiatric diagnoses. Pediatric BD has some
of the most pressing needs in this regard, because of its severity
and because of questions about how to best make the diagnosis,” said
senior author Ellen Leibenluft, M.D., Chief of the Unit on Bipolar
Spectrum Disorders in the Emotion and Development Branch of the
NIMH Mood and Anxiety Disorders Research Program.
In this study, scientists obtained EEGs of 35 children with classic
BD, 21 children with SMD, and 26 healthy children (average age
12 to13) while they performed a task repeatedly; each time they
did the task, they won or lost 10 cents. The task was frustrating
because the children often lost money.
The researchers found that while both the children with BD and
those with SMD became more frustrated than did healthy children
performing the same task, the brain mechanisms associated with
their frustration differed. Children with BD had an abnormality
in the brain’s P3 electrical signals, which measure ability to
purposefully direct attention, but children with SMD had abnormalities
in N1 signals, which occur when a stimulus grabs someone’s attention.
Both abnormalities suggest deficits in the brain’s attention-related
activity, but in different phases of that activity.
“If future research indicates that BD and SMD are two separate
disorders, this could guide parents and physicians toward the right
treatments,” said first author Brendan Rich, Ph.D., of the NIMH
Unit on Bipolar Spectrum Disorders. “A good example is that medication
prescribed for symptoms seen in SMD, such as stimulant medication,
might be inappropriate for a child with classically defined bipolar
disorder,” he said.
NIMH scientists Mariana Schmajuk, B.S., and Daniel Pine, M.D.,
also contributed to the research, as did University of Maryland
scientists Koraly E. Perez-Edgar, Ph.D., (currently at George
Mason University) and Nathan A. Fox, Ph.D.
The National Institute of Mental Health (NIMH) mission is
to reduce the burden of mental and behavioral disorders through
research on mind, brain, and behavior. More information is available
at the NIMH website: http://www.nimh.nih.gov/.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.