Brain imaging identifies differences in childhood bipolar disorder, ADHD

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Brain imaging identifies differences in childhood bipolar disorder, ADHD

Science Centric

13 October 2010 15:39 GMT

Researchers at the University of Illinois at Chicago are the first to use brain

imaging to examine the effects of emotion on working memory function in children

with paediatric bipolar disorder or attention deficit hyperactivity disorder.

The study is published in the October issue of the Journal of the American

Academy of Child and Adolescent Psychiatry.

PBD and ADHD are very severe developmental disorders that share behavioural

characteristics such as impulsivity, irritability and attention problems.

Using functional magnetic resonance imaging, researchers at UIC examined the

brain activity of children as they performed a working memory task while viewing

faces with different emotions, such as angry, happy or neutral expressions.

The children, ages 10 to 18, were asked to remember the faces and to press a

button in the MR-scanner if they saw the same face that was presented two trials

earlier. The study involved 23 non-medicated children with bipolar disorder, 14

non-medicated children with ADHD and 19 healthy controls.

'It's a simple yet elegant working memory test that tells us a lot about how

their brain remembers stimuli like faces or objects,' said Alessandra

Passarotti, assistant professor of psychiatry at UIC and lead author of the

study. 'We also added in an emotional component - because both disorders show

emotional deficits - to study how their working memory is affected by emotional

challenge.'

The researchers found that while both disorders show dysfunction in the

prefrontal cortex relative to healthy controls, the ADHD group had the most

severe dysfunction in this important region. The prefrontal cortex controls

behaviour, such as impulsivity, and executive function, as well as complex

cognitive processes such as working memory, attention and language.

From a treatment, learning and intervention perspective, the next step for

researchers and clinicians is to figure out how to help patients use their

prefrontal cortex, Passarotti said.

The researchers also found that while the ADHD group had greater dysfunction in

working memory circuits in the brain, the bipolar group had more deficits in

regions of the brain involved in emotion-processing and regulation.

Now that researchers are starting to differentiate between the two disorders at

a brain network level, rather than just at a behavioural level, the long-term

goal is to develop diagnostic tests based on neurological and behavioural

markers of illness that can be used in a clinical setting. Currently patients

are diagnosed using clinical measures, questionnaires, behaviour scales and

interviews with parents.

It is difficult for physicians to differentiate between the two disorders

behaviourally, which may lead to an incorrect diagnosis and wrong medications, a

worsening of symptoms, and greater frustration for children and parents, said

Passarotti, a researcher in UIC's Institute for Juvenile Research.

She said that while researchers still do not understand all of the neurological

deficits that characterise ADHD and PBD profiles, they know that drug treatment

that works for ADHD does not work for bipolar disorder.

'In fact, if you give a stimulant to a child with bipolar disorder, they become

more manic, and this makes their illness even worse, whereas if you give the

mood-regulation medicine commonly prescribed for PBD to a child with ADHD, they

still show a lot of attention deficits and do not show any improvement,'

Passarotti said.

'Our hope is that by better differentiating between these two severe

developmental illnesses, we can help develop more accurate diagnoses and more

targeted treatments for PBD and ADHD.'

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