Bipolar Youth Show Distinct Pattern of Brain Development
• Science Update
The first picturess of the brain changing before-and-after the onset of pediatric bipolar disorder reveal a distinct pattern of development, when compared to that seen in healthy youth or in childhood onset schizophrenia. Repeated magnetic resonance imaging (MRI) brain scans of youth, ages 7-22, followed prospectively as they developed symptoms of mania and depression, showed asymmetrical gains and losses of the brain's working tissue, or gray matter, report scientists at the National Institute of Mental Health (NIMH) and the University of California at Los Angeles (UCLA).
Nitin Gogtay, M.D., Judith Rapoport, M.D., NIMH Child Psychiatry Branch, and colleagues, report on their discovery in the September, 2007 issue of the Journal of Child Psychology and Psychiatry.
"Our findings should help put to rest speculation that pediatric bipolar disorder and childhood onset schizophrenia might stem from the same underlying illness process, despite overlapping symptoms and genetics," said Gogtay.
Some pruning of gray matter, neurons and their connections, is normal as the brain matures and circuitry is streamlined for efficiency. Cases of childhood onset schizophrenia, which are very rare, show an exaggeration of this normal pattern of pervasive gray matter loss — with affected teens losing gray matter in the prefrontal cortex at four times the normal rate.
By contrast, Gogtay's team found that children with bipolar disorder showed a more complicated pattern of gray matter gains in certain areas in the left hemisphere and losses in the right hemisphere, and in mood regulating circuitry in the mid-front part of the brain.
A pattern similar to that seen in bipolar youth was shared by youth diagnosed as "multi-dimensionally impaired" (MDI). These children had neither bipolar disorder nor schizophrenia, but experienced short psychotic episodes, attention problems, and — like their bipolar peers — unstable moods. The latter suggested that the developmental pattern might reflect a tendency toward mood instability in general.
The new pictures (see movie below) emerged from long-term, prospective studies in which children were scanned every two years to learn how the brain develops normally, and how it develops in childhood psychiatric disorders. Nine children who were initially suspected of having schizophrenia, but ultimately diagnosed with bipolar disorder, were included in the current study, along with 8 children with MDI.