ients who subsequently developed a first episode of psychosis. The white matter abnormalities were seen particularly in the superior longitudinal fasciculus (SLF) and were associated with increased severity of symptomatology. The overall degree of white matter alteration was also significantly related to clinical outcome 15 months later.
Editor’s Note: The SLF is a major neuronal conduit between prefrontal cortical systems, which are responsible for cognition and planning, and the parietal cortex, which is responsible for spatial abilities. Disruption of this fiber track has been related to difficulties in social cognition and “theory of mind” concepts, like inferring what others might be thinking.
There is considerable evidence that children with bipolar disorder have smaller amygdalas, and the amygdala also appears to be hyper-reactive when these children perform facial emotion recognition tasks. A symposium on longitudinal imaging studies in pediatric bipolar disorder was held at the 2012 meeting of the American Academy of Child and Adolescent Psychiatry to shed light on other brain abnormalities in these children.
Researcher Nancy Aldeman reported that there is some evidence children with bipolar disorder have decreased gray matter volume in parts of the brain including the subgenual cingulate gyrus, the orbital frontal cortex, and the superior temporal gyrus, as well as the left dorsolateral prefrontal cortex and amygdala. At the same time there is evidence of increased size of the basal ganglia. These abnormalities do not appear to precede the onset of the illness.
Some changes occur over the course of the illness. The basal ganglia seem to increase in volume in patients with bipolar disorder, but decrease in volume in those with severe mood dysregulation and comorbid ADHD. Moreover, parietal cortex and precuneus cortex volumes appeared to increase in children with bipolar disorder while decreasing or staying the same in normal volunteer controls.
A meta-analysis of brain imaging studies indicated that in general, the size of the amygdala appears to increase from childhood to adulthood in bipolar patients, starting out smaller than that of similarly-aged normal volunteers, but becoming larger than that of adult normal volunteers as the patients age into adulthood.
Lithium treatment increases gray matter volume in a variety of cortical areas and in the hippocampus in multiple studies. In contrast, treatment with valproate for 6 weeks appears to decrease hippocampal volume.
While the 4 major childhood-onset psychiatric illnesses we discussed this week (bipolar, unipolar, ADHD, and anxiety disorders) show long term difficulties into adulthood in the majority of instances, it appears that the most severely impacted are those with bipolar disorder. These data are also consistent with retrospective data from multiple cohorts of adults with bipolar disorder, which indicate that those whose illness began in childhood fared more poorly in adulthood than those with adult-onset illness. Thus, while there has been a modicum of treatment research in childhood depression and anxiety disorder and a plethora of treatment studies in ADHD, the dearth of treatment studies in children with bipolar disorder is all the more disconcerting.
Bipolar disorder is common, occurring in some 2 to 3% of children and adolescents, and carries a relatively grave prognosis into adulthood in the majority of instances, especially when it is inadequately treated. Virtually all of the investigators in the area of childhood-onset bipolar who presented at the AACAP meeting have pleaded for increased treatment research for bipolar disorder in children, and one can only hope that their message is soon heard.