The current wave of research in bipolar disorder
in children involves x-ray studies of the brain
along with psychological studies of brain functioning. Because these studies introduce to the general reader new vocabularies of brain and x-ray terminology, they can be intimidating. Awe over the impressive technical accomplishments that these studies display must not distract from a common sense appraisal of the evidence these studies generate. Some of these recent x-ray studies strongly suggest the surprising possibility that their authors had intended to describe the functioning of the brain in children and adolescents with bipolar disorder, but instead seemed to have described the brains of children and adolescents with Attention Deficit
Hyperactivity Disorder. The situation is roughly analogous to Christopher Columbus setting sail for the Indies and arriving in the Western Hemisphere instead.
An earlier radiological study of the brains of children and adolescents with ADHD by Dr. Pliszka and a radiological study of the brains of children and adolescents diagnosed with bipolar disorder in the June, 2012 APA journal will be briefly reviewed to highlight the similarities; the brain abnormalities found in children and adolescents clinically diagnosed with bipolar disorder are the same abnormalities as described in children and adolescents clinically diagnosed with ADHD.
The description of the studies will be greatly oversimplified by limiting consideration to only one of the brain areas studied. In the original studies several areas of the brain were studied simultaneously. Limiting the material to one area of the brain does not change the conclusions of the studies. Also the adult comparison groups will not be considered in this discussion; omitting them does not change the conclusion of the studies.
The area of the brain to be considered is the forward area of what is known as the cingulate gyrus. This area lies deep within the brain. Among other functions, it is involved in detecting and correcting errors and controlling impulses. A very well known test of cingulated gyrus function is called the Stroop Color Effect test, named for Dr. Stroop who invented it in 1935. This test requires a subject to suppress an initial response: in the test, names of colors are printed in ink that does not match the color name (for example the word “red” might be printed in blue ink). The subject is asked to name the ink color. If the word “red” is printed in blue ink, the correct response would be blue. This requires suppression of the word information and attention only to the ink color information. In current studies, tests similar to this are given to children and adolescents diagnosed with ADHD and/or bipolar disorder.
In the two studies to be described, the Stroop-like experiments were given to the children and adolescents while they were under the scrutiny of a radiological technology known as functional magnetic resonance imaging (fMRI). This technology allows the activity of various parts of the brain to be measured.
Dr Pliszka and colleagues studied 15 healthy children without ADHD with an average age of 13.2 years, nine of whom were males. Also, they studied 17 children with ADHD with an average age of 13.1 years. Of the 17 subjects with ADHD, 9 had been previously treated with stimulants and eight had never been treated with stimulants. No subjects were taking stimulants during the study. The 15 healthy children and the 17 children with ADHD had their brains visualized with fMRI while being given Stroop-like test. In Dr. Pliszka’s healthy control subjects without ADHD, activity in the cingulate gyrus increased greatly when the subjects failed to inhibit their responses to the Stroop-like task. In contrast, subjects with ADHD did not show an increase in activity in the cingulate gyrus when they failed to inhibit their responses to the Stoop-like task. Pliszka, S et al. Neuroimaging of Inhibitory Control Areas in Children With Attention Deficit Hyperactvity Disorder… Am J Psychiatry 163: 6 June 2006. Pp.1052-1060)
In a separate study of the brain functioning of bipolar children and adults, 16 children and adolescents with bipolar disorder with an average age of 14.7 years, evenly divided into males and females were studied and the results were compared to 21 healthy children without bipolar disorder or ADHD with an average age of 13.8 years and 12 males and 11 females (Weathers et al. A developmental study of the neural circuitry mediating motor inhibition in bipolar disorder, Am J Psychiatry 2012:169:633-641). The results of the adults will not be discussed here. The results of the fMRI of the cingulate gyrus of the children given the Stroop- like task were the same as the study of the cingulate gyrus in children with ADHD reported in the preceding paragraph. The children diagnosed with bipolar disorder failed to increase their activity of the cingulate gyrus when errors were made in the Stroop-like test and the healthy children increased their cingulate gyrus level activity greatly when errors were made in the Stroop- like test.
The functioning of the cingulate gyrus in the children with ADHD and the children diagnosed with bipolar disorder was identical, as Dr. Pliszka noted in an excellent editorial in the June,2012 issue of the American Journal of Psychiatry (Pliszka, S. Tracking the Development of Bipolar Disorder in Childhood, Am J. Psychiatry 169L:6, June 2012)
These studies lend some support to those who have believed that bipolar disorder in children is more correctly understood as a form of ADHD.
Pliszka notes that bipolar disorder and ADHD are both characterized by disturbances in impulsivity; thus he believes it is not surprising that the brain areas in each condition would appear similar. He speculates that two different disease processes, ADHD and bipolar disorder, are affecting the same areas of the brain in the same way. An alternative explanation is that bipolar disorder in children and ADHD are the same disorder and that is why brain functioning across the two disorders is identical.
Based on these preliminary studies there seems to be no difference between bipolar disorder and ADHD in children and adolescents. This is the opposite of what the studies set out to demonstrate. Those who cling to the belief in bipolar disorder in children are undeterred by evidence and will continue to generate new studies in a futile effort to prove that the disorder exists.
Copyright Stuart L. Kaplan, M.D.
Dr. Kaplan is author of Your Child Does Not Have Bipolar Disorder: How Bad Science and Good Public Relations Created the Diagnosis. Available on Amazon.com