Neural Circuitry Engaged During Unsuccessful Motor Inhibition in Pediatric Bipolar Disorder

Abstract

Dickstein, Daniel P.; Tone, Erin; and Pine, Daniel S., "Neural circuitry engaged during unsuccessful motor inhibition in pediatric bipolar disorder" (2007 Objective: Deficits in motor inhibition may contribute to impulsivity and irritability in children with bipolar disorder (BPD). Therefore, studies of the neural circuitry engaged during failed motor inhibition in pediatric BPD may contribute to our understanding of the pathophysiology of the illness. We tested the hypothesis that children with BPD and controls would differ in ventral prefrontal cortex (vPFC), striatal, and anterior cingulate activation during unsuccessful motor inhibition. We also compared activation in medicated vs.unmedicated children with BPD, and in children with BPD and ADHD (BPD+ADHD) vs.those with BPD but without ADHD (BPD-ADHD).Method: Event-related fMRI study comparing neural activation in children with BPD and controls while they performed a motor inhibition task. The sample included 26 children with BPD (13 unmedicated, 15 with ADHD) and 17 age, gender, and IQ matched controls. Results:On failed inhibitory trials, controls showed greater bilateral striatal and right vPFC activation than did patients. While our findings were somewhat more prominent in unmedicated than medicated, patients, and in BPD+ADHD than BPD-ADHD, the findings did not differ significantly (?) among these subgroups of children with BPD.

Abnormal Reward System Activation in Mania

“…Accordingly, unsuccessful motor inhibition was associated with decreased striatal fMRI activation in pediatric bipolar disorder. A lack of striatal error signals as demonstrated in our study was suggested to account for these motor regulatory deficits and contribute to impulsivity and irritability (Leibenluft et al, 2007) as observed in bipolar patients. Indeed, elevated measures of state and trait impulsivity have been observed in bipolar manic patients (Swann et al, 2003).…”

Medication Effects in Neuroimaging Studies of Bipolar Disorder

“…While the strength of these studies is the consistency of these main findings, there are inconsistencies regarding the potential effects of psychotropic medication and associated methodological limitations that make it difficult to draw firm conclusions. Some studies find no significant effects of psychotropic medication on functional neuroimaging measures (14)(15)(16)20,24). In many of these studies, however, the small sample sizes inherent in examining individuals taking versus those not taking each individual class of psychotropic medication make it possible that findings of no significant effect of psychotropic medication resulted from type II error, as authors of these studies have emphasized in discussions of their findings (e.g., reference 24).…”

“…Functional neuroimaging studies in bipolar adults and adolescents demonstrate abnormally decreased activity in prefrontal cortical regions during cognitive control and abnormally increased activity in subcortical limbic regions during emotion processing that may persist during remission, depression, and mania (14,15,27). More recent studies have examined neural activity in remitted bipolar populations, many of whom were medicated (13,(21)(22)(23).…”

Evidence-Based Treatment

“…For young people with bipolar disorder, increased activation of the striatum has been found in functional MRI studies of cognitive interference [76] and working memory [77], while reduced activation of the striatum was found in a study of unsuccessful motor inhibition [78].…”