 Studies of children diagnosed with ADHD have shown considerably higher scores on the Anxious/Depressed scale of the Achenbach Child Behavior Checklist, which implies a comorbidity of ADHD and anxiety.It has been suggested that impaired synaptic gating processes in the nucleus accumbens are the underlying cause of this comorbidity.This defect causes a reduction in synaptic gating of dopamine input from the prefrontal cortex and hippocampus on the nucleus accumbens.