Coherence abnormality of Temporal and Frontal areas in children with ADHD-combined type

In the recent years, the coherence index is used in many electroencephalographic studies for investigation of brain connectivity in children with ADHD disorder. It is suggested that the coherence is a useful index in discrimination of ADHD subjects from normal subjects. However, a few studies are accomplished in subtypes of ADHD to identify of differences in functional connectivity between ADHD subtypes. In this comparative study, the connectivity index of coherence between two hemispheres is compared between two groups with ADHD-combined type (ADHD-C, N=13) and ADHD-predominantly inattentive type (ADHD-I, N=10). The results show that the coherence between left temporal lobe and right frontal lobe is significantly increased in ADHD-combined type as compared with ADHD- inattentive type. This higher coherence is occurred in the Theta (4-8 Hz) and Alpha (8-12 Hz) frequency Bands. Results would suggest that hyperactivity and impulsivity in ADHD-combined type could be related to left temporal and right frontal connectivity deficiencies.