Synchronization stability analysis of functional brain networks in boys with ADHD during facial emotions processing

The study of the synchronization phenomenon in the functional brain networks of individuals with Attention Deficit Hyperactivity Disorder (ADHD) has always been of interest to researchers. ADHD is a prevalent psychiatric disorder among children, which in addition to other problems, makes it difficult to recognize facial emotions correctly. However, the synchronization stability, which indicates the ability of a network to remain in a synchronous state, is still unknown in ADHD. This study investigates the phase synchronization stability and robustness of functional brain networks in boys with ADHD while observing the facial emotions. The primary brain networks of 22 boys with ADHD and 22 healthy ones are constructed using their electroencephalogram signals by the Phase Locking Value (PLV) method. Then, significant subnetworks (P-Value < 0.05) are extracted from the primary brain network by applying the Network-Based Statistic (NBS) method. Three measures, including the second smallest eigenvalue, largest eigenvalue, and eigenratio of these eigenvalues, are calculated from all brain subnetworks as network robustness and synchronization stability criteria. The statistical tests indicate no significant differences between the second smallest eigenvalues in brain networks of two ADHD and healthy groups, representing the same robustness of brain networks topological features to perturbations in both groups. The largest eigenvalues and the eigenratios extracted from the functional brain networks of the ADHD group are significantly (P-Value < 0.05) lower than the healthy one, which shows an increased synchronizability in the brain networks of the ADHD group. This alteration in the phase synchronization stability may be associated with a deficit in the emotional processing of the brain network in the ADHD group.