  To uncover the underlying mechanisms of mental disorders such as attention
deficit hyperactivity disorder (ADHD) for improving both early diagnosis and
therapy, it is increasingly recognized that we need a better understanding of
how the brain's functional connections are altered. A new brain wide
association study (BWAS) has been developed and used to investigate functional
connectivity changes in the brains of patients suffering from ADHD using
resting state fMRI data. To reliably find out the most significantly altered
functional connectivity links and associate them with ADHD, a meta-analysis on
a cohort of ever reported largest population comprising 249 patients and 253
healthy controls is carried out. The greatest change in ADHD patients was the
increased coupling of the saliency network involving the anterior cingulate
gyrus and anterior insula. A voxel-based morphometry analysis was also carried
out but this revealed no evidence in the ADHD patients for altered grey matter
volumes in the regions showing altered functional connectivity. This is the
first evidence for the involvement of the saliency network in ADHD and it
suggests that this may reflect increased sensitivity over the integration of
the incoming sensory information and his/her own thoughts and the network as a
switch is bias towards to the central executive network.
