Abnormal spontaneous brain activity in medication-naïve ADHD children: a resting state fMRI study

Abnormal baseline brain functional connectivity in attention-deficit/hyperactivity disorder (ADHD) has been revealed in a number of studies by using resting-state functional MRI (rfMRI). The aim of this study was to investigate the spontaneous frontal activities in medication-naïve ADHD boys using the rfMRI derived index, amplitude of low-frequency fluctuation (ALFF). In total 17 ADHD boys and 17 matched controls were recruited to undergo rfMRI scan on a 3.0T MRI system. For each subject, six oblique slices covering the frontal areas were acquired with a rapid sampling rate (TR=400ms). Functional images were processed in AFNI for calculation of ALFF and then group comparison was performed using voxel-based t-test. With a corrected threshold of p<0.05 determined by AlphaSim, we found that in comparison with controls, ADHD patients demonstrated higher ALFF values in the left superior frontal gyrus and sensorimotor cortex (SMC), and lower ALFF values in the bilateral anterior, middle cingulate and the right middle frontal gyrus (MFG). Significant correlations were found between patients' WSCT measures and the peak ALFF located in the right MFG (r=0.69, p=0.02), and the left SMC (r=0.65, p=0.03). Our results revealed abnormal frontal activities at resting state associated with underlying physiopathology of ADHD, and suggested the ALFF analysis to be a potential approach in further exploration of this disorder.