[Event-related potentials in character semantic priming of attention deficit hyperactivity disorder children and normal children: a comparative study].

OBJECTIVE: To investigate the cognitive event related potentials in Chinese character priming effect of children with attention deficit hyperactivity disorder (ADHD) and to analyze the neural mechanism of the priming effect. METHODS: Fifty-two ADHD children aged (9.5 +/- 1.7) and 45 age-matched children without ADHD were asked to perform a Chinese character semantic priming task while electroencephalogram was recorded. During the Chinese character semantic priming task the subjects were instructed to judge whether the presented target word was a related word, unrelated word, or a pseudoword and event-related potentials (ERPs) were elicited and analyzed with the brain electricity source analysis (BESA) software. RESULTS: (1) The behavioral results showed that the reaction time to the unrelated character stimuli in the ADHD children was (1252 +/- 256) ms, significantly longer than that in the normal control [(1131 +/- 194) ms, P < 0.05]. (2) The amplitude of the character related N2 at the Cz lead in the ADHD children was -7.7 (-12.8, -5.0) microV, significantly larger than that of the normal controls [-5.6 (-9.4, -3.2) microV, P < 0.05]. (3) The amplitude of character unrelated stimuli P3 at the Cz lead of the ADHD children was 5.4 (2.0, 9.5) microV, significantly lower than that of the normal control [9.5 (4.2, 16.9) microV, P < 0.01]. CONCLUSION: There is a positive correlation between the amplitude of N2 and the difficulty in character semantic priming. It is more difficult for the ADHD children than normal controls to accomplish the same semantic task. ADHD children need more attention resources than normal controls. The amplitudes of character related-N2 and unrelated-P3 may become markers to measure the development of recognition in the ADHD children, thus being helpful in the ADHD diagnosis.