Resumo

OBJECTIVE: This study examined the event related potential (ERP) evoked by non-expected environmental sounds (distracters or novel stimuli) in children diagnosed with ADHD combined type and age-matched control. METHODS: A longitudinal study (case-control type) was conducted in 12 children from both genders between 7 to 11 years old from pediatric outpatient service specialized in ADHD from the University Hospital from the Federal University of Espírito Santo, Vitória - ES, Brazil, matched by 12 healthy controls from local schools (n = 12). They had ERP registered under "novelty" oddball paradigm. From ERP recorded in Fz, Cz and Pz locations, the mean amplitude and the 50% area latency for N2, P3 and late negativity (LN) waveforms were compared between gorups. RESULTS: In the ADHD group, the distracter sound induced significantly smaller mean amplitude of N2 component at Fz (1,02 ± 1,34), Cz (5,52 ± 2,06) and Pz (2,41 ± 1,27) (p < 0,0001) compared to the control group at Fz (-0,97 ± 1,53), Cz (3,19 ± 2,02) and Pz (-2,62 ± 1,59). ADHD children showed larger mean amplitude of P3 waveform at Fz (6,33 ± 2,26) location but it was smaller at Cz (4,22 ± 3,91) site compared to the control group at Fz (2,92 ± 3,19) and Cz (5,27 ± 4,69), respectivitly. The mean amplitude of late negativity waveform (LN) was significantly smaller at Fz (-0,75 ±1,03) and Pz (1,03 ±1,39) sites in the ADHD group compared to the control group at Fz (-3,30 ±1,37) and Pz (-0,82 ±1,65) (p < 0,0001). There were no significant differences in the 50% area latency of N2, P3 or LN waveforms between groups. CONCLUSIONS:These results suggest that ADHD children seem to have attributed too much relevance to novel (non-expected) environmental stimuli and they were less capable in reorienting their attention back to the main task after temporary distraction. Patrocínio - FACITEC