GSTM1 and attention deficit-hyperactivity disorder: Comparison between oxy-Hb signals of the control and pre-medicated ADHD subjects revealed marginally significant activation of oxy-Hb signal in the right CH 10 in the control subjects (independent two-sample t-test, p < 0.1 Bonferroni-corrected, Cohen's d = 0.884; Table 2).