GSTM1 and attention deficit-hyperactivity disorder: Moreover, as shown in Table 3, the oxy-Hb concentration of the right prefrontal cortex in the ADHD group was higher than that in the TD group during the Stroop task (−7.53×10−4±28.53×10−4 a.u. vs. −36.47×10−4±33.01×10−4a.u.; t = 2.62, P = 0.01).