| Attention deficit-hyperactivity disorder (ADHD) is a highly prevalent disorder among both adults and children characterized by pervasive patterns of inattention, impulsivity, and hyperactivity. One of the most common treatments of ADHD is the use of stimulant medications, which are prescribed on a trial-and-error basis that can be time intensive and costly for the patient. Acute medication challenge studies that utilize quantitative EEG (QEEG) imaging techniques can provide immediate evaluations of the efficacy of a medication, thus informing clinical decision-making. In this method, patients are administered visual and auditory attention testing, self-report mood measures, and QEEG; the patient is then orally administered methylphenidate or dextroamphetamine and these measures are repeated. While normalization of electrophysiological activity is achieved in many cases, a significant failure rate remains. This study examined differences among medication responders to methylphenidate and dextroamphetamine in physiological, attentional, and electrophysiological measures. Among positive medication responders, significant decreases were observed in BDI-II (t = 3.670, p = .006) and BAI (t = 2.954, p = .018) scores from pre- to post-medication conditions (Table 1), as well as on Tension ( t = 3.065, p = .015), Depression (t = 4.4, p = .002), Anger (t = 3.076, p = .015), and Confusion (t = 5.012, p = .001) subscales of the POMS. Negative medication responders exhibited a significant increase in systolic blood pressure pre- to post-medication ( t = -3.933, p = .006), significant decreases on the Depression (t = 4.889, p = .005) and Anger (t = 3.303, p = .021) subscales of the POMS, and a significant increase on the IVA+ Attention Quotient ( t = -2.763, p = .025). On measures of absolute power, neither medication group demonstrated significant differences between positive and negative responders. On measures of coherence, positive Adderall responders demonstrated significant improvement in interhemispheric coherence from pre- to post-medication at F3-F4 (p = 0.018) in alpha frequencies (Figure 4) and participants responding positively to Ritalin exhibited significant changes in interhemispheric coherence at T3-T4 (p = 0.016) in beta frequencies and O1-O2 (p = 0.033) in theta frequencies. On measures of cordance, positive medication responders demonstrated significant increases in cordance values at C3 (p < .028) and C4 ( p < .015) electrodes and significant decreases in cordance values at O1 (p < .008), O2 (p < .037), and FP2 (p < .011) in alpha frequencies and significant increases in cordance values were observed at P4 (p < .034), Pz (p < .034), and O2 (p < .022) electrodes in beta frequencies. Negative responders demonstrated significant decreases in cordance intensity at Pz (p < .022) and O2 ( p < .027) electrode sites. Overall, these results suggest a general pattern of frontal hyperactivity in Adderall positive responders and temporal and occipital hypoactivity in Ritalin positive responders in premedication states. Clinically, these patterns may provide information to guide clinicians in selecting and evaluating pharmacological treatments in patients with ADHD. |
