Predicting acute side effects of stimulant medication in pediatric attention deficit/hyperactivity disorder: data from quantitative electroencephalography, event-related potentials, and a continuous-performance test

BACKGROUND The aim of this study was to search for predictors of acute side effects of stimulant medication in pediatric attention deficit/hyperactivity disorder (ADHD), emphasizing variables from quantitative electroencephalography (QEEG), event-related potentials (ERPs), and behavior data from a visual continuous-performance test (VCPT). METHODS Seventy medication-naïve ADHD patients aged 7-16 years were tested with QEEG, including a go/no-go task condition (VCPT) from which behavior data and ERPs were extracted, followed by a systematic trial on stimulant medication lasting at least 4 weeks. Based on data from rating scales and interviews, two psychologists who were blind to the QEEG/ERP test results independently rated the patients as having no or small side effects (n = 37) or troublesome side effects (n = 33). We determined if the side effects were related to sex, age, IQ, ADHD subtype, comorbidities, clinical outcome, and variables in QEEG, ERPs, and VCPT. RESULTS There was a moderate negative correlation between clinical outcome and side effects. Three variables were significantly associated with side effects in a multivariate logistic regression analysis. In the ERP independent component - contingent negative variation - which reflected action preparation and time evaluation, patients with high amplitudes (close to normal values) experienced more side effects than patients with lower amplitudes. A faster-than-normal reaction time in VCPT was associated with side effects, as was a high amplitude in an early ERP component (early visual independent component), reported to be influenced by attention, perceptual sensitivity, and anxiety. CONCLUSION The group with troublesome side effects had normal action-preparation electrical brain activity, a faster-than-normal reaction time, and an increased level of anxiety (measured by ERP) compared with the no side-effects group.