Many individuals diagnosed with ADHD have abnormal patterns of brain electrical activity, including ‘under-arousal’ in frontal and mid-line cortical regions and frontal ‘hyper-arousal’ that is more frequent in individuals who do not respond to stimulant medications. EEG biofeedback is aimed at normalizing EEG activity in order to correct the brain’s state of relative under-arousal and improve cognitive and behavioural functioning. Two EEG biofeedback protocols have been extensively evaluated as treatments of ADHD. Sensorimotor rhythm (SMR) training reinforces EEG activity in the faster ‘beta’ frequency range (16–20 Hz) in the midline cortical regions with the goal of reducing symptoms of impulsivity and hyperactivity. ‘Theta suppression’ reduces EEG activity in the slower ‘theta’ frequency range (4–8 Hz) and is primarily used to treat symptoms of inattention. An EEG biofeedback protocol directed at suppressing theta activity (4–8 Hz) over the midline regions is probably the most effective strategy when treating primarily symptoms of distractibility and inattention.
