Why do patients with partial epilepsy improve their IQ after training to self-regulate slow cortical potentials?

In patients with epilepsy, not only seizures but also cognitive, emotional, and social functioning are of increasing interest in research (Kelley, Jacobs, & Lowenstein, 2009). As a decrease in cognitive functions over the course of the illness is usually reported, we wanted to explore changes in Intelligence Scores observed after a neurofeedback treatment in patients with drug-resistant epilepsies. In a controlled study that compared the outcome of three different interventions (training to regulate slow cortical potentials, N=34; training to regulate breath rate and the amount of carbon dioxide in the end tidal volume of the exhaled air, N=11; modification of drug regime, N=25), pre- and postmeasurements of a short version of the Wechsler Intelligence Scale were applied. The interval between the two assessments was more than 12 months, with a mean of 61 weeks. Mean age of the patients was 35, with a range from 17 to 57. The highly significant 7-point increment of IQ only after training of slow cortical potentials was not related to clinical (e.g., seizure reduction) or neuropsychological (e.g., attention and memory) variables. Instead, it was related to psychophysiological measures: IQ change was inversely related to the Latency of the P300 component of event-related brain potentials and directly related to the Latency of the P2 component and the increase of N2 Amplitude during training. We conclude that regulation training of slow cortical potentials improves IQ in patients with refractory partial epilepsy, which might be related to an improved ability for controlled allocation of cognitive resources.