Comparisons between AEDs An example of a study in which two drugs are com- pared in the same group of patients is provided by Vining et al. (27), who compared cognitive and behavioral effects of PB and valproate (VPA) in 21 children in a double blind crossover fashion. While on VPA, the patients scored significantly higher on FSIQ, PIQ, block design, and Berkeley Paired Association Learning Task. While on PB, patients were rated significantly lower by their parents on three items for behavior, and they were also measurably more hyperactive. PB and VPA were also compared by Calandre et al. (28) in a parallel open study involving 64 children each taking either PB or VPA chronically, with 60 nonepileptic children serving as a control group. The Wechsler Intelligence Scale for Children was administered at the beginning of the study and, in the majority of patients, again after 9-12 months. Baseline FSIQ and PIQ scores of patients on PB were significantly lower than in controls. Between the first and second evaluation, FSIQ and PIQ scores improved sig- nificantly for controls and VPA treated children, but not for the PB group. Ferrari et al. (29) found that seven children treated with PB or primidone had significantly