Using a randomized, double-blind, cross-over design, we investigated the effects of carbamazepine (CBZ) and phenytoin (PHT) on memory and spectral EEG components in 15 healthy adults. Each subject was treated with each drug for 1 month, separated by a 1-month washout. Evaluations were conducted at baseline, at the end of each treatment month, and 1 month after the last treatment phase. EEG was collected during an eyes-closed resting condition and a verbal memory activation task. Spectral analysis of the EEG in the nondrug conditions showed that the memory task significantly reduced theta components and increased delta components. As compared with nondrug conditions, the antiepileptic drugs (AEDs) significantly impaired memory performance and produced mild EEG slowing. Memory performance did not differ statistically between the AEDs, but minor differences in spectral EEG components were noted. The results suggest that differences in the cognitive and EEG effects of CBZ and PHT are not clinically significant.

We investigated neuropsychological effects of carbamazepine and phenytoin in 21 healthy adults using a randomized, double-blind, double-crossover design and treating each subject with each drug for 1 month, separated by a 1-month washout. There were neuropsychological evaluations at baseline, the end of each treatment month, and 1 month after the last treatment phase. Cognitive measures included Symbol Digit Modalities Test, Selective Reminding Test, Complex Figures, Paced Auditory Serial Addition Test, Stroop, Finger Tapping, Grooved Pegboard, Choice Reaction Time, P3 Event-Related Potential, Hopkins Symptom Checklist, and Profile of Mood States (POMS). Compared with nondrug conditions, the anticonvulsants significantly impaired Stroop, Choice Reaction Time, Grooved Pegboard, Hopkins, and POMS. Employing anticonvulsant blood levels as covariates, there were only two significant differences between drugs, one in favor of carbamazepine (ie, Finger Tapping) and one in favor of phenytoin (ie, Stroop). The results suggest that differences in cognitive effects of carbamazepine and phenytoin are not clinically significant.

Few studies have specifically addressed the cholinergic role in visuospatial memory. In the present study, we employed a randomized double-blind repeated measures design to investigate the effects of scopolamine on Judgement of Line Orientation (JLO) and two distinct visuospatial memory tasks. Complex Figures (CF) is a test of drawn reproduction similar to the Rey complex figure. The Spatial Array Memory Test (SAMT) is a two-dimensional free-recall visuospatial test which minimizes constructive skills and allows sensitive measurement of placement errors. Scopolamine impaired performance on JLO and CF. However, no effects of scopolamine on SAMT were apparent even though the SAMT is sensitive to aging and right temporal-lobe lesions. Selective effects of scopolamine on focused versus distributed attention may account for these differential results.