Randomized double-blind parallel-group study comparing cognitive effects of a low-dose lamotrigine with valproate and placebo in healthy volunteers

Purpose: This study aimed at investigating the cognitive and mood effects of lamotrigine (LTG) versus valproate (VPA) and placebo (PBO). Methods: By studying the effects in healthy volunteers, it is possible to separate the genuine effects of LTG from the cognitive improvements, caused by better seizure control. The study used a pretest-posuest comparison of 50 mg LTG, 900 mg VPA, or PBO in a double-blind single-dummy parallel-group design with 30 healthy volunteers. Study duration was 112 days (with a last control on day 13). Outcome measures included cognitive tests (FePsy neuropsychological test battery), mood scales (ASL; mood-rating scale), and a scale for subjective complaints (ABNAS Neurotoxicity scale). Total sleep time was controlled with actigraphic recordings. The results were analyzed by comparing the change over time (pretest with posttest) for the three treatments with Student's t tests. Results: Cognitive tests: significant differences between the treatments were found for measurements of cognitive activation (i.e., three of the four simple reaction-time measurements showed statistically significant differences in change between PBO and LTG in favor of LTG (p = 0.03:,0.03; 0.04); two of four tests showed statistically significant differences in change between LTG and VPA, both in favor of LTG (p = 0.03; 0.05). Subjective complaints: the ABNAS-neurotoxicity scale reveals a significant reduction of drug-related cognitive complaints for the subjects taking LTG, relative to VPA (p = 0.02). Mood rating: significant changes were found on the scale assessing "tiredness," showing increased tiredness/sedation for VPA relative to PBO (p = 0.02) and on the "timid scale" for LTG reporting "being more at ease" compared with both PBO and VPA (p = 0.02; 0.02). The general direction of change for the mood scales was toward "activation" for LTG (five of six scales improved), whereas for VPA, the reverse effect was found (four of six scales showed a change in the direction of "tiredness/sedation"). Conclusions: Short-term treatment in normal volunteers with a low dose of LTG resulted in improved cognitive activation on simple reaction-time measurements, a more positive subjective report about the impact of drug treatment relative to VPA, and mood changes concurring with the activating effect demonstrated by the cognitive tests.