Gabapentin has been available for more than a year in the United States, and has undergone extensive evaluation in clinical trials. There are no published, well-controlled data on cognitive effects of gabapentin, although studies are currently underway. In studies on normal subjects, psychotropic effects have been seen, consisting of improved memory, concentration, and reaction time. Lamotrigine has also been associated with psychotropic effects. This has led to the widely held belief that lamotrigine may have a mood-altering effect.
Further investigation is under way.
Vigabatrin has not produced adverse effects on cognition in controlled clinical trials. However, negative effects on mood have been reported. Rare psychosis has also been reported. Factors influencing development of psychosis may include a history of prior psychiatric illness, sudden control of seizures, or seizure clustering. 27 Withdrawal of vigabatrin has also caused psychiatric disturbance.