Drs. Barzman and DelBello Reply

To the Editor: Although the underlying biology of binge eating disorder, borderline personality disorder, pathological gambling, and disruptive behavior disorders remains largely unknown, our clinical observations, along with randomized controlled data, have shown that topiramate is effective for treating these psychiatric disorders, which are phenomenologically linked by impulse dyscontrol (1 – 4) . Furthermore, following our case report (5), there have been two open-label studies confirming our preliminary finding that topiramate is effective for the treatment of disruptive and impulsive behavior in children and adolescents with psychiatric illnesses (6 – 7) . Additionally, in contrast to the statement by Drs. Kruszewski and Klotz, a review of the literature reveals that the aforementioned disorders may be genotypically related. For example, the G allele of the 5H-T2A receptor gene (1438A/G polymorphism) is associated with both binge eating and borderline personality disorder (8) . More strikingly, a specific gene, GABRA2, has been associated with conduct disorder and adult alcohol dependence (9) . Finally, topiramate is a novel broad-spectrum anticonvulsant that inhibits glutamate activity at a subtype of glutamate receptors and augments the effects of GABA receptor subtypes (GABA _A ) (10) . Therefore, contrary to the assertion by Drs. Kruszewski and Klotz, topiramate may be effective for impulse control disorders through its effect on glutamate as well as other receptors (11) .

We agree that it is important to consider both efficacy and tolerability when prescribing any medication. However, topiramate is generally well tolerated in children and adolescents. In fact, data suggest that topiramate may be better tolerated in children and adolescents than in adults (12) ; for example, only 14% of 56 children and adolescents experienced paresthesia, and 14% experienced somnolence in a recent double-blind placebo controlled trial of topiramate for pediatric mania (13) .