A double-blind, placebo-controlled trial of lamotrigine for pathological skin picking: treatment efficacy and neurocognitive predictors of response.

Although a relatively common behavior, treatment data for pathological skin picking (PSP) are limited. The current study sought to examine the efficacy and tolerability of lamotrigine in adults with PSP and to examine neurocognitive predictors of treatment response. Thirty-two subjects (29 female subjects [90.6%]; mean age, 32.8 +/- 13.3 years) with PSP were treated in a 12-week randomized, double-blind, placebo-controlled trial of lamotrigine as monotherapy. Baseline cognitive assessment comprised the stop signal and intradimensional/extradimensional set shift tasks. Lamotrigine dosing ranged from 12.5 to 300 mg/d. The primary outcome measure was picking symptoms measured by the Yale-Brown Obsessive Compulsive scale Modified for Neurotic Excoriation. Subjects also were assessed with measures of psychosocial functioning. No significant overall differences were noted between lamotrigine and placebo on the primary or secondary end points. Seven subjects assigned to lamotrigine (43.8%) were considered responders (defined as >or=35% n the Yale-Brown Obsessive Compulsive scale Modified for Neurotic Excoriation) compared with 5 (31.3%) assigned to placebo. Those who ultimately responded to lamotrigine exhibited impaired cognitive flexibility (extradimensional shifting) at baseline compared with lamotrigine nonresponders. These findings suggest that, although safe and well tolerated, lamotrigine treatment may not be efficacious in patients with PSP as a whole, compared with placebo. However, these neurocognitive data suggest that lamotrigine may be valuable in a subset of patients who exhibit relatively impaired cognitive flexibility.