April 05, 2016
JAMA Psychiatry
Abstract
This abstract is available on the publisher’s site.
IMPORTANCE
Excoriation (skin-picking) disorder (SPD) is a disabling, underrecognized condition in which individuals repeatedly pick at their skin, leading to noticeable tissue damage. To date, there has been no clearly effective pharmacologic or psychological treatment for SPD.
OBJECTIVE
To determine whether N-acetylcysteine, an amino acid that appears to restore extracellular glutamate concentration in the nucleus accumbens, will be more effective than placebo in reducing compulsive picking behavior.
DESIGN, SETTING, AND PARTICIPANTS
A randomized, double-blind trial was conducted at ambulatory care centers at the University of Minnesota (September 12, 2011, to June 15, 2012) and the University of Chicago (December 17, 2012, to June 26, 2015) and included 66 adults with SPD. Data analysis was performed from July 16 to September 9, 2015.
INTERVENTIONS
N-acetylcysteine (dosing range, 1200-3000 mg/d) or placebo was administered for 12 weeks.
MAIN OUTCOMES AND MEASURES
Participants were assessed using measures of skin-picking severity, including the modified Yale-Brown Obsessive Compulsive Scale (NE-YBOCS); total scores range from 0 to 40, with higher scores reflective of greater symptom severity. Another measure of skin-picking severity was the Clinical Global Impression-Severity Scale; total scores range from 1 (normal) to 7 (among the most extremely ill patients), and improvement ratings range from 7 (very much worse) to 1 (very much improved). Selected cognitive tasks included the Intra-dimensional/Extra-dimensional Shift Task to examine cognitive flexibility, with the key outcome measures being the number of errors, and Stop-Signal Reaction Time task, which evaluates motor inhibition. Outcomes were examined using a linear mixed-effects model.
RESULTS
Of the 66 participants (31 randomized to placebo and 35 to N-acetylcysteine) included in the analysis, 59 (89%) were women; mean (SD) age was 34.8 (11.0) years. Compared with placebo, N-acetylcysteine treatment was associated with significant improvements in the NE-YBOCS. At baseline, NE-YBOCS scores were 18.9 and 17.9 for the treatment and placebo groups, respectively, and at 12 weeks, the scores were 11.5 and 14.1 for the treatment and placebo groups, respectively (P = .048). For the Clinical Global Impression-Severity scale, baseline scores were 3.5 and 4.0 and 12-week scores were 3.0 and 4.2, respectively (P = .003). These effects were significant both in terms of treatment by time interactions and post hoc tests at 1 or more individual time points. At the study’s end point, of the 53 participants who completed the study, 15 of the 32 participants (47%) receiving N-acetylcysteine were much or very much improved compared with 4 of the 21 participants (19%) receiving placebo (P = .03). There were no significant differences between the active and placebo arms in terms of psychosocial functioning.
CONCLUSIONS AND RELEVANCE
N-acetylcysteine treatment resulted in significant reductions in skin-picking symptoms and was well tolerated. The glutamate system may prove a beneficial target in treating SPD and other compulsive behaviors.
Written by
Skin picking disorder can be a very distressful disease for patients and often poses a challenge to clinicians. There are few well-established treatment options. Although not uniformly successful, some evidence suggests that SSRIs may be a good option for therapy.
This study suggests that N-acetylcysteine (NAC) may be a useful treatment option for these patients. NAC can help improve glutamatergic dysfunction and has been implicated in the pathophysiology of compulsive or habitual behaviors. There is a growing body of literature exploring the treatment uses of NAC in obsessive–compulsive spectrum disorders, addiction, pathological gambling, and trichotillomania. In clinical practice, NAC appears to be safe and well-tolerated, with a minority of patients developing mild side effects of nausea, constipation, and dry mouth. Considering the alternative treatment options for skin picking disorder, NAC has some distinct benefits for dermatologists. NAC is not a prescription medicine but rather an over-the-counter (OTC) dietary supplement. We expect that many of our colleagues who may or may not feel comfortable prescribing psychotropic medications will embrace the use of NAC as their first-line therapy in addition to counseling, UNNA boots, and antipruritic topicals.