N-Acetylcysteine for Skin Picking Disorder
Reviewer: Tori Hudson, ND
Author: Grant J, Chamberlain S, Redden S, et al.
Reference: N-Acetylcysteine in the treatment of excoriation disorder. JAMA Psychiatry. Published online March 23, 2016.
Design: Each participant was assigned to 12 weeks of N-acetylcysteine or placebo in a randomized double blind clinical trial design. Patients were seen every 3 weeks during the 12 weeks. The initial dose of N-acetylcysteine was 1,200 mg/day and was increased to 2,400 mg/day by week 3. At week 6, the dose was increased to 3,000 mg/day for the last 6 weeks of the study. Dosing was raised more slowly if clinically necessary.
Participants: This study included men and women aged 18 to 65 years with a primary and current diagnosis of excoriation (skin-picking) disorder. The average age was 34.8 years. The average age of onset of skin picking was 12.2 years old. Most of the participants picked skin from multiple sites and most had never sought mental health treatment for skin picking.
Patients were excluded if they had unstable medical illness, history of seizures, lifetime bipolar disorder/dementia or psychotic disorder, substance use disorder in the past 3 months, suicide risk at current time, previous treatment with N-acetylcysteine, asthma, were pregnant or using inadequate contraception and were fertile and who had initiated pharmacotherapy or psychotherapy with the 3 months prior to entry in the study. Of the 71 screened, 66 were randomized including 59 women and 7 men in which 31 received placebo and 35 received N-acetylcysteine.
Primary outcome: The primary outcome measure was the change from baseline using the Yale-Brown Obsessive Compulsive Scale modified for Neurotic Excoriation (NE-YBOCS). This is a 10 item scale that assesses picking symptoms during the past 7 days. The first 5 items are the urge/thought subscale and the next 5 items are the behavior subscale. The total scores for NE-YBOCS range from 0 to 40 and higher scores reflect greater severity of symptoms.
Key findings: There were statistically significant responses to treatment for the NE-YBOCS total, NE-YBOCS urge/thought subscale and the Clinical Global Impression (CGI) Severity Scale scores. Significant benefits for N-acetylcysteine over placebo were seen for the NE-YBOCS total and urge/thought subscale scores at weeks 3, 6, 9 and 12. For the CCGI-Severity-Scale, significant benefits for N-acetylcysteine were seen at weeks, 6, 9 and 12. CGI-Severity Scale scores improved from 3.5 at baseline to 3.0 at 12 weeks for N-acetylcysteine vs scores for placebo of 4.0 at baseline and 4.2 at 12 weeks. The NE-YBOCS total score demonstrated a 38.3% reduction in skin-picking symptoms for the N-acetylcysteine group compared with 19.3% for placebo.
Practice Implications: In this randomized, double-blind clinical trial, N-acetylcysteine was more effective than placebo for the treatment of skin picking disorder. This study is consistent with previous published clinical trials demonstrating N-acetylcysteine to be effective for adults with trichotillomania, case reports demonstrating benefit for skin picking and a case series in 35 individuals showing benefit for those with skin picking. The primary benefits shown in the current study seem to be in the reduction of urges or cravings to pick rather than a reduction in the actual behavior. This reduction of cravings is seen in other N-acetylcysteine research on reducing cocaine addiction. Alteration of the glutamate system is at the core of nutritional intervention in targeting compulsive behaviors. N-acetylcysteine also increases glutathione in glial cells and implicates that treating antioxidant mechanisms may also play a role.