Table 1

Summary of clinical findings of N-acetylcysteine (NAC) treatment in psychiatric illness

StudyDisorderNo. study participantsTotal daily dose, mgStudy designOutcome measuresFindings
Gray et al.31Marijuana addiction2424004-wk open-label trialMarijuana Craving QuestionnaireImprovement in 3 of the 4 domains of the scale
Knackstedt et al.32Reduction in nicotine use2924004-wk double-blind placebo-controlled trialQuestionnaire for Smoking Urges- Brief, Minnesota Nicotine Withdrawal ScaleTrend for improvement after covarying for alcohol use but overall a negative trial
Van Schooten et al.33Chemo-prevention trial in healthy smokers (unable to quit)4112006-mo double-blind placebo-controlled trialCotinine (plasma and BAL fluid), urine mutagenicity, 4-ABP-Hb adducts, lipophilic-DNA adducts (PBL and BAL cells), 8-OH-dG adducts (BAL cells), PAH-DNA adducts (MFC and BMC), micronuclei (MFC and SPC), TEAC (plasma and BAL fluid)Decreases in lipophilic DNA adducts, 8-OH-dG levels and number of micronuclei
LaRowe et al.34Cocaine addiction132400Crossover design, treatment for 2 d in each arm (NAC and placebo)CSSA, self-reported cocaine use, reported cravings, routine blood testsSignificant decrease in craving, withdrawal and self-reported use in NAC but not placebo group (no between- group differences)
LaRowe et al.35Cocaine addiction152400Crossover design, treatment for 2 d in each arm (NAC and placebo)Cue-reactivity (general and motivational measures)Decreased desire and interest in cocaine and reduced time spent looking at cocaine-related slides
Mardikian et al.36Cocaine addiction231200, 2400 and 36004-wk, open-label trialDays and amount of money spent on cocaine, CSSA and urine drug screenNonsignificant trends in reductions of amount spent and number of days of use on cocaine and improvements based on CSSA
Grant et al.37Pathological gambling29 O/L 16 random18008-wk O/L study followed by a 6-wk double-blind, placebo- controlled trial (in responders only)Y-BOCS adapted for Pathological Gambling (PGYBOCS), G-SAS, CGI Improvement and Severity scales, Sheehan Disability Scale, HAM-D, HAM-A, Quality of Life InventoryDecreased PG-YBOCS scores during O/L phase. Sixteen of original 27 were classified as responders, 13 of whom continued to double-blind phase. There was an increased number of continued response in the NAC group and trends toward significance in the PG-YBOCS and G-SAS scales.
Lafleur et al.38OCD1300013 wkY-BOCS and HAM-DImprovements between baseline and end point on Y-BOCS and HAM-D
Odlaug et al.39TTM2180010 and 13 wkSelf-reported behaviourComplete abstinence from hair pulling
Grant et al.40TTM501200–240012-wk double-blind, placebo-controlled trialMGH-HPS, CGI, PITS, Sheehan Disability Scale, Quality of Life Scale, HAM-A and HAM-DSignificant improvements in MGH-HPS, PITS, CGI severity scale scores in the NAC group compared with placebo
Odlaug et al.39Nail biting1*180013 wkSelf-reported behaviourComplete abstinence from nail biting after 9 weeks of treatment. A 2-week hiatus caused reinstatement of symptoms, but subsequent NAC treatment again ameliorated this.
Berk et al.41Nail biting320006 moSelf-reported behaviourComplete abstinence of symptoms that continued after 1-month washout period
Odlaug et al.39Skin picking1180013 wkSelf-reported behaviourDecreased urge and act of skin picking
Berk et al.42Schizophrenia14020006-mo double-blind placebo-controlled trialPANSS, CGI, GAF, SOFAS, BAS, Simpson–Angus Scale and the Abnormal Involuntary Movements ScaleImprovements seen in negative symptoms based on PANSS; improvements also seen on CGI and BAS. Improvements were lost at the 1-month follow-up visit.
Lavoie et al.12Schizophrenia1120008-wk double-blind crossover designMismatched negativity and plasma glutathione concentrationSignificant improvements in mismatch negativity in NAC group. Plasma glutathione levels were increased following NAC treatment.
Bulut et al.43Schizophrenia160030 dPANSS, CGI and Calgary depression scaleReduction in PANSS and CGI scores
Berk et al.44Bipolar disorder7620006-mo double-blind placebo-controlled trialMADRS, Bipolar Depression Rating Scale, Young Mania Rating Scale, CGI-bipolar version, GAF, SOFAS, SLICE/LIFE, LIFE-RIFT, and the Quality of Life Enjoyment and Satisfaction QuestionnairePositive results showed improvements on most rating scales (including primary outcome measure MADRS) in NAC group compared with placebo group
  • BAL = bronchoalveolar lavage; BAS = Barnes Akathisia Scale; BMC = buccal mucosa cell; CGI = Clinical Global Impression; CSSA = Cocaine Selective Severity Assessment; GAF = Global Assessment of Functioning; G-SAS = Gambling Symptom Assessment Scale; HAM-A = Hamilton Rating Scale for Anxiety; HAM-D = Hamilton Rating Scale for Depression; LIFE-RIFT = Longitudinal Interval Follow-up Evaluation Range of Impaired Functioning Tool; MADRS = Montgomery–Åsberg Depression Rating Scale; MFC = mouth floor cell; MGH-HPS = Massachusetts General Hospital Hair Pulling Scale; OCD = obsessive–compulsive disorder; O/L = open label; PAH = polycyclic aromatic hydrocarbon; PANSS = Positive and Negative Symptoms Scale; PBL = peripheral blood lymphocyte; PITS = Psychiatric Institute Trichotillomania Scale; random. = randomized; SLICE/LIFE = Streamlined Longitudinal Interview Clinical Evaluation from the Longitudinal Interval Follow-up Evaluation; SOFAS = Social and Occupational Functioning Scale; SPC = soft palate cell; TEAC = trolox equivalent antioxidant capacity; TTM = trichotillomania; Y-BOCS = Yale–Brown Obsessive Compulsive Scale.

  • * This participant also had TTM.

  • Titrated dose.