by Erin Hawkes, MSc

N-Acetylcysteine (NAC) is an antioxidant that also affects how certain brain cell populations communicate with each other using the “messenger” molecules glutamate and dopamine. Furthermore, NAC promotes cell survival and growth, heals inflammation, and influences metabolism. It readily passes through the blood brain barrier and can be taken orally.

Likely Effectiveness: Very likely to be effective, particularly in refractory patients.

Effective Dosage:  2 grams per day (1 gram twice daily) orally. A case study of a woman with refractory schizophrenia showed improvements with 600 mg (0.6 grams) per day (as an add-on to two other antipsychotics).

Research: High-quality, reputable randomized double-blind, placebo-controlled studies; pre-clinical and clinical experiments; case study.

Risks:  No side effects at therapeutic doses; high doses (400 mg/kg) may cause seizures. It is relatively inexpensive and available over-the-counter.

Selected references

1) Berk M, Copolov D, et al. N-acetyl cysteine as a glutathione precursor for schizophrenia–a double-blind, randomized, placebo-controlled trial. Biol Psych. 2008; 64:361-368.

This well-designed, 24-week study (randomized, multicenter, double-blind, placebo-controlled) included 140 subjects (84 completed the experiment). Using standard tests of symptoms of schizophrenia, they found that NAC improved some symptoms, but not “positive” ones (hallucinations, delusions), perhaps because almost half of the patients had treatment-resistant schizophrenia (as evidenced by being on clozapine). There were no adverse side effects observed. The authors concluded that one gram of NAC twice daily is an effective and promising adjunct to antipsychotic medication.

Additional References:

N-Acetyl cysteine in psychiatry: current therapeutic evidence and potential mechanisms of action, J Psychiatry Neurosci. 2011 Mar; 36(2): 78–86.