Authored by Susan C. Olmstead via The Epoch Times (emphasis ours),

The antioxidant n-acetylcysteine (NAC) is emerging as a promising treatment for obsessive-compulsive disorder, offering new hope for the approximately 50 percent of adults with obsessive-compulsive disorder (OCD) who do not respond to customary treatments.

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Researchers have been accumulating evidence over the last few years that NAC, a derivative of the amino acid cysteine, available as an over-the-counter supplement, could help people with OCD. It’s also showing promise in the treatment of patients with the hair-pulling disorder trichotillomania and is being investigated as a treatment for compulsive gamblers and drinkers.

However, research into NAC has been slow, in part because the drug, now available without a prescription, has limited commercial potential, according to Dr. Massimo Caroll,  a pharmacologist and clinical toxicologist in the Department of Diagnostics and Public Health at the University of Verona in Italy.

Currently, first-line treatments for OCD are usually selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT). However, “approximately 40 percent to 60 percent of OCD patients do not achieve adequate symptom relief from first-line treatments or experience adverse events/reactions that preclude continuation of the therapy,” Dr. Carollo told The Epoch Times.

“This high rate of treatment resistance underscores the complexity of OCD and the need for alternative therapeutic approaches,” he said. This complexity, he wrote in a letter in the February issue of the journal CNS Neuroscience & Therapeutics, “likely emerges from a multifaceted interplay of factors, encompassing neurochemical imbalances, genetic predispositions, environmental triggers, and psychological influences.”

Dr. Carollo and colleagues published the letter to raise awareness of the use of NAC to treat OCD.

In it, they wrote that to the best of their knowledge, despite NAC’s potential effectiveness, “only five randomized controlled trials have tested the potential efficacy of NAC as an adjunctive treatment in OCD.” Four of these studies reported significant symptom improvement as measured by Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores at dosages of 2,000 milligrams (mg) to 3,000 mg per day, they wrote.

NAC has been proven to be safe even at these high dosages, they claim. But because the NAC products now available on the market typically contain 200 mg to 600 mg, the practicality of achieving a therapeutic dose is limited.

OCD and Serotonin

NAC’s potential effectiveness in treating OCD suggests that the disorder’s cause may arise in the body’s glutamatergic system, according to Dr. Carollo.

OCD may be due to problems with the excitatory neurotransmitter glutamate, not the inhibitory neurotransmitter serotonin, some researchers believe, and so it may be better treated with NAC than with SSRIs. But investigation into the role of glutamate in OCD has been limited, Dr. Carollo said.

“The majority of OCD treatments have traditionally focused on modulating serotonin levels, as evidenced by the widespread use of SSRIs [to treat OCD],” Dr. Carollo told The Epoch Times. “This emphasis on SSRIs is not unique to OCD, but extends to other psychiatric disorders such as depression and anxiety, where serotonergic dysfunction is also a key target.”

Abnormal levels of glutamate have been observed in specific brain regions of people with OCD, such as the anterior cingulate cortex, crucial for attention allocation and emotion regulation, Dr. Carollo said.

These findings, along with documented altered functioning of glutamate receptors and transporters, suggest that glutamatergic dysfunction plays a significant role in OCD, he explained, although it likely does not explain the entirety of the disorder. “More research is needed to explore glutamate-targeted treatments,” he said.

More Evidence, Funding Needed

Dr. Carollo cited three reasons for the lack of large-scale trials on the use of NAC for OCD:

Limited financial incentives for conducting expensive large-scale trials. “Pharmaceutical companies typically fund large trials for new drugs with strong commercial potential, a scenario less applicable to NAC,” he said.
The need for more conclusive evidence regarding NAC’s optimal dosages, long-term efficacy, and safety in the treatment of OCD. “This necessitates phase II and III studies, which require considerable time and resources,” he said.
The historical focus on serotonergic mechanisms behind OCD, which may have diverted attention and resources away from exploring alternative pathways.

Does NAC Help Children With OCD?

NAC may be less helpful for children with OCD, according to a review article published in the June issue of the journal Pediatric Drugs.

In children, the practice guidelines recommend CBT monotherapy for youth with mild to moderate OCD, and combined treatment for those with more severe presentations, according to coauthor Eric Storch, a professor, vice chair, and head of psychology in the Menninger Department of Psychiatry and Behavioral Sciences at the Baylor College of Medicine in Houston, Texas.

“NAC should not be a first-line treatment, given the very limited supporting data for youth with OCD (as well as adults with OCD),” Mr. Storch, who has a doctorate in clinical psychology, told The Epoch Times.

“I certainly hope that there is more research, but at the same time what has been reported has not been supportive of NAC for pediatric OCD treatment,” he said. “Understanding underlying mechanisms better would be a helpful avenue. Researching dissemination of effective treatments would also be helpful.”

About 10 percent of children are refractory to treatment, he said, and a recent study (published in May in the Journal of the American Academy of Child and Adolescent Psychiatry) showed that 90 percent of youth with OCD were either in remission or much improved three years later.