Although medications for OCD such as serotonin reuptake inhibitors (SRIs) have shown to be effective in reducing symptoms, some patients with OCD experience little reduction. OCD is associated with hyperactivity in the orbitofrontal-subcortical circuit, in which glutamate (one of the most important neurotransmitters linked to learning, memory, and mood) serves as a key neurotransmitter.
This study by Drs. Greenberg and Javitt aimed to explore whether adding glycine (an amino acid that helps in glutamate receptor N-methyl-D-aspartate (NMDA) transmission) vs. placebo would help enhance medication treatments. 24 participants with OCD were randomized to adding either 60 grams of glycine a day to their medication (after drop-out, n=3) or adding a placebo (after drop-out, n=5). Over the course of at least 12 weeks, participants in the glycine group experienced statistically significant reduction in OCD symptoms compared to placebo. The high rates of drop-out in both groups were due to side effects, not adhering to the treatment plan, and a variety of other reasons.
*Greenberg, W.M., Benedict, M.M., Doerfer, J., Perrin, M., Panek, L., Louis Cleveland, W., & Javitt, D.C. (2009). Adjunctive glycine in the treatment of obsessive-compulsive disorder in adults. Journal of Psychiatric Research, 43, 664-670. doi:10.1016/j.jpsychires.2008.10.007