Obsessive-compulsive disorder, or OCD, is an often incapacitating condition that affects millions of people worldwide. OCD is characterized by uncontrollable, recurring, and/or unreasonable thoughts and behaviors, which can significantly affect quality of life.  Selective serotonin reuptake inhibitors, or SSRIs, are often used to treat OCD, yet these medications often benefit just 40-60% of patients. Additionally, SSRIs are associated with a variety of unwanted side effects. [1, 9] When seeking alternative or complementary therapies for OCD, it is essential to consider inositol supplementation, which research shows may be an effective solution.
The Natural Communication Aid
Inositol is a simple dietary polyol, or sugar alcohol, and an isomer of glucose. We consume inositol naturally in our diets; it is found in grains, beans, nuts, fruits, and animal organ meats. [2, 4, 5, 9] In the body, inositol is found in cell membranes as inositol phospholipids, and is especially important in the brain and for helping cell communication, or signaling. Inositol serves as a precursor for the second messenger system. [2, 4, 5, 6, 8, 9]
When a signal reaches a cell, it is passed from surface proteins and receptor complexes to molecules called second messengers. These second messengers pass on the signal from the cell surface to molecules in the cytosol and/or nucleus. This not only relays the signal, but also helps to amplify its strength. [5, 7]
As a precursor for this second messenger system, inositol is used to make phosphoinositides, or inositol triphosphate and diacylglycerol. [5, 6, 7, 8] These are the second messengers on the cell membrane. Inositol helps with the maintenance and effectiveness of cell signaling. It can also alter the sensitivity of receptors and control signaling proteins, among other cell activities. [6, 7]
Inositol’s functions in cell communication is important because this second messenger system is associated with neurotransmitter pathways and receptors, including dopamine, norepinephrine, serotonin, and glutamate. Inositol may modulate the interaction between neurotransmitters, drugs, receptors, and signaling proteins. [3, 6] Inositol may also reverse desensitization of serotonin receptors, a common effect of SSRIs. 
Efficacy in OCD
Although the exact mechanisms are yet to be understood, inositol supplementation has been shown to be effective for patients with OCD, due to its role in modulating neurotransmitter signaling and pathways. [1, 2, 4, 6, 9] Inositol has been shown to reduce anxiety and acute stress. [3, 8] In addition to being therapeutic for OCD, inositol may also be beneficial for people with depression, panic disorders, and bipolar depression. [3, 4, 6, 8, 9, 10]
In summary, as an essential component in the second messenger system, inositol helps enhance cell communication and neurotransmitter pathways, and can be efficacious in addressing OCD. Due to its efficacy, tolerability, and lack of side effects, inositol may be appealing to many people seeking alternative or complementary therapies for this often disabling condition.
1. Camfield, D. A., Sarris, J., & Berk, M. (2011). Nutraceuticals in the treatment of obsessive compulsive disorder (OCD): a review of mechanistic and clinical evidence. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 35(4), 887-895.
2. Carey, P. D., Warwick, J., Harvey, B. H., Stein, D. J., & Seedat, S. (2004). Single Photon Emission Computed Tomography (SPECT) in obsessive–compulsive disorder before and after treatment with inositol. Metabolic Brain Disease, 19(1-2), 125-134.
3. Chengappa, K. R., Levine, J., Gershon, S., Mallinger, A. G., Hardan, A., Vagnucci, A., … & Kupfer, D. J. (2000). Inositol as an add‐on treatment for bipolar depression. Bipolar disorders, 2(1), 47-55.
4. Cohen, H., Kotler, M., Kaplan, Z., Matar, M. A., Kofman, O., & Belmaker, R. H. (1997). Inositol has behavioral effects with adaptation after chronic administration. Journal of neural transmission, 104(2-3), 299-305.
5. Deans, E. (2011, May 14). Inositol – The Nervous System’s Pony Express. Retrieved from http://evolutionarypsychiatry.blogspot.com/2011/05/inositol-nervous-systems-pony-express.html
6. Harvey, B. H., Brink, C. B., Seedat, S., & Stein, D. J. (2002). Defining the neuromolecular action of myo-inositol: application to obsessive–compulsive disorder. Progress in Neuro-Psychopharmacology and Biological Psychiatry,26(1), 21-32.
7. Kimball, J. (2011, April 3). Second Messengers. Retrieved from http://www.biology-pages.info/S/Second_messengers.html
8. Kofman, O., Einat, H., Cohen, H., Tenne, H., & Shoshana, C. (2000). The anxiolytic effect of chronic inositol depends on the baseline level of anxiety. Journal of neural transmission, 107(2), 241-253.
9. Levine, J. (1997). Controlled trials of inositol in psychiatry. European neuropsychopharmacology, 7(2), 147-155.
10. Mukai, T., Kishi, T., Matsuda, Y., & Iwata, N. (2014). A meta‐analysis of inositol for depression and anxiety disorders. Human Psychopharmacology: Clinical and Experimental, 29(1), 55-63.