Clinical Endocannabinoid Deficiency was a theory posited by Dr. Russo back in 2001 in which he theorized that low endocannabinoid levels could be behind a range of chronic conditions such as IBS, fibromyalgia, migraines, and other treatment-resistant syndromes. Dr. Russo suggested that because these conditions are all developed over time, rather than congenitally, and that they could be a result of disturbances to the ECS. This also means there’s a possibility of reversing them.