Based on the scant knowledge available regarding the endocannabinoid system and cannabinoid science overall, some researchers have theorized that many diseases, like multiple sclerosis and fibromyalgia, may be caused by a simple deficiency of endogenous (internally produced) cannabinoids (also called endocannabinoids). This condition has been labeled Clinical Endocannabinoid Deficiency, or CECD (it is also sometimes called Endocannabinoid Deficiency Syndrome).