GAD autoimmunity and anxietyGAD stands for glutamic acid decarboxylase, an enzyme that triggers production of the brain’s primary calming chemical, called GABA. Some people develop an autoimmune reaction to GAD, which means their immune system erroneously attacks and destroys it. As a result, they can’t make enough GABA to calm the brain and anxiety goes up. GAD autoimmunity is also linked to obsessive compulsive disorder, motion sickness, vertigo, facial tics, and other symptoms. GAD autoimmunity is more common in those with gluten sensitivity or celiac disease and a gluten-free diet can alleviate symptoms.