Antiglutamic acid decarboxylase (GAD)-associated disorders are a group of rare neuroimmunological disorders that encompass an expanding spectrum of neurological syndromes. The pathophysiology of these disorders is not well understood, although the presence of very high levels of antibodies to GAD is indicative of immunological dysfunction. The most well-known disease within this class of disorders is stiff-person syndrome (SPS), which often manifests as painful spasms, stiffness/rigidity in axial and limb musculature, and increased lumbar lordosis. Other anti-GAD-associated disorders include isolated cerebellar ataxia, progressive encephalopathy with rigidity and myoclonus (PERM), and encephalitis. Treatment depends on the severity of disease, ranging from symptomatic to immunomodulating/immunosuppressant therapies.