Propranolol is a blocker of beta-adrenergic receptor that acts both peripherally and centrally. Peripheral effects primarily target the autonomic nervous system where it affects primarily heart rate and blood pressure. Centrally targets include the wide spread norepinephrine circuits, including targets in the brainstem, cortex and most notably for ASD, amygdala. Propranolol has emerged as an interesting treatment for ASD that appears to improve social function