This document provides methods and materials involved in treating hypertension (e.g., age-associated hypertension, resistant hypertension, or chronic refractory hypertension), heart failure (e.g., congestive heart failure), or kidney disease (e.g., chronic kidney disease). For example, methods and materials involved in administering one or more sympatholytic agents to a patient to identify the patient as having an elevated baseline level of sympathetic nerve activity and treating the identified patient with a sympatholytic therapy to reduce the symptoms of hypertension (e.g., resistant hypertension), heart failure (e.g., congestive heart failure), or kidney disease (e.g., chronic kidney disease) are provided.