Microglia Activation in Asthma

The goal of this clinical trail is to learn about how asthma influences brain function. The main questions it aims to answer are: * How airway inflammation in asthma affects the brain; and, * Whether airway inflammation in asthma is related to symptoms of depression and anxiety Over the course of 6 visits, participants will: * Complete questionnaires * Complete computer tasks * Undergo allergy skin test * Undergo breathing tests including two whole lung allergen challenges * Give four blood samples * Complete brain imaging scans