CAT and major depressive disorder: Oxidative stress results from an imbalance between ROS andthedefense system meant to neutralize these ROS, preventing damage.44 Excess ROS can cause tissue damage and are associatedwith neurobehavioral problems such as depression.45 Additionally, CAT, an important antioxidant enzyme, helpsscavenge hydrogen peroxide, a major ROS, reducing the level of oxidativecell damage.