A brain injury reduction system provides a protective measure that temporarily or decreases venous drainage out of the intracranial compartment during or immediately before and during a sudden change in acceleration of an individual's head. Specifically, a wearable helmet or other wearable structure of the brain injury reduction system detects an impending collision and determines whether a protective measure is needed. If so, one or more actuation devices provides the protective measure to reduce venous drainage through one or both of the internal jugular veins or paravertebral venous plexus. A first actuation device stimulates a gag reflex or valsalva-like maneuver to reduce venous drainage through the paravertebral venous plexus. A second actuation device can physically compress the internal jugular veins. Thus, the brain injury reduction system minimizes the detrimental impact that may occur due to the sudden change in acceleration of the individual's head.