You're running late. You have a lot to do. You're getting anxious. You're feeling stressed. You're becoming forgetful. Here's why. Too much stress will trigger the release of a hormone known as cortisol, which can interfere with memory. An episode of severe stress can kill off new nerve cells in your brain. This is what occurs in post-traumatic stress disorders (PTSD), which is simply an exaggeration of what occurs during times of stress. Actually, the type of stress that is discussed here is distress. Stress itself is not bad, as it is what keeps things moving within our systems. Those without stress of any type are dead. Good stress is known as eustress, but that's another issue.