The most terrifying part of having memory issues is when you can feel something from 5 seconds ago be thrown out the window and there's an empty hole where it once was. You remember that you forgot something.
The pit-of-your-stomach dread you feel when you finally remember what your forgot only to realize you've run out of time to do it... It would have been better if you had missed it entirely, but no, you remembered just in time to be paralyzed with fear over not being ready, like being woken up 30 minutes before a test you didn't study for.