The hippocampus reacts to stress and it damages the neurons, which causes it to shrink and shrink. This part of the brain is partly for memory function. So if someone constantly has you repeat things then they might have a small hippocampus, maybe due to depression or stress.

When I was going through my schizophrenic break from reality towards the end my memory was shot. It took a year for my hippocampus to grow back to normal.