“Scientists say players navigate the screen using a key area of the brain called the caudate nucleus, which leads to loss of grey matter in the hippocampus.”
Does this statement make sense? Is it kind of like saying that exercising your legs makes your arms weaker?
Yes, that part makes sense. Muscles do weaken and atrophy quickly if not used. Brain tissue is quite dynamic, growing new connections, compensating and decompensating as needed. To some degree one part of the brain can take over function for another part that is diseased or lost. So that part is believable.