I think as people go through various life changes their focus changes and they begin inhibiting prior function in order to incorporate new ones. This is usually the result of stressors which leads to the release of cortisol which stimulates neurological interweaving as a way of coping with the flood of data so that it can be processed holisitically. This is just a temporary process however, as the person increases their ability homeostasis begins to be achieved and the brain enters a new homeostasis where prior function is reintegrated.