Without knowing which eight signs you have, I'll try listing some, and hope I hit the ones you have not yet found.
Although not directly a sign of Charlie's regression, the deterioration of Algernon's abilities, his death, and the way the brain looks are a reflection of Charlie's own current and coming decline. Charlie starts having problems with higher scientific thought, reading the classics he had recently loved,and finding the right words for things he wants to say. He turns his music up in attempt to not think about what is happening to his abilities, and smashes the records he loved, when his intelligence was high. He notices that he is having more difficulty with physical tasks, such as typing, and with intellectual tasks like solving mazes, and seeing anything complex in Rorschach tests. Eventually, he gets lost trying to find his way home. He goes back to the bakery and has an accident when one of his co-workers won't let him go to the bathroom. He forgets the relationship he had with Alice, and shows back up at her class.