my 9 year old

i put my son on risperdal .25mg half a pill a day it was for 3 weeks i took him off he seemed experience not remembering very forgetful lost of interest in things he loves such as a favorite show to a favorite outing or sport is that normal and are they back to normal after this medicine or do people change after risperdal for good or does it take time for one to be back to normal and does behavior come back to the way it was before risperdal and is there a weaning process