My Son Is 12 And Had Been Taking Vivance For

My son is 12 and had been taking vivance for a years. we usualy take him off of it for summer vacation and most weekends during school. we started himback on it two days ago to get him used to taking it again before school starts. It seems to be having an adverse effect on him this time. He is very confused and has trouble with any decisions. His mind seem to be in a jumble. This has never happened before. H started going through puberty right as school ended for summer break and now is full puberty change mode. Could pubert have made the changes in how the vivance effects him?