Its rare but possible for a child to have bipolar disorder. If he is diagnosed with Asperger's that is a developmental disability and although those can have behavioral problems that can be severe they don't generally respond to medication like psychiatric disabilities such as bipolar or ADHD but both diagnoses can occur together. They need to provide specific diagnoses as for follow up and treatment and you should discuss this further with them. As for Asperger's cognitive behavioral therapy can be quite helpful. Regardless of what they are treating any decrease in the dose of Abilify would lead to it being less effective so that should be discussed with a psychiatrist and as Tegretol (one of the names for the medication you are speaking of) that medication has a short half life (time it remains in the blood stream) so it can easily run out during the day and the dosage and titration and spacing of it should be discussed with a psychiatrist to prevent this from happenning.
Abilify was just proven to treat the aggressiveness/irritability associated with autism spectrum disorders.
ABA has been a Godsend for my son (he was dx as severely autistic at 26 months old, and boy oh boy have we had behavioral/aggression issues).
That being said, when my son is on medication, he has weird reactions. Ibuprofen makes him crazy hyper (my daughter too). Steroids he is an absolute nightmare. I have bruises on me right now all up and down my arms from the related biting from croup-necessitated steroid use. Ugh.
Keep in mind also that your son is likely holding it all together during the day and falling apart at night when he just can't do it anymore. Kids with ASD's end up having to work so darn hard just to make it work that once they can relax they melt down.
So, if the Abilify level is going down, and it's being used to treat the irritability and aggression... if he goes lower than the dose needed to treat it, he will have an increase in the behaviors.
Hope that helps :)
I was recently asking my psychiatrist the same question ( about the mood-stabilizer wearing off) she didn't give me an exact answer but from my experience..... I was taking three 900mg lithium and by about 4 pm I felt like death warmed over. She switched me to extended relief and I haven't felt better. So, I'm pretty sure that it's possible and I know for a fact that with me, the evenings and the afternoons are the worst for me as a person with bi-polar disorder.