In my experience, ANY medication change can cause instability in my difficult children brain, thus his behavior. The mood type stabilizers especially. So, it does not seem abnormal for your son to feel the effects of going down a dose on his Lithium. However, it will take some sustained time to just see if it is the bump in medications that is making him irritable, or if it is actually the lower dose.
The Lithobid is the only thing that has made a noticeable impact in my son, however, when he was on Depakote and Lithobid his cognitive functions were impaired.
I think your difficult child was the one who became manic on Lamictal, right? So maybe that would not be the best fit.
Other medications that can help mood are the mood stabs like Topomax, Tegretol, Trileptal - none worked well for us.
And anti-psychs like Seroquel, and Risperdal - both worked well for a time, but had icky side effects.
Any & all of these can cause cognitive dulling.
Clonidine has worked very well for us in reducing anger, however, I know in some it can make it worse.
Unfortunately it is all a cr$p shoot.........because every metabolism is different.
Good Luck, and do not be too anxious to d/c or increase a medication because he is having a hard time during the holidays. Sometimes it is simply environmental, and changing the metabolism can not take away what is physically going on.
