I went back on vyvanse extended release recently, and thought that it gave me more drive to get more done. But, I'm noticing with some alarm that my concentration for reading, comprehension, retension, and ability to organize and express thoughts is worse than ever. Or at least it seems that way. Anxiety and depression can cause this. Stimulants also make me feel tense, wired. My muscles are in a knot. Before vyvanse, I tried dextroamphetamine and then adderall. My Pdoc thought that up to 80 mg. was fine, but this seemed excessive to me, even hazardous. Sometimes, I find a balance if I take xanax, but that's not wise in the long-term.