For about the last week I've been not taking my ritalin. About 2 days after I stopped I started having a severe problem concentrating on everything. I also experienced some behavioral changes and anxiety as a result of this. I find that I can concentrate, but only if I put my mind hard to work at doing so and it eventually causes a headache while trying? I'm afraid I may be developing some degenerative mental disease, but my doctors say that possiblity is very remote since things like CJD, Alzheimers, and Huntington's Disease are very rare, most of them occur in older people, and because I am known to be a hypochondriac who suffers from anxiety because of it they think it could be related to that. Is it possible that the symptoms I'm describing could be attributed to withdrawl from the ritalin? Or should I start writing my last will and testament while I still have enough brain left to do so? Has anyone ever had these experiences. I'm now on Xanax which controls the anxiety to a decent extent, but I find it hard to perform many tasks because my concentration just isn't there.