Ladislav Volicer MD is almost correct. The active ingredient works on one area of the brain; the active ingredient in Exelon works in at least 5. There are two studies using tracers confirming this.
Those with a dementia brought on by Lyme disease see symptom improvement superior to use of Aricept alone.
On the downside: side reactions of use of either the patch form or oral of Excelon can cause an allergy enhancement reaction (disseminated allergic dermatitis) that appears after 2-weeks of use, and may exacerbate 'colitis-like' symptoms (poor absorbtion of Ca, K, etc.).