I am often confronted by questions about whether to take cholinesterase inhibitors such as Aricept, Exelon, or Razadyne. Anyone with a diagnosis of Alzheimer’s disease is better off taking one of these medications (it may not matter which one based on limited studies that directly compare these drugs) – if they tolerate them. The most troublesome early side effects are gastrointestinal, neuromuscular, and vivid dreams. Longer term use may slow heart rate and cause fainting.

There are studies demonstrating the effectiveness of these medications in all stages of Alzheimer’s disease from mild to severe. For example, I conducted a study a few years ago on the effect of Aricept on total score on the Dementia Rating Scale. The Dementia Rating Scale provides an objective measure of severity of cognitive decline. A perfect score is 144 points and we should all be able to score above 140. A score of 123 or below is consistent with a diagnosis of dementia. Scores were obtained from both participants who could tolerate the drug and those who couldn’t. Whereas those who could not tolerate the medication showed decline in scores 9-12 months later, those who tolerated the drug showed an average improvement of about 6 points.

Aricept was shown to have a positive effect on residents with severe Alzheimer’s disease in skilled nursing facilities. A special test, the Severe Impairment Battery, was necessary in that these residents were too impaired to complete a meaningful Dementia Rating Scale. Furthermore, treating these residents with both Aricept and Namenda improved scores more than either medication alone.

I am also asked about how long to take the medications. This is a very complex question to answer. Part of the problem is that Alzheimer’s disease is progressive and gets worse over time. This leads to the inference that the medications quit working. To this point, there is both empirical and clinical data showing that there is a risk for more rapid decline in those who stop taking the medication. Current medications slow the decline; they do not reverse the disorder.

A study published March 8 (The New England Journal of Medicine, 2012) demonstrated that Aricept and Namenda both improved scores on testing as well as improved ratings by observers. The unique aspect of this trial was that participants (with moderate to severe Alzheimer’s disease) still resided in the community and were already on Aricept. Those who continued with the drug scored higher than participants who were taken off Aricept 52 weeks later. Those who switched to Namenda were also better than those switched to a placebo. In this study, the combination of Aricept and Namenda was no better than either alone.

In short, cholinesterase inhibitors help many with Alzheimer’s disease do better over time. Furthermore, once Aricept is started (presumably this also applies to the other cholinesterase inhibitors), it should be continued unless there is a compelling reason to stop. The effect is not large but it appears to be consistent in those who tolerate it.