Writer David Shenk's book The Forgetting has been called "the definitive work on Alzheimer's"-the story of the disease, its impact on patients and families, and the search for a cure. A few days after the death of Ronald Reagan from Alzheimer's, David Shenk spoke to Beliefnet's executive editor Elizabeth Sams about the trajectory of the president's illness and the spiritual meaning of the disease.

Everyone is of course wondering what impact his Alzheimer's may or may not have had on Reagan's time as president. Given that he died in 2004-and was diagnosed in 1994-what would our general knowledge of the disease say about that?

The first thing to say is that Reagan did not have Alzheimer's as president. It's more complex than that, but if you have to answer "Did he or did he not," he definitely did not have Alzheimer's, despite what some of his critics want to believe.

Reagan was very aware of senile dementia. Two members of his family had had it and he had been asked about it as he was running for president. He joked about it quite a bit as President-and I think he intuitively knew that if he lived long enough, he was headed in that direction.

He definitely joked about it while he was president. I have no doubt he was having some kind of what I would characterize as annoying memory issues-probably in his second term. And there's the suspicion that "Oh, they didn't want to admit it." And I'm sure they wouldn't have wanted to admit it if it had been there. But I think it's pretty clear from looking at the evidence that he could not have been diagnosed with Alzheimer's at that point. I don't think he had any real disorientation. I don't think his memory problems were anything really out of the ordinary for someone his age.

We all have memory problems as we get older. We also, more to the point, all have memory complaints as we mature, as we have higher and higher expectations of what we want to remember in this world. As we get older we meet more people, we learn more things, we want to remember it all. And it's not that the brain doesn't have the capacity to do that-it does. But the brain is actually built to help you forget a lot of the minute details so you can form executive summaries of things. That's really what intelligence comes down to-the ability to take a step back and not remember every tree and leaf in the forest but to recognize the shape of the forest-to be able to characterize it.

After [Reagan] left the Presidency I think it's clear that he had progressively more difficulty with his memory and started to have issues of disorientation in the early '90s. And I think by the time he was diagnosed [in 1994] there wasn't any doubt. He probably could have been diagnosed a little earlier.

Alzheimer's is a very predictable disease. It can vary in how long it actually takes to completely overcome you. It can range from say five to even 15 or 20 years, but Reagan's ten years from diagnosis to death is right there in the average.

In all your conversations and research for the book, did you get any insight into how Alzheimer's affects spirituality?

I think Alzheimer's has an enormous effect on our spiritual lives in that those of us who come into contact with it-as friends, family members, doctors, scientists, or other level of observer-because you're seeing this excruciating loss going on in very slow motion. You're seeing these "shaves" of a person-like the layers of an onion-slowly peeling away. And it's hard to watch. But there's also something very profound and meaningful in the loss-seeing it so up close. Also in the idea of going through stages of mourning in such an incredibly slow way-which is very rare. I don't think there's any other disease quite like this-where people mourn, are forced to mourn the loss [over so long.] I mean, you have slow diseases, but this one is not just killing you slowly but it's taking you away slowly-taking the person that we recognize away from us. It's not like you're here one day and then gone the next. You are here, and then a little bit less of you is here, and then a little bit less-and that goes on for ten or 15 years.

I've heard some observers say that on one level Nancy Reagan must be relieved, and she's not going through the classic mourning process that you would see if her spouse had a heart attack. Of course there's probably a lot of grieving going on now and will for some time. But a lot of that loss has already happened and happened so slowly that it really does shake you and you're forced to come up with some kind of spiritual meaning. Whether that means a return to your religious roots or some new idea of religion or whether it's not really religious per se. I know for me the experience of being in this [Alzheimer's] world has just been incredibly spiritual. It hasn't sent me to my religious roots, but it has been very, very meaningful in a way that I tried to write about, but it's difficult.

You seemed to touch on that, late in your book where you wrote that Alzheimer's is "our best lens on the meaning of loss." Which is tantalizing-and also, potentially for people dealing with the disease-irritating. I don't know many families who while they're in the midst of it are finding a lot of meaning in the experience. They're finding it awful.

I don't think the two are mutually exclusive. Certainly, by saying "it's our best lens on loss" it sounds like something that you want, something that's useful. And I don't mean to suggest that it's something people would wish to have. But I think it can be awful and still illuminating at exactly the same time.

Some people are just offended by that-that I could suggest that there is something not positive-but something that is not purely awful and negative and destructive about this disease. And I understand that. It is purely destructive and awful, and it is excruciating and something you wouldn't wish on your worst enemy. But there is something about it that I think also teaches us about who we are.

As I was doing my research, I wanted to know how far back the disease went. So I got in touch with all these historians from different periods and I asked what sort of words should I be looking for-obviously Alzheimer's the term is only 100 years old. And I got all these words thrown at me through various periods and various languages. And I said, Have you seen these words in your research, in your specialty? And it was everywhere. It is everywhere if you know what to look for. In fact, the list of writers who have written about senile dementia--it's like a "Who's Who" of literature. You could almost just mention a writer anywhere in time and the chances are pretty good they wrote about senile dementia.

[Yet] it wasn't that common back then [because most people died much younger]. It's not like that many of these writers could have had firsthand experience with the disease in their family and were moved to write about it. So my question was: Why is this so prominent in literature if it wasn't so prominent in actual, physical human experience? And the best answer I can come up with is that there are lessons we learn, intuitive lessons about what it is to be alive, what it is to be human, that we get from Alzheimer's disease that we don't get anywhere else. Because of that slow fading away. It's a useful tool for writers obviously, but it's also, I think, an insight into what we're made of that has been very powerful and very useful not just for writers but for readers.

In a strange way I think if we are lucky enough to beat Alzheimer's in the next handful of years, we're still going to want to make some effort to remember what it was. I think it's been a part of thousands of years of history. If we could take all the Alzheimer's literature and just burn it, and say let's forget it ever existed, I think we would lose something.

Nancy Reagan has become an outspoken advocate for stem cell research as a possible route to treatment for people with Alzheimer's. What kinds of things do scientists hope for in that direction?

As I understand it, and I'm not a scientist, the fruits of stem cell research are more long term than short term. There's no doubt that using stem cells to understand the brain and to be able to recreate sections of the brain that have been damaged holds a lot of promise in the long term.

The most important point to be made about stem cell research is not that it wouldn't be great, but it's a little misleading to talk about it as much as we have. Stem cell research is not going to cure Alzheimer's disease in the short run. There are all sorts of promising leads that we have with Alzheimer's disease in the short run. We could actually cure this thing in the next 5 or 10 years, potentially. But it's not going to come from stem cells.

I'm not criticizing Nancy Reagan. I think, you have to get involved with what you're passionate about and she's passionate about stem cells. But if you really wanted to put your money and your attention towards curing this disease as fast as possible, in my judgment, you would not be putting the vast majority of that effort toward stem cell. [It would go toward running many more drug trials simultaneously.] The Alzheimer's community knows where to spend the money. The NIH knows where to direct the research. What we need to do is increase that budget. And we need to do it dramatically and we need to do it very soon.

Do you think ten-year trajectory for cure that you wrote about in your book is plausible, if there's a lot more money?

First, we could come up with some very significant developments in the next handful of years-even if we don't get more money. It could happen. There is a lot of money-it's not like Alzheimer's is ignored, there's a lot of money going into it. It just doesn't get the federal funding it deserves.

Alzheimer's was headed toward funding of about a billion dollars of NIH funding a year which people seemed to think would be about the right amount. [They] were getting very generous increases every year and when the book came out [in 2001]-it looked like we were about two to three years away from hitting that mark. Every target was being hit. And then, came 9/11 and that just changed everything. Now they're just clawing to keep the funding they have.