Alzheimer's disease and other dementias correlate with aging. And what are the innovative approaches to cognitive aging? Yeah, Alzheimer's disease is fascinating to a comparative biologist like me. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. I mean, we have been spectacularly failing at being able to do anything about Alzheimer's disease. There still aren't any treatments, even though we've had more than 300 treatments that we've developed in mouse models of Alzheimer's disease. This leads me to think that the mouse is not enough to understand human biology. One of the problems is that we don't have good animal models of Alzheimer's disease. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. All we've done so far is we've taken some human genes that we know cause Alzheimer's disease, we put them in a mouse, and there's some caricature of Alzheimer's disease. There don't seem to be any natural models. And you would think that chimpanzees that are more than 99% genetically identical to humans would have something like Alzheimer's disease. But so far, we haven't seen it. It's certainly not common enough to study. 

So what we need are some better natural models. Now there are a couple that is intriguing and may be helpful. One of them, believe it or not, is a very tiny primate called the gray mouse lemur. It was only 100 grams. It seems to show something very similar. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. Looking at the brains post mortem, they seem to have similar lesions to Alzheimer's disease. However, they're not in the same places as in humans. This may be something that's a human-specific disease. We're still not sure about that. But that makes it very, very difficult to study because humans are terrible experimental models. We can't have them all eat the same food and live the same lifestyle. And Alzheimer's disease also seems to be affected by so many social determinants. 

There's another level of biology that we don't understand. It is, well, this. Why does a higher level of education reduce the risk for Alzheimer's disease? That kind of thing. Why do people who make more money are more protected from Alzheimer's disease? I think we're starting to learn a little bit because now we understand that physical activity is protective against Alzheimer's disease. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. So I guess if you put all these things together, it makes us realize the limitations of a mouse for trying to understand a complex human disease like Alzheimer's disease.