Earlier this week, the Food and Drug Administration gave its stamp of approval to Biogen's (BIIB -0.43%) new drug to treat Alzheimer's. With a price point of $56,000 for the drug, and tens of millions of possible patients around the world, the market opportunity is staggering.

Corinne Cardina, bureau chief of Healthcare and Cannabis for the Motley Fool, and Fool.com writer Taylor Carmichael run some Biogen numbers and try to make sense of it. This Fool Live segment was recorded on June 18.

Corinne Cardina: Let's also talk about the price. What did they end up pricing it at?

Taylor Carmichael: $56,000 is what they're talking about. I'm like, "Wow, why is it so much?" Because the market for Alzheimer's is huge. There's 6 million people in the United States with Alzheimer's, and the number in the world is 44 million people in the world. So if you do that math, you try to figure out the market opportunity -- if they get away with that $56,000 price point, which I don't think they will -- I mean, that's a $336 billion drug. We call a drug a blockbuster if it's 1 billion -- so $336 billion just seems insane to me. Just my initial reaction is, "How do you think you're going to get that much money?" I mean, that much money from Medicare?

Corinne Cardina: Yeah, that's the total addressable market. When I talked to Dr. Brian Orelli about this and he basically said that he thinks they priced it at $56,000 because they know that this is not going to be prescribed to every single patient with Alzheimer's. This is going to be kind of like a special-case drug, it will be for a certain niche of Alzheimer's patients -- you don't want to be so far along Alzheimer's. It'll be for a very small group of the 6 million people in the U.S., a small group of the 44 million people worldwide.

Taylor Carmichael: That makes more sense. 

Corinne Cardina: Those are some mind-boggling numbers, [laughs] but I don't think they'll get that close.

Taylor Carmichael: I don't, either. There's so many doctors who are against this drug. Let me read what Public Citizen wrote to the Biden administration about this, about the FDA approval: "Shows a sudden disregard for science. It viscerated the agency standards for approving new drugs and ranks as one of the most irresponsible and egregious decisions in the history of the agency." To have your doctors who were reviewing the data all resign en masse after you overlook what they said -- I don't know, this is a very interesting situation. I mean, Biogen's stock has done really well, obviously, because this was a big surprise, the FDA approval.

Corinne Cardina: It doesn't give you a lot of faith [laughs] in the drug, but on the flip side of this. Obviously, on one side are the doctors who want to see very clear efficacy and safety data. But on the other side, you have the Alzheimer's patients and their families and loved ones, and they don't have good treatments for this awful devastating disease. They've been advocating for more options. If you are desperate for your loved one or for yourselves to delay the progression of this devastating disease, I could see wanting to try everything.