. >> dan miller is just 61 years old.wife, kathy, began noticing changes four years ago. >> he kind of hid it pretty well. and then i noticed he was having trouble, his clothes would be backwards. and those kinds of things. >> just little things. >> just little things, yes. >> a scan of his brain revealed what dan had been hiding. >> mr. miller had very large amounts of beta amyloid. >> the red spots indicated a buildup of those beta amyloid proteins, the so-called brain plaque, a marker of alzheimer's. dr. rezai explained to miller he couldn't cure him of the disease, but he hoped to slow its progression. >> why take part in the trial if it's not a cure? >> i have to explain to you that i was at the point, like in dante's inferno, where it says, abandon all hope, ye who enter here. for me, it was just like, let's do this. what do i have to lose? >> reporter: here's how it worked. hours before the procedure, miller was given an iv treatment of adacanamab, one of those new drugs to reduce beta amyloid plaque. miller was th