"Unlike other organs in the body, there is a significant challenge to understanding the complexity of the brain," said Loewenstein. "There are billions of neurons, unlike other organ systems that are more straightforward to study."
Despite the grim statistics, Shriver says there's been a lot of progress.
"There's been a lot written about it, a lot of trials, we've certainly been able to tie cardiovascular health to brain health," she said. "There's a lot of good preventive information that's gone out, so there's a lot of hope, but people get pessimistic because there's no cure."
One of her biggest hopes is to get people talking about Alzheimer's.
"We're trying to take it out of the closet and put it into the living room."