Paul Humphrey is a vascular surgeon and an avid runner. He says he's run five days a week for the last 10 or 15 years. But this time he's not just running for himself. Humphrey has run seven marathons, but that is nothing compared to what he's about to attempt.

"Just seemed like a great challenge. I guess I'm kind of goal oriented so I hope I can get it done," said Humphrey.

Its a 50-mile ultramarathon in Huntzville, Texas, about two marathons in one day.

"I'll feel twice as worse or even quadruple. I think it will be a challenge and it's more of an endurance event," Paul said.

Endurance is something Paul understands. His mom's endured a debilitating disease for the past seven years.

"It's very frustrating. In fact sometimes it's so frustrating that I don't want to go over there because I can't fix it," said Paul.

Doctors diagnosed Paul's mom Janice Humphrey with Alzheimer's disease seven years ago.

"Everyday I go in and say, Janice it's your husband Loren. She's very confused after the night," said Loren Humphrey, Paul's father.

"Equally sad is my father. I say that my mom has the disease, but my father is living it," said Paul.

Paul is running to honor his mom, along with raising awareness and money for Alzheimer's disease research.

"I think that will pull me through. I think she'll be running with me, my two buddies running with me and the good lord as well. I think I can get it done," said Paul.

Paul hopes to get it done in 10 hours.

"When I'm at mile 48 and crawling to the finish line with maybe two miles to go. I'll think of mom's perseverance," said Paul.

Loren is still optimistic.

"You say hey, we've been married 55 years. We're 77 and we had a fabulous marriage. We're lucky to have this much," said Loren.

So when his legs are heavy and steps are strained, Paul knows he has mom's encouragement to push him through.

"Having someone that loves there mother that much, that's why you need to share burdens. That's what it's all about," said Loren.

"She'll be there obviously in my mind and I think she'll carry me through, she'll carry me to the finish line," said Paul.

Paul practiced for the ultramarathon with a 30 mile run. It took him five hours.

The Rocky Racoon is on February 7th. Humphrey is going to match all donations up to 10,000 dollars.

There are as many as 5.2 million Americans living with Alzheimers.