So what are the typical signs of aging, and what signals that something's wrong?

"A lot of times, people dismiss things, saying 'Oh, it's OK, because she's getting older,'" said Jennifer Reynolds, manager of Senior Care Services at Mary Washington Hospital. "But you shouldn't be losing functionality just because you're older."

According to Mary Beth Reckmeyer, nurse practitioner with Senior Care Services, there's a relatively simple rule of thumb.

"You should be able to do what you've always done, even if you do it more slowly or less frequently," she said. "You can slow down, but you shouldn't lose abilities. If someone has lost any basic skills, there's something that needs to be checked."

For caregivers or friends, anything that catches your attention should be noted. If there's rotting food in the refrigerator, burned pots and pans in the kitchen, or your loved one is suddenly argumentative, don't ignore it.

"There's a reason something catches your attention," Reynolds said. "Don't just let it go."

But it's difficult for caregivers to pressure their older friends or loved ones into seeking assistance.

"It's a delicate balance for caregivers," Reynolds said. "There's a level of respect, particularly if this is parents you're dealing with. But sometimes you have to have that role reversal."

Here are some specifics about what's normal, and what's not, when it comes to getting older.

MEMORY AND COGNITIVE ABILITIES

It's typical, as a person ages, for cognitive abilities and recall to slow, according to Dr. Timothy Salthouse, of the Salthouse Cognitive Aging Lab at the University of Virginia.

"Memory tends to be a little less accurate, particularly in retrieving names for people or objects," Salthouse said. "And people will experience a slowdown in how quickly they're able to do things like arithmetic or searching for something in a display."

There are great extremes in the level of memory problems, Salthouse said.

"If you can't remember where your keys are, don't worry," he said. "If you're holding your keys in your hand, and you don't recognize what they are, that's a problem."

Research has shown there are some "protective factors" that are associated with higher performance and slower declines over time, Salthouse said.