This is the tenth and final article in a series about the issues that arise over time for older people who experience mental declines - and how you, as a family member or friend, can help.

Recent columns have painted a picture of a situation that you would probably love to avoid - having to guide or make big decisions for your elderly relatives, often without much help from them.

Who wants to decide where the people who raised you will live for the rest of their lives?

Who wants to guess what characteristics matter most to them in a continuing care retirement community or in an assisted living community?

When my husband and I were buying a house a number of years ago, we listed all the characteristics that we cared about. Space for a garden? Four bedrooms? Tree-lined street? We weighted them all by importance, then scored each house we saw against these requirements.

Then we added another characteristic and weighted it most heavily of all. We called it "je ne sais quoi," a French phrase that defines as "an indefinable, elusive quality, especially a pleasing one."

We meant, "Ok, the house has most of the features we want. But does it feel right for us?" The Realtors couldn't tell, but we always knew instantly.

Do you like having to guess which care community would pass your elderly relative's "je ne sais quoi" test? Probably not. That's why it's a good idea to get decisions made while older relatives can still participate.

But do you realize that you may be putting your own children or spouse or other relatives in the same position of guessing what you'd want, if you needed care?

"But I'm still young!" you may protest. "My parents are old! It's not the same situation at all!"

Maybe the two situations are more alike than you think.

A Pew study a few years ago found that people under age 30 believe that old age begins at 60. Sixty-five-year-olds, though, believe that old age begins at 74. The study reports, "Even among those who are 75 and older, just 35 percent say they feel old."

You may assume that because you are "young" and take care of yourself, you don't need to plan for your care.

But you can still be hit by a drunk driver as you drive your hybrid car home from the health food store with your order of organic vegetables in the back seat.

You can still end up with a disease or disorder that doesn't notice or care that you hike a nearby mountain - all the way to the end of trail - three times a week.

Research suggests that most people think that they will be healthy until they die peacefully in their sleep of old age.

In fact, 85 percent of people experience some period of significant decline -- often for years -- before they die, and 76 percent of those over the age of 65 die someplace else besides home.

Sure, maybe that won't be you. But the odds are that it will be.

Jeremy Kisner, a Certified Estate Planner in Phoenix, noted that adult children may give up their careers or get divorced because they put so much energy into care for an elderly parent, and feel guilty if they do less. But the parent would never have wanted to create such issues.

He suggested that all adults write a "what-if" letter to clarify their wishes.

It might say, for instance, "If I become ill or injured and require a significant amount of care, it is okay to put me in Assisted Living or in a nursing home. Two that I think would be fine are ABC on Main Street and XYZ on Center Street. Of course, I hope that the situation doesn't arise. But if it does, I don't want you to give up your career or damage your marriage to take care of me. If a family member without such commitments decides to move in to take care of me, he/she should have a clear job description and get paid market rates, out of my assets."

By writing a few sentences, you could save your family massive turmoil.

Why not write them?