Financial planning for our older years is tricky business. There are so many unknowns. Will you be one of the 20 percent who need long-term care for more than five years? Will you die at a relatively young age and miss most of your retirement years? Or will you outrun the odds and become a member of the centenarian club?

These are just a handful of the variables that affect you personally. Then you have to mesh these what-ifs with an anticipation of market behavior.

Tricky business indeed.

What most of us tend to do is aim for the middle. We’ll probably have an average lifespan, with average medical needs, and the market will, on average, grow at a given rate. It’s really the best we can do without a crystal ball.

But most of us won’t hit the average mark in every category, and that’s where things can move from tricky to ugly. If your retirement doesn’t turn out the way you’ve planned for it to, what will you do?

Probably the wrong thing. Research presented in the Proceedings of the National Academy of the Sciences demonstrates that elderly adults are poor financial decision makers.

This research looked at individuals from ages 12-90 and their decisions with respect to potential for gain and risk. The cohort aged 65-90 adults made decisions that resulted in “the lowest expected monetary outcomes on average.” This group’s choices earned them 39 percent less than young adults and 37 percent less than mid-life adults.

Further, there was less consistency in decision-making by the older group than in younger ages. They might make one choice today and a completely different decision tomorrow based on the same information.

I’m not even done with the bad news. These were healthy adults. There was no dementia or significant cognitive decline in the group studied. In real life, 13 percent of adults over 71 have evidence of dementia.

While this is disappointing news, there are things we can do to save ourselves from this common fate.  First, put as many of your plans on autopilot as you can, to minimize the number of future decisions. Second, as you plan your retirement years, consider the three possible outcomes – expected, worse than expected, and better than expected.

Make contingency plans for what you will do if you need far more medical care than anticipated. How aggressive will you want to be with treatments and therapies?  Will you pay for it by selling your family home earlier than anticipated?

What if we experience a 2008 market the year after you accept your gold watch? Do you have a plan for waiting it out and benefitting from the eventual upswing?

And what about the upside? What if the markets outperform your imagination? How will you manage that found money?

You can make these decisions earlier to take advantage of more consistent decision-making ability and to take the pressure off of your future self. Communicate these thoughts in writing and with loved ones whom you trust.

According to Carol Tavris and Elliot Aronson, authors of Mistakes Were Made (But Not By Me),we like to believe that the decisions we make are good ones. In fact, we’ll go through a lot of discomfort to prove ourselves right rather than having to admit we are wrong.

With a little planning, we can stand by good decisions instead of stubbornly defend poor ones.