Skills fade with time. You know you’re not going to become a major league ballplayer at 30 or start a career as a math genius at 40. But chances are you weren’t going to do those things anyway, so it’s no big deal.

But almost all of us have financial lives. It is worth noting, then, that new academic research shows that the average person’s financial decision-making skills peak at age 53, then gradually decline.

What’s to be done about it? I have some suggestions. But first, the research.

The study, “The Age of Reason: Financial Decisions Over the Lifecycle,” by researchers at the Federal Reserve, Princeton and Harvard, looked at the financial records of tens of thousands of borrowers and found that the young and old made poor decisions. Middle-aged folks did better.

For the young, the lack of experience outweighs the sharp mind. With older folks, dimming faculties undermine even a lifetime of experience.

Of course, there may be other factors at play. Many of today’s complex financial products, such as mortgages with tricky payment options, didn’t exist 10, 20 or 30 years ago. Poor choices by older people, like those of the young, may in fact be due to a lack of experience with these options rather than weakened acuities.

Also, I suspect that many older folks came of age in more trusting times and may be easier marks for salesmen and advisers pushing high-cost products.

But let’s assume you’re either young or old – or will be old someday. Here are a few helpful principles:

¢ Fees matter. Sales commissions, annual account maintenance fees and other “incidentals” add up.

If you’re in your 20s, paying annual fees equal to, say, 2 percent of your investment holdings could leave you at age 70 with only half the assets you’d have if you did not pay those fees. An older person with conservative holdings earning, say, 6 percent a year would lose a third of her income by paying 2 percent in annual fees.

¢ Don’t rush. Whether you are young or old, assume that investments, loans and other financial choices are commitments you will stick with for years, meaning you have nothing to lose by taking a few weeks to make decisions. Con artists push their victims to make quick, emotional decisions and to avoid shopping around.

¢ Read all sales materials, prospectuses and other disclosures. Be sure you know your options if things don’t turn out as you expect. Suppose interest rates change or you have a financial crisis? Would you be able to reverse a decision, or would you be stuck?

¢ Get objective advice. That means relying on advisers who have no stake in whether you do what they suggest. A broker who earns sales commissions has a financial incentive to urge you to buy and sell, even if that’s not in your best interest. Or he may steer you to a mutual fund, loan or insurance policy offered by his firm when a competitor’s might be better.

¢ Consider hiring a “fee-only” adviser who is paid a flat or hourly rate instead of commissions. For referrals, try the National Association of Personal Financial Advisors at (800) 366-2732 or online at www.napfa.org.

¢ Keep it simple. For investors, this has become much easier over the past few years with the rise of lifecycle, aged-based and target date mutual funds.

These automatically change your asset allocation as you age, putting most of the money into stocks when you are young and gradually shifting it to bonds and cash as you age. That changes the emphasis from high growth to safety.

Ask your adviser about these funds, or shop yourself at www.morningstar.com. Even if your financial abilities stay sharp as you age, keeping things simple will let you sleep at night – and leave time for the other things you care about.