NEW YORK ( TheStreet) -- How bad have things gotten for millennials? Their financial situation is so grim that they may never get completely out of debt -- in their entire lives. That's the conclusion of a study from Ohio State University. The real culprit is credit card debt, which tends to stifle economic growth of younger Americans, primarily because they pay it off so slowly, the OSU study says. But millennials are paying off all their debts so slowly they may accumulate credit card debt well into their 70s and die still owing, researcher say. "If what we found continues to hold true, we may have more elderly people with substantial financial problems in the future," says Lucia Dunn, a lead author of the study and an economics professor at Ohio State. Perhaps -- let's go out on a limb here and say definitely -- that's a big reason millennials say debt is their "biggest financial concern" of their lives. That dour sentiment comes from another study, this one from banking giant Wells Fargo ( WFC), which has 54% of millennials saying it's debt that keeps them up at night. Another 42% of younger Americans say their debt is "overwhelming," double the percentage of baby boomers who feel the same way. And 51% of millennials say they aren't saving for retirement, primarily because they just don't have enough extra cash to start a savings program. Any extra cash they do have needs to go to pay down debt, 81% of millennials say. "I am glad to see about half already saving for retirement, but we're also seeing that half of this generation has not started to save and is putting it off until the 30s," says Karen Wimbish, director of retail retirement at Wells Fargo. "I can't stress enough how important it is for this generation to start saving now -- the benefits of starting young can't be recreated later." The trouble starts in their early 20s, with ever-skyrocketing student loan debt, Wells Fargo reports. More than 64% of millennials funded their college education through loans, compared with 29% of baby boomers. The report cites statistics from the Consumer Financial Protection Bureau, which estimates total student loan debt topping $1 trillion last year, far and away the highest figure ever for U.S.-based college loans. Yet younger Americans aren't turning to the stock market to grow their financial assets, a potentially big mistake given the historical returns from stocks, which tend to easily best the rate of inflation. About 52% of millennials (and 67% of younger women) in the Wells Fargo study say they are either "not very confident" or "not at all confident" in the stock market. "But many are already in the stock market. While it is understandable that this generation is wary, millennials have time on their side and a long runway for future growth," Wimbish says. Wells Fargo advises millennials to squeeze more money out of their budget and add it to their 401(k) plans or individual retirement accounts. The good news is that they have time for their retirement savings to grow.