Student-loan debt is not just a problem for young, recent college graduates searching for their first jobs. Growing numbers of adults nearing the ends of their careers are accumulating such big debt, too, and they don't have a lifetime to pay it back. In fact, student-loan debt is growing fastest among adults ages 60 and older, with more than two million people in that age group now owing an average of $19,000, according to the Federal Reserve Bank of New York. Their default rates are rising, too, and increasing numbers of retirees are seeing their Social Security checks garnished because they fell behind on student-loan payments. Many of these older borrowers thought they could increase their marketability by earning an advanced degree later in life but are struggling to make ends meet instead. Many factors lead to increasing debt loads for older borrowers. The recent recession drove more people back to graduate school. Tuition is rising. And the number of full fellowships being offered to graduate students is declining. As they struggle to repay their student-loan debts, some older borrowers have been through bankruptcy and home foreclosures. Some had move in with their children. Robert M. Applebaum, a former assistant district attorney from Brooklyn, started StudentDebtCrisis, an advocacy group, and created a Facebook page to serve as a virtual support system for borrowers to talk about how student debt affects their lives. "Many seniors are at their wits' end, contemplating suicide," says Mr. Applebaum, whose Facebook page has nearly 10,000 followers. "They're so desperate for any kind of help." Holly L. Sherlock, 54, earned a doctorate in health-care administration from Capella University in 2010 thinking it would help her find a better job, but, she concludes that in this economic climate, she doesn't think going to graduate school is worth it.