In her 20s, Connie Swain shelled out a lot of money to a private vocational school to learn computer skills, relying on student loans for tuition and expenses.

"I was young and didn't really have a sense of how to do things," said Swain, now 44. "I should have gone to community college. I didn't realize what I was getting myself into at the time."

The debt she accumulated - she owes about $13,000, down from $23,000 - has followed her for two decades.

She's among legions of Americans who took on student debt in pursuit of a better future - only to find out that that debt itself cast a shadow over that future.

"It has made things really difficult," said Swain, a case manager for homeless families at a San Francisco nonprofit. "It made it harder to purchase certain things."

Most notably, a house.

"I want to buy a house so we have some place that is our own," said Swain, who lives in a rented San Francisco house with her disabled mother and her 20-year-old son, a student at a vocational school. Her daughter is away at college. (She advised her children to be careful in taking on student debt.)

"I want to create something long term for my kids and their children," she said. "As much as I pay in rent, I feel like I should have an opportunity to own. But I can't even look into (purchasing) until I figure out my whole student loan and my credit."

Americans' outstanding student loan debt now stands at a staggering $1 trillion, more than credit cards and auto loans combined. Many borrowers find that their debt burden limits their ability to pursue "lifecycle events" - buying a house or car, starting a family, launching a business.

"We hear (graduates with debts) say they feel they can't ever afford to buy a house," said Lauren Asher, president of the Institute for College Access & Success, which runs the Project on Student Debt. "We hear them worried about getting married, how they can afford to live, the cost of housing for both rent and mortgage, how they can afford to retire."

Average debt growing

At the same time, "We've seen an increase in the average debt at graduation of about 5 percent a year for the past several years," she said. The average debt stands at about $25,000, but that does not include private colleges.

Unlike most other loans, student debt cannot be discharged in bankruptcy.

To be sure, student debt can have more flexibility than other forms of debt, with forbearance, deferment and income-based repayments all possible options, at least for federally backed loans. Amovement is afoot in Washington to try to make student loans less of a burden. And the loans did come from something of value. Studies show that college graduates will make an average of $650,000 more in their lifetimes than high school graduates.

But the huge amounts are causing some experts to worry that student debt could be a ticking time bomb, akin to subprime mortgages.

Scrimping to make loan payments means people with student debt refrain from spending that would stimulate the economy.

"This issue has a huge impact on the economic stability of the country," said Paul Wrubel of San Mateo, who counsels families on college issues including financial aid. "A kid goes to college, gets a job, and then has to spend the next 10 years of wages paying back student loans.

Bad credit

"Not only do they have a ball and chain, but the chances are very good that the student hasn't been able to service that debt and his credit has gone to hell in a handbasket," Wrubel said. "If he does (get a mortgage or other loan), it will cost more" in higher interest rates.

He's right about failing to make payments on time. Delinquency rates on student loans are also rising. As many as a quarter of student loans were past due in the third quarter, according to a report released last month by the Federal Reserve Bank of New York.

New graduates, inexperienced in handling money, may not realize the long-term repercussions - a big hit on their credit - of skipping payments or paying late without arranging for forbearance or deferment.

That was true of Swain. "I went through a bunch of forbearances because I didn't find the high-paying jobs (the computer school) had promised," she said. "But sometimes when I didn't make arrangements (for forbearance), it went on my credit."

She's working now to clean up her credit score as a step on the road to buying a home.

"Not a lot of people are equipped to understand the contract they're signing and read it chapter and verse," said Stephen Watkins, who heads the financial education program at the Mission Economic Development Agency.

Housing market

First-time home buyers, usually young people in their 20s and early 30s, have traditionally helped spur the housing market. Their absence, which experts say is due in part to the increasing student loan burden, is yet another factor stifling the moribund market.

Even though the real estate crisis has made homes more affordable, the number of young first-time buyers has dropped dramatically. A Federal Reserve study showed that 9 percent of people ages 29 to 34 got a first-time mortgage from 2009 to 2011, versus 17 percent a decade earlier.

"Definitely, I see (student debt) as a problem for clients, said Lisa Melby, a broker-associate with Firestone Financial Group in San Jose. "The real burn is in this market, a lot of those graduates aren't getting jobs in their chosen field."

Lenders don't view student debt any differently from other forms of debt, such as a car loan, but it's one more factor that can reduce buying power when it's calculated as part of debt-to-income ratios. And if it's hurt credit, that's another factor.

"On a regular basis I see clients coping with five-figure student debt that just won't go away," said Watkins, the financial counselor. "Many of them want to buy a home, but their student debt is a big issue in terms of dollars (that they owe), and (impact on) their credit. One or two delinquencies or defaults can really wreak havoc, especially if student loans show up as separate accounts."

It isn't just graduates who are burdened with student debt. It's often their parents as well. Wrubel worries about the retirement hit for parents who dipped into their nest eggs and took out loans to help their offspring through college.

"Parents are saddled with bigger and bigger loans," he said. "They're taking their retirement money and the equity in their houses and pouring it into college. That's going to come back to bite us big time. Our failure to underwrite the education of young people will result in having to underwrite the survival of old people."

Carolyn Said is a San Francisco Chronicle staff writer.