(USA TODAY) -- The financial burdens on middle-aged caregivers -- the so-called "sandwich generation" -- are increasing, a new survey finds.

About15% of U.S. adults in their 40s and 50s provided financial support toboth an aging parent and a child in 2012, according to a surveyof 2,511 adults from the Pew Social and Demographic Trends Project.That's up from 12% in 2005. And almost half (47%) of those currentlyraising or financially supporting a child have a parent 65 or olderstill living, who may require support in the future.

But thesurvey finds that more emphasis is on supporting grown children. About48% of adults 40 to 59 provided financial support to grown children in2012, findings show, up from 42% in 2005.

The increase reflectseconomic challenges, says Kim Parker, a co-author of the report. "Grownchildren are struggling to find jobs and establish themselves in theeconomy."

But there is an upside, says Parker, an associatedirector with the Pew Social and Demographic Trends Project. "Themiddle-aged adults who are supporting their grown children financiallyreport that they have stronger emotional ties with those children."

Membersof the sandwich generation report feeling closer to their children thanto their parents, Parker adds. "Generations relying on each other maycreate stronger ties."

Despite their growing burdens, middle-agedcaregivers are just as happy as other adults, the survey suggests. About31% say they are very happy with their lives, compared with 28% ofother adults. But they are more likely to feel pressed for time: 31% ofthose in the sandwich generation say they always feel rushed, comparedwith 23% of other adults.

What happens to families when the burdens rain down?

Stephanie Coontz, director of research and public education of the Council on Contemporary Families,a non-profit organization based at the University of Miami, says stresscan contribute to the deterioration of relationships. But she says manyfamilies report that they are closer.

"We have developed muchhigher standards of family relationships and much higher expectations offamily cooperation," adds Coontz, who was not involved in Pew's report."I wouldn't call that a silver lining, but I would call it anumbrella."