BY ALLISON BOND

(Reuters Health) - A lifetime's worth of acquisitions and mementos may bring comfort to older adults, but this "material convoy" can also become more burdensome with age, U.S. researchers say.

Based on a national survey, a new study finds that after age 50, people become less and less likely to sell or donate items they no longer need - possibly because doing so becomes more and more difficult, physically or emotionally.

"Having too many things is an obstacle to (older adults) being able to move to or live somewhere" smaller that better suits them, said lead author David Ekerdt, who is director of the gerontology center at Kansas University in Lawrence.

The problem has spawned a new industry of "senior move managers," but little has been known about why older people tend to hang on to things that no longer fit their lifestyles.

"For the first time, we have data about older people's regards for their possessions," Ekerdt told Reuters Health.

He and a coauthor analyzed data from the Health and Retirement Study, an annual survey of health, social and economic trends among Americans age 50 and older that started in 1992. Twenty-two thousand people filled out the 2010 survey, which included questions about how participants handled belongings.

They included how often people had "cleaned out or reduced the number" of belongings, and how often these possessions were sold, given to friends or family or donated to organizations.

Ekerdt and his colleague found that among people over age 70, about 30 percent of people reported they had done nothing over the past year to give away any belongings. And 80 percent in the same age group said they had sold nothing in the past 12 months.

Yet more than half of the respondents in all age categories believed they had too many belongings. For example, 56 percent of those aged 50 to 59 and 62 percent of those 70 to 79 reported having more things than they needed.

The results are published in the Journals of Gerontology: Series B.

"I was surprised by the finding that so many people say they have more things than they need," Ekerdt said. "You wonder, why is that so? Why don't they get rid of things?"

It's possible some people had divested themselves of excess stuff earlier in life, or before a move to a new home, so they didn't feel pressure to do it later, the authors write. It's also possible that with increasing age, failing health makes it physically harder for some to organize and disperse their goods.

In addition to logistics, emotions stirred by the prospect of parting with items linked to one's own identity and fond memories can make downsizing difficult.

"Sometimes when an adult child steps in to help mom or dad move, they bring emotional baggage. A lot of people are afraid they will lose the memory if they lose the item," said Mary Kay Buysse, executive director of the National Association of Senior Move Managers, who was not involved in the study.

Senior move managers help older people de-clutter and downsize later in life by figuring out which belongings are no longer needed and how best to get rid of these items.

For younger adults, the study serves as a reminder to survey one's own possessions now - not in a few decades, she noted.

"As a culture, we need to look at whether we need all of our stuff," Buysse said.

To avoid regret later on, people of all ages should be thoughtful about what they are giving away or selling.

"Not everything has to go, but not everything should stay," she said.