HACKENSACK, N.J. — The often emotion-wrought step for senior citizens of leaving behind a house — and community — they've lived in for decades has spawned a fast-growing business: moving seniors.

Senior move managers help the elderly — and their adult children — come to terms with the arduous decision to downsize to a smaller living space. Among the factors involved in this choice are high taxes that pose a challenge to people on fixed incomes, a medical condition that renders maintaining a home difficult or impossible, or the fact that a large home is no longer needed.

"You're faced with moving 50 years of stuff from a 2,500-square-foot home to a 500-square-foot apartment or assisted-living place," said Jennifer Pickett, associate executive director of the National Association of Senior Move Managers, or NASMM. "It becomes an overwhelming situation. Sometimes it's not so much the objects — what to take, what to give the children and grandchildren, what to sell, what to get rid of — that's the real issue. It's the memories they don't want to part with."

The percentage of Americans 65 and older has risen to 12.6 percent, or 37.9 million, as of 2007, from 12.4 percent, or 35 million, in 2000, according to U.S. Census figures. As the number of aging Americans grows, so does the number of people forced to downsize from a home where they have lived for much of their lives.

NASMM has had a bird's-eye view of the growth in demand for consultants who, at their best, can offer more objective advice on what senior citizens making a move should take with them, and sell, give away or discard.

Two years ago, the organization had 60 members nationwide. Today, it reports more than 500, Pickett said. And more than half of its members have been in business two years or fewer, according to the group's Web site.

"When I decided I wanted to move from my apartment in Bergen County, N.J., to Las Vegas, I couldn't figure out what to take, what to get rid of, how to get rid of it," said Louis "Larry" Liebster, a retired pediatric dentist. Liebster lived in Ridgefield Park, N.J., until last fall, when he moved to Nevada.

"I thought, 'Maybe I just won't take anything with me.' Then I thought 'I can't do this, leave everything, I have a whole life in my past, I wanted mementos.' But I couldn't pick."

So Liebster, who recently turned 80, called a Teaneck, N.J., move manager, Sharon Bregman, owner of 360 Demenager, after Googling the concept of senior move manager associations.

Bregman, he said, took the anxiety out of the experience, offering him a mix of reassurances, her opinion on whether to drive to Las Vegas, and exchanged e-mails with him right through the time he settled in his new apartment.

"I left on Sept. 11 last year, and she dealt with my landlord, she got me my full security deposit back, she closed out my apartment and gave the keys to the landlord on Sept. 20," Liebster said. "For me, it offered a bit of hand-holding, but also it made things move more expeditiously and gave me a sense of direction."

Managers typically do not handle the physical part of moving — they generally help in the planning, packing, sometimes overseeing the move, and sometimes help their clients settle into the new place. Many charge about $150 an hour.

"It's hard for seniors to move," Bregman said. "They generally don't want to leave, they don't like the sense that they're losing their independence. They're giving up the familiar, where they raised a family."