Significant numbers of older adults admit betting more money than they can afford to lose or wagering sums above $100, a new study reports in warning about elderly gambling.

Researchers from the University of Pennsylvania and Penn State College of Medicine did not find that older adults necessarily gamble more than the rest of the population. They suggested, however, that a rate similar to younger adults poses more risks because of the higher percentage of seniors on fixed incomes, with mental impairments, or with health-care needs that could be sacrificed to invest in gambling.

The study, published today in the American Journal of Geriatric Psychiatry, found that of 843 Philadelphia-area residents 65 and older, 70 percent had gambled in the past year on lottery tickets, bingo, Atlantic City casinos or other options.

About 4 percent of those interviewed admitted betting more than they could afford to lose. Nearly 8 percent, including some of the latter group, had risked at least $100 on a single wager. The researchers grouped those two categories together into an "at-risk" population representing about one of every nine survey participants.

"I didn't think it was going to be this much," said Dr. David Oslin, lead author and an assistant professor and geriatrician at the University of Pennsylvania. "I would have thought it would be lower in older adults because not too many people come to me talking about their gambling."

The study is timely because Pennsylvania, a state with one of the highest percentage of seniors, is about to take its biggest leap in decades in legalized gambling opportunities. Up to 61,000 slot machines have been authorized for 14 casino, racetrack and resort locations, expected to be operating by 2006 or 2007.

The study's release also comes four months after the gambling industry gained some favorable publicity in a Yale University report that showed older recreational gamblers to be healthier than their non-gambling peers.

One common interpretation of that data was that someone in a bingo hall or casino was more likely to be active and healthy to begin with, rather than receiving any cause-and-effect benefit from gambling. Some researchers allow that social benefits can come from gambling as a group within a population that's sometimes isolated.

The casino industry's American Gaming Association and some organizations that focus on problem gambling said it was hard to react to the new study because they hadn't yet seen it. Some in the field agreed, however, that attention needs to be focused on the elderly because of the increasing prevalence of gambling opportunities.

"It definitely should be studied because [the older population] does have a large number of people with time on their hands ... and it's really good to keep an eye on vulnerable populations," said Christine Reilly, executive director of Harvard Medical School's Institute for Research on Pathological Gambling and Related Disorders.

In the Penn-Penn State College of Medicine study, more than three-fourths of the gamblers were lottery players and more than half visited casinos or played machines such as illegal video poker.

The Pennsylvania Lottery reports that age does not appear to factor into whether people are more likely to play the game. The proportion of lottery players age 55 or older, 32 percent, is nearly identical to their share of the overall population, said Pennsylvania Revenue Department spokesman Steve Kniley.

Anyone visiting a bingo hall has seen a heavy number of older adults among the players, and casinos and racetracks with slots make no secret of targeting seniors by the bus load to form a core group of daytime customers.

Most of those are considered recreational gamblers. Some national studies have estimated that "pathological" gamblers who can't control themselves make up 1 to 2 percent of the adult population, and "problem" gamblers who possess some of those traits, but less severely, are another 3 to 4 percent.

Oslin said his study's finding of 4.2 percent among the elderly who bet more than they could afford would typically fit in that problem group, but those wagering $100 or more at a time may not belong there if they're affluent. His worst fear as a geriatrician, he said, is that some people lose money gambling that they normally depend on for medications and other health care.

"This confirms to us it's probably something we need to pay attention to," Oslin said. "Now we're justified in going ahead with that groundwork, seeing if patients are making those trade-offs."