FRIDAY, April 10 (HealthDay News) -- Debate about the ideal age to retire has been going on for years. But with the U.S. economy in a dramatic slump, the flip side of that question -- how old is too old to work? -- has become uppermost in many people's minds.

As workers young and old fret about dwindling retirement accounts in the wake of the mortgage crisis and stock market tumbles, they joke that they'll have no choice but to work until they're 90 or beyond.

But many also wonder: Will I be able to?

Research has offered some reassurances. Researchers have learned that there is no ideal retirement age and that older adults who keep their thinking skills sharp by learning new things off the job can stay more competitive in the job market, too.

"In today's economy, it becomes more of a necessity than a luxury to keep working," said Dr. Joseph Sirven, a professor of neurology at the Mayo Clinic in Scottsdale, Ariz. The short answer to the question, "How old is too old to work?" is, Sirven said, "when you are not able to do the job."

But there's much you can do to prevent that from happening, he and other experts have found. "What we find now from research and a neurological perspective is [that] the secret to good aging is, you have to keep busy," Sirven said. "Sometimes that means exercise, physical activity. But it means a lot of mental and cognitive activity" also, he said.

Today, Sirven said, older adults frequently retire from one career and transition into another -- something that's matched to their skills and experience and takes into account any age-related disadvantages.

His advice for people who plan to work well beyond the traditional retirement age of 65: "Focus on what work can you do that you can keep up with as you age."

Take stock of your attributes and drawbacks: "You may not be the quickest or most agile," Sirven said, "but you could be the wisest or the most experienced, which also counts."

That wisdom might be doubly appreciated by co-workers, even younger ones, in our shaky economy, he said. Older workers, after all, have been through several recessions. "That stability of wisdom, of living through it [before], can be the most important of all," he said.

Joy L. Taylor, an associate clinical professor of psychiatry at Stanford University, stressed that keeping skills sharp can make a difference in on-the-job performance. She studied 118 noncommercial pilots, age 40 to 69, to determine how age affects cognitive performance in the real world.

She did the study as the Federal Aviation Administration was proposing that the mandatory retirement age for commercial airline pilots be raised from 60 to 65, which was later signed into law.

Though she did find that the older pilots, those 60 to 69 years of age, initially performed worse than the younger pilots, she also found that the older pilots showed less of a decrease in their overall flight summary scores. And over time, they improved more on their "traffic avoidance" performances than did the younger pilots.

The study was published in the journal Neurology, accompanied by an editorial co-authored by Sirven.

Now, Taylor and her team are studying whether extra training for pilots helps them overcome age-related changes in motor performance skills they need, such as flying in a holding pattern.

So, how to best ensure that you can work longer than average, if you have to or want to?

Try constantly to learn new skills, Sirven suggested. "Pick up a new language, learn a new instrument," he said. "Give yourself a push to try something new."

And Taylor had additional ideas. "Keep your work-related skills, exercise, and eat the best diet, a heart-healthy diet," she said. "Our emphasis is on physical health as well as cognitive health and stimulation -- both being equally important."

More information

To learn more about work-related issues for older Americans, visit AARP  .

THURSDAY, April 9 (HealthDay News) -- Seniors who were overweight or obese earlier in life are at increased risk for physical disabilities, even if they've shed the excess weight they had when they were younger, says a new U.S. study.

"In both men and women, being overweight or obese put them at greater risk of developing mobility limitations in old age, and the longer they had been overweight or obese, the greater the risk," lead investigator Denise Houston, an expert on aging and nutrition and an assistant professor of gerontology at the School of Medicine at Wake Forest University Baptist Medical Center, said in a center news release.

"We also found that, if you were of normal weight in old age but had previously been overweight or obese, you were at greater risk for mobility limitations," she added.

Houston noted that weight loss later in life is usually caused by an underlying chronic condition.

The study included 2,845 participants who were an average of 74 years old when they were enrolled. They had no mobility problems at the start of the study. During seven years of follow-up, women who were overweight or obese (body mass index of 25 or greater) from their mid-20s to their 70s were nearly three times more likely to develop mobility problems than women who were normal weight throughout their lives. Overweight or obese men were 1.6 times more likely to develop mobility problems.

The researchers also found that women who were obese (BMI of 30 or greater) at age 50, but not in their 70s, were 2.7 times more likely to develop mobility limitations than women who weren't obese throughout their lives. Men with a similar weight history were 1.8 times more likely to develop mobility problems.

The study is in the April 15 issue of the American Journal of Epidemiology.

Excess weight can put stress on joints, make exercise difficult, and lead to chronic conditions such as diabetes, arthritis and heart disease -- all of which are directly related to the development of mobility problems, Houston said.

More information

The AGS Foundation for Health in Aging has more about walking problems in seniors  .

THURSDAY, April 2 (HealthDay News) -- A daily nap may boost an elderly woman's risk of dying, a new study suggests.

In contradiction of numerous past studies that have found that napping may have health benefits, researchers from the California Pacific Medical Center Research Institute found that elderly white women who took a daily siesta were 44 percent more likely to die from any cause, 58 percent more prone to dying from heart problems, and nearly 60 percent more likely to die from non-cardiovascular or non-cancer causes.

The results -- based on studies done over seven years on more than 8,000 white women aged 69 or older -- held true even if the women were relatively healthy, the researchers said. However, a little napping seemed to be fine -- participants who napped less than three hours a week showed no increased chance of death, the team said.

The study, published online in the Journal of the American Geriatrics Society, also found that these elderly women had a greater mortality risk if they clocked between nine and 10 hours of sleep each day compared to those who slept between eight and nine hours.

Still, the researchers said people shouldn't link napping to poor health or recommend that seniors skip napping. They noted that underlying sleep disorders or other medical conditions could be leading to daytime drowsiness.

"Since excessive sleep suggests that night time sleep is disrupted, interventions to treat sleep disorders and improve sleep quality in older women may reduce mortality risk," co-author Katie L. Stone, a scientist at the medical center, said in a news release issued by journal's publisher.

More information

The U.S. National Sleep Foundation has more about sleeping and aging  .

MONDAY, March 23 (HealthDay News) -- People with osteoporosis are much more likely to have vertigo than people with normal bone density, Korean researchers say.

Vertigo is an inner ear disorder that's a common cause of dizziness. It's believed to be caused by loose calcium carbonate crystals in the sensing tubes of the inner ear.

The researchers compared 209 people with benign positional vertigo with no known causes -- such as ear surgery or head trauma -- with 202 people with no history of dizziness. Compared to participants with normal bone density, those with osteoporosis (low bone density) were three times more likely to have vertigo and those with osteopenia (the stage before osteoporosis) were two times more likely to have vertigo.

Among women, 25 percent of those with vertigo had osteoporosis, compared to 9 percent of those without vertigo, and 47 percent of those with vertigo had osteopenia, compared to 33 percent of those without vertigo. Among men, 12 percent of those with vertigo had osteoporosis, compared to 6 percent of those without vertigo, and 40 percent with vertigo had osteopenia, compared to 27 percent of those without vertigo.

The study will be published in the March 24 issue of Neurology.

"These findings suggest a problem with calcium metabolism in people with vertigo," Dr. Ji Soo Kim, of the Seoul National University College of Medicine, said in a journal news release.

"Women most often have their first case of vertigo in their 50s, when they are also having a drop in bone mass due to loss of estrogen. Estrogen is one of the main hormones that influence calcium and bone metabolism," Kim said.

The role that estrogen plays in vertigo hasn't been determined. Since this study also found an association between osteoporosis and vertigo in men, other factors must also play a role, Kim noted.

More information

The U.S. National Institute on Deafness and Other Communications Disorders has more about balance disorders.