Image: Senior man in wheelchair looking out window © Tetra Images, Getty Images

Lucy Lazarony was 34 when her mother was diagnosed with Alzheimer's disease.

The diagnosis didn't immediately change Lazarony's life. She had recently left her reporting job at to travel, and she followed through with her plans to spend several months in Scotland.

When Lazarony returned in February 2006, though, she moved into her parents' home in Delray Beach, Fla. For the next five years, she lived off her savings and any freelance gigs she could cobble together while helping to care for her parents as their health declined. The couple recently moved into an assisted-living complex, and Lazarony is trying to restart her career at a time when unemployment rates are the highest since the Great Depression.

"I felt good at the time I made the decision. . . . I knew I wanted to spend that time with my mom, because you don't get that time back," said Lazarony, now 40. What she hadn't realized is how much of her life she was committing. "A lot of people I know did really well in their careers in their 30s, or they started families. I've had a different type of caregiving experience."

Caring for aging parents can be rewarding, frustrating and exhausting in turns. It also can be expensive in more ways than caregivers may realize.

One-quarter of adult children provide physical or financial care to an aging parent -- a proportion that has tripled in the past 15 years, according to a recently released MetLife study. Employed caregivers over 50 stand to lose an estimated $3 trillion in wages, pensions and Social Security benefits because of their caregiving responsibilities, the study found. The average losses total more than $300,000 per person.

That toll doesn't include out-of-pocket expenses associated with caregiving, such as travel costs and purchasing needed household items. Those expenses average about $5,531 per year, according to the study. And it certainly doesn't include the costs of professional care, such as home health aides or nursing homes, which can total tens of thousands of dollars annually.

Some people find their parents require so much time that it's impossible to hang on to a job -- the caregivers either quit or get fired for missing so much work. The cost in lost wages and retirement benefits can be enormous, with estimates ranging from $303,260 to $659,139 per person.

Those who remain employed may have to reduce their hours, pass up promotions, turn down relocations and bypass educational opportunities -- all of which can reduce current wages and future retirement benefits.

"The time you used to spend working . . . you're now spending making phone calls, sending emails, dealing with finances, going on doctor visits," said Elizabeth Roberts, a senior vice president at Bryn Mawr Trust who frequently advises clients as they assume caregiver duties -- and who cares for an elderly mother. "It's harder to get the next promotion. If there are layoffs, well, you're not doing as much as you used to," so you're more vulnerable to getting the ax.

And the toll can afflict future generations as well. Caregivers who lose the opportunity to save adequately for their retirements may someday become a financial burden to their own children.

In addition, caregivers' physical and emotional health can take a beating. Nearly a third of caregivers reported problems with stress, anxiety or depression in a 2009 survey conducted by the National Alliance for Caregiving and AARP. Caregivers were more likely to report their health as "fair" or "poor" than those not providing care. Caregivers' health declined more the longer they provided care.

"If you're taking time off for doctor's appointments and crises," Roberts said, "you don't have as much time for your own vacations to rest up or for your own doctor's appointments."

Family caregivers may not have a lot of options, unfortunately. Medicare, the government health insurance program that covers people 65 and over, typically doesn't pay for custodial care -- help with activities like bathing, cleaning or cooking that elderly parents may need. Medicaid, which does cover such custodial care, is available only to the poorest elderly and may require the care to be in a nursing home.

If the parents don't have long-term-care insurance or savings to cover the cost of hiring help, the adult children usually have to figure out a way to provide it themselves.