Walking. Driving. Working. Most of us take these activities for granted, but millions of elderly Americans do not because they cannot fully care for themselves. In many cases, little-understood diseases are to blame.

The loss of independence that results from frailty, falls and other conditions costs the nation billions of dollars for care in nursing homes, assisted-living facilities and private homes.

“What drives these costs are not the big-name, marquee diseases…but diseases that are little known,” says Daniel Perry, executive director of the Alliance for Aging Research, a Washington, D.C., nonprofit that promotes aging-related medical research.

Vertigo, sarcopenia and restless legs syndrome are three “diseases in the shadows” that researchers are trying to better understand and treat. Experts shed light on them at a May 17 briefing on Capitol Hill, stressing the need for further research to prevent out-of-control costs as the U.S. population becomes older and sicker.

Vertigo is a common yet underdiagnosed disorder of the vestibular system, which regulates balance and body position. It affects about half of elderly Americans.

“Vertigo is a kind of spatial disorientation,” explains Helen Cohen, EdD, associate professor and co-director of the Center for Balance Disorders at Baylor College of Medicine in Waco, Texas. “Every time you move your head, the world starts spinning around.”

These illusions of movement -- triggered by such actions as turning over in bed, bending over and looking up -- can be unpredictable, so people with vertigo often cannot drive or work safely. There are direct medical costs, too -- 20% of all falls that lead to hospitalization of seniors are due to vertigo, one study shows.

The root cause of vertigo is an accumulation of microscopic calcium “stones” in the labyrinth, an organ of the inner ear. It can be brought on by head injuries, viral infections and aging. The most common type is benign paroxysmal positional vertigo, or BPPV.

The good news is that health professionals can treat most vertigo effectively with patient-specific head movements. These exercises work well and cost relatively little, Cohen says, but not enough people get them because they are not diagnosed properly.

More research is needed, she adds, to investigate the epidemiology of balance disorders – most current studies are incomplete or outdated -- to develop other treatments and to train health-care providers to recognize vertigo.

Like vertigo, sarcopenia, the aging-related loss of muscle mass and strength, is widespread, affecting roughly 45% of Americans 60 and older. It, too, robs many elderly people of their independence by interfering with everyday functions such as walking and climbing stairs.

“We start to lose muscle mass around [age] 30, so sarcopenia is really a condition of aging,” says Chhanda Dutta, PhD, chief of the clinical gerontology branch at the National Institute on Aging in Bethesda, Md. By age 50, people on average have lost 10% of their muscle mass; by age 70, they’ve lost 40%.

Sarcopenia, taken from the Greek words for “flesh” and “loss,” has serious health consequences, including $18.5 billion in related disability costs and contribution to falls, obesity and type 2 diabetes, Dutta says. Its exact causes are not well known, but physical inactivity, hormonal deficiencies and changes in protein metabolism are likely involved, she adds.

Although sarcopenia is not preventable, its progression can be slowed through weightlifting and other muscle-strengthening exercise, studies show. “No matter what age you are, the earlier you start, the better off you’ll be,” Dutta notes – and the more likely that sarcopenia-related costs will be avoided as the population ages.

A third condition, restless legs syndrome (RLS), has been described as “the most common disorder you never heard about.” This sensorimotor condition, characterized by tingling, pain or other unpleasant sensations in one or both legs, affects about 7% of adults, many of them elderly.

“One of the problems with RLS is it is too little known, but it can be a serious and disabling condition,” says Wayne Hening, MD, assistant clinical professor of neurology at the UMDNJ-Robert Wood Johnson Medical School in New Brunswick, N.J.

RLS symptoms typically begin when people sit or lie down to rest or sleep in the evening and at night. Walking around usually relieves the symptoms, which can occur repeatedly. As a result, sufferers wake up often, lose sleep and feel fatigued the next day.

“It’s a frustrating condition because it kicks in just when you want to rest,” Hening says. Half of people with RLS get five or fewer hours of sleep on a bad night, he adds.

The condition, which is often misdiagnosed, can lead to depression and a poor quality of life, as patients avoid travel, theater and other activities that require long periods of sitting.

The causes of RLS are unclear, but scientists believe it is linked to genetic factors and low levels of iron in the brain. It’s more common in women than in men. RLS is also seen in people with certain medical conditions, such as pregnancy, kidney failure and diabetes.

More research is needed to investigate these causes as well as ways to better diagnose and treat RLS, experts say. Better accommodations are needed in the workplace and during transportation, Hening notes.

One recent breakthrough is ropinirole (brand name Requip), the first RLS drug approved by the U.S. Food and Drug Administration to treat adults with moderate to severe primary RLS. Other therapies include good sleep habits, leg stretching, dopaminergic drugs, sedatives and iron supplements. No one drug works for everyone with RLS. So far, the condition has no cure.