Johns Hopkins psychiatrist says a recent study of patients suffering from dizziness shows that almost half also suffered from depression or anxiety.

That's significant, says Dr. Michael R. Clark, a member of a specialized clinic at Hopkins that examines all aspects of dizziness.

He says that by treating those patients -- with anti-depressants, therapy or both -- the symptoms of dizziness either cleared up or became less severe.

And, he believes, if general practitioners would begin looking for and dealing with psychiatric symptoms in patients who complain of dizziness, they could resolve complaints by many who are now subjected to unneeded tests -- and left frustrated and still dizzy.

"The traditional approach has been to sort dizziness complaints into one of four categories," he says. These include vertigo, where the world seems to be spinning out of control; Maniere syndrome, where built-up pressure in the inner ear causes severe pain and imbalance; and labyrinthitis, presumably a viral infection of the ear that affects hearing and physical stability.

"But the fourth category is kind of a waste-basket category," he says. "It's that last category -- the nonspecific dizziness -- that almost all people shove psychiatric conditions into.

"They say, 'If you don't have anything really wrong with you and we can't find anything wrong with you, it must be that you've got a psychiatric disorder.' They say, 'If it's not real, it must be emotional or imaginary or something.' "

But Dr. Clark, whose study took place while he was at the University of Washington and was recently described by him in the Archives of Internal Medicine, says the problem is anything ,, but imaginary.

"These people are just as disabled as people with other chronic medical conditions," he says. "And if there is any component of a psychiatric disorder as well, they're much more disabled."

His study of 75 patients divided the group into those who had definable physiological symptoms of dizziness -- usually connected to inner-ear problems -- and those whose complaints were less specific.

Both groups, he says, showed higher-than-usual levels of anxiety and depression.

"Dizziness is a symptom, not a disease or a condition or an illness," he says. "And it's a pretty common symptom."

It's the ninth most common reason people have for going to their doctors, he says, increasing with age, so that by 65, it's the third most common, and by 75, it's the most common complaint.

Generally, complaints of dizziness turn out not to be severe, says Dr. David S. Zee, professor of neurology and otolaryngology at Hopkins, and director of the multidisciplinary clinic of which Dr. Clark is a member.

"Dizziness can mean, 'I'm lightheaded because it's hot, or I get dizzy when I stand up quickly because I'm on some medication which drops my blood pressure a little bit when I stand up. Or I'm anemic. Or I'm having a panic attack or feeling claustrophobic or I feel dizzy.' It can mean lots of things."

His clinic, he says, deals with those unusual problems involving the inner ear, the place where various sensing mechanisms orient one to the flow of gravity.

"It's called the vestibular system," says Dr. Zee, "the whole mechanism of detecting movement in the ear and the brain's processing and all the reflexive responses. It allows us to move our head and see and to stay upright and not lose our balance. It's essentially a very simple system, and most of it is subconscious. We just let it all happen automatically.

"When you have a problem, that's when you realize how important this mechanism is. And it can be extremely, extraordinarily disabling."

One's sense of position or balance is based on input from a variety of systems in the body, adds Dr. Clark. "Your vision tells you where you are in space; your hearing allows you to locate where things are in space; your sense of touch tells you where you are."

Problems increase with age, he says, "because all these systems are beginning to incrementally decline. As they all fail a little bit, the cumulative effect is that balance becomes much more difficult."

But those problems, he notes, are often expressed to a doctor by a patient with the medically vague term "dizziness." It doesn't mean much to a physician until it can be sorted out as to what exactly the patient means.

But general practitioners -- the doctor most patients see first with a dizziness complaint -- find a specific cause in only 1 out of 5 cases, he says.

"So you get a whole bunch of people we don't really know what to tell them, a whole bunch of people out there having this problem over a long period of time," he says.

His study, though, suggests a new approach to diagnosis at that primary care level.

It found that people with nonspecific chronic dizziness were more likely to have other physical complaints as well.

It also discounted the idea that psychiatric symptoms, such as anxiety and depression, stem only from patients' frustration of .. not being able to get help for their dizziness. In the study, many patients whose symptoms were nonspecific were shown to have had a history of depression or panic attacks, anxiety symptoms or unexplained physical symptoms long before their dizziness.

"These people did have lifetime problems," he says. "So there clearly is evidence [the psychiatric findings] are not just a secondary phenomenon."

And the message is clear.

"If you could find those people up front and make the diagnosis and say they don't have an inner-ear problem, but it's very clear they have a major depression," he says, "you could treat that and see if the dizziness gets better. It may be that it goes completely away."

Psychiatric disorders, he notes, are more easily treatable. "If somebody has a major depression and you treat it with medicine and/or psychotherapy, they've got an 80-90 percent chance of having a complete response to that treatment. "

Easier said than done, though. "Psychiatry carries with it a big stigma in our society, and patients often are in a state of distress to begin with," he says. "They will be prone to say, 'Right, you think I don't have a physical problem, you think I have an emotional problem or a mental problem, or that I'm imagining this.' "

But, he says, "There is never a distinction between real and imaginary in my world. Everything is real. If you tell me you hurt, I believe you. If you tell me you're dizzy, I believe you. It's a given.

"I never try telling my patients their complaints are imaginary or in their head. Because there really is no way to distinguish between mind and body."

Future research, he says, will focus on exactly how dizziness is generated within the body and whether the physiological variety shares any common pathway with the psychiatric.

While doctors suspect some unknown dysfunction in the vestibular system, the mystery remains.

"It's very easy to go in and find the heart and say this is why the person has heart failure," says Dr. Clark. "But it's not easy to say this is the seat of depression. Nobody knows where, in the mind or the body, depression is generated."