BY MICHAEL WOODS

The wall dividing physical and mental illness, a solid fixture of the medical landscape for almost 400 years, is tumbling down thanks to new insight on the human brain. Scientists now know that clinical depression, schizophrenia and other forms of "mental" illness actually are physical disorders. The symptoms occur because of physical changes in the brain -- just as diabetes or a heartattack occur because of physical changes in the pancreas or heart. Nevertheless, medicine clings to the outdated and hurtfulterm "mental illness." That term's stigma -- the topic of a 1999 White House conference and numerous reports -- discourages millions from getting treatment. Nearly two-thirds of people with mental disorders never seek treatment. The stigma causes bias, distrust, stereotyping, fear, embarrassment and anger.

Studies also suggest this stigma contributes to the public's reluctance to pay for better mental health services through insurance premiums or taxes. People think health insurance should cover "real" physical diseases, not emotional problems. The 1999 Surgeon General's Report on Mental Illness suggested a strange solution: Eliminate the term, "physical health," and replace it with "somatic health." Somatic is a Greek word meaning "body." Perhaps a better option would be to eliminate the term "mental illness."

A French philosopher named Rene Descartes, who lived from 1596-1650, erected the wall between mental and physical health. He viewed the mind as separate from the body. Health of the mind was the concern of organized religion. The body, to Descartes, was the concern of physicians.

By the 20th century, the distinction was firmly entrenched. People thought mental illness was the victim's own fault -- the result of sin, moral weakness, a flawed character. Later, scientists realized that mental illness resulted from biochemical disorders in the brain. A major research effort in the 1990s, termed "The Decade of the Brain," amassed proof with computerized imaging and other studies.

While the brain carries out all mental functions, it also controls some body functions, such as movement, the sense of touch and balance. That's why not all brain diseases are mental disorders. A stroke, for instance, may paralyze parts of the body or affect balance or speech. When a stroke affects mainly the body, it's considered a physical condition. A stroke that affects mainly thought, mood, or behavior is considered a mental condition called dementia. Erasing the term "mental illness" may be difficult, particularly since the identities of powerful funding agencies such as the National Institute of Mental Health and patient advocacy groups such as the National Alliance for the Mentally Ill depend on the term.

The only option may be greater public understanding that mental illness is as physical an illness as diabetes or heart disease.