Whey seem almost alive: snapshots of the living human brain.
Not long ago, scientists predicted that these images, produced by sophisticated brain-scanning techniques, would help cut through the mystery of mental illness, revealing clear brain abnormalities and allowing doctors to better diagnose and treat a wide variety of disorders. And nearly every week, it seems, imaging researchers announce another finding, a potential key to understanding depression, attention deficit disorder, anxiety.
Yet for a variety of reasons, the hopes and claims for brain imaging in psychiatry have far outpaced the science, experts say.
After almost 30 years, researchers have not developed any standardized tool for diagnosing or treating psychiatric disorders based on imaging studies. Several promising lines of research are under way. But imaging technology has not lived up to the hopes invested in it in the 1990s -- labeled the "Decade of the Brain" by the American Psychiatric Association -- when many scientists believed that brain scans would turn on the lights in what had been a locked black box.
Now, with imaging studies being published at a rate of more than 500 a year, and commercial imaging clinics opening in some parts of the country, some experts say that the technology has been oversold as a psychiatric tool. Other researchers remain optimistic, but they wonder what the data add up to, and whether it is time for the field to rethink its approach and its expectations.
"I have been waiting for my work in the lab to affect my job on the weekend, when I practice as a child psychiatrist," said Dr. Jay Giedd, chief of brain imaging in the child psychiatry branch at the National Institute of Mental Health, who has done MRI scans in children Monday through Friday for 14 years.
"It hasn't happened. In this field, every year you hear, `Oh, it's more complicated than we thought.' Well, you hear that for 10 years, and you start to see a pattern." Psychiatrists still consider imaging technologies like MRI, for magnetic resonance imaging, and PET, for positron emission topograph, to be crucial research tools. And the scanning technologies are invaluable as a way to detect physical problems like head trauma, seizure activity or tumors. Moreover, the experts point out, progress in psychiatry is by its nature painstakingly slow, and decades of groundwork typically precede any real advances. But there is a growing sense that brain scan research is still years away from providing psychiatry with anything like the kind of clear tests for mental illness that were hoped for.
"I think that, with some notable exceptions, the community of scientists was excessively optimistic about how quickly imaging would have an impact on psychiatry," said Dr. Steven Hyman, a professor of neurobiology at Harvard and the former director of the National Institute of Mental Health.
"In their enthusiasm, people forgot that the human brain is the most complex object in the history of human inquiry, and it's not at all easy to see what's going wrong." For one thing, brains are as variable as personalities, Hyman said.
In a range of studies, researchers have found that people with schizophrenia suffer a progressive loss of their brain cells: A 20-year-old who develops the disorder, for example, might lose 5 percent to 10 percent of overall brain volume over the next decade, studies suggest.
RSS