Brain scans may detect markers of some mental disorders
■ Imaging could provide a biological basis for ADHD and bipolar disorder, but it is too soon to become a part of clinical practice.
By Victoria Stagg Elliott — Posted Dec. 20, 2004
In the early days of his career, John D. Port, MD, PhD, worked with a psychiatrist who suggested he go into radiology and develop tests to make it easier to pin down a diagnosis of mental illness.
"Psychiatry is really one of the last frontiers of medicine where you don't have a blood test," said Dr. Port, assistant professor of radiology and consultant at the Mayo Clinic in Rochester, Minn.
Now, if his recent efforts pan out, the wish of his mentor and that of many physicians who work with mentally ill patients may be fulfilled -- at least in terms of bipolar disorder.
This diagnosis, in particular, can be tricky to nail down.
According to a patient advocacy group, the Depression and Bipolar Support Alliance, most people with bipolar disorder have symptoms for a decade and see an average of four doctors before being diagnosed.
Dr. Port and his research team used magnetic resonance spectroscopy to compare the brains of 19 bipolar disorder patients who were not on any medication to the brains of healthy controls.
According to study findings presented at last month's Radiological Society of North America annual meeting in Chicago, magnetic resonance spectroscopy detected striking differences in the metabolites of four areas of the brains of those with bipolar disorder.
Dr. Port suggested that these markers could eventually be used to diagnose the condition.
"The psychiatric community clearly needs a tool to help diagnose bipolar disorder," said Dr. Port.
"We are hopeful that very high-field MR spectroscopy will prove helpful by identifying metabolic markers of the disease," Dr. Port added
Potential to unlock ADHD clues
Imaging may also offer insights that will aid in the diagnosis of other illnesses of the brain. Two papers presented at RSNA's annual meeting, for instance, suggested scanning could detect differences in the brains of children with attention-deficit/hyperactivity disorder and that usual treatment approaches seemed to address the problem directly.
In the first paper, researchers used diffusion tensor imaging to compare the brains of 18 children with ADHD to 15 normal controls. The scans detected a disruption in the cabling that connects the cerebellum to the frontal lobe in ADHD children. The second study compared the brains of 10 children with ADHD on medication to another 10 with ADHD but who were not being treated with any drugs. This paper found that stimulants seemed to correct the disruption.
"Typically ADHD is described as a chemical imbalance, but our research has shown that there may also be subtle anatomical differences in areas of the brain that are important in this disorder," said co-principal investigator Sanjiv Kumra, MD, a psychiatrist at the Zucker Hillside Hospital in Glen Oaks, N.Y.
There is hope that studies like these might reduce the stigma associated with ADHD, bipolar disorder and other mental illnesses by proving the biological basis underlying these conditions.
"Psychiatrists have long assumed that there were biological bases for many of the disorders that we treat, and it is encouraging and exciting to see that recent research confirms these beliefs," said David Fassler, MD, clinical associate professor of psychiatry at the University of Vermont College of Medicine in Burlington.
Researchers noted, though, that these scans were not ready for regular use. Experts agreed.
"It is absolutely not time for parents to be taking their children in for scans," said Manzar Ashtari, PhD, who presented the ADHD papers at the meeting. Dr. Ashtari is an associate professor of radiology and psychiatry at North Shore-Long Island Jewish Health System in New Hyde Park, N.Y.
Here and now
For the moment, most believe that these tools may make subject selection for trials more reliable and lead researchers to new drug targets and more tailored treatment.
"I could see more radiologic studies helping us understand which specific chemicals may help certain people. Having spent all the years that I have [treating ADHD], I still can't tell who is more likely to respond to what or not respond well to anything," said Susan Louisa Montauk, MD, professor of family medicine at the University of Cincinnati. She is also the medical director of the Affinity Center, which specializes in the care of adults and children with attention-deficit and related disorders.
Critics charged, however, that these studies were too small to draw any conclusions beyond that of the need for additional research. In the case of the ADHD papers, experts expressed concern that the findings could be confounded by other conditions such as oppositional defiant disorder or mood disorders that are particularly common for these children.
"The sample size was small," said Michael Wasserman, MD, a general pediatrician at Ochsner Clinic Foundation in New Orleans. "And how did they distinguish children who didn't have comorbid conditions?"
Some physicians also worried that these tests might add too much to the cost of the process of getting a diagnosis without providing much benefit. In the case of ADHD, some physicians said that history-taking and current questionnaires used for detecting cases were sufficient.
"It's not that hard to make a diagnosis [of ADHD]," said Thomas Bent, MD, associate clinical professor of family medicine at the University of California, Irvine. "We already have a lot of good studies that show that the tools we have have good sensitivity and specificity, and we could be spending a lot of money on a procedure that could be uncomfortable and frightening to the child."