fMRI Mental Maturity Scan Tracks Brain Development

Five minutes in a scanner can reveal how far a child's brain has come along the path from childhood to maturity and potentially provide insights on a range of psychologic and developmental disorders. Researchers emphasized that their study shows that brain-imaging data can offer more extensive help in tracking aberrant brain development.

"Pediatricians regularly plot where their patients are in terms of height, weight, and other measures, and then match these up to standardized curves that track typical developmental pathways,” remarked senior author Bradley Schlaggar, M.D., Ph.D., a pediatric neurologist at Washington University (St. Louis, MO, USA). "When the patient deviates too strongly from the standardized ranges or veers suddenly from one developmental path to another, the physician knows there's a need to start asking why.”

Dr. Schlaggar and his colleagues reported that a new way of looking at brain scanning data may be able to provide similar assistance for monitoring and treating of patients with psychiatric and developmental disorders. Dr. Schlaggar, an associate professor of neurology, noted that he has sent children with obvious, profound psychiatric conditions for MRI scans and received results marked "no abnormalities noted. That's typically looking at the data from a structural point of view what's different about the shapes of various brain regions. But MRI also offers ways to analyze how different parts of the brain work together functionally.”

Compare functional data to standardized models of how brain function or disease normally develops, Dr. Schlaggar noted, and a range of new clinical insights becomes available. He and his colleagues use an approach to brain scanning called resting state functional connectivity. By correlating increases and decreases in blood flow to the various brain regions as subjects rest in the scanner, scientists determine which of these regions work together in brain networks.

In a study published in 2009, Washington University scientists demonstrated that as the brain matures, these brain networks change. The overall organization switches from networks involving regions physically close to each other, which is the dominant theme in a child's brain, to networks that connect distant regions, the primary organizational principal in adult brains.

For the new study, lead author Nico Dosenbach, M.D., Ph.D., a pediatric neurology resident at St. Louis Children's Hospital (MO, USA), took this and other distinctions that indicate the transition from child to adult brain and modified them for use in a technique for mathematical analysis called a support vector machine.

The technique is employed in many contexts in science and economics and on the Internet. It is a way that mathematicians have developed for predicting something with high specificity and sensitivity when you have huge amounts of data instead of one really good measurement,” Dr. Dosenbach explained. "Any one of these measurements doesn't tell you much, but if you put them together and use the right math to sift through and restructure them, you can get good predictive results.”

Researchers charted the results of 238 brain maturity analyses, with age on the horizontal axis and maturity on the vertical axis. Dr. Dosenbach used data from five-minute functional MRI (fMRI) scans of 238 normal subjects ranging in age from 7 to 30. The support vector machine analyzed approximately 13,000 functional brain connections and selected the best 200 produce a single index of the maturity of each subject. The data allowed scientists to predict whether subjects were children or adults, and generally formed a curving line that tracks the path of normal functional brain development.

The researchers suspect patients with brain disorders will appear out of alignment with this normal developmental curve. "The beauty of this approach is that it lets you ask what's different in the way that children with autism, for example, are off the normal development curve versus the way children with attention-deficit disorder are off that curve,” Dr. Schlaggar said.

Dr. Schlaggar suggests that functional brain scans might be performed on a group of children at risk but not yet suffering from a developmental disorder. "When a fraction of them later develop that disorder, you can go back and construct an analysis like this one that will help predict the characteristics of the next child at highest risk of developing the disorder,” he stated. "That's very powerful both clinically and from the perspective of understanding the causes of these disorders.”

This approach might enable treatment prior to onset of symptoms, according to Dr. Schlaggar, and should help physicians more rapidly and closely track the results of clinical trials of new therapies. "MRI scans are expensive, so this may not be what we use for everyone right now,” Dr. Dosenbach concluded. "But many children with these types of disorders already receive regular structural MRI scans, and five more minutes in the scanner won't add that much to the cost.”

The study's findings were published September 10, 2010, in Science.

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St. Louis Children's Hospital