Imaging & aging: Structural MRI may accurately measure brain development
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Biomarkers identified on structural MRI can be used to assess brain maturity and produce an accurate biological metric of a person’s age, according to a study published online Aug. 16 in Current Biology.

The method could offer a noninvasive, imaging-based method of assessing biological maturity and development that is more clinically useful than conventional metrics, such as height, weight, dental age or secondary sexual characteristics, which are highly variable and subjective, according to Timothy T. Brown, PhD, of the University of California, San Diego, School of Medicine, and colleagues.

“In developing a composite neuroanatomical metric of biological maturity, we sought to address several fundamental questions about the multidimensional nature of human brain development—questions that could not easily be answered using conventional methods looking at individual brain characteristics in isolation,” they wrote.

The researchers collected structural MRI data from 885 typically developing children and teens, ages three to 20, at nine different institutions. Brain size and shape, as well as tissue properties in various regions, were assessed. In all, Brown et al identified 231 biomarkers of brain anatomy that formed a composite profile of different phases of brain development.

“Measures of brain morphology, diffusivity, and signal intensity show varying contributions to the prediction of developmental phase at different ages, reflecting a dynamic cascade of biological changes within different tissue types,” wrote the authors. “Perhaps most interestingly, our findings precisely quantify the multidimensional variability that exists in human neuroanatomical growth, revealing for the first time a latent brain phenotype that is tightly linked to chronological age.”

Results showed the method could predict an individual’s age with an accuracy rate greater than 92 percent. While other biological measures of age could vary from person to person, the authors reported that the composite measure they identified has an average phase difference of roughly a single year. "We have uncovered a 'developmental clock' of sorts within the brain—a biological signature of maturation that captures age differences quite well, regardless of other kinds of differences that exist across individuals," Brown said in a release.

What remains to be explained is how anatomical changes in the brain relate to the maturation of behavior and changes in psychological development.

“This collection of multimodal, multisite imaging advances now makes it possible for researchers across institutions to establish large-scale, shared databases that can be explored with unprecedented power in order to address critical scientific and clinical questions about human brain health and disease,” wrote Brown and colleagues.