One of the big challenges of raising a child with developmental disabilities is the struggle to predict the future: How much will the child be capable of learning? What kind of support will he need? What abilities will she have in the long term?
In new research published this week in the Proceedings of the National Academy of Sciences, a Stanford-led team has shown that early brain scans may help answer these future-oriented questions for children with fragile X syndrome, the most common genetic cause of developmental disabilities and autism. Ultimately, some children with fragile X have more severe impairments than others, but in early life it's hard to tell how any individual child will progress.
To help provide earlier guidance to families and caregivers, neurodevelopmental disorder experts Allan Reiss, MD, Jennifer Bruno, PhD, and their colleagues examined a group of boys with fragile X. (Because of how fragile X syndrome is inherited, girls are usually much less severely affected, so studies of the disease tend to focus on one sex.) In 2014, the team found that applying a new method of data analysis to anatomical data from MRI scans taken around age 3 could be used to divide fragile X boys into two groups with lower and higher levels of cognitive and behavioral functioning.
In the new study, the team followed up on the same boys, conducting repeat MRIs around age 5. They could still pick out the same two groups from the brain-scan data, and the higher-functioning children still had better adaptive functioning and cognition and less severe symptoms of autism at age 5.
The longitudinal study design increased the researchers' confidence in the predictive value of early brain scans. Importantly, membership in the two groups stayed stable: of 41 children scanned at ages 3 and 5, 16 were originally classified as higher-functioning, and all of them remained in this group. Of those in the lower-functioning group at age 3, four moved up to the higher-functioning group by age 5; the others remained lower-functioning.
"These results confirm the presence of two longitudinally defined, neuroanatomically distinct subgroups that are associated with clinically relevant phenotypes among young boys with fragile X syndrome," the scientists write in their paper's conclusion. "This information may be utilized to predict outcomes and guide design of targeted therapies for individuals with FXS."