Up to 2.9 Million US Kids and Teens May Have Nonverbal Learning Disability

By Lisa Rapaport

April 22, 2020

(Reuters Health) - Approximately 3% to 4% of U.S. children and teens may have nonverbal learning disability (NVLD), a neurodevelopmental disorder characterized by deficits in visual-spatial processing as well as challenges with math calculation, fine motor skills, and social skills, a new study suggests.

Although NVLD has been discussed for more than 50 years, few studies have estimated its prevalence, likely due to a lack of consensus on criteria for the disorder, and a lack of awareness, researchers note in JAMA Network Open.

"Prior studies estimated NVLD in groups of children who had already been diagnosed with a learning disorder - a very limited group of about 5 to 15 percent of all children," said lead study author Amy Margolis, an assistant professor of medical psychology at Columbia University Irving Medical Center in New York City.

"Our study estimated the prevalence of NVLD in a sample representative of all children, not just those already diagnosed with a learning disorder," Margolis said by email. "We hope our findings will raise awareness of NVLD and pave the way for more treatment research, which should help patients and families."

For their analysis, Margolis and colleagues leveraged phenotypic data from three large-scale samples in prior studies centered around brain imaging. The current analysis was restricted to records with sufficient neuropsychological data to estimate the prevalence of NVLD.

Data came from the Healthy Brain Network (HBN) sample, a community-self-referred sample focused on mental health and learning disorders; the Nathan Kline Institute-Rockland Sample (NKI), a community-ascertained sample focused on normative and abnormal brain development; and the Saguenay Youth Study (SYS) sample, a community-ascertained population sample focused on brain and cardiometabolic health in adolescents who differed in their exposure to maternal cigarette smoking during pregnancy.

Margolis' team counted children as having NVLD based on meeting three criteria: they scored at or below the 16th percentile in visual-spatial skills measured by the Wechsler Intelligence Scale or a discrepancy between verbal and visual-spatial abilities of 15 points or more and intact single-word reading abilities; they had deficits in at least two domains among fine motor skills, math calculation, visual executive functioning, or social skills; they could not have evidence of autism spectrum disorder.

Among 2,596 children and adolescents aged 6 to 19 years (mean (SD) age, 12.5 (3.4) years; 1449 male (55.8%)), the researchers estimated NVLD prevalence to range from 2.8% to 3.9% in two psychiatrically weighted cohorts, and to be 3.1% in a community-ascertained sample.

The most common DSM-5 diagnoses among children and teens with NVLD were attention deficit hyperactivity disorder (ADHD), anxiety, and specific learning disorder.

One limitation of the analysis is that visuomotor skill is a key component of visual-spatial deficits that characterize NVLD, and researchers lacked data on visuomotor skill. They also lacked data on gross motor skills, which might be present in some children who have many characteristics of NVLD but don't have the condition.

Because NVLD is not currently recognized in the international diagnostic manuals, however, the results do offer some evidence to suggest there are many children who could potentially be diagnosed with this condition, said Irene Cristina Mammarella, an associate professor of developmental psychology at the University of Padua, in Padua, Italy, and author of an invited commentary accompanying the study.

Some characteristics of NVLD may help parents or teachers identify children who could potentially be diagnosed with this, Mammarella said by email.

"To identify the disorder, parents should pay attention to visuospatial skills of their kid," Mammarella said. "Many children who have received this diagnosis never played with puzzles or building blocks, they usually do not like drawing, sometimes they do not understand spoken commands which involve spatial relationships, or show poor spatial orientation abilities."

At school, students with NVLD might have a sophisticated vocabulary but struggle with spatial relationships needed for certain calculations, such as adding numbers in a column.

At school, often they do not understand spatial relationships in the calculation, such as writing numbers in a column correctly.

"NVLD is a complex disorder and impairments can be observed not only in specific visuospatial skills but also in academic and social abilities," Mammarella said. "Generally, using oral or written instructions and explanations instead of visual maps and schemas are useful for these children."

SOURCE: https://bit.ly/2KmNdWb and https://bit.ly/2RXlr6z JAMA Network Open, online April 10, 2020.