What is a nonverbal learning disorder? Tim Walz's son Gus ...

Gus Walz stole the show Wednesday when his father, Minnesota Gov. Tim Walz, officially accepted the vice presidential nomination on the third night of the Democratic National Convention. 

The 17-year-old stood up during his father’s speech and said, “That’s my dad,” later adding, “I love you, Dad.”

The governor and his wife, Gwen Walz, revealed in a People interview that their son was diagnosed with nonverbal learning disability as a teenager.

A 2020 study estimated that as many as 2.9 million children and adolescents in North America have nonverbal learning disability, or NVLD, which affects a person’s spatial-visual skills.

The number of people who receive a diagnosis is likely much smaller than those living with the disability, said Santhosh Girirajan, the T. Ming Chu professor of biochemistry and molecular biology and professor of genomics at Penn State.

“These individuals are very intelligent and articulate well verbally, but they are typically clumsy with motor and spatial coordination,” he told NBC News. “It’s called a learning disorder because there are a lot of cues other than verbal cues that are necessary for us to keep information in our memory.”

People with NVLD often struggle with visual-spatial skills, such as reading a map, following directions, identifying mathematical patterns, remembering how to navigate spaces or fitting blocks together. Social situations can also be difficult. 

“Body language and some of the things we think about with day-to-day social norms, they may not be able to catch those,” Girirajan said. 

Unlike other learning disabilities such as dyslexia, signs of the disability typically don't become apparent until adolescence. 

Early in elementary school, learning is focused largely on memorization — learning words or performing straightforward mathematical equations, at which people with NVLD typically excel. Social skills are also more concrete, such as playing a game of tag at recess. 

“But as you get older, there’s a lot more subtlety, like sarcasm, that you have to understand in social interactions, that these kids might not understand,” said Laura Phillips, senior director and senior neuropsychologist of the Learning and Development Center at the Child Mind Institute, a nonprofit organization in New York.

In her own practice, she typically sees adolescents with NVLD, who usually have an average or above average IQ, when school demands more integrated knowledge and executive functioning, such as reading comprehension or integrating learning between subjects. They also usually seek help for something else, usually anxiety or depression, which are common among people with NVLD. 

Often misdiagnosed as autism

Amy Margolis, director of the Environment, Brain, and Behavior Lab at Columbia University, is part of a group of researchers that is beginning to call the disability “developmental visual-spatial disorder” in an effort to better describe how it affects people who have it.

People with NVLD are “very much verbal,” Margolis said, contrary to what the name suggests.

The learning disability is sometimes misdiagnosed as autism spectrum disorder. Margolis led a 2019 study that found that although kids with autism spectrum disorder and NVLD often have overlapping traits, the underlying neurobiology — that is, what’s happening in their brains to cause these traits — is unique between the two conditions.

Margolis is trying to get NVLD recognized by the DSM-5, the handbook health care providers use to diagnose mental health conditions. Without such official recognition, people with NVLD can struggle to get the resources they need, such as special class placements or extra support in school.

“Without an officially recognized diagnosis, it’s hard for parents to understand how to seek information, and then communicate to other people what kinds of things might be challenging for their kid,” Phillips said, adding that widespread awareness is key to helping these families navigate NVLD.