At least 1 in 4000 infants is born without a corpus callosum. This powerful body of connective white matter serves as the primary bridge between the brain's hemispheres, allowing us to rapidly integrate complex information.

"It's a hidden disability," says University of California Institute of Technology psychologist Lynn Paul. Many born without this structure go undiagnosed for years—only neuroimaging can confirm the agenesis, or failed development, of this brain area. Instead people are diagnosed with disorders such as autism, depression, or ADHD.

People born without a corpus callosum face many challenges. Some have other brain malformations as well—and as a result individuals can exhibit a range of behavioral and cognitive outcomes, from severe cognitive deficits to mild learning delays.

Paul is also the founding president of the National Organization of Disorders of the Corpus Callosum, a non-profit that offers resources and support to those affected and their families. She believes psychologists and neuroscientists can learn much from this disorder, including how varied biological problems can result in the same behavioral outcomes.

But what may be most remarkable is how the acallosal brain adapts to its limitations and finds new connective routes. Precisely how the brain does this is a biological mystery, but there are several possible routes of compensation, which effectively re-route the brain's connections in novel ways. Similarly, each individual born with this condition must find his or her own way to overcome unique challenges. As is clear from their stories, individuals often find strength in one another and in sharing their experiences.

Sarah Mellnik, a young woman –introduced in Scientific American Mind's "The Mystery of the Missed Connection"– who has known about her agenesis of the corpus callosum all of her life explains that in sharing experiences, she and those around her learn that they truly are not alone. "If my story is going to help somebody, even if it's just one person, then I want to tell it," she says.


Kath Mitchell

Mitchell discovered her agenesis of the corpus callosum in February 2012, when a doctor asked her to undergo magnetic resonance imaging (MRI). The physician had noticed that she took unusual pauses when she spoke. For Mitchell, now 60 years old, the discovery was a shock: "When I'm stressed or overtired, it's easy to believe that a practical joke of cosmic proportions has been played on me—and I'm not laughing."

Mitchell is still trying to accept her diagnosis. "It reinforces my decades-old isolation," she says. Mitchell's patterns of movement and speech have always caused her to stand out. Throughout her life she has felt socially ostracized from so-called 'normal' people, yet clearly not disabled either. She hopes that as she reaches out to others with this brain malformation through conferences and online forums she will feel a greater sense of belonging.

In the meantime, Mitchell refuses to allow her sense of social displacement to keep her from what she loves. Although learning to read is a struggle for young people with agenesis of the corpus callosum, Mitchell today is a voracious reader. She holds a degree in theater arts, volunteers as a drama teacher, and writes scripts and children's books. She loves train trips and boating; she never learned to drive a car but proudly rides a bicycle-- "it's also my major way of reducing my carbon imprint upon the earth." She adores folk music and is a self-proclaimed anglophile.

"Just out of shock or trying to explain to friends, I have told people about my agenesis of the corpus callosum and have received varied reactions," Mitchell says. Many, such as 'You're special,' or 'So that's what wrong with you,' have hurt her, but one response, she says, is best: "'So, what?' That is the correct answer."


Joseph Galbraith

Galbraith, 50, felt validated when he learned his diagnosis. He had always felt there was a part of him that had been misunderstood or overlooked. "It made sense," he says. "I grew up with all kinds of labels and developmental disabilities." As an adolescent, his difficulty with social cues led doctors to question earlier diagnoses of ADHD. Galbraith also struggles with confabulation, or the creation of false memories. "For years I was told I was lying," he says. "My mind has so much trouble with short-term memory that I'll even imagine I've seen myself do something that I didn't and I'll construct a whole story." As an adult he was told that he had one of the most severe cases of ADHD his doctors had ever seen.

Learning about his agenesis of the corpus callosum as an adult, however, changed his life. MRI revealed that Galbraith had experienced several strokes as a child, certain brain regions were abnormally enlarged and that he had no corpus callosum. Learning the diagnosis and reading about associated outcomes allowed Galbraith to finally begin healing rifts within his family and himself.

Galbraith has found several practices that help him cope. "What I need is someone to constantly put me back on task," he says. He makes lists regularly to remind him of every step he needs to follow in his day. He loves writing and uses blogging to work through his emotions. He has also found meditation techniques extremely effective. "You can just let a thought flow through you and disappear," Galbraith says. "It has brought me a lot of serenity, a lot of peace."


Sara last name withheld

Sara, learned of her condition when she was 19, but the diagnosis had relatively little impact on her life until she had children. Sara was born with hydrocephalus, a condition in which fluid builds up inside the skull, epilepsy and chiari malformations, which affect the cerebellum, and she has suffered from seizures and other health problems throughout her life. When her four-year-old daughter was diagnosed with autism, however, she became more curious about agenesis of the corpus callosum and wondered whether her children might have it as well.

"There are quirks that I have that come from agenesis of the corpus callosum," says Sara. She had always assumed they were simply 'her quirks,' but in reading about the range of behaviors associated with her condition she began to identify the familiar traits as related to agenesis of the corpus callosum. Many are similar to those exhibited in autism —such as a powerful reliance on routines—but others are specific to agenesis of the corpus callosum, such as long delays in learning.

As a mother, she has always been open with her children about her diagnosis, explaining her hospital visits and difficulties. She uses it to help encourage perseverance. "I have to work extra hard to help my daughters with their homework," Sara says. "That means they don’t get to throw down the pencil and quit either."

Although her daughters do not, to her knowledge, have agenesis of the corpus callosum, learning about the condition has spurred her to encourage other parents, particularly those whose children have been diagnosed with autism, to reevaluate their child's condition. "I've convinced people to get MRIs for their child. It helps them and their child to have a better picture." The diagnosis, she adds, is crucial for getting children necessary services and help early.

Sara sees herself as a "quiet advocate." She urges those who receive a diagnosis to learn more and connect with others with similar conditions. "You may not be able to change the diagnosis, but learning about yourself is the most powerful tool you can have in your advocacy."