Whenever Matt Maxion approached the counter at McDonald’s, he wanted nothing more than to order chicken nuggets. But the chubby, bespectacled 7-year-old knew what would happen when he reached the “n” in “nuggets”: the tremulous, uncontrollable stutter that sometimes made his jaw clench and his chest ache as he felt himself shrink with shame. His tongue caught on harsh consonants — “n,” “d,” “c.” But soft consonants, like “h,” spilled out smooth as oil. So he ordered hamburgers instead.
Maxion, now 24, is among the roughly 7.5 million people in the United States who struggle to use their voices: They stutter, can’t articulate certain consonants or have trouble making out different sounds. He’s also among the millions who stand to benefit from recent discoveries into the neurological and genetic roots of speech disorders. Today, scientists are rushing to identify the DNA sequences, synapses and other biomarkers of speech problems, and their work could herald a huge drop in the incidence of speech disorders. Genetic testing, for instance, could predict which babies are susceptible to developing them, and allow for intervention while their little brains are still pliable. Brain stimulation could supplement — and maybe even replace — painstaking, anxiety-producing therapy. And down the road, a simple pill could offer relief.
All of these developments are part of a wave sweeping the health industry: precision-based medicine. It means, basically, an emphasis on precise diagnostic measures that allow clinicians to tailor treatments to individual patients. Already this personalization has begun to transform mental health — think blood tests that could predict depression — and experts say speech therapy is next.
As it stands, diagnosis of speech pathology is kind of like shooting in the dark. Pathologists rely on subjective behavioral tests, but many speech disorders share symptoms. For example, childhood apraxia, or difficulty pronouncing words, can sound much like stuttering. The wrong diagnosis, in turn, can lead to the wrong type of therapy. Worse, kids often don’t display enough symptoms to qualify for therapy — insured or otherwise — until they’re already in grade school, and by then their brains are less receptive to behavioral therapy. That’s the standard treatment, and it comes with relapse rates as high as 84 percent for stuttering — and plenty of shame, guilt and frustration, besides. After all, speech is “one of the most basic human abilities,” says Soo-Eun Chang, director of the Speech Neurophysiology Lab at the University of Michigan and Michigan State University.
Genetic tests might predict at-risk newborns, allowing for “early interventions … that could give them a better head start in life.”
Genetic tests might offer an objective diagnostic for speech disorders, several of which — like stuttering — have a strong genetic link: Half of those who stutter report having a close relative with the same problem, says Dennis Drayna, chief of the NIH’s Laboratory of Communication Disorders. While stuttering often disappears spontaneously, it persists in 20 percent of cases. What if we could identify those susceptible to persistent stuttering early on? Ideally, tests would identify newborns at risk for speech disorders, allowing for “early interventions … that could give them a better head start in life,” says Beate Peter, an assistant professor of speech and hearing science at Arizona State University. Peter has begun assembling a catalog of genetic causes of speech disorders. Early intervention is key because “it’s easier to unlearn a motor pattern if it hasn’t been too deeply ingrained yet,” Peter says.
In a 2010 New England Journal of Medicine study, Drayna traced persistent stuttering to three genes and will soon unveil a fourth. But many speech disorders show heterogeneity, which means that multiple genes and gene combinations can result in variations of the same disorder. That makes pinpointing the genes involved complicated; those identified so far explain only a sliver of cases. Still, untangling all this genetic complication could result in very precise treatments, including, possibly, pharmaceuticals.
One study will explore whether brain stimulation raises activity levels in regions that show lowered activity in people who stutter.
Other biomarkers of speech disorders might lurk in the brain — namely, neural activity patterns, or the way the brain lights up in brain scans. As part of a long-term imaging study, Chang reported in Brain that children who stuttered had poorer connectivity between the auditory and motor regions, and in neural networks involved in motor control; and according to another study, they had a hard time distinguishing between rhythms. Chang also launched a study exploring whether brain stimulation can boost activity levels in certain brain regions, and whether that translates into improved performance in tasks like finger-tapping.
To be sure, the diagnostics are for now quite expensive. An MRI alone can cost thousands of dollars, although Chang thinks clinicians could instead use behavioral measures that have high correlations with neuroimaging-based measures. And, of course, brain stimulation still needs to undergo clinical trials. If shown to work, it will likely enhance, not replace, behavioral therapy.
Some speech disorder sufferers feel hesitant about seeking such treatments. Maxion, now a behavioral tutor who lives in Hayward, California, considers stuttering part of his identity, even though he sometimes struggles with job interviews. But others voice full-throated approval: “The research out there is fascinating,” says Melissa Jensen, a 26-year-old who spent years in speech therapy to cope with shame and isolation, and to coax her “huge personality” out. Today she’s a speech language pathologist in Washington.