By Pam Belluck
In the Oscar-nominated movie “The King’s Speech,” King George VI begins stuttering at 4 and struggles with it throughout his life. But he rarely talks like the stereotypical stutterer, Porky Pig, rapidly repeating letter sounds; usually the king has trouble getting sounds out from the get-go, blocked by sputtering pauses.
His stutter is aggravated by stressful situations, like confronting his brother or addressing the public. He speaks better when playing with his daughters, singing words or inserting profanity, or when music blaring in his ears keeps him from hearing himself.
These are complicated symptoms, but experts say these details, devised by a screenwriter who stuttered, mirror many aspects of actual stuttering.
In that complexity are clues to this often devastating disorder’s cause, say scientists who are starting to untangle the underpinnings of stuttering in hopes of finding better treatment.
Dispelling longstanding misconceptions that the underlying causes of stuttering are language problems or psychological problems like anxiety or trauma, researchers say stuttering is really a speech-production problem: a snag in the cascade of steps that our brains and bodies undertake to move the proper muscles to produce words.
“People who stutter have motor difficulties in producing fluent speech,” said Luc De Nil, a speech-language pathologist at the University of Toronto. “They don’t have difficulty developing words or syntax, although they may process language differently. They have difficulty with efficient coordination of motor movements, and speech is such a high-demand fine-motor skill that requires extremely fast sequencing and timing.”
Speaking involves brain areas responsible not only for language, but for hearing, planning, emotion, breathing and movement of the jaw, lips, tongue and neck. Anne Smith, a stuttering expert at Purdue University, said that in stutterers, “the generals in the brain, who control soldiers which are the muscles, aren’t sending out the right signals to the soldiers, so they just get all mixed up and run around.”
Stuttering, which affects about 5 percent of children, usually begins between age 2 and 6. While about 50 percent of stutterers have family members who stuttered, it is so far impossible to know who will develop it.
One of the disorder’s most intriguing characteristics, scientists now say, is that a child exhibits no signs of the disorder until it strikes, usually when talking becomes more complicated.
While communication disorders and speech delays may be predicted from a baby’s babble or developmental trajectory, “we really have not been able to find indicators of stuttering before the first day it emerges,” said Nan Ratner, an expert at University of Maryland. “Everything looks fine and suddenly it doesn’t look fine.”
The late start contributed to myths that bad parenting could cause stuttering, she said.
Stuttering usually begins not with a child’s first words, she said, and “not even with two-word utterances like ‘doggie bark,’ ” but “when you’re starting with the grammar of the language, prepositions and helping verbs and little words of the kind that you leave out” when composing a text message.
The complexity of grammar, in fact, seems to be part of the hang-up. Dr. Smith has monitored the brain waves of children watching cartoons in which sentences with meaning errors (“Daddy puts the horse in his coffee”) and grammatical errors are inserted. Stutterers’ brains respond to meaning errors as normal speakers’ brains do, but have a much lower response to grammatical errors, she said.
For unclear reasons, boys are twice as likely to stutter, and up to four times as likely to continue stuttering into adulthood. About 75 percent of children eventually stop stuttering, some with therapy and some without, but there is no predicting who will recover. So far, drugs have shown unimpressive results, or caused side effects more severe than the stuttering, and experts say the problem is so complex that a single pill is unlikely to cure all stuttering.
Scientists are finding some answers, though. By examining images of the brains of people who began stuttering as children and people who started stuttering after a stroke, Dr. De Nil has found excess activity in areas involved in speech motor control and coordination of the movements needed for speech.
These brain areas may be working overtime because stutterers do not develop the “automatic pattern of speaking” that nonstutterers have, said Dr. Smith. “It’s the difference between driving a Mercedes you can trust that you just get in and it’s going to go and driving a 40-year-old Toyota that doesn’t go very well.”
Dr. De Nil also found less activity in a brain area involved in hearing oneself. Reasons are unclear, but it may reflect, as in the movie, that stutterers find speaking easier when they tune out their stutter, Dr. Ratner said.
Scientists have also found motor difficulties in some nonverbal activities that involve sequences. Dr. De Nil has found that stutterers have trouble tapping out number sequences on a keyboard. Dr. Smith has found that stuttering children have trouble continuing to clap a beat after music is turned off.
Only about a third of stuttering children have other language or speech problems, but Dr. Ratner found that while stutterers perform within normal limits on standardized tests, on average their scores are lower than nonstutterers.
Genes almost certainly play a role for about half of all stutterers. Dennis Drayna, a scientist at the National Institute on Deafness and Other Communication Disorders, has identified gene mutations that appear to be associated with stuttering in a Pakistani family and others. But he and others say there are likely to be different mutations related to stuttering in other families.
Environmental factors may contribute too. Trauma and stress do not cause stuttering, but can exacerbate it, Dr. Ratner said, and stuttering can cause anxiety that makes the experience worse.
Kelly Love, 45, of West Lafayette, Ind., knows that well. She has worked hard to control her stuttering; the disorder also afflicted her father and grandmother, and her son and daughter, twins who are now 9. Both children participated in Dr. Smith’s research, and her son still stutters, especially when he is excited.
“There are a lot of misconceptions about people who stutter — that they aren’t as smart, that they don’t have the vocabulary — when it’s so much out of our control,” said Ms. Love, who has not seen “The King’s Speech.”
“I might want to go see it by myself,” she said. “It might be hard.”