VOA健康报道2022--研究人员寻找口吃背后的生物学原因

Researchers Look for Biological Reasons Behind Stuttering

Researchers are looking into the biological causes of stuttering. Stuttering is a speech problem that causes the speaker to repeat the beginning sound of some words.

For centuries, people have feared being judged for stuttering. It is a condition often misunderstood as a psychological problem caused by things like bad parenting or emotional trauma¹. But research presented at a recent science conference explores its biological causes: genetics and brain differences.

Stuttering affects 70 million people around the world, including U.S. President Joe Biden. Biden has spoken publicly about being bullied³ by classmates for his speech problem. He has said that overcoming his stutter was one of the hardest things he ever did.

After a campaign event in 2020, he met a New Hampshire teenager who also stuttered, Brayden Harrington. They ended up talking for an hour.

Living with a stutter has not been easy, Brayden told The Associated Press.

"I want to carry on what Joe Biden said to me," he said. "That this does not define⁴ you and that you can be much more than you see yourself as."

Why do people stutter?

Stuttering has been recorded as far back as ancient China, Greece and Rome. But no one really knew what caused it until modern genetic² science and brain imaging helped provide some answers.

Researchers identified the first genes⁵ strongly linked to stuttering more than a decade ago. Imaging studies looked at brains of adults and older children. And in the last few years, University of Delaware researcher Ho Ming Chow started looking at 3- to 5-year-olds. That is around the age many kids begin stuttering, with about 80 percent outgrowing⁶ it.

Chow said the imaging shows small brain differences in young children who keep stuttering, compared with those who recover or those who never stuttered. He discussed his research earlier this month at a conference of the American Association for the Advancement⁷ of Science.

For example, Chow and his team found that genetic mutations related to stuttering are linked to structural⁹ problems in the corpus callosum and thalamus areas of the brain. The corpus callosum is an area that connects the two sides of the brain and helps them communicate. The thalamus sends sensory¹⁰ information to other parts of the brain. Past research has also linked stuttering to the basal ganglia, a group of brain structures involved in body movements.

Though several genes may be involved and the exact genetic causes may vary by child, "they probably affect the brain in a similar way," Chow said.

Still, many people incorrectly believe that people stutter because they are nervous or suffered childhood trauma. Some also think stutterers could stop if they just tried harder.

"We have a long way to go" to change such beliefs, said University of Maryland researcher Nan Bernstein Ratner.

Moving ahead

Speech therapy is currently¹¹ the main way to treat stuttering. But the medications now being tested could be approved for stuttering in the next few years.

Studies have suggested that stuttering may be related to high levels of a chemical in the brain called dopamine. Some medicines reduce dopamine activity or block its action.

Holly¹² Nover is a speech pathologist and member of the National Stuttering Association. She grew up trying to hide her stutter. Her 10-year-old son, Colton, also has a speech problem.

She said many people will surely be interested in trying stuttering medications. But not her. She is happy with her life as it is and says she has accepted her stuttering. If Colton were struggling and wanted to try medication as a teenager, however, she would be open to the idea.

Brayden, who is now 14, does not plan to try medication.

Taking medicine is "just taking away a part of you...taking away part of your personality," he said.

Words in This Story

psychological — n. of or relating to the mind

trauma — n. a very difficult or unpleasant experience that causes someone to have mental or emotional problems usually for a long time

bully¹³ — n. someone who frightens, hurts, or threatens smaller or weaker people

mutation⁸ — n. a change in the genes of a plant or animal that causes physical characteristics that are different from what is normal

1 trauma   

n.外伤，精神创伤

参考例句：

• Counselling is helping him work through this trauma.心理辅导正帮助他面对痛苦。
• The phobia may have its root in a childhood trauma.恐惧症可能源于童年时期的创伤。

2 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

3 bullied   

adj.被欺负了v.恐吓，威逼( bully的过去式和过去分词 )

参考例句：

• My son is being bullied at school. 我儿子在学校里受欺负。
• The boy bullied the small girl into giving him all her money. 那男孩威逼那个小女孩把所有的钱都给他。 来自《简明英汉词典》

4 define   

vt.解释，下定义，阐述，限定，规定

参考例句：

• Please define the words.请解释这些字的意义。
• It's hard to define exactly what has changed.很难解释清楚到底发生了什么变化。

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 outgrowing   

长[发展] 得超过（某物）的范围( outgrow的现在分词 )； 长[发展]得不能再要（某物）； 长得比…快； 生长速度超过

参考例句：

• Vibrant colors last year around without wilting, watering, or outgrowing their pots early, quantities are limited. 它高贵优雅，不容易萎蔫，不用经常浇水，也不会长出花盆之外。

7 advancement   

n.前进，促进，提升

参考例句：

• His new contribution to the advancement of physiology was well appreciated.他对生理学发展的新贡献获得高度赞赏。
• The aim of a university should be the advancement of learning.大学的目标应是促进学术。

8 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

9 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

10 sensory   

adj.知觉的，感觉的，知觉器官的

参考例句：

• Human powers of sensory discrimination are limited.人类感官分辨能力有限。
• The sensory system may undergo long-term adaptation in alien environments.感觉系统对陌生的环境可能经过长时期才能适应。

11 currently   

adv.通常地，普遍地，当前

参考例句：

• Currently it is not possible to reconcile this conflicting evidence.当前还未有可能去解释这一矛盾的例证。
• Our contracts are currently under review.我们的合同正在复查。

12 holly   

n.[植]冬青属灌木

参考例句：

• I recently acquired some wood from a holly tree.最近我从一棵冬青树上弄了些木料。
• People often decorate their houses with holly at Christmas.人们总是在圣诞节时用冬青来装饰房屋。

13 bully   

n.恃强欺弱者，小流氓；vt.威胁，欺侮

参考例句：

• A bully is always a coward.暴汉常是懦夫。
• The boy gave the bully a pelt on the back with a pebble.那男孩用石子掷击小流氓的背脊。