Dyslexia and the Developing Brain
閱讀障礙與大腦發展

As a child, Roberto Olivardia didn’t enjoy reading. Processing the words on a page fatigued him. But Olivardia — now a psychologist at McLean Hospital and a lecturer at Harvard Medical School — never considered that he might have dyslexia. He remembers watching an episode of the ABC Afterschool Specials series about a boy with dyslexia who wrote words backwards. Since Olivardia’s writing looked normal, he thought “that’s not me.”
小時候，Roberto Olivardia 不喜歡閱讀。處理頁面上的文字讓他感到疲憊。但 Olivardia——現為 McLean 醫院的心理學家及哈佛醫學院的講師——從未想過自己可能有閱讀障礙。他記得曾看過 ABC Afterschool Specials 系列的一集，講述一個有閱讀障礙、會把字寫反的男孩。由於 Olivardia 的書寫看起來正常，他便認為「那不是我」。

Decades later, Olivardia witnessed his six-year-old son experiencing a similar fatigue. Only the six-year-old’s was worse. “His vocabulary was off the charts, it was so extensive,” Olivardia recalls, “but with reading, there was a real difference between him and other kids.” Only after his son’s diagnosis of dyslexia did Olivardia become aware of the condition’s complexities: how misunderstood it is among parents, teachers, and doctors; how it manifests in myriad ways; and how a diagnosis can change everything.
數十年後，Olivardia 目睹他六歲的兒子經歷類似的疲憊感。只是這位六歲兒子的情況更嚴重。「他的詞彙量非常驚人，十分豐富，」Olivardia 回憶道，「但在閱讀方面，他和其他孩子之間有明顯的差異。」直到兒子被診斷出閱讀障礙後，Olivardia 才意識到這種狀況的複雜性：家長、老師和醫生對它的誤解；它以多種方式表現出來；以及診斷如何能改變一切。

The road to diagnosis  診斷之路

Yet getting that diagnosis is not always easy because physicians and scientists are still putting together the many puzzle pieces of dyslexia, a language-based learning disability that affects an estimated 7 to 10 percent of the population. The condition is marked by a person’s difficulty to accurately and fluently read words and to accurately decode and spell words.
然而，獲得這個診斷並不總是容易，因為醫生和科學家仍在拼湊閱讀障礙這個語言基礎學習障礙的眾多拼圖。據估計，約有 7%到 10%的人口受到影響。這種狀況的特徵是個體在準確且流暢地閱讀單詞，以及準確解碼和拼寫單詞方面存在困難。

Although the causes for dyslexia are complex, a main factor is a person’s difficulty with phonological and phonemic awareness; that is, their ability to recognize and manipulate the spoken parts of words, which sets the stage for decoding, blending, and, ultimately, reading words. Imagine, for example, being presented a word from a language other than your native language, written using symbols or an alphabet associated with that language. It may be possible to get a sense of the sounds in the word — but remembering all of them and blending them together could be hard. Each letter would need to be deciphered, and their sounds stitched together to form a word. It’s a process that can take time.
雖然閱讀障礙的成因複雜，但主要因素之一是個人在語音意識和音素意識上的困難；也就是說，他們辨識和操作口語中詞語部分的能力，這為解碼、融合，最終閱讀單詞奠定了基礎。舉例來說，想像你被呈現一個非母語的單詞，該單詞使用該語言的符號或字母書寫。你或許能感受到該單詞中的聲音，但要記住所有聲音並將它們融合在一起可能很困難。每個字母都需要被解讀，並將它們的聲音縫合起來形成一個單詞。這是一個可能需要時間的過程。

Doctors in Europe began talking about dyslexia in the nineteenth century — around the time compulsory schooling became more common. They described a curious paradox: cases of individuals who, despite being otherwise healthy, had trouble reading. In 1896 in the British Medical Journal, physician William Pringle Morgan wrote about a 14-year-old patient who he described as a bright and intelligent boy whose “great difficulty has always been … [an] inability to learn to read.”
歐洲的醫生在十九世紀開始談論閱讀障礙——大約是在義務教育變得普及的時期。他們描述了一個奇特的矛盾：有些個體雖然身體健康，卻在閱讀上遇到困難。1896 年，英國醫學期刊刊登了醫師 William Pringle Morgan 的文章，描述一名 14 歲的病患，他是一個聰明伶俐的男孩，但「他最大的困難一直是……無法學會閱讀。」

In the ensuing decades, various hypotheses for the causes came and went. It wasn’t laziness. It wasn’t a vision problem. It wasn’t the result of an infection. Some scientists began to suspect structural differences in the brain.
在接下來的幾十年裡，關於成因的各種假說此起彼落。這不是懶惰，也不是視力問題，更不是感染所致。一些科學家開始懷疑大腦結構存在差異。

Neural enigma  神經之謎

Searching for dyslexia clues in the brain is not simple. In part, that’s because there isn’t a single region of the brain devoted to reading. In the course of human history, reading is a relatively recent innovation. Unlike with spoken language, humans haven’t evolved a natural capacity for learning to read through exposure. Instead, learning to read requires that different areas of the brain that evolved for other purposes — including vision and sound perception — be retrained to work together to recognize and interpret written words. If scientists wanted to pinpoint the basis of dyslexia, they would need to explore the many brain regions involved in reading, as well as the neural pathways connecting them.
在大腦中尋找閱讀障礙的線索並不簡單。部分原因是大腦中並沒有專門負責閱讀的單一區域。在人類歷史的進程中，閱讀是一項相對較新的發明。與口語語言不同，人類並未進化出透過接觸自然學習閱讀的能力。相反地，學習閱讀需要將大腦中為其他功能演化而來的不同區域——包括視覺和聲音感知——重新訓練，使其協同工作以識別和解讀書寫的文字。如果科學家想要找出閱讀障礙的根源，他們必須探索參與閱讀的多個大腦區域，以及連接這些區域的神經通路。

Another hurdle? “It’s not really a disease,” says Albert Galaburda, the Emily Fisher Landau Professor of Neurology, Emeritus, at HMS. When Galaburda began searching for brain evidence of dyslexia back in the 1970s, advanced imaging techniques like functional magnetic resonance imaging (fMRI) were not yet available; instead, researchers studied postmortem brains. And since people didn’t typically die of dyslexia, it was rare to find a donated brain linked to a recorded case of the condition.
另一個障礙？「這其實不算是一種疾病，」哈佛醫學院榮譽神經學教授艾伯特·加拉布達（Albert Galaburda）說。當加拉布達在 1970 年代開始尋找閱讀障礙的大腦證據時，像功能性磁振造影（fMRI）這樣的先進影像技術尚未問世；研究人員只能研究死後的大腦。而且由於人們通常不會因閱讀障礙而死亡，因此很少有捐贈的大腦與已記錄的病例相關聯。

In 1979, Galaburda found an exception: a donated brain from a young man who had fallen through an elevator shaft to his death because his dyslexia prevented him from reading a cautionary sign. In one of the first studies exploring anatomical brain differences in people with dyslexia, published in Annals of Neurology in 1979, Galaburda and a colleague highlighted some interesting patterns that he would later also find in brains of other dyslexic people, including unusual symmetry between the two hemispheres and anomalies in the development of the cortex. Along with his mentor, Norman Geschwind, MD ’51, Galaburda’s work raised myriad associations for researchers to test, such as links between dyslexia and autoimmune disorders or levels of sex hormones.
1979 年，Galaburda 發現了一個例外：一位年輕男子的捐贈大腦，該男子因為閱讀障礙無法看懂警告標誌，結果不慎從電梯井墜落身亡。在 1979 年發表於《神經學年鑑》（Annals of Neurology）的一項首批探討閱讀障礙者大腦解剖差異的研究中，Galaburda 與一位同事指出了一些有趣的模式，他後來也在其他閱讀障礙者的大腦中發現了這些特徵，包括兩個半球之間不尋常的對稱性以及大腦皮層發育的異常。與他的導師 Norman Geschwind 醫師（MD ’51）一同，Galaburda 的研究為研究人員提供了許多可供檢驗的關聯，例如閱讀障礙與自體免疫疾病或性激素水平之間的聯繫。

 “Geschwind and Galaburda were among the first ones thinking about a multifactorial model — looking at all the different factors that sort of work together to cause atypical reading development,” says Nadine Gaab, an associate professor of pediatrics at HMS and a professor at the Harvard Graduate School of Education.
「Geschwind 和 Galaburda 是最早提出多因素模型的人之一——他們著眼於所有不同因素如何共同作用，導致非典型的閱讀發展，」哈佛醫學院兒科副教授、哈佛教育研究所教授 Nadine Gaab 說。

Clues found in the developing brain
在發育中的大腦中發現的線索

By the time Gaab began her own research into dyslexia in 2007, new neuroimaging techniques were available for researchers to examine the brains of children living with dyslexia or those who had a familial risk for the condition — that is, a biological parent or sibling with dyslexia. At that point, “we knew a lot about how the brain of a person with dyslexia differed in activation patterns and different tasks,” Galaburda says. But an important question remained: Did dyslexia cause these differences, or did these differences cause dyslexia?
到了 2007 年 Gaab 開始進行她自己的閱讀障礙研究時，已有新的神經影像技術可供研究人員檢視患有閱讀障礙的兒童或有家族風險的兒童的大腦——也就是說，他們的生物學父母或兄弟姐妹有閱讀障礙。當時，「我們已經對閱讀障礙者大腦在不同任務中的活化模式有了很多了解，」Galaburda 說。但一個重要的問題仍然存在：是閱讀障礙導致了這些差異，還是這些差異導致了閱讀障礙？

Gaab focused on answering this question. An MIT research group she was a part of focused its study on one white matter tract called the arcuate fasciculus, or the “the arc,” which connects key brain areas involved in reading: those related to vision and sound processing at the back of the brain and the inferior frontal gyrus, an area responsible for comprehension and meaning. In a subsequent longitudinal study in which the brains of kindergartners were scanned, Gaab and colleagues demonstrated that children who had lower phonological processing skills, a risk factor for dyslexia, also had smaller arcs.
Gaab 專注於回答這個問題。她所參與的麻省理工學院研究團隊將研究焦點放在一條名為弓狀束（arcuate fasciculus），或稱「弧線」的白質束上，這條束連接了閱讀過程中關鍵的大腦區域：位於大腦後方負責視覺和聲音處理的區域，以及負責理解和意義的下額回。在隨後的一項縱向研究中，Gaab 和同事們對幼稚園兒童的大腦進行掃描，證明了語音處理能力較低的兒童——這是閱讀障礙的風險因子——其弧線也較小。

After identifying that link, Gaab and colleagues set out to learn when these differences emerge. They compared brain scans from children with a familial risk for dyslexia with those from children without the familial risk and found that children at risk for the condition showed differences in the arc even before beginning formal schooling. Moreover, the rate of the structure’s development was slower among those who later developed poor reading skills regardless of familial risk. To the researchers, this suggested that some children began kindergarten with brains that were less well equipped for learning to read.
在確認了這個關聯後，Gaab 和同事們開始研究這些差異何時出現。他們比較了有家族性閱讀障礙風險的兒童與沒有家族性風險的兒童的腦部掃描，發現有風險的兒童在正式入學前，弓形束就已經顯現出差異。此外，無論是否有家族性風險，後來閱讀能力較差的兒童，其該結構的發展速度都較慢。對研究人員來說，這顯示有些兒童在幼稚園入學時，腦部尚未充分準備好學習閱讀。

To explore how early these differences emerged, the researchers examined the brains of participants who had thus far been largely neglected in dyslexia studies: babies. Their initial study, published in Cerebral Cortex in 2017, found that infants of parents who had struggled with reading showed alterations the arc compared to infants of parents who hadn’t struggled to read. In subsequent studies, they observed a link between these alterations and phonological processing and oral language skills in kindergarten. They also found that the microstructure of the arc can be shaped by lifestyle factors, such as how early and often a child is read to.
為了探究這些差異出現得有多早，研究人員檢視了迄今在閱讀障礙研究中大多被忽視的參與者大腦：嬰兒。他們於 2017 年發表在《Cerebral Cortex》期刊的初步研究發現，父母有閱讀困難的嬰兒，其弓狀束（arc）與沒有閱讀困難父母的嬰兒相比，出現了變化。在後續研究中，他們觀察到這些變化與幼稚園階段的語音處理及口語能力之間存在關聯。他們也發現，弓狀束的微結構會受到生活方式因素的影響，例如孩子被閱讀的時間早晚及頻率。

We now know that some kids who step into kindergarten on their first day, with their little backpacks, have a heightened risk for struggling with learning to read.
我們現在知道，有些孩子在第一天背著小書包踏入幼稚園時，就已經有較高的風險在學習閱讀上遇到困難。

While the arc is only one of several brain areas exhibiting differences in people with dyslexia, Gaab’s findings have provided an impetus for action. In addition to linking risk factors for dyslexia to specific parts of the brain, her work shows that some of these risks can be inherited. And the findings indicate that while genetics matter, environment can matter, too. Perhaps more important, they suggest that risk factors for dyslexia exist early — very early. “We now know that some kids who step into kindergarten on their first day, with their little backpacks, have a heightened risk for struggling with learning to read,” Gaab says. “That’s a really important distinction in terms of policy and how early we should find these kids and intervene.”
雖然弧形束只是閱讀障礙者大腦中多個顯示差異的區域之一，Gaab 的發現卻為行動提供了推動力。除了將閱讀障礙的風險因素與大腦特定部位連結外，她的研究還顯示這些風險有部分是遺傳的。研究結果指出，雖然基因很重要，環境因素同樣也很重要。或許更重要的是，這些風險因素在很早期——非常早期——就已存在。「我們現在知道，有些孩子在背著小書包踏入幼稚園第一天時，就已經有較高的閱讀學習困難風險，」Gaab 說。「這在政策制定以及我們應該多早發現並介入這些孩子的問題上，是一個非常重要的區別。」

The value of early intervention
早期介入的重要性

Despite so many children already at risk before starting school, U.S. school systems tend to identify children with dyslexia only after it’s clear that something is wrong — at around nine or ten years old. Gaab, who describes herself as a “translational neuroscientist,” has become a tireless proponent of early intervention. She advocated for a new Massachusetts law that was signed by the governor in 2018, requiring screening for dyslexia for children in kindergarten. And she’s been developing a tablet-based tool that can be used to screen children for reading problems as early as age four. This latter tool is especially useful because fMRI data, while good for exploring overall patterns of brain differences between groups, is impractical in educational contexts and does not have the sensitivity and specificity necessary to identify at-risk children.
儘管許多兒童在入學前就已經處於風險之中，美國的學校系統通常只有在明顯發現問題時——大約在九、十歲左右——才會識別出有閱讀障礙的兒童。Gaab 自稱為「轉譯神經科學家」，她成為早期介入的堅定倡導者。她推動了一項於 2018 年由州長簽署的新麻薩諸塞州法律，要求對幼稚園兒童進行閱讀障礙篩檢。她也一直在開發一種基於平板電腦的工具，能夠在兒童四歲時就用來篩檢閱讀問題。這項工具特別有用，因為雖然功能性磁振造影（fMRI）數據適合用來探索群體間大腦差異的整體模式，但在教育環境中並不實用，且缺乏識別高風險兒童所需的敏感度和特異性。

Gaab hopes that pediatricians — who often screen for autism and ADHD — will adopt dyslexia risk screening, too. “We embrace preventive medicine; we get mammograms and checkups to identify risk factors and try to address them so that we don’t get sick,” she says. “That’s the same idea with dyslexia, to find at-risk kids early and intervene early, so that they never develop problems with reading. We call it preventive education.”
Gaab 希望小兒科醫師——他們經常篩檢自閉症和注意力不足過動症（ADHD）——也能採用閱讀障礙風險篩檢。「我們支持預防醫學；我們會做乳房 X 光攝影和健康檢查，以識別風險因子並試圖解決，避免生病，」她說。「閱讀障礙也是同樣的概念，及早發現有風險的孩子並及早介入，讓他們永遠不會出現閱讀問題。我們稱之為預防性教育。」

Dyslexia itself is not hazardous to anyone’s health. It really is the fact that they’re not being identified, they’re not being diagnosed, and they’re not getting the services that they need.
閱讀障礙本身並不會危害任何人的健康。真正的問題是他們沒有被識別、沒有被診斷，也沒有獲得他們所需的服務。

Proper early identification is key, adds Gaab, because studies indicate that 50 to 90 percent of at-risk readers can reach average levels of performance with targeted instruction, and that interventions are more effective in kindergarten and first grade than later on.
Gaab 補充說，適當的早期識別是關鍵，因為研究顯示，50% 到 90% 的有風險讀者透過針對性的教學可以達到平均表現水準，且介入在幼稚園和一年級時比之後更有效。

According to Olivardia, children who are never identified, or who live in communities without access to these interventions, might get lumped into generic remedial reading classes. But if their instruction isn’t tailored to dyslexia, “it’s as if you don’t understand the language someone is speaking, so they just speak louder,” he says. “You’re like, that doesn’t help me at all.”
根據 Olivardia 的說法，那些從未被識別出來，或生活在無法取得這些介入措施的社區的兒童，可能會被歸入一般的補救閱讀課程。但如果教學沒有針對閱讀障礙量身訂做，「就好像你聽不懂別人在說什麼，他們只好講得更大聲，」他說。「你會覺得，這根本一點幫助都沒有。」

Early intervention does more than help get reading levels on track. Children with dyslexia are more likely to experience depression, anxiety, and other mental health issues. But that’s not due to differences in their brains; it’s because in our society, literacy is key to academic and workplace success. “Dyslexia itself is not hazardous to anyone’s health,” says Olivardia, whose private psychotherapy practice specializes in treating children with learning disabilities. “It really is the fact that they’re not being identified, they’re not being diagnosed, and they’re not getting the services that they need.”
早期介入不僅有助於讓閱讀能力回到正軌。患有閱讀障礙的兒童更容易經歷憂鬱、焦慮及其他心理健康問題。但這並非因為他們的大腦有差異；而是因為在我們的社會中，識字能力是學業和職場成功的關鍵。「閱讀障礙本身並不會危害任何人的健康，」Olivardia 說，他的私人心理治療診所專門治療有學習障礙的兒童。「真正的問題在於他們沒有被識別、沒有被診斷，也沒有獲得他們所需要的服務。」

Education provides perspective
教育提供了視野

Olivardia understands the importance of reframing dyslexia for his patients. He talks to them about the many successful people who are thought to have had dyslexia — from Einstein to Picasso to British business magnate Richard Branson — and stresses his own observations that people with dyslexia exhibit above-average creativity and entrepreneurial skills. Research backs this up: A 2009 study in Dyslexia found a prevalence of dyslexia three times higher among entrepreneurs than people in the general population, while a higher prevalence of dyslexia has also been identified among students who pursue art or engineering. Other research points to a superior ability to connect unusual combinations of ideas among people with dyslexia.
Olivardia 理解為他的病人重新定義閱讀障礙的重要性。他會跟他們談論許多被認為患有閱讀障礙的成功人士——從愛因斯坦到畢卡索，再到英國商業巨擘理查德·布蘭森——並強調他自己的觀察，認為閱讀障礙者展現出超越平均水平的創造力和企業家精神。研究也支持這一點：2009 年發表在《Dyslexia》期刊的一項研究發現，企業家中閱讀障礙的盛行率是一般人口的三倍，而在選擇藝術或工程學科的學生中，也發現閱讀障礙的盛行率較高。其他研究則指出，閱讀障礙者在連結不尋常的想法組合方面具有優越的能力。

Olivardia also draws from his experience parenting a child with dyslexia. Following his son’s diagnosis, they practiced role-playing conversations with teachers and peers about the learning disability. One day, a few weeks after diagnosis, Olivardia’s son was given lyrics to read in music class, but his dyslexia was so severe at that point that he couldn’t read the words at all.
Olivardia 也從他撫養一位有閱讀障礙孩子的經驗中汲取靈感。在他兒子被診斷出來後，他們練習與老師和同學進行角色扮演，討論這種學習障礙。有一天，在診斷後幾週，Olivardia 的兒子在音樂課上被要求閱讀歌詞，但當時他的閱讀障礙非常嚴重，根本無法讀出那些字詞。

Olivardia’s son asked a classmate to sit and sing along with him. The girl, confused, asked him why he couldn’t read. Instead of shrinking away, he calmly explained that his brain was just different — and pointed out that Tom Cruise has the same thing. “She was like, oh, OK, and that was it,” Olivardia says. “And he sat next to her. And when I picked him up, he said, ‘Dad, it was a great day.’”
Olivardia 的兒子請一位同學坐下來和他一起唱歌。那位女孩感到困惑，問他為什麼不能閱讀。兒子沒有退縮，而是冷靜地解釋他的腦袋就是不一樣——並指出湯姆·克魯斯也有同樣的情況。「她就說，喔，好的，就這樣了，」Olivardia 說。「他就坐在她旁邊。當我去接他時，他說，『爸爸，今天真是美好的一天。』」

“There’s a lot of hope in a label and a name,” Olivardia adds. “It gives parents, teachers, and doctors the opportunity to emphasize that these kids’ brains are wired differently — but that different does not mean they are defective.”
「一個標籤和名稱帶來很多希望，」Olivardia 補充說。「它讓家長、老師和醫生有機會強調，這些孩子的大腦連結方式不同——但不同並不代表他們有缺陷。」

Molly McDonough is the associate editor of Harvard Medicine magazine.
Molly McDonough 是 Harvard Medicine 雜誌的副主編。

Images: John Soares (Olivardia); courtesy of Anna Olivella and the Harvard Brain Science Initiative (Gaab)
圖片：John Soares（Olivardia）；由 Anna Olivella 及哈佛腦科學計畫提供（Gaab）