Although more children have developmental language disorder (DLD) than autism — most people have never heard of it. Tiffany Hogan, director of the Speech and Language Literacy Lab at MGH Institute, wants greater awareness of this language disorder, especially among educators and parents. In this episode of the Harvard EdCast, she discusses what DLD is and how it can affect children's learning ability.
Jill Anderson: I'm Jill Anderson. This is the Harvard EdCast.
Tiffany Hogan is on a mission to educate about a common and yet hidden language disorder many children have called developmental language disorder or DLD. She's the director of the speech language literacy lab at MGH Institute in Boston. Although more children have DLD than autism, most of us have never ever heard of DLD. It can impact children's ability to learn on many different levels. Tiffany spoke to me about that and why she's pushing for greater awareness of the disorder.
Tiffany Hogan: Developmental language disorder is the low end of the distribution of language abilities. So children have a range of abilities on lots of different abilities. So if you think about the child's motor abilities, their cognitive abilities, we have lots of different abilities. Attentional abilities. Language ability is the ability to understand and use language and we have a normal distribution, so we have persons in the population that are really, really good at it. And you could think about someone who knows lots and lots of languages and they learn words really easily.
But then there's the lower range of the distribution and those are children who have difficulty learning languages. It's a neuro-biological difference. So children are born with this the range of seven to 9% and it can go up to 10 I usually say it's about one in 12 children have this difficulty in learning language in their primary language, also other languages, and this means that they have difficulty understanding and using language, but it's often a hidden impairment. Because it's not so obvious when a child is not understanding you, it can be misinterpreted as attention deficit.
It can be misinterpreted as laziness. I've heard parents say, "Well, I just thought he wasn't interested." It can be misinterpreted as a social issue, but as speech language pathologists, this is our area where we study speech and language development of children and we've done several longitudinal and epidemiologic studies that show that about one in 12 children have this difficulty. And unfortunately, it's often hidden, but it has a huge impact on a child's life. And only about 30% of children ever get the diagnosis. And so this is something that children can live with and it's undetected.
It can be detected later as a specific learning disability, because language permeates all of what we do. It's the foundation of learning. So it can be diagnosed then, but it's a little late. We want to diagnose it early at the beginning of school, ideally in the preschool years. And if we don't diagnose it early, it can create a lot of shame in the child themselves and they can make decisions or feeling really down about themselves and academic performance if they don't have the support they need.
Jill Anderson: Right. You're talking about this being something that's hidden?
Tiffany Hogan: Yes.
Jill Anderson: So how do you even recognize this in maybe your own child or if you're a teacher working with kids?
Tiffany Hogan: So in the past, that 30% that receives a diagnosis and is not hidden, their parents know about it, the school knows about it. They typically have some type of other problem that brings them to the attention of the teacher or the speech pathologist. So for instance, those who are identified often have a comorbid or co-occurring speech sound disorder. So they may use immature speech to produce words, that's different than a language disorder.
The speech production that has to do with producing speech sounds, but if the child has difficulty producing speech sounds, that can be something very obvious that the teacher may say, "I'm not understanding this child." Then they are referred for speech and language evaluation and they'll do the language evaluation and uncover this hidden deficit.
Another one that happens quite often is if the child has a co-occurring ADHD, they act out in the classroom or they have more obvious attentional problems, they'll go get a full evaluation and they'll say, "Oh, lo and behold they also have a language deficit." Or maybe it was a language deficit and that was what was causing the acting out, which can be true if you're having difficulty understanding, you can look quite inattentive.
The other factor that we know influences whether a child is identified as having a mother with high education. That's a common factor and we're not exactly sure why that is the case, but we hypothesize it's because that mother may be is reading a lot of information and maybe just goes to the pediatrician says, "I want a full evaluation."
If a child is referred for a full evaluation with the language impairment, ideally that full evaluation should include a language assessment and then the impairment would be identified. What we're advocating for is universal screenings of language. This can be done in kindergarten, so we screen for hearing impairment, we screened for vision impairment. We now have laws across the United States to screen for word reading deficits associated with dyslexia.
We are hoping to capitalize on those laws to screen for dyslexia and to add in screening for developmental language disorder and my lab has been working on a group screener. So it's actually not horribly difficult and doesn't take that much time. We have a screener we've developed that you can give to a full classroom of kindergartners in about 20 minutes that can give us an idea of whether a child's at risk and then we take those at risk and we do a more full evaluation.
So if we can get these more universal screeners in place, we can actually uncover this hidden deficit and provide those children and parents the education and support they need.
Jill Anderson: That's so interesting. I have never thought about language screening. Is that something hard to do because it seems almost like an easy solution.
Tiffany Hogan: It's actually quite easy. As a field studying language disorders, we've been thinking a lot the markers of language impairment and how do we discover these and there's a lot of work. So we have a strong foundation now to pull from and it's really just as speech language pathologists and language researchers thinking about how we can implement the work that we do. There's always, unfortunately a gap between what we know in research and what's implemented. And there's a whole field implementation science where we look at how do we translate what we know in research to practice.
And this is one of those examples. It also has to do, I think with understanding what screening brings you. So screening would be looking for warning signs. There would still have to be more testing, but it actually fits really nicely into the educational system now, because we do have more of the screening model that's set up and so we need to push that for language.
Jill Anderson: I just want to back up a little bit to when you were talking earlier about how you might see signs of this. It is hidden and you mentioned that it's often mislabeled or misdiagnosed as just a kid being lazy or attention issues. We're talking with young kids and I'm imagining this is better to diagnose when they're younger.
Tiffany Hogan: Absolutely. What's tricky is that we have a large variation of language skills early on. That variation reduces a bit as children get older. But let's take for example a two-year-old. So a two-year-old is starting to develop a vocabulary. First words occur around 12 months, but there's a range. Some children don't get their first words until 18 months, that's also not abnormal. So children are developing their first words and two, we start to see this burst of vocabulary develop. They start to use more words. They start to use two and three word combinations, but the range of vocabulary you'd expect for a two-year-old for instance, is 75 to 225 words. That's a huge range.
It also requires parents to write down with vigilance all the words that their child is using. When you do that, you often see it's more than you think. There's been a lot of work looking at children we call late talkers. So late talkers are those by definition who have less than 50 words at age two and know two-word combinations. However you'd think, well, that might be a good indication of a language disorder, but only about 25% of late talkers go on to have a language disorder that shows you the variability.
Seventy-five percent kind of outgrow late talking. So this is tricky because of those who have a language disorder most if not all were late talkers, but only 25% late talkers have language disorder. So it gets really tricky. So what I say is if you have concerns, your child's a late talker for instance, and you have some concerns. Getting evaluation is really the best approach because you really need to take a look at the whole context. What's the speech development? What's the cognitive development? What's the language development? And try to get a full evaluation through your pediatrician or local school districts have early intervention, you can get an evaluation there or your insurance company can give referrals.
But if there's a concern, it's best to get the evaluation. We do know that as children get a little bit older, for instance, three and four-year-olds, they start using more complex grammatical aspects. So they put together longer sentences and they start to, for instance, say the dog ran versus the dog runned. You know, those kinds of things. They start to figure out the grammar of the language. And that's a real difficulty for children with language disorders. That's one of the key markers. But it's interesting because they tend to not make errors that are abnormal, but they tend to hold onto the immature patterns longer.
So it can also make it a little bit tricky. And then there's the understanding part, right? So following directions; two-step directions. These are some of the signs of early language impairment, but ultimately you need to have an evaluation to really figure it out.
Jill Anderson: And so in a child who has this developmental language disorder or DLD, Tiffany, what does that actually look like in those scenarios?
Tiffany Hogan: Mm-hmm (affirmative). I think this is why it's often hidden because these children are developing, most of them are just developing typical in every way. This is an outlier for them. So this language ability, they could be developing, they're walking as they should. They're doing very outward things. Many of them even produce speech sounds as you would expect. So it's not an obvious difference. So what they look like is they have more immature language production. They have difficulty understanding, especially multi-step directions. You may tell them to go get their shoes, their socks, get their backpack, grab their coat, they do a couple of those, but then they forget the last one.
And this is tricky because that can also be seen in ADHD. So there's a lot of overlap until you dig a little bit deeper. They do have difficulty learning vocabulary. So let's say you teach a new word to them and it seems like they don't remember it the day later. It takes them longer to learn new vocabulary words. That's another really key factor that we know about these children. But the tricky part is it's not obvious they're functioning in many, many ways very typically.
Social skills can be also very typical. Some of them even have extra ordinary social skills and we argue maybe as a way to compensate for not understanding. So you look at these differences in language that can seem slight, but what happens is if we don't detect it early language is a foundation for all of academic achievement. It just is. So science concepts, math concepts, word problems are difficult for these children. Learning how to understand what they read. All of these things are difficult.
They have difficulty sometimes I'm learning how to decode words on a page. So it really starts to show up very dramatically in academic achievement. Their teacher will say, "Pay attention, pay attention." And so they made start to not try as hard and it becomes a downward spiral. And so we're trying to stop that downward spiral. If you have a child now who's in school and struggling and maybe you've looked at some obvious things, maybe they don't have ADHD or maybe they do, you're trying to understand why they're having problems. I would encourage you to have their language examined. Because it can often be this undercurrent that is driving a lot of differences and it's not so obvious.
Jill Anderson: I imagine there's a lot of kids with this who have just slipped beneath the cracks. I mean, now they're adults.
Tiffany Hogan: Yes. There's some staggering statistics that have come out fairly recently and some not so recently. For instance, there's a very high population of persons with language disorder that are in the juvenile justice system. The prison population has a very high occurrence of language disorder. There's self-esteem issues associated with this. It runs in families, so that's tricky too because you may, you know, you're a parent, you're, you have concerns and they say, "Well, just read your child more." Well, maybe you have difficulty reading and you don't understand what you're reading. So it can be very difficult.
And what do we do when we want to look up information? We look on the internet, we read a ton. If you have difficulty comprehending complex language, it's not the best way to get information. It can be very tricky. And we also know that unfortunately girls who have DLD, we know that later on in their adolescence, in their 30s they're more likely to have had a sexual assault.
So we know that this really has a huge impact. And the mechanism is thought to kind of go like this. They have difficulty learning language, they start to have academic problems because they don't have an obvious reason for academic problems, then the teachers and parents tell them, "You need to work harder, you need to work harder." Maybe the parents have had problems and they say, "I hated school too. So that's just how it is. School's not for us." And so then they start to see themselves as less academic. It starts to limit their choices. They have difficulty negotiating.
We use language as our way to communicate. And if you have difficulty communicating, you may not be able to negotiate your social interactions as well. You don't maybe get some of the inside jokes. You can't negotiate with a teacher who tells you something that you don't think is right. We do a lot of negotiation our life and that translates to adults too. So negotiating in the workplace, not just negotiating in the narrow sense of of something like negotiating a pay raise, but I'm talking about navigating this world.
Mabel Rice, who's a strong researcher and language impairments has talked about this a lot in the family study she's done where she follows children to adults and now she's following their children, is that there's a lot of regret about not being able to really verbally engage with the people around them. And so it really does lead to some pretty negative outcomes.
However, on the flip side, if a child does get support early on, we see much more positive outcomes. They feel they are educated on what this is. They can advocate for themselves and they have the support to learn the grammatical and know how to learn vocabulary in these kinds of things. And we try to intervene early so that we can mitigate some of the self-esteem issues that are associated with it.
They're often told they're stupid and actually if you look at intelligence tests, they're non-verbal and verbal and if you give them an verbal intelligence test, it's going to look low. It's the non-verbal that looks typical and if you average those together it's going to give a lower performance. We know that DLD is not associated with intellectual disability. It's a separate ability to learn language and it's not associated with socioeconomic status. So it cuts across all of socioeconomic status from poverty to to high levels. And so we know this is an individual difference that cuts across lots of different other individual differences.
Jill Anderson: Is there a specific age that is best to intervene for something like DLD?
Tiffany Hogan: Ideally, you would want to intervene early. So preschool level three, four, five before they go to school. But definitely by kindergarten is ideal. But I have to say that any time period is a good time to intervene, so because this is a developmental disorder that cuts across the entire lifetime. Even if someone is listening and says, "I think my child in middle school might have this difficulty." Having an evaluation, getting support right now is great.
I've been a part of some advocacy campaigns. This was started by a researcher in the UK Dorothy Bishop who had studied dyslexia, autism and developmental language disorder. And she got very frustrated over time that the public knew about autism, they knew about dyslexia but no one knew about developmental language disorder. So she started a campaign a few years ago and it's called Rattle and we have websites RADLD.org and then we have a DLDandMe.org website that anyone who's listening who wants to know more can go there.
It talks all about how to get evaluation, what it looks like across the lifespan, just trying to get information out to the public. We've had two international DLD awareness days. The last one was October 18th. We lit up over 20 monuments across the world in Ireland, UK, Australia, South America. Niagara Falls was even lit up in purple and yellow, the colors of DLD and it was very exciting to see the awareness that came about.
And we had a video campaign, so parents, educators, persons who have DLD could send in videos. Very interesting and heartwarming, and sometimes heartbreaking. You're not alone. I mean, this is five times more prevalent than autism. If you think about it as about two in every classroom that we expect to have this difference in language learning and we really want that to be something that the public knows about.
Jill Anderson: I mean, just hearing that it sounds crazy that we know so much about autism and so it's just mind-blowing to hear that DLD just is not.
Tiffany Hogan: I think there's a few factors. One is that it's been called lots of different things, so it was called specific language impairments, actually been called childhood aphasia. There was actually a group of researchers that got together and through a process decided we have to have one label. So they came up the label of developmental language disorder. So that first needed to be done for us to rally around it. I think that was one critical factor. The other factor I think is that this has been the purview of speech language pathologists.
Jill Anderson: One of the things I keep thinking about is what is the state of speech pathology in schools? Are there enough of them? Are the positions filled?
Tiffany Hogan: No. I mean, we definitely have overloaded case loads and I think they get filled with the more obvious types of conditions to be honest, like speech, sound disorder, stuttering, voice problems. We need more speech pathologists in schools so we can have lower case loads. And I also think speech pathologists need to be more integrated into the general education system. They're often kind of pushed into a room off in a closet. Okay, you pull your children out that you need to see and you fix them up and then you send them back to the classroom.
And we as a profession are fighting that because we want to be integrated because language, as I said, it permeates all aspects of education and I think there is some major good progress happening on that front. Speech pathologists are sitting at the table more. They're on literacy teams, they're on screening teams, but we have to push forward and we have to have more speech pathologists educated. We have to have more of that education focused on academic outcomes and how do we work within school systems to find these children. How do we interface with pediatricians?
My pediatrician here in Boston, I'm thrilled. It was one of the reasons I chose this practice. They have speech pathologists in the practice. If I said I had a concern about speech and language development, they say, "No problem. Let's schedule an evaluation right now." This is actually very unusual across the nation to have this type of integration, but that's the type of integration we really need to have and we need to have more funding for speech language services throughout the schools.
Jill Anderson: When you think about educators, teachers, people working really on those front lines with kids, seeing them every day, what would be one message you'd have for them about DLD that you think is important for them to know?
Tiffany Hogan: I think the most important message is children want to do well. If a child's not doing well, there's typically a reason for that. Assuming that children aren't doing well because they're not academically inclined or they're lazy or they're not trying hard enough, that really never pans out. When you pull those children who are struggling, there's usually an underlying reason and they need support. It's tricky because these children don't all look the same. They can have variables in many other areas and so they're very unique, but they do share a common thread and that is they have difficulty using an understanding language.
So if you have children who you're seeing struggling in your classroom, please work with special educators, speech language pathologists, and get that referral to have them further tested. Because again, a child doesn't want to do poorly. Children are really not lazy. They're really working hard and we know what children are DLD from the brain imaging studies, they're actually using more of their brain to do less. So it's actually quite an insult to think that they're not trying hard when they're actually trying harder to get less results.
Children want to do well and helping them to do well is really the ultimate goal and I hope that educators and parents listening will find some inspiration in the advocacy work that we're doing to bring light to this hidden disability.
Jill Anderson: One of the things I found myself thinking about, reading about DLD was the recent reading score dip that everyone has been talking about and I was curious what you thought about that.
Tiffany Hogan: Yes, actually I'm so glad you asked me this because in schools, especially with the movement towards more awareness in dyslexia, we're focusing a lot on reading words appropriately and that is so critical for literacy. You have to be able to read the words on a page. So we need systematic, explicit phonics instruction in the classroom, the evidence base is there, but that's only about, and this is probably an overestimate 50% of the equation.
The other 50% is comprehension and understanding what we read. So you need to be able to read the words on the page, but once you read those words, then the child has to understand those words. And I say they're turned into spoken language, whether you're reading out loud or even reading in your head, that's a spoken language in your head, but you have to be able to understand it.
Children with language disorders do not understand language, so they're missing at least 50% of reading comprehension. And because they're not getting those services, it's a major issue. And with the schools I work with are recognizing this. I'm working with several districts who have been working very hard to get their word reading instruction ready and good, and they're seeing improvements in word reading, but that doesn't translate automatically to reading comprehension scores. And that's those NAPE scores that everyone's talking about.
Those are two abilities and when you ignore the language comprehension portion of it, then you're not going to see those improvements. There are some great initiatives to improve language comprehension even in the classroom. I've been a part of one called the Language and Research Consortium and we have focused on that comprehension piece from pre-K to grade three and beyond and so I think as we see more awareness for language disorders, more focus on stimulating language in the classroom at the same time that you're working on word reading, then we're going to see those scores improve.
But until we have more focus on language comprehension skills, it's not going to improve and that always strikes me when I see these scores come out. It's always a... My heart drops a bit because we're ignoring a huge part of the equation. I'm glad you asked about it.
Jill Anderson: And it makes so much sense.
Tiffany Hogan: I think there's just a lot of misunderstanding about language comprehension. I've had reading researchers tell me and educators, "Well, as long as they can read words, they'll understand it unless they're in poverty." They always assume this is associated with poverty. Children in poverty have the range of language abilities that we see in other groups of children. Some children in poverty learn language quickly, some don't. And we see this across all the SES or socioeconomic statuses.
And so it's not just a problem with poverty, it's an individual difference in language comprehension. And we need to think about focusing on those who have that difficulty learning language and comprehending language and that will help us improve those scores.
Jill Anderson: How does that look with English as a second language with that group of kids?
Tiffany Hogan: That's a great question. Now that is a struggle right now in terms of identifying language disorders. So children who are learning another language tend to have a slower language development of those languages. But it corrects over time and that's great and learning multiple languages is amazing and critical and I think more children should do that and have the opportunity to do that. Children with language disorders do have difficulty learning that second language. However, we know that that we don't want them not to learn a second language because they're going to have some difficulty, but they're still going to make improvements.
So children with language disorders I should say are, when I say that low end of normal, they do develop over time. They're just developing at the same rate typically as children who are typical developing, but they're behind. So let's say two years behind. It's not that easy, but they're still developing language. So if you in the past speech language pathologists would erroneously tell parents, "Oh, don't speak another language to your child. They're going to have trouble enough learning one language. Don't add another one to it."
This was really not great on so many levels. One, it's not true. They are not hurt by learning another language. They might be a little slower, but then they're still going to learn it. It's just going to take more time. Plus it really isolated that child further from their culture and their community not learning that language of their culture and community. But what it does for measurement is it makes it trickier. So when you give an assessment of language, a child who's learning two languages or English as a second language could look like they have a disorder when they're actually just still catching up.
So what we do with those children, there's a lot of great research out there now, but what we do is we do more of a dynamic assessment with them. So we test their language and then we wait just a little bit of time and then we test it again. And what we'll find is that we look at the slope of growth. So if they're growing as you'd expect and you say, "Well there's not a risk here," but if they're not growing as expected, it's flatter development, then you say, "Oh, there's a risk here."
So we use a dynamic assessment and we also use effort rating. So how hard it is for the child or the teacher to teach language. That's another really promising area. So there's a lot of research right now being done in how do we diagnose children with a language disorder that are learning more than one language and that there's some really promising results out there, and dynamic assessment is one of them.
Yeah, and I don't want to negate the effect of poverty on education. That's strong for many reasons, many, many, many reasons, nutritional reasons, family reasons. So I don't want to negate that. I just want to make sure that we don't exclude the focus on language differences by focusing only on poverty. We need to focus on both, but it's definitely not the driving factor.
Jill Anderson: What's it going to take to make that universal screening happen?
Tiffany Hogan: Well, it's going to take a lot of advocacy, number one, to get the word out. And so I really appreciate the opportunity to talk to you today about this. We do research on these children, so I'm an NIH funded researcher. I have these studies in my lab, but we're getting ourselves out more into the community to talk to parent groups, talk to pediatricians, and just get the word out, write for popular press magazines and tried to disseminate.
It's also going to take some funding. We need more of a focus on policy measures and funding focused on pushing these screeners forward. I think policy is also just such a critical factor. So if we have policy that says we have to screen for language, then it usually happens. So starting with talking to the senators and the policymakers is also another critical aspect that we're trying to move forward on.
Jill Anderson: Tiffany Hogan is director of the speech and language literacy lab and professor in the department of communication sciences and disorders at MGH Institute, a graduate school founded by Massachusetts General Hospital in Boston. She also hosts the SeeHearSpeak podcast.
I'm Jill Anderson. This is the Harvard EdCast produced by the Harvard Graduate School of Education. Thanks for listening and please subscribe.