Editor's note: This text-based course is a transcript of the webinar, Understanding And Supporting Adults With Intellectual And Developmental Disabilities With Cognitive Decline And Regressive Illness, presented by Christina Marsack-Topolewski, PhD, MSW, LMSW.
*Please also use the handout with this text course to supplement the material.
Learning Outcomes
- After this course, participants will be able to recognize trends and prevalence of dementia for adults with IDD.
- After this course, participants will be able to identify the signs of cognitive regression in adults with IDD.
- After this course, participants will be able to list the types of dementia that exist and relevant organizational resources for adults with IDD experiencing regressive illness in order to support occupation.
Introduction
Today, we’ll discuss understanding and supporting adults with intellectual and developmental disabilities, which I’ll occasionally refer to as IDD throughout this session. Our focus will be on this population specifically in the context of cognitive decline and regressive illness. It’s a subject that isn’t often brought to the forefront, yet it’s increasingly relevant—not just in the United States but globally. The fact that so many of you have chosen to spend your time exploring this speaks volumes.
We’ll be talking about adults with IDD and how they may present with signs of dementia or other forms of cognitive decline. This can include clinical characteristics that differ from what we typically see in the general aging population.
One thing we often discover when we look more closely—not just at our systems of support, but even at how research is conducted—is that we tend to separate “disability” populations from “aging” populations. That’s a pretty big divide, and it can leave a gap in how we think about and serve those who are aging with IDD. The reality is that aging doesn’t happen in isolation. People with intellectual and developmental disabilities are aging across the lifespan, just like everyone else. Being able to talk about that intersection—what aging looks like for this population and what that means for their lives, for their families, and for us as providers—is something I’m grateful to contribute to.
We’ll also examine the symptoms we might observe. With IDD, there can be a variety of co-occurring conditions and experiences that may look a bit different from what we expect in typical age-related changes. We’ll discuss normative versus non-normative patterns of decline and explore the adaptations we might consider in our provider roles. These adaptations can make a difference in supporting the individuals we serve.
Finally, we’ll dive into the unique characteristics of this population and explore what we can do to offer meaningful, effective support as individuals begin to experience cognitive changes. This includes thinking creatively and compassionately about how we recognize, interpret, and respond to those changes.
I’m so glad you’re here, and I look forward to continuing the conversation as we explore this important and evolving area together.
Today's Focus
We’ll begin by exploring trends and prevalence—what we’re seeing regarding cognitive regression in adults with intellectual and developmental disabilities, and where we go from there. I serve as one of the appointed board members for the U.S. National Task Group on Intellectual Disabilities and Dementia Practices. Through that role, I’ve learned of various resources—not just through our national body, but scattered across the country.
That said, one of the biggest ongoing challenges we hear from family caregivers is just how hard it is to find specialized, targeted resources for individuals with IDD who are experiencing cognitive decline. Most people are aware of general dementia services or Alzheimer’s support networks, which are incredibly important. But when someone has had a lifelong disability, and we start to see regression or signs of dementia on top of that, the question becomes: where do families turn? It’s not always clear where to find help, and often the answers aren’t readily available. I’ll be sharing some of the resources I’ve seen, and I hope this information will prove helpful to someone here today, whether for your practice or the families you serve in the future.
Now, regarding limitations and risks, I wish I could say there was a one-size-fits-all solution—but, as you know, that’s rarely the case when working with people. We can’t simply wave a magic wand and expect everything to fall into place. Each person we work with brings a unique set of strengths, needs, and life circumstances, and the presentations we see can vary not only between individuals but even within the same person over time.
Because of this variability, I’m not offering clinical recommendations in the prescriptive sense. Instead, I encourage a thoughtful, team-based approach. Whenever possible, I strongly advocate for drawing upon the expertise of an interprofessional or multidisciplinary team. That kind of collaboration is often where we find the most comprehensive, effective, and sustainable support strategies for the individual and their support network.
We’ll continue to unpack these ideas as we move through the session. There’s a lot to cover, but I hope our discussion today will serve as a foundation for further exploration, conversation, and connection in this essential and often under-addressed care area.
Terminology
I want to offer a bit of clarification when it comes to terminology. As I mentioned earlier, IDD stands for intellectual and developmental disabilities, while ID refers more specifically to intellectual disabilities. You’ll hear me use both terms throughout today’s presentation.
I also want to take a moment to talk about language because this has evolved, particularly over the past seven years or so, and I’ve been closely following the conversation. There’s been ongoing discussion around the use of person-first language versus identity-first language, and I want to acknowledge that I use these interchangeably at times.
The choice between person-first and identity-first language is not always straightforward. There’s active dialogue—both in the research and practice—about what individuals with disabilities and their families prefer. We see variations not only between communities but also across different professional settings. For example, some healthcare providers may lean toward person-first language, while certain disability rights advocates or behavioral health professionals might prefer identity-first terms. This variation is real and meaningful.
I tend to publish using person-first language—phrases like “people with dementia” or “people with disabilities.” That’s consistent with my training and reflects the preferences I shared with many of the families I’ve worked with. However, I want to be clear that there’s no single right answer and that preferences can and do differ.
Throughout today’s discussion, I’ll use terminology intended to be respectful, thoughtful, and inclusive. My goal is to honor the individuals and families we’re talking about by using language that reflects dignity and care while acknowledging that this is an area of ongoing growth and learning for all of us.
What is Dementia?
When we hear cognitive decline, many may picture different things depending on our experiences and professional backgrounds. Suppose we refer to the DSM, the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. In that case, cognitive and functional decline is outlined as a category encompassing a range of symptoms. These changes can affect individuals in many ways, and the progression is rarely uniform.
The way these symptoms show up can vary greatly from person to person. For some, the decline may be gradual and subtle, while for others it can emerge more rapidly or with fluctuating intensity. The frequency, rate, and even the specific nature of symptoms often differ, making it essential that we don’t treat cognitive decline as a one-size-fits-all phenomenon.
I’ll be going into more detail about specific types of dementia, but first, let’s consider a few examples of what this decline might look like in practice. Often, we begin to notice a decrease in abilities related to attention and memory. Individuals may struggle to concentrate or recall previously familiar information. We may also see difficulties with executive functioning—things like planning, organizing, sequencing tasks, or problem-solving. And for some, motor functioning can also become impaired, adding another layer of complexity to daily living. These are just a few of the early indicators we often observe, and they serve as important starting points when assessing cognitive changes in adults with IDD.
Executive Functioning
People often ask, “What exactly is executive functioning?” It’s a great question, and an important one, especially in the context of cognitive decline.
For those of you familiar with ADHD, you may already know that it’s considered a condition involving executive dysfunction. In many ways, executive functioning is like the orchestra of our minds. If you’ve ever been to a symphony, you’ve likely marveled at how each musician plays a different instrument. Yet, somehow it all comes together—ideally in harmony—under the guidance of a conductor. That conductor is an excellent metaphor for executive functioning. It’s our internal system for coordinating our mental and behavioral efforts. It allows us to plan, reason, organize, prioritize, and adapt to life’s many moving parts. It helps us take in information, filter it, act on it, and shift direction when needed.
Now, when executive functioning begins to decline, as it often does in dementia, things can start to unravel—often in ways that aren’t immediately obvious. Let me offer a quick example to help ground this. There was an individual in the early stages of cognitive decline, and while the family had started to notice a few subtle changes, nothing had yet raised serious concern. One day, he drove to visit his daughter. He got to the neighborhood on the right street, but things started going awry. He couldn’t remember which house was hers. Rather than calling or retracing his steps, he knocked on doors and peered into windows, hoping to recognize something familiar.
Now, depending on where you live, this behavior might be met with confusion or concern, if not outright alarm. And for the family, it was a pivotal moment. His reasoning was impaired. He couldn’t pause, problem-solve, or use available tools like his phone to ask for help. It wasn’t just memory that had failed him—it was his executive functioning.
Those working with individuals with disabilities, as many of you do, are often very familiar with executive functioning challenges. You’ve likely seen how difficult it can be for someone to prioritize tasks, follow multi-step directions, or manage time effectively. But in the context of dementia, these difficulties may emerge in ways that feel more unexpected or sudden, especially if they appear layered over a lifelong disability.
Executive functioning is the system that helps us manage life’s complexity. When that system begins to falter, we see disorganization, poor judgment, difficulty sequencing actions, and confusion about what comes next, even in environments that once felt familiar. Recognizing these signs can be essential in diagnosing and supporting someone through cognitive regression.
Trends & Prevalence of Dementia in IDD
When we look at trends in Alzheimer’s disease, both globally and here in the U.S., we see a clear and steady rise in prevalence due to aging populations and increased life expectancy. For adults with intellectual and developmental disabilities, this trend is particularly significant, as they are now living longer and facing a higher risk of developing dementia, often earlier and with distinct challenges that require specialized support and recognition.
General Rates of Dementia
To give some context, in 2022, there were more than 55 million people worldwide living with dementia, according to figures from Alzheimer’s Disease International. That’s a staggering number—and it’s one of the reasons I find this topic so compelling. Beyond the personal and professional connections many of us have to individuals impacted by dementia or Alzheimer’s disease, there’s also the broader trajectory we need to pay attention to. The numbers are rising rapidly, and the projections are pretty sobering.
That global number is expected to double to around 110 million by 2040. Projections from the World Health Organization estimated that by 2023, we’d reach approximately 78 million people worldwide living with dementia, with that figure climbing to an estimated 139 million by 2050. These are not just numbers—they reflect real people, families, and communities who will be impacted.
This makes this even more concerning because we are not maintaining a population replacement rate globally. In many countries, birth rates are falling below the threshold needed to sustain the size of the current population. This trend is especially relevant to aging services, and I’ve encountered it in research and policy discussions across different countries, including parts of Asia. Many of these nations are already grappling with the reality that they don’t have enough younger people to meet the growing demand for caregiving, whether at home or within professional care systems.
So as dementia rates increase, we’re also confronting a parallel crisis: a shortage in human capital and caregiving bandwidth. This affects family caregivers and professionals across the healthcare and aging services spectrum. We’re being stretched—emotionally, logistically, and systemically—and it raises important questions about how we prepare for the future, not just regarding medical care, but also community support, infrastructure, and workforce development.
Trends and Prevalence
When we look at trends and prevalence, particularly the intersection of intellectual disability and dementia, the impact can be profoundly debilitating, especially when these conditions co-occur. In 2020, I published a piece with Dr. Seth Keller that explored what this comorbidity means for the affected individuals and their families. We found that many family caregivers were aging mothers, often in their 70s or 80s, trying to navigate systems that didn’t offer clear pathways to care. They struggled to find services, support, and professionals who understood both the disability and the emerging cognitive decline.
Another crucial trend we’ve observed is that individuals with intellectual and developmental disabilities have a markedly increased risk of developing dementia. The risk is significantly higher than in the general population. I say this in nearly every presentation I give: take prevalence numbers with a grain of salt. Variations depend on how studies are conducted, how populations are defined, and what methodologies are used. Still, what remains consistent is the elevated risk. One study found that individuals with intellectual disabilities were four to five times more likely to develop dementia compared to the general population. That’s a staggering statistic—and one that’s echoed across several meta-analyses, despite differences in precise estimates.
My background began in special education, working closely with students with Down syndrome, and my academic path has since taken me into social work and aging. That intersection—disability and aging—has long fascinated me. It’s an area that is often overlooked, yet so essential, especially when we talk about juvenile-onset conditions and lifelong disabilities. Within the Down syndrome population, in particular, the risks are especially elevated. Families are frequently left to decide what to do next, often without access to specialists or clear diagnostic pathways. Neurological assessments may be hard to obtain, and diagnostic overshadowing remains a persistent barrier, where symptoms of dementia are misattributed to the pre-existing disability.
According to a frequently cited 2013 study, adults with intellectual disabilities are about five times more likely to develop dementia than those in the general population. While we don’t yet have precise, consistent figures due to the limited research base, these numbers give us a strong indication of the scope of the issue. For individuals with Down syndrome, the biological connection to Alzheimer’s disease is well established. Research has shown that Alzheimer’s pathology—specifically the presence of amyloid plaques—can begin to appear neurologically as early as age two, even though functional symptoms typically don’t emerge until much later.
For most people with Down syndrome, the physical markers of Alzheimer’s disease are present by age 40. That number—40—continues to weigh heavily on my heart. It’s incredibly young. And it raises a critical question: What can we be doing earlier? How can we help families better prepare? How can we promote cognitive stimulation, physical activity, and sleep hygiene? While none of these are curative, they may contribute to improved quality of life, reduced stress, and delayed onset of more severe symptoms.
What we often see is that the hallmark signs of dementia may go unrecognized until they become disruptive. However, in hindsight, many families can point to subtle changes that started a decade earlier—slight shifts in mood, memory, or function dismissed at the time because the person was still relatively independent. This mirrors what we see in the general population, though the timeline and prevalence rates differ. For individuals with Down syndrome, the risk of developing Alzheimer’s disease over a lifetime is estimated at around 90%. That number speaks volumes.
And we’re also seeing emerging research highlighting other disability groups. For instance, individuals with autism spectrum disorder—particularly those with co-occurring intellectual disabilities—are also at increased risk for dementia. It’s an area currently under review by our national task group, and we’re working on a manuscript that focuses specifically on this population. Traditionally, the conversation about regressive illness in IDD has centered on Down syndrome, and for good reason. But we now know that other groups, including those with autism and lifelong intellectual disabilities, deserve equal attention.
For individuals under the age of 65 with autism, research suggests they are 2.6 times more likely to receive a dementia diagnosis than their neurotypical peers. That statistic alone invites us to broaden our lens. There’s something significant happening here. And it underscores the importance of proactive screening, early intervention, and better-informed services tailored to these populations' unique needs.
So, while we have more to learn, what we do know already points to the urgent need for more inclusive, coordinated, and informed care across the lifespan.
Background: Dementia & IDD
As we think about supporting adults with intellectual and developmental disabilities, it’s essential to understand the broader context shaping their experiences today. One of the most significant changes we’ve seen over the past few decades is that individuals with IDD are living longer than ever before. That’s a tremendous success story resulting from advances in healthcare, early interventions, and support systems. But with that longevity comes new challenges, especially when it comes to the increasing prevalence of dementia.
I’ve heard so many stories from aging maternal caregivers who’ve spent their lives supporting their children with IDD. These are women in their 70s or 80s, and their children—now adults—are in their 40s or 50s. One mother told me, “My son used to be able to do all these things. And now, it’s like something’s slipping.” She knew it was more than the expected ebb and flow of ability. But when she raised concerns with healthcare providers—neurologists included—she was often dismissed. “Your child has Down syndrome,” they’d say as if that explained everything. But these mothers noticed real changes, clear regression that didn’t match the baseline. And they weren’t being heard.
This points to a larger issue: many adults with IDD already face challenges with activities of daily living and instrumental activities of daily living. They might need help with money management or household tasks, or they may present with social naivety that places them at risk. Add cognitive regression into that mix—especially dementia—and it creates a compounded set of vulnerabilities that caregivers are often left to manage alone. Sometimes the decline is subtle and gradual; other times it progresses rapidly. Either way, families are left in a challenging position without the right information and support.
Another complicating factor is that many adults with IDD remain in the family home for much longer than the general population. Often, it isn’t until the caregiver parent becomes too elderly or ill to continue that a transition in living arrangement is even considered. So, when you introduce dementia into that equation, the complexity of caregiving skyrockets. And this is not just emotional complexity—it’s logistical, physical, and systemic.
Dementia affects communication and behavior. However, when someone’s expressive and receptive language is already limited, the signs of decline can be more challenging to detect and much harder to interpret. Providers may miss the early cues. Behavioral changes might be misattributed to the lifelong disability rather than recognized as new or progressive. This is referred to as diagnostic overshadowing and happens far too often.
Our services for adults with IDD are already stretched thin. One of my primary research and advocacy areas is service access and utilization. Are the services appropriate? Are they affordable? Can someone physically get to them? These are real, foundational questions that too often go unaddressed. And when dementia enters the picture, it magnifies every gap in the system. A 40- or 50-year-old with Down syndrome may need access to aging services, but those systems may not be prepared to accommodate a younger adult. At the same time, disability-specific services may not be equipped to deal with age-related cognitive decline. This dual need creates a disjointed service landscape that can be incredibly hard to navigate.
Families consistently tell me they are not getting a timely diagnosis. Just like in other disability-specific communities, the people who are often the most informed and most supportive are not the professionals, but other family caregivers. These families form a grassroots network of knowledge, emotional support, and hard-earned insight. They’re filling in the gaps without the recognition or resources they need.
So when discussing background considerations for this population, we must acknowledge both the progress and the challenges. We have people living longer, which is something to celebrate. But we also have a growing need for informed, accessible, and integrated care that takes into account the full spectrum of someone’s life experience—from childhood disability through the realities of aging and cognitive decline.
Signs of Regression in Adults with IDD
My colleague Dr. Preethi Samuel and I conducted a study using data from a small national sample I led. We carried out a qualitative, retrospective analysis of spontaneous conversations among 15 caregivers, using content analysis to understand better how they perceived the onset of dementia in individuals with intellectual and developmental disabilities.
These caregivers, whom I often call “invisible caregivers,” are usually the first to notice subtle shifts. Their insight is invaluable, yet their voices are frequently overlooked in healthcare settings. We hoped to identify meaningful patterns that could guide other families in the U.S. and globally.
We identified five broad categories of changes caregivers noticed in their loved ones. These weren’t clinical symptoms in the traditional sense, but rather relational and contextual observations that something was different. These moments often served as early indicators—small shifts that gradually revealed a larger pattern over time.
What stood out was the profound wisdom and strength these caregivers showed. They weren’t just managing tasks but creating emotional and informational lifelines for each other while facing immense daily challenges. Many expressed deep frustration with the lack of provider training, systemic gaps in care, and the absence of services designed for this population. They were navigating complex systems, often with limited guidance, and still found ways to support one another.
Caregivers tracked changes, documented behaviors, and helped connect the dots long before formal systems did. Their lived experience provides an essential window into what the onset of dementia looks like in the context of IDD—something that can’t always be captured through clinical tools alone.
They are advocates, companions, and tireless observers—working without the support they deserve. Their stories must inform how we design support systems, identify early signs, and plan long-term care for individuals with IDD and dementia.
Observed Changes By Caregivers
I’ve been following this work informally for about seven years now, and what continues to move me most is the incredible strength and unity of the caregiver community, especially when supporting adults with Down syndrome who are also living with comorbid depression or dementia. Even in the final days of life, when everything becomes so delicate and emotionally charged, this community doesn’t step away—they wrap around one another. It’s one of the most powerful and humbling things to witness.
These families provide so much more than physical care. They offer presence, comfort, and deep emotional support. They reach out to others who have walked similar paths, often transforming their pain into wisdom to help someone else. I’ve seen caregivers continue to offer solace long after their own loved one has passed, still showing up, staying connected, and being that pillar for someone just beginning the process. This compassion goes far beyond what any formal service system can replicate.
All this work was conducted with full informed consent and institutional review board (IRB) approval. That’s important to note because we were entering a deeply personal space, often involving profound grief and vulnerability. Our approach was intentional, ensuring that these stories were treated with care, respect, and integrity at every step.
This was not traditional data collection. But to truly understand what families are living through—the complexity of caregiving, the emotional toll, the moments of resilience—we had to approach it differently. By doing so, we were granted access to some of the most sincere, honest, and meaningful insights that I’ve ever encountered.
Five Observed Changes
Our study observed five distinct areas of change that caregivers reported noticing in their loved ones. These included behavioral issues, physical changes that impacted functioning, noticeable mood shifts, procedural and short-term memory difficulties, and atypical behaviors. I want to briefly walk through these and share a few examples to illustrate what we heard.
When I refer to behavioral problems, I use that term cautiously and only for lack of a better descriptor, not in a derogatory way. Caregivers described new or intensified behaviors such as aggression or compulsive actions that were previously uncharacteristic. These changes were often early signs that something significant was shifting, particularly because they stood in contrast to the person’s established baseline.
Physical changes that impacted function were also widely reported. These weren’t just isolated health concerns, but observable shifts in the ability to perform daily activities. Caregivers described difficulties with movement, increased fatigue, or a slowing down that made everyday routines more challenging.
Mood changes were another frequent theme. Caregivers spoke about increased anxiety, sadness, irritability, and social withdrawal. These emotional changes were sometimes subtle at first, even misinterpreted, but they gradually became more pronounced and often appeared alongside other symptoms.
Procedural and short-term memory issues were also commonly observed. Families described their loved ones forgetting to do familiar tasks or struggling to retain new information. These lapses were unsettling, particularly when they involved routines consistently performed for years.
Finally, there were atypical behaviors—actions that didn’t match the individual’s established personality or behavioral history. Examples included stealing or lying, which families emphasized had never occurred before. These shifts were especially jarring and often served as a wake-up call that something deeper was happening.
These observations offer a clear, humanized picture of how dementia may manifest in adults with intellectual and developmental disabilities. Though often without formal training, caregivers are the closest to these changes. Their lived experience and day-to-day insight are invaluable; we must continue to listen closely and learn from what they see.
Reminders
As we think more deeply about what these findings mean, it’s important to reflect on the broader implications of our study and how they can help guide both practice and awareness. The thematic findings illuminated the ways caregivers come to recognize cognitive decline in individuals with IDD, often through informal social support networks. When I say “informal,” I’m referring to support that is not paid—help from a neighbor, a friend, or a family member, rather than through structured, government-funded, medical, or therapeutic services.
These caregiver observations often mirror what formal providers might notice, but the key difference is that family caregivers are usually the first to witness the changes. They’re living alongside their loved ones. They’re at home or receiving late-night phone calls. Even if they’re not present around the clock, they’re deeply embedded in the care experience and often receive feedback from care staff in settings like subacute rehab, group homes, or semi-independent living environments. This puts them in a critical position to detect early signs. That early awareness can be a powerful signal that further evaluation is needed.
Given that 90% of individuals with Down syndrome are expected to develop dementia if they live long enough, it becomes essential to work proactively with families. The how, when, and where of initiating those conversations will always depend on context, but we can begin by equipping families with information—what to watch for, how to make sense of subtle shifts, and how those signs might fit into a broader picture of change. These signs may show up cognitively, behaviorally, emotionally, or functionally, and often they intersect in meaningful ways.
It’s also important to exercise caution. In the general population, outside the context of IDD, many secondary conditions can resemble dementia but originate elsewhere. I recently had a conversation with Dr. Kathy Bishop, a colleague on our national task group who conducts training across the country. We discussed the importance of quality neurological assessments—evaluations that go beyond surface-level symptoms and take the whole person into account.
From a gerontological perspective, I’ve seen how conditions like Parkinson’s disease or hearing loss can mimic cognitive decline. Hearing loss, the most common disability in the United States, can create confusion when someone appears forgetful or disengaged but simply doesn’t hear key information. What looks like memory loss might be a sensory barrier.
Both caregivers and professionals need to remain mindful of these secondary factors. They also need concrete support, recognizing the signs and navigating the diagnostic process, and connecting with appropriate services. Many aging parents I’ve spoken with have been caregiving for decades. They know their children intimately, yet when dementia enters the picture, it brings an entirely different layer of complexity. Realizing that more help is needed doesn’t always come easily. There’s an emotional reckoning that happens. Families must recognize the change and determine what kind of help is appropriate, and then find the energy and resources to pursue it.
We also have to consider the broader caregiving network. Adults with IDD are often supported by multiple people—family, direct support professionals, residential teams, day program staff, medical providers, and therapists. With so many hands involved, communication becomes critical. Who needs to know what? How do we ensure everyone has the right information at the right time? We’ve all had the experience of starting a new task and only later realizing we missed a key piece of information. That same dynamic plays out in caregiving, and when it does, it can impact the person receiving care.
This is one reason I strongly advocate for specialized training—for both formal and informal caregivers. There are excellent programs out there, but we need more. We need training that speaks directly to the overlap between IDD and dementia, and that incorporates awareness of secondary factors like sensory changes—hearing, vision, balance. These factors influence safety, independence, and how we perceive cognitive functioning. Balance, in particular, is something I can’t stress enough. When the brain and body are both changing, the risks and challenges compound quickly.
Suppose we want to support adults with IDD and dementia with the dignity and care they deserve. In that case, we have to support their caregivers—with the correct information, with accessible resources, and with responsive systems. And we have to keep listening, always, to the people living this reality every day.
Types of Dementia
Let’s discuss briefly some of the types of dementia. We now know of over 200 subtypes, which speaks to just how complex and varied this condition can be. One important distinction to understand—both for ourselves and for the families we support—is the difference between dementia and other forms of cognitive change, like mild cognitive impairment (MCI), which I’ll discuss on the next slide.
It’s also important to clarify that dementia is not the same as age-related cognitive decline. I pause here intentionally because it is essential to make this distinction clear in our own understanding—and when appropriate, in our communication with families. Dementia is a clinical syndrome that extends far beyond what we expect from normal aging. It’s also different from delirium, which is acute, often reversible, and typically related to medical illness or environmental changes.
When we talk about the main types of dementia, there are four that are most commonly referenced. Alzheimer’s disease is the most well-known, and as you might expect, the most frequently diagnosed. It gets a lot of attention, and rightly so. The Alzheimer’s Association, for example, has done a tremendous amount of research, education, and advocacy work.
However, the other three—vascular dementia, Lewy body dementia, and frontotemporal dementias (often abbreviated as FTD)—tend to receive far less public attention, despite being relatively prevalent and usually deeply impactful. Each has its distinct clinical profile, underlying pathology, and progression pattern. I’ll discuss each of these in more detail in the upcoming slides.
Mild Cognitive Impairment (MCI)
With mild cognitive impairment, or MCI, we’re looking at a stage that falls between typical age-related cognitive changes and the more significant symptoms associated with dementia. It’s an important clinical distinction because it helps us recognize when something more than normal aging might occur, while noting that it doesn’t yet meet the threshold for a dementia diagnosis.
People with MCI may experience noticeable challenges with thinking, judgment, memory, or language. However, they are still generally able to manage their daily routines. They may continue to work, socialize, and live independently, but with increasing awareness—either by themselves or those around them—that something is shifting cognitively.
Common signs might include mild memory loss, difficulties with planning or organization, or trouble retrieving words during conversation. One example that comes up often is misplacing keys. And to be fair, many of us have experienced this at different times without it being clinically significant. I always say this with humor—I have three young daughters, and I’ve been misplacing many things lately. That alone doesn't indicate MCI.
What we’re looking for are patterns—changes that feel different from a person’s typical cognitive functioning. For example, someone who’s always been organized suddenly forgets appointments or struggles to follow a recipe they’ve made for years. Or someone who’s always been articulate now frequently loses track of words. These subtle shifts can be red flags and warrant a closer look, especially when they represent a noticeable departure from a person’s long-standing baseline.
Alzheimer's Disease (AD)
With Alzheimer’s disease—the most common cause of dementia—we’re often looking at a process that begins long before any outward signs appear. Many neurological changes may have started a decade or more before symptoms become noticeable. Over time, the brain sustains progressive damage, and several genes have been linked to this process. Neuroimaging studies offer powerful insight into these changes for those who are curious, showing structural and functional differences in the brain as the disease advances.
People may experience subtle memory loss or difficulty with cognitive tasks early on. As the disease progresses, these impairments intensify. What may begin with mild forgetfulness can ultimately lead to profound functional decline—situations where individuals lose the ability to speak, move with intention, eat, or even sit upright. In the most advanced stages, we sometimes see individuals curled into a fetal position, with little to no awareness of their surroundings.
Severe language deficits are common in the later stages, making communication almost impossible. And yet, one of the most hopeful and beautiful aspects I’ve seen is how music can still reach individuals even in the depths of cognitive decline. I’ve spoken about this often, particularly in the college classroom, because it never ceases to move and inspire me.
There’s something extraordinary about how music and language are processed in the brain. Our capacity to remember and respond to music often resides in brain regions that are affected later in Alzheimer’s disease. I’ve shared, during longer sessions, a video clip of a woman who had lost the ability to speak due to her advancing condition. Her care team played a biblical hymn she had known since childhood. She began to hum. Then, slowly, a word emerged—then another. It was breathtaking. That connection through music lit something inside her that allowed her to access words that had otherwise vanished.
Moments like this remind us of the humanity that remains, even amid profound decline. Music offers a bridge to connect, comfort, and communicate when other pathways are no longer available. It’s one of our most powerful tools, and I often return to it when discussing how we can meaningfully engage with people living with Alzheimer’s disease.
Vascular Dementia
With our second type of dementia—vascular dementia—we see some clear differences from Alzheimer’s disease, both in cause and in how symptoms present. Vascular dementia results from damage to the blood vessels in the brain, which leads to reduced blood flow and impaired brain tissue. This damage disrupts how different brain areas communicate and function, and it's a key part of what sets this condition apart.
Vascular dementia accounts for about five to ten percent of all dementia cases. While memory loss can certainly occur, it’s not always the first or most prominent symptom. More often, the earliest changes involve impairments in judgment, decision-making, planning, and organization. These executive functioning difficulties tend to stand out early and may appear suddenly, especially if the dementia follows a stroke or series of mini-strokes.
Compared to the gradual, steady decline often seen in Alzheimer’s, vascular dementia can sometimes progress in a stepwise pattern. Abilities decline sharply, then stabilize for a while before another sudden drop occurs. This pattern can be especially confusing for families, as the fluctuations may mask the overall trajectory of decline.
Understanding these distinctions helps guide both support and care planning, particularly because vascular dementia often coexists with other health conditions like high blood pressure, diabetes, or heart disease. Addressing those underlying risk factors is essential not only for symptom management but also for overall brain health.
Lewy Body Dementia
With Lewy body disease, which accounts for roughly 5 to 10 percent of dementia cases—similar to vascular dementia—we see a unique set of features rooted in neurological changes. DLB stands for dementia with Lewy bodies, and it’s named after the abnormal clumps of protein—called Lewy bodies—that develop in neurons. These protein deposits disrupt brain function and are a defining feature of this condition. It’s also worth noting that mixed pathology is common, meaning that an individual might have features of more than one type of dementia, such as Alzheimer’s and Lewy body disease occurring together.
Some of the early symptoms that may point toward Lewy body dementia include sleep disturbances, visual hallucinations, slowness in movement, and balance problems. These can significantly impact gait and mobility. In some individuals, you may also see Parkinsonian features—such as stiffness, shuffling, or tremors—or impairments in visual-spatial awareness, even in the absence of memory loss. For others, memory may be affected early on, but it’s not always the dominant initial symptom.
One example that comes to mind is an individual in what appeared to be a progressing stage of Lewy body dementia. Visually, you could see the slowness in movement, balance challenges, and even difficulty with basic motor tasks, like putting on shoes. Another compelling case involved a man here in Michigan during the middle of winter, freezing temperatures, and he was found outside in only his underwear, hallucinating in his front yard. His family took him to a geriatric psychiatric unit for evaluation, where the initial impression was schizophrenia. But his family, understandably confused, questioned this. He was in his 70s and had never shown symptoms of a psychiatric condition throughout his life. The late onset didn’t make sense.
Their persistence led to further evaluations, and it was eventually determined that this was not schizophrenia but rather a medication-induced reaction. It underscores how essential it is to consider other factors—sensory issues like hearing or vision, underlying neurological conditions like Parkinson’s disease, and especially medication. Polypharmacy is a major concern, particularly in populations with intellectual and developmental disabilities. Individuals with conditions like cerebral palsy may be managing chronic pain, spasticity, or seizures, often with multiple medications that carry cognitive side effects.
Frontotemperal Dementia
As we move into frontotemporal dementia (FTD), there’s even more to consider. As the name implies, FTD primarily affects the frontal and temporal lobes of the brain, regions associated with personality, behavior, and language. We can see regional atrophy or shrinkage in these areas, leading to some very specific clinical features. Depending on the subtype, individuals may experience significant changes in social conduct, emotional regulation, speech, and comprehension, often well before memory is affected. FTD can appear earlier in life than other dementias, sometimes in the 40s or 50s, and is frequently misdiagnosed because of its behavioral presentation.
Each of these dementias presents in its own distinct way, and understanding the differences is crucial for diagnosis and appropriate care and support planning. Always, we must consider the full picture—including medical history, medication use, sensory status, and behavioral changes—before arriving at conclusions, particularly in populations already navigating complex developmental or neurological conditions.
So, some things just to be aware of with frontotemporal dementia: Early symptoms might include changes to personality, changes in behavior, and challenges in producing and understanding language. Memory is typically intact in the early stages. Okay.
Span of Cognitive Regression
When considering the span of cognitive regression, we often think of early, middle, and advanced stages. But another critical factor to keep in mind is whether there may be mixed pathology—multiple underlying causes of dementia co-occurring. This becomes increasingly common with age, even in the general population. While Alzheimer’s disease is the most frequently diagnosed, and we know there are over 200 identified subtypes of dementia, an individual can have more than one type at the same time.
This is where our clinical approach needs to be especially thoughtful. Establishing a clear baseline is essential. What was the person’s typical cognitive, behavioral, and functional profile before the changes began? Once a baseline is established, seeking evaluation from a memory specialist or neurologist is often the next step. Follow-up is critical for reaching an accurate diagnosis and ruling out contributing factors like medication effects or co-occurring conditions.
I come back often to the story of the man who, in his 70s, was initially diagnosed with schizophrenia after a dramatic and unexpected episode involving hallucinations. His family, understandably confused, pushed back. He had never exhibited symptoms of schizophrenia before, and the late onset didn’t make sense. Further investigation revealed the diagnosis was not psychiatric illness, but rather dementia—and more specifically, it was related to a medication reaction. Having stayed in contact with this family over the years, I can say that their persistence and the follow-up care they pursued ultimately led to what seems to be an accurate and thoughtful understanding of his condition.
This case underscores the importance of digging deeper and being open to multiple explanations. When we look at dementia—especially in populations with existing intellectual or developmental disabilities—we must consider all the layers: baseline functioning, age-related changes, the possibility of mixed pathology, and secondary contributors like polypharmacy or sensory decline. Only by looking at the full picture can we support families in navigating this complex terrain.
Common Behaviors Associated With Dementia
The eight most common dementia-related behaviors:
- Tendency to repeat the same question
- Wandering
- Resistance to bathing
- Incontinence
- Insomnia
- Delusions, hallucinations, paranoia
- Sexual inhibitions
- Loss of appetite
These examples are taken from AARP, and I’ve included the website below for your reference. They highlight some of the behavioral expressions that can occur in individuals living with dementia, including wandering, resistance to bathing, delusions, and sexually inappropriate behavior.
For those who work in nursing facilities or dementia-specific units, these behaviors are likely all too familiar, and we know how challenging they can be to manage. These expressions often arise not out of willful defiance but from confusion, fear, sensory overstimulation, or unmet needs. They require thoughtful, compassionate responses and a care environment prioritizing dignity, safety, and individualized strategies. Understanding the root causes of these behaviors is key to supporting the person experiencing them and the staff or family members working to provide care.
Screening
For screening, there are many resources and links in the handout.
Resources
We know that service navigation for adults with disabilities and their family caregivers is challenging at best. When we add in other complexities, such as dementia, polypharmacy, declines in activities of daily living, depressive symptoms, other mental health concerns, or even something as seemingly simple as a vitamin deficiency, the process becomes even more overwhelming. The number of providers, specialists, and appointments that families often juggle for a single loved one can be daunting. And this is especially true for compound caregivers—those caring for more than one person at the same time.
A significant area of my work has been studying the experiences of these compound caregivers. What happens when someone is caring for a loved one with dementia and intellectual disability, while also supporting a spouse or aging parent? These scenarios are increasingly common, and they highlight the societal pressures being placed on families today. I’ve published extensively in this area because I believe it's critical that we recognize the weight caregivers are carrying—and begin to find ways to support them meaningfully.
Regarding finding support, we need to help families access both disability-specific and aging-related services. If dementia is a factor, connecting with dementia-specific organizations is also key. Across the country, many families are finding support through community networks, faith-based groups, local neighborhoods, and informal or online caregiver groups. These supports often provide valuable information and the emotional solidarity that caregivers so deeply need. Sometimes it’s just knowing that someone out there gets it—someone else can say, “You wouldn’t believe what happened today,” and genuinely understand.
Technology has opened new doors for connection. Caregivers, especially those unable to leave home due to their responsibilities, can now access online training, support groups, and educational resources. This is a critical shift because caregivers often cannot attend even a local meeting just minutes away if no one can step in for them at home. Reaching people in different ways is one of the silver linings of our digital age.
I’ve also gathered a collection of organizational resources to support families and professionals navigating this space. Some are more general and apply broadly to brain health or Alzheimer’s disease. Others are more targeted, like resources specifically for families supporting a loved one with Down syndrome and dementia. These resources offer practical tools, screening guides, and caregiver support materials.
Examples include:
Alzheimers.gov, which offers educational materials on dementia and brain health
The AARP Brain Health Resource Center, which includes dementia resource guides and connections to tools from the CDC
The National Task Group on Intellectual Disabilities and Dementia Practices (NTG), which provides free webinars, factsheets, and a family series aimed at increasing access to high-quality, accessible information
The National Alzheimer’s and Dementia Resource Center (NADRC), which supports national efforts to address dementia through technical assistance and tools
Some state-specific resources, such as the Intellectual Disability and Dementia Caregiver Resource Guide from Rhode Island, contain highly relevant information even for those outside the state. I’ve seen firsthand how global the need for these tools is—our national task group has followers and collaborators from around the world. One colleague I’m working with in Ghana shared that these U.S.-based materials have become a critical starting point in the absence of locally available information.
I also want to highlight the National Down Syndrome Society, which provides an excellent practical guide for caregivers. It’s free to access, downloadable, and tailored to the unique needs of families navigating both Down syndrome and dementia. On the autism front, there are emerging resources focusing on ASD and dementia, including materials from the International Summit on Autism and Dementia Work Group, which I’ve contributed to.
Though this is not a chronic pain training, I want to make a brief note about that topic. When supporting individuals with intellectual disabilities and dementia, we must not overlook the possibility of chronic pain, especially in those who may have difficulty communicating due to social or cognitive limitations. In our autism and dementia work, one of the takeaways was the importance of assessing pain even when verbal communication is limited. Whether or not it’s part of your direct role, someone on the team must be prepared to evaluate and address this critical need.
Other organizations that may be helpful include:
Area Agencies on Aging (AAA), which offer dementia-friendly resources and geographically tailored supports
Local senior centers and community hubs
Faith-based communities, which continue to be an essential support network for many
The Benjamin Rose Institute on Aging, which offers caregiver tools and education
The Alzheimer’s Association, which, when contacted, can provide location-specific support and services based on zip code
This kind of targeted information is crucial. Our family caregivers often don’t have the time to search across multiple systems or sort through what is or isn’t available in their part of the state. Pointing them directly to accessible services in their community can make all the difference.
I’ve included links to my email, LinkedIn, and Google Scholar. I’d love to connect and continue this conversation. I’m always inspired by the incredible work being done across the country, and it’s an honor to be in dialogue with others committed to supporting this population.
Exam Poll
1)According to research, how much more likely are individuals with intellectual disabilities to develop dementia compared to the general population?
2)Which of the following statements is TRUE regarding Alzheimer’s disease and individuals with Down syndrome?
3)What is one key takeaway from the caregiver study on cognitive regression in adults with IDD?
4)What percentage of dementia cases are accounted for by the four most common types: Alzheimer’s disease, vascular dementia, Lewy body dementia, and frontotemporal dementia?
5)Which of the following types of dementia is most commonly associated with impaired decision-making and planning rather than memory loss in its early stages?
References
See additional handout.
Citation
Marsack-Topolewski, C. (2025). Understanding and supporting adults with intellectual and developmental disabilities with cognitive decline and regressive illness. SpeechPathology.com, Article 20742. Available at www.speechpathology.com.
