Posted on June 24, 2026

By Kathryn Pears, MPPM, Chief Operations Officer, National Task Group on Intellectual Disabilities and Dementia Practices (NTG)

Over the past several decades, one of the most significant public health successes has been the dramatic increase in life expectancy for people with intellectual and developmental disabilities (IDD). Individuals who once faced drastically shortened lifespans are now living well into middle and older adulthood. This progress reflects advances in medical care, improved social supports, and greater inclusion in community life.

Yet this success story carries a new and complex challenge: a rapidly aging population of adults with intellectual disabilities who are increasingly at risk for dementia.

Service systems, healthcare providers, families, and disability organizations are now confronting a reality that few anticipated decades ago. As people with IDD live longer, many are reaching ages where age-related conditions – including dementia – become more common. For individuals with Down syndrome in particular, the risk of Alzheimer’s disease is significantly elevated.^[3] The result is a growing need for awareness, training, and systemic preparation to support this population with dignity and quality care.

A Population Aging Faster Than Systems Are Prepared

Across the United States and globally, adults with intellectual disabilities are living longer than ever before. In the early 20th century, the average lifespan of a person with Down syndrome was approximately eight years. Today, many individuals with Down syndrome live into their 60s and beyond, due largely to medical advances such as improved cardiac surgery and infection control.^[1]

While this progress represents a remarkable achievement, it also means that many individuals with IDD are now reaching ages where dementia becomes a concern. Service providers are increasingly encountering older adults with intellectual disabilities who are developing cognitive decline, behavioral changes, and functional impairments associated with dementia.

Many disability organizations, however, are only beginning to recognize the scope of this issue. Agencies that historically focused on supporting children and younger adults with developmental disabilities are now finding themselves caring for individuals who have aged within their service systems.

The number of older adults with intellectual disabilities is growing rapidly, and in the coming decade the trend is expected to accelerate.^[2] As a result, disability service systems face a significant challenge: adapting policies, training, and care models designed for younger individuals to meet the needs of an aging population.

Why Dementia Risk Is Higher for People with Down Syndrome

Among all individuals with intellectual disabilities, people with Down syndrome face the highest risk for Alzheimer’s disease.^[3]

The reason lies in genetics. Down syndrome is caused by the presence of an extra copy of chromosome 21. Chromosome 21 contains the gene responsible for producing amyloid precursor protein (APP), which is involved in the formation of amyloid plaques – one of the hallmark features of Alzheimer’s disease.^[4] As a result, plaque buildup begins earlier and occurs more extensively than in the general population.

By the age of 40, nearly all individuals with Down syndrome show the neuropathological markers of Alzheimer’s disease, including plaques and tangles, even if clinical symptoms have not yet appeared.^[5]

Although not every person with Down syndrome will develop clinical dementia, the risk is extremely high. Many begin showing symptoms of Alzheimer’s disease in their early to mid-50s, decades earlier than typically seen in the general population.^[6]

This earlier onset is often linked to what researchers call accelerated aging in people with Down syndrome.^[7]Physiologically, a 50-year-old adult with Down syndrome may exhibit health characteristics similar to those of someone 15 – 20 years older in the general population.

Aging With Intellectual Disabilities: A Complex Health Picture

Aging for individuals with intellectual disabilities often differs from aging in the general population.

Many individuals with IDD experience multiple co-occurring medical conditions throughout life. These conditions may influence how aging unfolds and can complicate the identification of dementia.

For example:

• People with cerebral palsy may experience chronic pain that affects function and behavior.
• Sensory impairments such as vision or hearing loss may develop earlier.
• Sleep disorders, including sleep apnea, are common in individuals with Down syndrome.^[8]
• Thyroid disorders and vitamin deficiencies may occur at higher rates.

These medical factors can produce symptoms that resemble dementia, making accurate diagnosis more challenging.

Moreover, research on aging among individuals with intellectual disabilities – particularly outside of Down syndrome – remains limited.^[9] Historically, research funding and attention have focused largely on children with developmental disabilities rather than adults who are aging.

As a result, important questions remain unanswered about dementia risk among individuals with autism, fetal alcohol spectrum disorders, and other forms of intellectual disability.

Understanding Dementia: More Than a Disease

One of the most important concepts in dementia care is understanding what dementia actually is…and what it is not.

Dementia is not a single disease. Instead, it is a broad umbrella term describing a group of symptoms affecting cognitive function and behavior. These symptoms may include:

• Memory loss
• Personality changes
• Impaired judgment or reasoning
• Reduced impulse control
• Emotional changes

These symptoms can be caused by many different conditions. Some causes are irreversible, such as Alzheimer’s disease, Lewy body dementia, or vascular dementia. Others, however, may be treatable or reversible.

For individuals with intellectual disabilities, distinguishing between these possibilities is critical.

Conditions That Can Mimic Dementia

A number of medical or environmental factors can produce symptoms that resemble dementia but are actually treatable. Misidentifying these conditions can lead to inappropriate care and missed opportunities for intervention.

Polypharmacy

Many individuals with intellectual disabilities take multiple medications. Polypharmacy is common in this population.^[10] Side effects, drug interactions, or prescribing cascades can create confusion, behavioral changes, and cognitive impairment that may be mistaken for dementia.

Depression

Severe depression can produce symptoms that closely resemble dementia, sometimes referred to as pseudodementia.

In adults with intellectual disabilities, particularly those with Down syndrome, significant life changes such as the death of a parent, sibling, housemate, or long-term support professional can result in profound grief, emotional distress, and changes in daily functioning. Individuals with Down syndrome are often highly sensitive to disruptions in familiar routines and relationships. These changes may sometimes be mistaken for dementia when they are actually signs of depression, grief, or difficulty adapting to change.

Delirium

Delirium is a sudden change in mental status caused by an acute medical condition and is considered a medical emergency. Unlike dementia, which typically develops gradually over months or years, delirium often appears suddenly over hours or days. Common causes include infections, dehydration, medication side effects, pain, metabolic imbalances, or other acute medical conditions. Individuals experiencing delirium may appear confused, agitated, unusually sleepy, or unable to pay attention. Whenever a sudden change in thinking, behavior, or functioning occurs, underlying medical causes should be investigated promptly.

Sensory Loss

Vision or hearing problems can make individuals appear confused or disoriented when they are simply struggling to interpret their surroundings. This can be particularly challenging for autistic individuals, who rely heavily on sensory cues and routines to navigate daily life.

Sleep Disorders

Sleep apnea is highly prevalent among individuals with Down syndrome and can significantly affect cognition, behavior, and overall health.^[8] Untreated sleep apnea can contribute to excessive daytime sleepiness, memory problems, mood changes, and declines in daily functioning that may resemble dementia.

Medical Conditions

Other treatable conditions include:

• Hypothyroidism
• Vitamin B12 deficiency, folate deficiency, and Vitamin D deficiency
• Undiagnosed celiac disease, especially in people with Down syndrome.^[11]
• Kidney or liver disorders that can contribute to confusion or changes in functioning
• Untreated pain

These factors highlight the importance of comprehensive medical evaluation before concluding that dementia is present.

The Problem of Diagnostic Overshadowing

A major barrier to accurate diagnosis is a phenomenon known as diagnostic overshadowing.^[12]

Diagnostic overshadowing occurs when clinicians attribute new symptoms to a person’s intellectual disability rather than investigating potential medical causes.

For example, a physician may assume that changes in behavior or function are simply part of the individual’s disability – or alternatively assume that Alzheimer’s disease is inevitable because the person has Down syndrome.

Both assumptions can be dangerous. Without proper assessment, treatable conditions may go unrecognized, leading to delayed treatment and severe consequences.

Early Signs of Dementia May Look Different

Another challenge in identifying dementia among people with intellectual disabilities is that early symptoms may differ from those seen in the general population.^{[12, 13]}

In many adults without intellectual disabilities, early Alzheimer’s disease often presents itself with short-term memory loss. For individuals with intellectual disabilities, however, the first signs may be behavioral or functional changes rather than memory problems.

Examples include:

• Loss of interest in activities once enjoyed
• Changes in personality
• Increased anxiety or withdrawal
• Difficulty performing familiar tasks
• Changes in sleep patterns

Among individuals with Down syndrome, the sudden onset of seizures can also be an early indicator of Alzheimer’s disease.^[14]

Because these symptoms may appear subtle or ambiguous, careful observation and documentation are essential. With that, since early symptoms can be subtle and may look different from those seen in the general population, having a structured method for tracking changes over time is particularly important.

The Importance of Establishing a Baseline

One of the most effective strategies for early detection is establishing a baseline of an individual’s abilities before significant decline occurs.

The National Task Group on Intellectual Disabilities and Dementia Practices (NTG) developed the NTG-Early Detection Screen for Dementia (NTG-EDSD).^{[1, 12]}

This screening tool can be completed by family members, direct support professionals, or other caregivers who know the individual well. It tracks changes across several domains, including:

• Activities of daily living
• Behavior and personality
• Memory and thinking
• Sleep patterns
• Functional abilities

Because it does not require clinical training, the tool empowers caregivers and support staff to monitor changes over time.

The NTG recommends to begin using the tool annually in the mid-30s for individuals with Down syndrome and in the mid-40s for individuals with other intellectual disabilities.

Early detection allows families and providers to pursue appropriate medical evaluation, plan services, and prepare for future care needs.

A Systemic Shift in Care Philosophy

Supporting individuals with intellectual disabilities who develop dementia requires more than clinical awareness – it demands a fundamental shift in care philosophy.

Disability services historically focus on skill development, independence, and rehabilitation. Dementia care, by contrast, focuses on supporting individuals as they gradually lose abilities.

This shift can be difficult for both staff and families. Support strategies must adapt to changing abilities while preserving dignity and quality of life.

For example, caregivers may use therapeutic reassurance to reduce distress and support emotional well-being. If an individual asks when a deceased parent is coming to visit, repeatedly reminding them of the death may cause them to experience grief repeatedly. Instead, a caregiver may provide reassurance and gently redirect attention toward a comforting activity or memory. The goal is not deception, but rather reducing distress and supporting emotional well-being.

Such approaches differ significantly from traditional disability support strategies and require specialized training.

Program and Policy Challenges

The rise of dementia among individuals with intellectual disabilities also exposes gaps in existing service systems.

Many regulations governing disability services were developed decades ago with younger individuals in mind. They often do not account for the needs of older adults with progressive cognitive decline.

For instance, wandering occurs in a substantial proportion of people with dementia.^[15] In long-term care settings, doors may be secured to protect residents. In many disability service settings, however, regulations prohibit locked exits due to policies promoting community integration and personal freedom.

Providers must navigate these conflicting priorities while ensuring safety.

Other challenges include:

• Adjusting day programs for individuals who can no longer tolerate busy environments
• Adapting group homes to meet increasing care needs
• Providing one-on-one support in advanced stages of dementia
• Addressing end-of-life care planning

In some cases, providers assume that individuals will eventually move to nursing homes. Yet many nursing homes lack experience supporting individuals with intellectual disabilities and may be reluctant to accept them.

The Critical Role of Training and Education

A major obstacle to addressing these challenges is the lack of professional training in this specialized area.^{[16, 20]}

Medical schools and nursing programs generally provide little instruction on intellectual disabilities, aging, and dementia. As a result, many healthcare providers lack the knowledge necessary to accurately diagnose and manage dementia in this population.^[21]

Education and training are therefore essential.

Organizations such as the NTG offer workshops, webinars, and training programs designed to build capacity among service providers, clinicians, and family caregivers.

Training initiatives aim to equip caregivers with practical knowledge and confidence so they can recognize changes, understand when further evaluation may be needed, advocate effectively within healthcare systems, and provide appropriate support.

Preparing for the Future

As the population of older adults with intellectual disabilities grows, proactive planning will become increasingly important.

Organizations can begin preparing by establishing internal aging committees to discuss emerging challenges and develop strategies for supporting individuals with dementia.

Important questions include:

• How will we support individuals who begin wandering?
• What services will replace day programs if individuals can no longer attend?
• How can we adapt homes and environments to support sensory changes?
• What partnerships can we build with healthcare providers and dementia specialists?
• Do we have the staffing, expertise, environmental supports, and financial resources necessary to enable individuals to age in place safely and successfully?

Across the country, innovative programs are already emerging, including specialized memory care homes designed specifically for individuals with intellectual disabilities.^[17]

Learning from these models can help organizations develop sustainable approaches.

A Call for Research and Collaboration

Despite growing awareness, many aspects of aging with intellectual disabilities remain poorly understood.

More research is needed on dementia risk among individuals with autism, fetal alcohol spectrum disorders, and other developmental disabilities. The first generation of individuals formally diagnosed with autism is now reaching older adulthood, and little is known about how dementia may affect them.^[18,19]

Collaborative research, policy development, and cross-disciplinary partnerships will be essential to addressing these questions.

Supporting Aging with Dignity

The aging of people with intellectual disabilities represents both a triumph and a responsibility.

Longer lives mean greater opportunities for community participation, relationships, and meaningful experiences across the lifespan. But longer lives also require thoughtful planning to ensure that individuals receive appropriate care as they age.

By expanding education, improving diagnostic practices, investing in research, and adapting service systems, society can ensure that individuals with intellectual disabilities who develop dementia continue to live with dignity, safety, and quality of life.

The wave of aging within the IDD community is already here. The question now is: Is your organization prepared to meet it?

Endnotes

1. National Task Group on Intellectual Disabilities and Dementia Practices. (n.d.). NTG-EDSD manual and dementia practice resources. National Task Group on Intellectual Disabilities and Dementia Practices. https://www.the-ntg.org
2. Heller, T., & Arnold, C. K. (2010). People with intellectual and developmental disabilities growing old: An overview. Impact, 23(1), 2–3. 
3. National Institute on Aging. (2021). Alzheimer’s disease in people with Down syndrome. U.S. Department of Health and Human Services, National Institutes of Health. https://order.nia.nih.gov/sites/default/files/2021-02/alzheimers-down-syndrome.pdf
4. Wiseman, F. K., Al-Janabi, T., Hardy, J., Karmiloff-Smith, A., Nizetic, D., Tybulewicz, V. L. J., Fisher, E. M. C., & Strydom, A. (2015). A genetic cause of Alzheimer disease: Mechanistic insights from Down syndrome. Nature Reviews Neurology, 11(10), 564–574. https://doi.org/10.1038/nrneurol.2015.154
5. Fortea, J., Carmona-Iragui, M., Benejam, B., Fernández, S., Videla, S., Barroeta, I., Alcolea, D., Pegueroles, J., Muñoz, L., Belbin, O., & others. (2021). Alzheimer’s disease associated with Down syndrome: A genetic form of dementia. The Lancet Neurology, 20(11), 930–942. https://doi.org/10.1016/S1474-4422(21)00245-3
6. McCarron, M., McCallion, P., Reilly, E., & Mulryan, N. (2014). A prospective 20-year longitudinal follow-up of dementia in persons with Down syndrome. Journal of Intellectual Disability Research, 58(1), 61–70. https://doi.org/10.1111/jir.12074
7. Zigman, W. B. (2013). Atypical aging in Down syndrome. Developmental Disabilities Research Reviews, 18(1), 51–67. https://doi.org/10.1002/ddrr.1128
8. Bull, M. J. (2020). Down syndrome. New England Journal of Medicine, 382(24), 2344–2352.
9. Strydom, A., Livingston, G., King, M., & Hassiotis, A. (2007). Prevalence of dementia in intellectual disability using different diagnostic criteria. British Journal of Psychiatry, 191(2), 150–157.
10. O’Dwyer, M., Peklar, J., McCallion, P., McCarron, M., & Henman, M. C. (2016). Factors associated with polypharmacy and excessive polypharmacy in older people with intellectual disability differ from the general population: A cross-sectional observational nationwide study. BMJ Open, 6(4), e010505. https://doi.org/10.1136/bmjopen-2015-010505
11. Chicoine, B., McGuire, D., Rubin, S. S., & Henderson, C. M. (2021). Mental wellness in adults with Down syndrome: A guide to emotional and behavioral strengths and challenges. Woodbine House.
12. Moran, J. A., Rafii, M. S., Keller, S. M., Singh, B. K., Janicki, M. P., & Alzheimer’s Association National Task Group on Intellectual Disabilities and Dementia Practices. (2013). The National Task Group on Intellectual Disabilities and Dementia Practices consensus recommendations for the evaluation and management of dementia in adults with intellectual disabilities. Mayo Clinic Proceedings, 88(8), 831–840. https://doi.org/10.1016/j.mayocp.2013.04.024.
13. Janicki, M. P., Heller, T., Seltzer, G. B., & Hogg, J. (1996). Practice guidelines for the clinical assessment and care management of Alzheimer’s disease and other dementias among adults with intellectual disability. Journal of Intellectual Disability Research, 40(4), 374–382. https://doi.org/10.1046/j.1365-2788.1996.785785.x
14. Lott, I. T., & Head, E. (2019). Dementia in Down syndrome: Unique insights for Alzheimer disease research. Nature Reviews Neurology, 15(3), 135–147. https://doi.org/10.1038/s41582-018-0132-6
15. Alzheimer’s Association. (n.d.). Wandering. https://www.alz.org/help-support/caregiving/stages-behaviors/wandering.
16. Bishop, K. M., & Pears, K. (2019). National Task Group dementia training curriculum: Development, implementation, and outcomes. Intellectual and Developmental Disabilities, 58(1), 25–38.
17. Belperio, I., & Walker, R. (2025). Disability service providers supporting adults with intellectual disabilities and dementia living in group homes: A qualitative, exploratory study. Disabilities, 5(3), 83. https://doi.org/10.3390/disabilities5030083
18. Mason, D., Ingham, B., Urbanowicz, A., Michael, C., Birtles, H., Woodbury-Smith, M., Brown, T., James, I., Scarlett, C., Nicolaidis, C., & Parr, J. R. (2022). A systematic review of what is known about autism and aging. Autism Research, 15(5), 780–803. https://doi.org/10.1002/aur.2687
19. Piven, J., & Rabins, P. (2011). Autism spectrum disorders in older adults: Toward defining a research agenda. Journal of the American Geriatrics Society, 59(11), 2151–2155. https://doi.org/10.1111/j.1532-5415.2011.03632.x
20. Jokinen, N., Janicki, M. P., Keller, S. M., McCallion, P., Force, L. T., & the NTG Community Care Workgroup. (2013). Guidelines for structuring community care and supports for people with intellectual disabilities affected by dementia. Journal of Policy and Practice in Intellectual Disabilities, 10(1), 1–24. https://doi.org/10.1111/jppi.12016
21. Escudé, C. (2023). Aging, intellectual disabilities, and missed diagnoses. Today’s Geriatric Medicine, 16(1), 34.