People who have Down syndrome have three full or partial copies of chromosome 21 instead of two copies as seen in the general population. This chromosome plays a key role in the relationship between Down syndrome and Alzheimer’s disease.
What Is the Connection Between Alzheimer’s Disease and Down Syndrome?
Researchers and scientists have located several genes on chromosome 21 that are involved in the aging process which contribute to the increased risk of Alzheimer’s disease. It is this unique property of chromosome 21 which makes this a specific concern for people with Down syndrome, and not for all individuals with other forms of intellectual disability.
What Is Alzheimer’s Disease?
Alzheimer’s disease is a progressive impairment of memory functions that interfere with overall function and daily activities. It is usually characterized by a gradual decline that generally progresses through three stages, as follows:
Areas of decline include:
(Lines with * refer to losses that may be more apparent in people who have Down syndrome)
- Short term memory
- Learning new information
- Language changes: word finding difficulties, decline in speech complexity, reduced vocabulary
- Planning and calculation (with milder ID)
- Behavior changes*
- Personality changes*
- Spatial disorientation, difficulty navigating familiar areas*
- Fine motor control and reaction time*
- Work productivity*
- Doing complex tasks and understanding directions (Dyspraxia) *
In the broad middle stage of the disease, people are unable to perform everyday tasks without supervision. They have poor memory of the recent past but may remember more distant events. There is increased disorientation to time, place and person.
Additional areas of decline include:
- Expressing and understanding language
- Expressing emotions appropriately
- Recognizing familiar people; recognizing familiar objects
- Personal safety
- Independence related to self care tasks
- Mood and behavior fluctuations (anxiety, paranoia, hallucinations, restlessness, agitation, wandering)
In the late stage, people are usually unable to communicate, have poor recent and remote memory, and require complete care. However, the capacity to feel and exhibit emotion persists.
Final areas of decline include:
- Mechanics of chewing and swallowing
- Marked intellectual deterioration
- Inability to communicate verbally
- Immobility with hypertonia (decreased flexibility)
- Dependence on all self-care skills
Is Alzheimer’s Disease Inevitable In People with Down Syndrome?
NO. While all people with Down syndrome are at risk, many adults with Down syndrome will not manifest the changes of Alzheimer’s disease in their lifetime. Although risk increases which each decade of life, at no point does it come close to reaching 100%. This is why it is vitally important to be careful and thoughtful about assigning this diagnosis and looking at all other possible causes for why changes are taking place with aging.
How Can I Be Proactive Regarding Alzheimer’s Disease and My Loved One with Down Syndrome?
Alzheimer’s disease is characterized by a change or a series of changes that are seen in an individual compared to their previous level of functioning. In order to observe change effectively, you must be well informed of what the individual was capable of doing at his/her very best. This could be considered the individual’s “baseline.” The primary importance of having a good description and understanding of an individual’s baseline is so it can be used as a basis of comparison if changes are observed as the individual grows older. Baseline information is helpful to keep track of informally, by recording information throughout adulthood – achievements, academic and employment milestones, talents, skills, hobbies, and basic abilities. A baseline can also be established formally at an office visit with a memory specialist, where these components can be reviewed and memory abilities can be tested. Screening for memory concerns is recommended beginning at age 40 and followed periodically thereafter.
What Should I Do If I Suspect Alzheimer’s Disease Has Developed In My Loved One with Down Syndrome?
Alzheimer’s disease is a diagnosis that is given after excluding other correctable conditions. Take a moment to review this list of common conditions associated with aging and Down syndrome.
- Sensory losses
- Obstructive sleep apnea
- Atlantoaxial instability
- Celiac disease
Note: Many of these conditions can cause symptoms that may look like confusion and memory problems if not detected properly. If dementia is suspected, consult with the primary care doctor to consider assessing for the presence of these other correctable conditions.
How Can I Obtain a Memory Evaluation for My Loved One with Down Syndrome?
Look for a memory specialist –either a geriatrician, neurologist, psychiatrist, neuropsychologist. Ideally, the specialist would have experience with assessing individuals with intellectual disabilities. Assessments should be comprehensive and adapted appropriately for patient’s baseline intellectual disability. A thorough assessment should take into account all other potential contributing factors (medical, psychiatric, environmental, social) that could also account for or contribute to the reported changes. (Refer to the list above of common conditions).
Note: Alzheimer’s disease is a clinical diagnosis. That means that it requires a doctor make the diagnosis based on his/her judgment. There is no blood test or brain scan that will confirm the diagnosis (aside from brain autopsy). Thus, it is important to seek the opinion of a specialist who will take all factors into account to arrive on a diagnosis thoughtfully.
- Alzheimer’s Association (National Office)
800-272-3900 (24-hour hotline)
The nation's leading resource for information and resources on Alzheimer’s disease
- Alzheimer’s Disease International
Fact sheet on dementia and intellectual disabilities
- Adults with Down Syndrome. Pueschel, S. M. Baltimore, MD: Brookes Publishing (2006)
- Alzheimer’s Disease and Dementia in Down Syndrome and Intellectual Disabilities. Prasher, V. P. Radcliffe Publishing. (2005)
- Dementia, Aging, and Intellectual Disabilities: A Handbook. Janicki, M. Dalton, A.J.P. Brunner/Mazel Publisher. Now Routledge Mental Health. (1999)
- Down Syndrome and Dementia. Holland, A. In Dementia. London, UK: Oxford University Press (2000)
- Mental Wellness in Adults with Down Syndrome. McGuire, D. and Chicoine, B. Bethesda, MD: Woodbine House. (2005)