Alzheimer’s disease is a form of cognitive impairment and decline in skills that is more common in people with Down syndrome. It is one, but not the only, type of cognitive impairment. In fact, there are a variety of other factors, many of them reversible that can cause people with Down syndrome to decline cognitively or lose skills.
What can cause cognitive decline or loss of skills?
Some conditions that are (or seem to be) more common in people with Down syndrome that can cause cognitive decline or loss of skills include:
Hypothyroidism (underactive thyroid)
Hyperthyroidism (overactive thyroid)
Vitamin B12 deficiency
Cervical subluxation (atlantoaxial instability)
Mental illness such as depression, posttraumatic stress disorder, and anxiety
Some other potential causes include:
Younger people with Down syndrome, often in their teens or early twenties, can experience a condition that is now unofficially called Down syndrome regression disorder (there is not a formally agreed upon name, yet). An individual in his 40s generally would be considered too old for that diagnosis. A webinar on Decline in Skills and Regression in Adolescents and Adults with Down Syndrome is available in our Resource Library.
When evaluating a person with Down syndrome (and people without Down syndrome) for Alzheimer’s disease, it is important to remember and assess for the many other causes for a decline in skills/cognitive impairment. This will help prevent over diagnosing Alzheimer’s disease and will often detect causes for the decline that are potentially reversible. Some individuals will have both Alzheimer’s disease and a potentially reversible cause, and it is important to treat the potentially reversible cause as well to limit overall impairment.
At what age do people with Down syndrome get Alzheimer's disease?
The changes in the brain caused by Alzheimer’s disease occur years earlier than the onset of symptoms. Symptomatic Alzheimer’s disease is thought to be uncommon in people with Down syndrome younger than age 40. It can occur before age 40 but it is not common. As people with Down syndrome reach age 40 and older, the number of individuals with Alzheimer’s disease increases. The average age of onset is around the mid-50s.
What does the progression of the disease look like for people with Down syndrome?
Alzheimer’s disease is a progressive loss of cognitive skills and other functions such as walking, control of the bowel and bladder, mood regulation, swallowing, and others. Although the decline is progressive, the rate of decline may vary. There may be fluctuations in skills and function, particularly earlier in the disease. Additionally, there may be times in which it appears that there is a plateau of function.
At times, families may not recognize the decline in cognitive function because they are gradually and often subtly doing more of the individual’s daily care. The person’s loss of skills may be overlooked as the family provides more support to make sure the daily tasks get done.
Some individuals will have a rapid course of disease, some longer, and some much longer. At our clinic, it seems that a common course of disease is about 5 years from the onset of symptoms to death. However, the course of the symptomatic disease may be longer. As we have assessed more people with Down syndrome and Alzheimer’s disease over the years, it has become clear that the mild early symptoms of the disease may not be recognized (and thus, the course of the symptomatic disease is actually longer than thought).
If someone with Down syndrome that has been diagnosed with Alzheimer's disease is not continuing to lose skills, a few questions to consider are:
Is Alzheimer's disease the incorrect diagnosis and was another potentially reversible diagnosis overlooked or missed?
Are we doing more for the individual that is masking the underlying decline?
Is the diagnosis of Alzheimer's disease correct but the person is one of those who seems to have a functional plateau for a period of time?
Aging and Down Syndrome: A Health & Well-Being Guidebook (National Down Syndrome Society)
Alzheimer's Disease & Down Syndrome: A Practical Guidebook for Caregivers (National Down Syndrome Society)
All resources in the Alzheimer's Disease & Dementia category of our Resource Library.
This article was adapted from a Q&A developed in partnership with LuMind IDSC Foundation. This Q&A is available for free along with other Q&As at www.myDSC.org.