Alzheimer's Disease

Adults with Down syndrome are at increased risk of Alzheimer’s disease as they grow older, but Alzheimer’s disease is not inevitable. There are many other possible issues to consider when concerns about memory arise, so a thoughtful approach is very important.

The Connection between Alzheimer’s Disease and Down Syndrome

Down syndrome occurs when an individual has a full or partial third copy of chromosome 21. Chromosome 21 plays an important role in the relationship between Down syndrome and Alzheimer’s disease because it carries a gene that produces one of the key proteins involved with changes in the brain caused by Alzheimer’s disease. Additionally, scientists have located several genes on chromosome 21 that are involved in the aging process and that contribute to the increased risk of Alzheimer’s disease. It is this unique property of chromosome 21 that makes the disease a more acute concern for people with Down syndrome than those with other forms of intellectual disability.

General Overview

Alzheimer’s disease is a type of dementia that gradually destroys brain cells, affecting a person’s memory and ability to learn, make judgments, communicate and carry out basic daily activities. Alzheimer’s disease is not inevitable in people with Down syndrome. While all people with Down syndrome are at risk, many of them will not manifest the changes associated with Alzheimer’s disease in their lifetimes. Risk increases with each decade of life, but at no point does it come close to reaching 100%. This is why it is especially important to be careful and thoughtful about assigning this diagnosis before looking at all other possible causes for why changes are taking place with aging. Estimates show that

Alzheimer’s disease affects about 30% of people with Down syndrome in their 50s. By their 60s, this number is closer to 50%.

The Span of Alzheimer’s Disease

Alzheimer’s disease is characterized by a gradual decline that generally progresses through three stages: early, middle and late stage disease.

Early Stage:

  • Short term memory loss (difficulty recalling recent events, learning and remembering names and keeping track of the day or date; asking repeated questions or telling the same story repeatedly)
  • Difficulty learning and retrieving new information
  • Expressive language changes (word finding difficulties, smaller vocabulary, shorter phrases, less spontaneous speech)
  • Receptive language changes (difficulty understanding language and verbal instructions)
  • Worsened ability to plan and sequence familiar tasks
  • Behavior and Personality changes
  • Spatial disorientation (difficulty navigating familiar areas)
  • Worsened fine motor control
  • Decline in work productivity
  • Difficulty performing complex tasks requiring multiple steps (including household chores)
  • Depressed mood

Middle Stage:

  • Decreased ability performing daily tasks and self-care skills
  • Worsened short term memory with generally preserved long term memory
  • Increased disorientation to time and place
  • Worsened ability to express and understand language (vocabulary shrinks even further, communicates in short phrases or single words)
  • Difficulty recognizing familiar people and objects
  • Poor judgment and worsened attention to personal safety
  • Mood and behavior fluctuations (anxiety, paranoia, hallucinations, restlessness, agitation, wandering)
  • Physical changes including: new onset seizures, urinary and possibly fecal incontinence, swallowing dysfunction, mobility changes (difficulty with walking and poor depth perception)

Advanced Stage:

  • Significant memory impairment (loss of short term and long term memory, loss of recognition of family members and familiar faces)
  • Dependency on others for all personal care tasks (bathing, dressing, toileting, and eventually eating)
  • Increased immobility with eventual dependence on a wheelchair or bed
  • Profound loss of speech (minimal words or sounds)
  • Loss of chewing and swallowing mechanics, leading to aspiration events and pneumonias
  • Full incontinence (both urinary and fecal)

 

Recognizing Alzheimer’s Disease

Establishing a Baseline

Most adults with Down syndrome will not self-report concerns about memory. Instead, it will take an astute caregiver who knows the individual well to identify early changes or concerns. Alzheimer’s disease is suspected when there is a change or a series of changes seen in an individual as compared to their previous level of functioning. Thus, in order to observe change effectively, one must be informed about what the individual was capable of doing at his or her very best. This could be considered the individual’s “baseline.”

Formal screening for memory concerns should be a priority throughout mid to late adulthood. Alzheimer’s disease is a clinical diagnosis. The doctor must make it according to his or her judgment. No single blood test, x-ray or scan can make or confirm the diagnosis. It will depend largely on an accurate history detailing progressive loss of memory and daily functioning. It is vitally important to remind caregivers that a history must be provided. The specialist should take all factors into account before arriving at a thoughtful diagnosis since many of the common conditions related to aging and Down syndrome (hearing loss, vision loss, low thyroid function, sleep apnea, etc.) can be mistaken with dementia.

Seeking a Memory Evaluation

A memory specialist (geriatrician, neurologist, psychiatrist or neuropsychologist) must examine the patient. Ideally, this specialist should have experience assessing individuals with intellectual disabilities. Assessments should be comprehensive and adapted appropriately for each 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.

References

The information featured in this section is reproduced via an exclusive arrangement with National Down Syndrome Society [ONLINE] Available at http://www.ndss.org