What is Down Syndrome?
Down syndrome, also known as trisomy 21, is a genetic condition in which a person is born with an extra copy of chromosome 21. Humans typically have 23 pairs of chromosomes, for a total of 46. Chromosomes are threadlike structures located in the nucleus of cells. These structures house DNA, which contains instructions for our development and reproduction. Each person gets half of their chromosomes from their mother and the other half from their father.
Having an extra copy of chromosome 21 affects the development of the brain and the body, which can cause both mental and physical disabilities in people affected. Individuals with Down syndrome have an increased risk for several health issues, including Alzheimer’s disease—the most common cause of dementia. Dementia is a general term used to describe changes in memory and thinking abilities that are severe enough to affect daily life.
Symptoms of Down Syndrome
Some common physical features of Down syndrome include:
- Eyelids that slant upward
- Flattened face
- Short in height
- Shorter than average neck
- Smaller than average hands, with a single line across the palms
- Smaller than average head and ears
- Tiny white spots on the iris of the eye
- Poor muscle tone
- Protruding tongue
The following may be early signs of Alzheimer’s disease and warrant further evaluation:
- Decreased or poor judgment
- Difficulty concentrating
- Loss of interest in activities and socializing
- Memory loss and forgetfulness
- Mood changes
- New communication challenges
- Sleep disturbances
Treatments for Down Syndrome
Down syndrome is a lifelong condition, but a team of specialists can help provide medical care and develop the individual’s skills as fully as possible.
For individuals with Down syndrome who develop Alzheimer’s disease, treatment largely revolves around support from caregivers. They play an important role in providing the individual with comfort and security.
Medication for Alzheimer’s disease specifically may moderately slow the progression of the disease, but it won’t stop or reverse the disease course. Other medications may be prescribed for coexisting conditions, such as prescribing antidepressants for depression.
How common is Down syndrome?
Down syndrome is the most common chromosomal condition. The Centers for Disease Control and Prevention estimates that about 6,000 babies are born with Down syndrome in the United States each year. That’s approximately 1 in every 700 babies.
According to the National Down Syndrome Society, about 30 percent of people with Down syndrome who are in their 50s have Alzheimer’s disease. That percentage increases to 50 for people with Down syndrome who are in their 60s.
Who gets Down syndrome?
Scientists do not yet fully understand why some individuals have an extra copy of chromosome 21. They are also still investigating the connection between Down syndrome and Alzheimer’s disease. Autopsy studies have found that by age 40, nearly all individuals with Down syndrome have significant amyloid plaques and tau tangles. These abnormal protein deposits have been associated with Alzheimer’s disease. However, for reasons that are not yet fully understood, not everyone with a buildup of these proteins will develop symptoms of dementia.
How is Down syndrome diagnosed?
Down syndrome can be diagnosed during pregnancy through screening and diagnostic tests. Screening tests typically include a combination of bloodwork and ultrasound imaging. If the screening results are positive, diagnostic tests may be ordered. These may include examining samples from the placenta, amniotic fluid, and/or the umbilical cord.
Currently, there is no single test that can diagnose Alzheimer’s disease. There are tests, however, that can rule out other causes of symptoms that mimic dementia. For example, bloodwork may reveal thyroid dysfunction—which can also impair memory and concentration.
Experts recommend obtaining a baseline evaluation for individuals with Down syndrome by the time they reach age 35. Performing ongoing evaluations can help detect changes in intellectual, behavioral, and social functions, which may indicate Alzheimer’s disease.
Information and Resources:
Centers for Disease Control and Prevention
National Down Syndrome Society