Does Having Down Syndrome Increase the Risk of Alzheimers?

Alzheimer’s disease is a type of dementia that affects your behavior, communication, and memory. Aging increases the chances of developing Alzheimer’s in all adults, but the risk is higher in those with Down syndrome.

Down syndrome, or Down’s syndrome, is a chromosomal disorder in which a person has an extra copy of their 21st chromosome. This causes various mental and physical disabilities.

Over the last few decades, people with Down syndrome have been living longer. According to the Journal of the American Medical Association (JAMA), in 1983, the life expectancy for those with Down syndrome was 25 years old. In 2020, the average life expectancy was 60 years old. Many live into their 70s.

Among those with Down syndrome ages 65 years and older, more than 75% have Alzheimer’s disease. That’s six times more than the general population of the same age group.

This is due to genetics and natural aging. Let’s explore how each factor increases your risk, as well as early symptoms of Alzheimer’s and dementia in people with Down syndrome.

What causes a higher risk of Alzheimer’s in people with Down syndrome?

In people with Down syndrome, the increased risk of Alzheimer’s is related to genetics and natural aging.

Genetics

Chromosomes carry genes that control how your body builds proteins. This determines all of your biological functions.

Humans have 23 pairs of chromosomes. One copy comes from each of your biological parents.

One of the 23 pairs is chromosome 21. Chromosome 21 is the smallest human chromosome. One specific gene in chromosome 21 is responsible for producing amyloid precursor protein (APP).

In people who have Down syndrome, they have an extra copy of chromosome 21. This increases their production of APP, which breaks down into beta-amyloid protein.

Beta-amyloid protein may clump together between neurons, resulting in plaques. These beta-amyloid plaques are a hallmark characteristic of Alzheimer’s.

Thus, the increased accumulation of beta-amyloid plaques in people with Down syndrome may increase their risk of Alzheimer’s.

Aging

Alzheimer’s isn’t a typical part of aging. But aging is the greatest risk factor for developing the condition. This is due to the turnover of beta-amyloid protein that occurs with aging combined with the fact that life expectancy continues to rise.

In your central nervous system, APP naturally breaks down into beta-amyloid protein. Your brain then clears it out using certain cells and enzymes.

But this process slows down with age. In a small 2015 study, researchers determined that beta-amyloid clearance takes 3.8 hours at 30 years old. This slows down to 9.4 hours by 80 years old.

As a result, beta-amyloid is more likely to accumulate before it’s cleared out, potentially leading to Alzheimer’s. This age-related change can further increase the risk in people with Down syndrome.

Symptoms of Alzheimer’s in people with Down syndrome

In the general population, symptoms typically involve memory loss and forgetfulness. But in people with Down syndrome, symptoms mainly involve personality and overall functioning.

Examples include:

  • reduced interest in socializing or conversing
  • reduced enthusiasm for usual activities
  • decreased attention
  • anxiety
  • fearfulness
  • sadness
  • irritability
  • aggression
  • unwillingness to cooperate
  • restlessness
  • sleep difficulties
  • being more noisy or excited than usual
  • changes in walking or coordination
  • seizures starting in adulthood

When is Alzheimer’s typically diagnosed in people with Down syndrome?

Most people with Down syndrome have developed beta-amyloid plaques by the time they’re 40 years old. But they usually receive a diagnosis of Alzheimer’s in their 50s, according to a 2020 study.

About 30% of people with Down syndrome have Alzheimer’s disease in their 50s. This statistic is closer to 50% by the time they’re 60 years old.

Reporting memory issues and how caregivers can help

In the early stages of Alzheimer’s, people with Down syndrome may not report symptoms of memory loss. As a result, caregivers who know the person well should watch for changes and contact a doctor or healthcare professional.

To start, it’s important to establish the person’s baseline function by age 35. This includes aspects such as skills, hobbies, and habits. This will help caregivers compare and contrast any changes that occur later on.

A doctor can help caregivers understand a person’s baseline. Together, doctors and caregivers can work together to monitor the person’s function.

When to contact a doctor

If you have Down syndrome, speak with a doctor if you notice the following symptoms:

  • changes in usual daily functioning
  • decreased enthusiasm for daily activities
  • reduced interest in social interactions
  • personality changes
  • behavioral changes

Similarly, if you’re a caretaker, get medical help if you notice these changes in a person with Down syndrome.

Is there treatment for Alzheimer’s in people with Down syndrome?

There’s no cure for Alzheimer’s. Most Alzheimer’s treatments are directed at relieving symptoms and improving quality-of-life for those affected. Currently, the Food and Drug Administration (FDA) hasn’t approved any medications to specifically treat Alzheimer’s in people with Down syndrome.

Resources for caregivers

Takeaway

People with Down syndrome are more likely to develop Alzheimer’s disease, a form of dementia. Alzheimer’s is characterized by an accumulation of beta-amyloid protein plaques in your brain.

In people with Down syndrome, the chromosomal anomaly that causes the condition increases beta-amyloid production. Natural aging also slows down your brain’s ability to clear out beta-amyloid, further increasing the risk of accumulation.

Early symptoms of Alzheimer’s in people who have Down syndrome don’t usually involve memory loss. Instead, it typically involves changes in their behavior and personality. If you’re a caregiver, or if you have Down syndrome, talk with a doctor if you notice these changes.

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