About Down Syndrome

What Is Down syndrome?

Down syndrome, or Trisomy 21, as it is called within the medical community, is caused by an extra copy of the 21st chromosome. An error in cell division, called non-disjunction, happens at the moment of conception for reasons we still do not understand. The extra chromosome causes varying degrees of cognitive impairment and physical abnormalities. Most people with Down syndrome have cognitive impairment falling in the mild to moderate range, and they have speech and language difficulties.

How many people have Down syndrome?

About one in every 691 American babies is born with Down syndrome, and it is estimated that about 250,000-400,000 people in the United States and just under 6 million people worldwide live with this condition today. Because of the limitations of available data to date, additional research studies are required to determine more accurately the population of individuals with Down syndrome. There is a false impression that pregnancy screening has eliminated or substantially reduced the incidence of Down syndrome in the population. Studies indicate that the Down syndrome population in the country has increased over the past several decades and suggest that it will continue to do so.

Isn’t Down syndrome too complex to treat and once someone is born with it, isn’t it too late?

For many years, scientists believed that Down syndrome was too complex to understand, and they believed that there was no way to reverse or reduce the severity of cognitive impairment. However, scientific advances have made it possible to understand how specific genes are linked to specific abnormalities in the structure and function of the brain.

Although the 21st chromosome has hundreds of genes, researchers believe that there may be only a handful that significantly impact cognition. Using advanced techniques and methods, researchers believe they will be able to isolate the effects of these specific genes and determine how their expression in the brain can cause problems with cognition. As researchers define the mechanisms responsible for cognitive dysfunction, they can begin the process of discovering treatments that enhance brain function, including cognition. Today we can predict that Down syndrome is not too complex to understand and it is not too difficult or too late to treat.

Is a treatment a cure?

No. Once a baby is born with Down syndrome, he or she will always have an extra chromosome. The objective of the treatment is to improve cognition by improving learning, memory, and speech for individuals with DS. No one can say for sure how much cognition could be improved. However, even a modest improvement of 10-20% in cognition could have enormous impact on the life of a person with Down syndrome. Because the majority of individuals with Down syndrome fall into the mild to moderate range of cognitive impairment, a 10-20% improvement would enable most persons with Down syndrome to function much more independently in school and the workplace.

Why is research into cognition important?

The quality of life for individuals with Down syndrome has improved tremendously as a result of improved health care, expanded educational and community opportunities, and the support of families and advocacy groups.  The life expectancy of those with Down syndrome more than doubled, highlighting the importance of the need to attain skills essential for independent living.

Yet, over these intervening years, Down syndrome cognitive research had been largely lacking because many in the medical field and those in the agencies that supported them with funding had considered the problem too complex. The thinking was that little could be done to alter the impact on cognition imparted by the extra chromosome 21 in individuals with Down syndrome. Supporting this argument was the assumption that cognitive impairment is permanent, as it develops very early in development.