Affects on the Brain and Intelligence
Almost always, the diagnosis of Down syndrome comes with some level of intellectual disability. This simply means that compared to other people, it takes those with Down syndrome longer to learn new things, reason, and judge. On a scale of mild to severe, people with Down syndrome usually fall on the mild to moderate side of the spectrum although this varies greatly from person to person. The most common way to measure intelligence is in the form of the standardized test: Intelligence Quotient (IQ). While the "normal" range of intelligence is from about 70-130, the range of scores of people with Down syndrome is about 50-70. In the U.S., individuals who score a 70 or below on the test are usually considered to have a mental impairment. Scientists and researchers still do not know why the extra chromosome involved in Down syndrome affects the intellectual capability of a person. One hypothesis is that the extra genetic material interferes in some way with the normal brain development but they do not know how. |