For this reason, some items on this page will be unavailable. These symptoms may vary widely from person to person. Scientists do not know yet exactly what causes these differences for most people with ASD. However, some people with ASD have a known difference, such as a genetic condition.
There are multiple causes of ASD, although most are not yet known. There is often nothing about how people with ASD look that sets them apart from other people, but they may communicate, interact, behave, and learn in ways that are different from most other people. The learning, thinking, and problem-solving abilities of people with ASD can range from gifted to severely challenged. These conditions are now all called autism spectrum disorder. ASD begins before the age of 3 and last throughout a person’s life, although symptoms may improve over time. Some children with ASD show hints of future problems within the first few months of life.