Intelligence is sometimes described as the capacity to acquire and apply knowledge (although there are numerous other definitions).
Some people on the autism spectrum (sometimes referred to high-functioning) are reported to have average or above average intelligence. That is, they have a non-verbal IQ of 70 or more.
Other people on the autism spectrum (sometimes referred to as low functioning) are reported to have intellectual abilities significantly below average. That is, they have a non-verbal IQ of 70 or less. They may also be non-verbal or have very limited speech. The latter group is sometimes described as having an intellectual disability (also known as learning disability or mental handicap.)
High-functioning autism and Asperger syndrome may be the same thing (this is still being debated). Most research has not shown enough difference to justify it being a separate diagnosis. However, some researchers do believe high-functioning autism and Asperger syndrome are different and need to be separated at diagnosis.
The terms 'high-functioning' and 'low-functioning' autism are also debated. Some people say they are not useful or they are insulting. For example, some individuals classified as having 'severe' autism may be highly intelligent and can function very well with the right kind of support. Some 'high-functioning' individuals on the autism spectrum, on the other hand, may face considerable difficulties which are overlooked because they appear to be coping