What proportion of people with autism have a learning disability?

Between 44% – 52% of autistic people may have a learning disability.
Between 48% – 56% of autistic people do not have a learning disability.

Research findings on the proportion of people with autism spectrum disorders who also have learning disabilities (IQ less than 70) vary considerably as they are affected by the method of case finding and the sample size.

Fombonne et al (2011), in their research review of 14 prevalence studies that mentioned IQ, found a range of 30% to 85.3%, with a mean of 56.1%, of people without learning disabilities, p. 99.

Emerson and Baines (2010) in their meta-analysis of prevalence studies found a range of people with learning disabilities and autism from 15% to 84%, with a mean of 52.6%.

Explanation of why these findings are so variable and the reliability of the figures can be found in both Emerson and Baines (2010) and in Fombonne et al (2011).

What proportion of people with a learning disability are autistic?

Around a third of people with a learning disability may also be autistic.

Around a third of people who have learning disabilities (IQ less than 70) are also autistic, according to research published by Emerson and Baines in 2010. The adult prevalence study, The NHS Information Centre, Community and Mental Health Team, Brugha et al.(2012), found between 31% and 35.4% of people with a learning disability are autistic.