Clinical reports suggest that anxiety is a pertinent issue for adults with autism. We compared 34 adults with autism with 20 adults with intellectual disabilities, utilizing informant-based measures of anxiety and stress. Groups were matched by age, gender and intellectual ability. Adults with autism were almost three times more anxious than the comparison group and gained significantly higher scores on the anxiety subscales of panic and agoraphobia, separation anxiety, obsessive-compulsive disorder and generalized anxiety disorder. In terms of sources of stress, significant differences between the two groups were also found, and stress was found to correlate with high anxiety levels for the autism group, particularly the ability to cope with change, anticipation, sensory stimuli and unpleasant events. That is, the more anxious the individual with autism, the less likely they were able to cope with these demands. This has important implications for clinicians in terms of both assessment and treatment.
Gillott et al. (2007) studied this question.