Researchers at Canada's York University used an online survey involving 95 adults with Autism Spectrum Disorder (ASD) and 117 without, ranging in age from 19 to 43.
Of the 95 participants with ASD, 78 per cent reported at least one occurrence of sexual victimisation compared to 47.4 per cent of the 117 adults without ASD who participated in the study.
"Adults with ASD gain more of their sexual knowledge from external sources such as the internet and the television whereas social sources would include parents, teachers and peers," said researcher Professor Jonathan Weiss.
The study, conducted by Weiss, and clinical developmental psychology PhD candidates Stephanie Brown-Lavoie and Michelle Viecili, found that the lack of sexual knowledge in adults with autism played a role in increasing the risk of sexual victimisation experiences of sexual coercion, unwanted sexual contact, attempted rape or rape.
Brown-Lavoie pointed out that the study participants were asked about specific situations, not just a general "have you been sexually victimised" question.
"Some may not know that the experience they had is actually classified as sexual victimisation. But if you give them a specific situation, like someone touching you inappropriately after you said no, they may be more able to identify that it has happened to them," Brown-Lavoie said.
The study will be published in the Journal of Autism and Developmental Disorders.