Repetitive Behaviors in Autism and Obsessive-Compulsive Disorder: A Systematic Review.

Only 4 of the 31 studies reported participants' ethnicity; across those 4 studies, 231 of 253 people (91.3%) were White. Only 2 studies included people with below average intelligence or intellectual impairment, and 23 of the 31 excluded people on that basis, so the results may not apply to autistic people with intellectual disability or language impairment. Most autistic participants were male (74%), and none of the included studies examined sex or gender as a possible factor. None of the included studies reported input from autistic people or people with OCD. Grey literature and non-English publications were not included. Studies were not excluded on the basis of quality, and the authors say findings from poorer-quality studies should be read cautiously. The included studies used many different measures, which the authors say may explain some of the inconsistent results. Most included studies were cross-sectional or case-control, so they describe people at one point in time and cannot show what causes these behaviours or how they change. Factors such as anxiety or executive function were usually reported in relation to diagnosis rather than to the behaviour itself, and only as overall scores, so links with specific types of behaviour could not be examined.

The review was funded by Griffith University, named in the funding and conflicts statement. No competing interests are reported in the supplied text.

This review compared how repetitive behaviours look, not what treatment works, so nothing here shows any therapy is effective. The main wrong conclusion is treating a high score on a repetitive behaviour questionnaire as proof of one diagnosis: the review found autistic people and people with OCD often score the same, and concludes that a total score alone cannot separate the two.