Motor stereotypies in autism spectrum disorder: Clinical randomized study and classification proposal
Authors: Melo Cláudia , Ribeiro Tiago Pinto , Prior Catarina , Gesta Camila , Martins Vânia , Oliveira Guiomar , Temudo Teresa 
Published: June 2022

Motor stereotypies are frequently reported in individuals with autism spectrum disorder, but determinants of stereotypies remain poorly understood. In this study, a randomized sample of children with diagnosis of autism spectrum disorder was investigated to identify the prevalence and determinants of stereotypies. A total of 134 children who carried the diagnosis of autism spectrum disorder were included (aged 2.3–17.6 years; 79.1% male). Stereotypies were classified during a standardized protocol with video recording. The prevalence of stereotypies was 56.7%. Among 1198 captured stereotypies, hand/arm stereotypies were the most frequent. Thirty-five morphology patterns were identified, the most frequent being hand flapping, tapping, and jumping. In univariate analysis, an association was found between stereotypies and younger age (odds ratio = 0.74), developmental delay, or intellectual disability (odds ratio = 5.25), being nonverbal (odds ratio = 0.06), epilepsy (odds ratio = 3.89), Autism Diagnostic Interview–Revised-A score (odds ratio = 1.17), Autism Diagnostic Interview–Revised-C score (odds ratio = 1.25), and Autism Diagnostic Observation Schedule–2 score (odds ratio = 1.65). After multivariate analysis, only younger age, being nonverbal, and Autism Diagnostic Interview–Revised-A and Autism Diagnostic Observation Schedule–2 scores remained as determinants of stereotypies. The prevalence of stereotypies in autism spectrum disorder was close to the values obtained in a previous meta-analysis and seems to represent a valid value. The combination of younger age, being nonverbal, and autism severity seems to increase the odds of stereotypies. Lay abstract Motor stereotypies are one of the most frequent features in children with a diagnosis of autism spectrum disorder. They may disrupt children’s functioning and development and be a potential source of stress for families. Several factors, including sex, age, cognitive ability, and severity of autism spectrum disorder, may influence the presence and intensity of stereotypies. The present study aimed to identify the prevalence of motor stereotypies in a group of children with autism spectrum disorder. In addition, it sought to investigate whether sex, age, cognitive ability, verbal language, neurological comorbidities, and severity of autism spectrum disorder were associated with an increased probability and higher number, duration, and variability of stereotypies. A total of 134 participants aged 2.3–17.6 years underwent a clinical protocol with standardized video-recorded sessions. Stereotypies were identified and classified by two independent evaluators. The prevalence of stereotypies was 56.7%, and a total of 1198 motor stereotypies were captured. Children who were younger, nonverbal, and had higher severity of autism spectrum disorder had an increased probability of presenting stereotypies. Being nonverbal or having higher severity of autism spectrum disorder was also associated with presenting a higher number of stereotypies. Children with developmental delay, intellectual disability, or epilepsy displayed longer stereotypies, and children with developmental delay or intellectual disability additionally presented more diverse stereotypies. As part of the study, the authors present a clinical classification model, a glossary, and video samples of motor stereotypies. The findings of this study suggest that children who are younger, nonverbal, have lower cognitive ability, and have higher severity of autism spectrum disorder may have a higher burden of stereotypies. Earlier intervention and monitoring of these children have the potential to improve their long-term outcomes.