Correlates of Repetitive Movements In Autism Spectrum Disorders

Background:  Characterization of clinical phenotypes in autism spectrum disorders (ASD) may be useful in identifying potential complications and establishing treatment plans.  Stereotypic and repetitive movements may help identify subtypes of ASD.

Objectives:  To determine clinical findings associated with stereotypic movements in individuals with ASD enrolled in a large ASD registry.

Methods:  Children and adolescents with a diagnosis of ASD (autism, Asperger disorder, or PDD-NOS) confirmed by ADOS, age 2 – 18 years were enrolled into the Autism Treatment Network (ATN) Registry which collects data on children with ASD at 14 sites across the US and Canada.  Upon entry into the registry, parents complete a medical history questionnaire and subjects undergo a battery of assessments including cognitive testing and detailed neurologic examination.  Repetitive movements were assessed and observed by clinician during examination.

Results:  

Examination of 2482 children with ASDs revealed 892 with repetitive movement abnormalities (36%).  Rates across ASD categories showed 41.6% in autism, 21.2% in Asperger syndrome, and 25.0% in PDD-NOS.  Of the 892 children with at least one repetitive movement abnormality the most common abnormality was hand flapping (59%).

	Child's Diagnosis
	All ASD		Autism		Asperger’s		PDD/NOS
	n	%	n	%	n	%	n	%
Total with repetitive movement abnormalities	892	100.0	699	100.0	42	100.0	151	100.0
Hand flapping	529	59.3	438	62.7	15	35.7	76	50.3
Finger licking	184	20.6	157	22.5	6	14.3	21	13.9
Knocking	33	3.7	31	4.4	0	0.0	2	1.3
Body rocking	160	17.9	128	18.3	11	26.2	21	13.9
Head banging	57	6.4	45	6.4	1	2.4	11	7.3
Hand wringing	54	6.1	40	5.7	3	7.1	11	7.3
Other	369	41.4	271	38.8	24	57.1	74	49.0

The relationship between repetitive movements and language regression, EEG results, IQ, and parent reported GI problems and sleep problems was examined.  Using a p-value of 0.0055 as evidence of an association (Bonferroni adjusted for multiple (9) looks per item) two significant associations were found.  Children with parent reported language regression and lower IQ had significantly higher presence of repetitive movements (p-value = 0.002 and 0.000, respectively).

Conclusions:  Repetitive or stereotypic movements are common in ASDs, with hand flapping movements most frequently reported. Although common, stereotyped behaviors are not universal as a core feature of ASD. Individuals with lower cognitive ability <70 and with history of language regression were significantly more likely to demonstrate repetitive movement abnormalities. It is possible that children with higher cognitive abilities have more verbally related obsessions, or are able to process verbal or physical redirection better than lower functioning children. While repetitive behaviors can be environmentally influenced, the association with other neurodevelopmental abnormalities suggests further study of a neurologic and genetic basis is indicated.