Clinical Approach to Motor Stereotypies in Autistic Children

Ahmad Ghanizadeh^1,2, MD

1.    Research Center for Psychiatry and Behavioral Sciences, Hafez Hospital, Shiraz University of Medical Sciences, Shiraz, IR Iran

2.    Department of Psychiatry, Shiraz University of Medical Sciences, Shiraz, IR Iran

 

Received: Dec 29, 2009; Final Revision: Mar 10, 2010; Accepted: Mar 15, 2010

Iranian Journal of Pediatrics, Volume 20 (Number 2), June 2010, Pages: 149-159

Key Words: Motor; Stereotypy; Autism; Clinical Approach; Children

Introduction

Restricted repetitive behaviors (RRB) and stereotypic behaviors (SB) count among the key symptoms of autism. Movement disorders such as stereotypies indicate the severity and progression rate of Rett disorder⁽¹⁾, and the severity of autism symptoms and pragmatic competence at later ages⁽²⁾. Social involvement of children with autism with their peers increases their adaptive behavior skills and improve outcome of the disorder⁽³⁾. Repetitive and stereotyped movements with objects in children with autism spectrum disorders late in the second year of life predict unique variance in the severity  of autism  symptoms  in  the fourth year

beyond that predicted by social communication measures alone⁽⁴⁾. So, intervention program on cognitive abilities should be focused and started in early ages so that its influence continues into adolescence and adulthood⁽³⁾.

     More studies are required to be conducted to improve knowledge about the pathophysiology of stereotypies in autism⁽⁵⁾. This is a review for definition, classification, epidemiology, and management of motor stereotypies in children with autism.

Definition of Motor Stereotypies

Motor stereotypies are suppressible, repetitive, rhythmical,  coordinated,  purposeless, fixed, and nonfunctional pattern of movements (Fig 1)^{(6, 7)}. These movements may happen together and many times in day⁽⁷⁾. The periodic movements are high-frequency. However, rhythmicity is not a characteristic of stereotypy. Stereotypies in autism are associated with severity of autism⁽⁸⁾ and lower cognitive development⁽⁹⁾. However, another study did not find association of autism severity and motor stereotypies⁽⁶⁾. The repertoire and manner of movement for each individual is specific. More than one type of stereotypies is usually seen at one moment.

     Excitement⁽¹⁰⁾, stimulation, stress, anxiety, boredom, fatigue, sensory isolation, or social demands increase stereotypies^{(6, 7)}. Different types of stereotypic behaviors are displayed in Table 1. Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defines stereotypies as a repetitive and non functional behavior lasting 4 or more weeks. It also emphasizes that the behavior interferes with normal activity or it may lead to self injury.

Classification

The rate of repetitive behaviors in PDD is higher than those with mental retardation^[11]. Some authors classified repetitive behaviors into two distinctive groups of 'lower-order' and 'higher-order' sub-groups. The lower-order repetitive behaviors are associated more with developmental delays while the higher-order behaviors are correlated with autism⁽¹¹⁾. Another classification classifies stereotypies into two groups of 1) primary or physiological; this type does not have any specific cause for stereotypies such as pencil tapping, hair twisting, and 2) secondary or associated with other conditions such as neurological, sensory problems, with pervasive developmental disorder (PDD), tumor, or infection. For example gazing atypically at objects may be present in PDD⁽⁷⁾.

Underlying Disorders

The continuum of repetitive behaviors can be seen in typically developing children^{(10, 12)} and it is not limited to autism spectrum disorders (ASD) (Table 2)^{(6, 13)}.

     It also can be seen in children with developmental delay or sensory deprivation⁽⁷⁾ syndromes such as Smith-Magenis Syndrome⁽¹⁴⁾ and Cri-du-Chat syndrome⁽¹⁵⁾. The number and diversity of stereotypies in autism is more than in typically developing children⁽⁶⁾. The rare behavior of atypical gazing at fingers and objects was only observed in autism⁽⁶⁾. Some authors report that self-injurious behavior is a more rigorous type of stereotyped movements and self-injurious behavior is rarely performed in the absence of other stereotyped movements⁽¹⁶⁾.

Autism spectrum disorders

Autism is one of the most common types of autism spectrum disorders. These disorders are behavioral syndromes with various degrees of social impairments, verbal, nonverbal and as well as restricted or stereotyped interests and activities. The age of onset is before 3 years. The other types of autism spectrum disorders are Aspeger’s syndrome, Rett’s disorder, childhood disintegrative disorder, and Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS). Etiology of these disorders is not clearly known⁽²⁵⁾.

     Autism spectrum disorders impact different aspects of the children and also their families, parents, and siblings⁽²⁶⁾. The rate of symptoms of ASD in community is considerable⁽²⁷⁾. Medications such as antipsychotics and serotonin specific reuptake inhibitors are suggested for management of autism spectrum disorders⁽²⁸⁾.

 

Epidemiological factors

The mothers reported point prevalence of stereotypic movement among 3079 children of 1-15 years age in the primary health care centers referred for vaccination was 2.3%⁽²⁹⁾. It usually starts before age 3 years^{(7, 30)}. Boys more than girls are afflicted and its ratio is about                   3:2^{(7, 10, 31, 32)}. Stereotypic behavior levels in 2-, 3- and 4-year-old children with autism or PDD-NOS is more than in the typically developing same- age peers⁽¹⁷⁾. Even, infants with autism show stereotypic   behavior⁽³³⁾.  Forty-four percent of children with autism have at least one subtype of stereotypy⁽⁶⁾. Developmental age is not associated with the presence of repetitive behaviors in autism but lower chronological age is associated more with simple or low-level repetitive behaviors⁽³⁴⁾.

     Stereotypies are more common in children with autism than cognitively-matched non-autistic developmentally disordered children. The occurrence, number, and variety of stereotypies are higher in autism co-occuring with mental retardation (nonverbal Intelligence Quation (IQ)⁽⁶⁾.

 

Pathophysiology

Foundation and developmental course of stereotypic behavior in autism is not well known⁽⁵⁾. Frontal white matter and both of the left and  right  caudate  nuclei  volume  reduction and cortico-striatal-thalamo-cortical circuitry dysfunction is reported in children with stereotypy without autism⁽³⁵⁾. Dopaminergic system is involved in stereotypies⁽³⁶⁾. Basal ganglia dysfunction is correlated stereotypies in ASD. The higher right caudate and total putamen volume is associated with higher repetitive behaviors⁽³⁷⁾. There is a relative hyperplasia of white matter in the cerebellum and brainstem in children with Down syndrome and ASD in comparison to Down syndrome only. Severity of stereotypies is associated with cerebellar white matter volume⁽³⁸⁾. Frontal lobe volume has a positive association with stereotypies in autism⁽³⁹⁾.

     Hand stereotypies without bruxism, and the other stereotypies is highly a sign of an MECP2 mutation in Rett syndrome⁽⁴⁰⁾. There is a 25% positive family histories of motor stereotypies⁽³¹⁾. Underlying genetic abnormality for non-autistic motor stereotypies is suggested⁽³¹⁾.

     Repetitive behaviors do not differentiate high functioning autism and Asperger's disorder⁽⁴¹⁾. The association of social-communication impairments and stereotypies in literature has been exaggerated in autism⁽⁴²⁾.

     Association of stereotypic behavior and response to growth hormone in adults with autism is suggested⁽⁴³⁾ and the infusion of oxytocin deceases repetitive behaviors⁽⁴⁴⁾. The repetitive symptoms of ASD are associated with some executive processes including cognitive flexibility, working memory, and response inhibition, while it is not associated with executive processes of planning and fluency⁽⁴⁵⁾.

     The rate of RRB is negatively associated with non verbal IQ while circumscribed interests are positively associated with non verbal IQ⁽⁴⁶⁾. Lower hours of sleep per night predict stereotypic behavior in autism⁽⁴⁷⁾. Sensory and social reinforcers maintain stereotypy⁽⁴⁸⁾.

Co-morbidities

The co-morbidity of stereotypies with tics, obsessive-compulsive  behaviors,  and   attention deficit hyperactivity disorder (ADHD) (25%) and learning disabilities (20%) is very high (Table 3)⁽⁷⁾.

     In a study, nearly 50% of typically developing children with motor stereotypies had ADHD (30%), tics (18%), and obsessive-compulsive behaviors/obsessive-compulsive disorder (10%) ⁽³¹⁾. Tic is a stereotyped repetitive involuntary movement or sound⁽⁴⁹⁾. The presence of repetitive behaviors is correlated with hyperactivity in autism⁽⁵⁰⁾. Restrictive or repetitive behaviors in autism are related with obsessive compulsive symptoms in parents of afflicted individuals⁽⁵¹⁾.

     Family history of stereotypies in children is 25%, tics 33%, ADHD 10%, and mood-anxiety disorder 8%⁽¹⁰⁾. Cognitive level is a moderator for expression of stereotypic behaviors in individuals with intellectual disability but not for the autism⁽⁵²⁾.

     Repetitive behaviors predict the presence or absence of autism at a high rate of diagnostic accuracy in adults with intellectual disability⁽⁵³⁾. A loss of skill and regression in autism is associated with slightly higher repetitive behaviors⁽⁵⁴⁾. Finally, 17% of older adolescents and adults with autism may have severe catatonic-like symptoms⁽⁵⁵⁾. Of course, association and relationship of stereotypies and catatonia should be studied in future studies⁽⁵⁵⁾.

Whom to Investigate

Tics, obsessive compulsive behaviors, unusual sensory responses, social communication difficulties, rhythmic behaviors of sleep, and epileptic automatisms should be differentiated from motor stereotypies (Table 4)⁽⁷⁾.

     Of course, sometimes tic, compulsive behaviors, and automatism occur with stereotypies. EEG may help to differentiate seizure from stereotypies.

     Autism and obsessive compulisive disorder  can be differentiated by types of current repetitive thoughts and behavior.

     Thoughts with contamination, sexual, religious, and symmetry, content and behaviors of cleaning, checking, and counting are less likely observed in autism than in obsessive compulsive disorder⁽²²⁾. Children with OCD focus more than children with ASD on routines and rituals. Obsession and compulsions in children with OCD are more sophisticated than those with ASD⁽⁵⁶⁾. Some of the points that may help to differentiate stereotypies from other problems are mentioned in the Table 2.

     Repetitive behavior also occurs in mental retardation⁽⁵⁷⁾. However, autistic individuals more than those with mental retardation show greater severity and higher number of topographies of stereotypy and compulsions⁽⁸⁾. Asperger syndrome and high functioning autism cannot be differentiated regarding repetitive behavior⁽⁶⁰⁾.

Outcomes

The three domains of autism improve and this improvement is not associated with age and cognitive function level⁽⁶¹⁾. This improvement is part of a ‘natural history’ of the development problems⁽⁶¹⁾. However, remission will not happen for the majority of children with autism⁽⁶²⁾. Even in the children with improved language ability, the symptoms of autism were not fading. Severity of repetitive behaviors at the first assessment was in association with severity of autism symptoms and pragmatic competence at later ages⁽²⁾.

     The outcome of stereotypies is not clear⁽⁷⁾ and it is usually chronic⁽¹⁰⁾. Motor stereotypies especially arm/hand movements types are chronic⁽³¹⁾. The severity and frequency of repetitive behaviors in ASD decrease with increase of age⁽⁶³⁾. A study reported that it did not change in 50%, and worsened in 13%⁽¹⁰⁾.

     Complexity of motor repetitive behaviors in children with autism increases with the increase of age and higher IQ⁽⁹⁾. However, it is not clear whether all stereotyped behaviors need to be treated because some of them do not interfere with explorative and cognitive activities⁽⁶⁴⁾.

How to investigate children

Stereotypies can be assessed using the recently developed  43-item  questionnaire  of  Repetitive

Behavior Scale-Revised (RBS-R) (Bodfish et al, 2000). Its validation has been confirmed in children with autism spectrum disorders^{(8, 65)}.

     Repetitive and Restricted Behaviour Scale (RRB)  is  another  recently  introduced  scale  for

assessment of stereotypies in autism spectrum disorders⁽⁶⁶⁾. RRB includes 35 items that cover whole range of stereotypies. The degree of expression of each behavior is evaluated according to a five-level rating. RRB has been recently translated and back translated into English by author (A. G.). We are studying its Farsi version of psychometric properties. Some items of the RRB are:“repetitive body rocking”, “bizarre gait”, and “play and leisure rituals”. Direct observation, video analysis, and motion sensors may be considered for RBB evaluation (Table 5).

Management and treatment

Management for stereotypies is mostly behavioral⁽⁵⁵⁾. The role of medications for treatment of motor stereotypy disorders in typically developing children is not clear and behavioral therapy can be beneficial (Figure 2)^{(7, 67)}.

     Positive outcomes were usually reported after behavioral interventions such as “mechanical restraints alone or with other intervention variables”, “response blocking alone or with other intervention variables”, “non-contingent stimulation”, “various contingency manipulations”, and “microswitch clusters”⁽⁶⁷⁾. Habit reversal and differential reinforcement of other behavior improve stereotypic behaviors in non-autistic children⁽⁶⁸⁾.

     Vibroacoustic music decreases stereotypic behaviors in individuals with autism and developmental disabilities⁽⁶⁹⁾. The peer- mediated intervention and social engagement and educating social     interaction decrease stereotypic behavior of children with autism^{(70, 71)}. Self-management procedures consisting of self-assessment, self-recording, and self-reinforcement decrease stereotypic behaviors in autism⁽²⁴⁾. There is a report that improvement in sleep improves repetitive behaviors in autism spectrum disorder⁽⁷²⁾.

     Instructional prompts reduce time spent in stereotypies⁽⁷³⁾. Mother-child warmth relation-ship reduces repetitive behaviors in autism⁽⁷⁴⁾. Antecedent aerobic exercise decreases stereotypic behaviors ⁽⁷⁵⁾. There is a report that massage therapy improves autism⁽⁷⁶⁾.

     A randomized clinical trial showed that medication plus parent training reduces stereotypies in ASD more than medication alone⁽⁷⁷⁾. The results of studies for medication management for RRB in autism are mixed⁽⁷⁸⁾.

     Antipsychotics reduce stereotypies⁽⁷⁹⁾.  Risperidone may improves some sensory problems such as hyperacusia in children with autism⁽⁸⁰⁾. Double-blind, placebo-controlled trial studies indicated that risperidone improves the restricted, repetitive, and stereotypic behavior of autistic children^{(81, 82)}. The synergistic effect of combination of risperidone and pentoxifylline improves behavioral problems and stereotypies in autism⁽⁸³⁾.

     Stimulants reduce hyperactivity and improve attention but they may increase stereotypies⁽⁷⁹⁾.

     Another randomized, placebo-controlled, crossover study of methylphenidate for ADHD symptoms in preschoolers PDD or intellectual disability (ID) indicated that methylphenidte increased stereotypic behavior in half of children⁽⁸⁴⁾. However, another double-blind crossover study using placebo and two mehylphenidate doses did not indicate worsening stereotypic movements⁽⁸⁵⁾. Secretin does not show any benefit in autism. Alternative treatments have not shown efficacy in well-designed studies⁽⁷⁹⁾.

     Serotonin reuptake inhibitors (SRIs) such as fluvoxamine and serotonin non-specific reuptake inhibitor of clomipramine improve repetitive behavior in autism⁽⁸⁶⁾. An open-label investigation in adults with autism indicated that sertraline is effective for treatment of their repetitive and aggressive symptoms⁽⁸⁷⁾. A double-blind, placebo-controlled study of fluvoxamine in adults with autism reported that repetitive thoughts and behavior were decreased⁽⁸⁸⁾. Meanwhile, a randomized controlled trial indicated that citalopram was not effective to decrease repetitive behavior in children with ASD⁽⁸⁹⁾. Divalproex is suggested for treatment of repetitive behaviors in ASD⁽⁹⁰⁾.

     The efficacy of naltrexone on stereotypic behavior in children with ASD was not confirmed in double-blind placebo-controlled trials^{(91, 92)}. Implications for electroconvulsive therapy in children with ASD for management of some behavioral problems is encouraged⁽⁹³⁾.

Conclusion

The key symptom of stereotypic behaviors is related to severity and progression of ASD. Intervention programs should be undertaken in early ages because stereotypic behaviors impact on later ages and its early detection plays an important role in its management. Considering the classification system directs clinicians for future decision making. Sometimes its management is part of an underlying disease or common co-morbid conditions such as tics, autism and mental retardation. So, sometimes wider assessment may be required to prevent misdiagnosis or incorrect treatment⁽⁹⁴⁾. Its management is most likely behavioral interventions. The effect of pharmacotherapy on stereotypic behaviors is not well studied. However, anti-psychotics such as risperidone may improve it.

References

1.   Temudo T, Ramos E, Dias K, et al. Movement disorders in Rett syndrome: an analysis of 60 patients with detected MECP2 mutation and correlation with mutation type. Mov Disord. 2008;23(10):1384-90.

2.   Michelotti J, Charman T, Slonims V, et al. Follow-up of children with language delay and features of autism from preschool years to middle childhood. Dev Med Child Neurol. 2002;44(12):812-9.

3.   McGovern CW, Sigman M. Continuity and change from early childhood to adolescence in autism. J Child Psychol Psychiatry. 2005; 46(4):401-8.

4.   Morgan L, Wetherby AM, Barber A. Repetitive and stereotyped movements in children with autism spectrum disorders late in the second year of life. J Child Psychol Psychiatry. 2008;49(8):826-37.

5.   Symons FJ, Sperry LA, Dropik PL, et al. The early development of stereotypy and self-injury: a review of research methods. J Intellect Disabil Res. 2005;49(Pt 2):144-58.

6.   Goldman S, Wang C, Salgado MW, et al. Motor stereotypies in children with autism and other developmental disorders. Dev Med Child Neurol. 2009;51(1):30-8.

7.   Muthugovindan D, Singer H. Motor stereotypy disorders. Curr Opin Neurol. 2009;22(2):131-6.

8.   Bodfish JW, Symons FJ, Parker DE, et al. Varieties of repetitive behavior in autism: comparisons to mental retardation. J Autism Dev Disord. 2000;30(3):237-43.

9.   Militerni R, Bravaccio C, Falco C, et al. Repetitive behaviors in autistic disorder. Eur Child Adolesc Psychiatry. 2002;11(5):210-8.

10.  Mahone EM, Bridges D, Prahme C, et al. Repetitive arm and hand movements (complex motor stereotypies) in children. J Pediatr. 2004;145(3):391-5.

11.  Carcani-Rathwell I, Rabe-Hasketh S, Santosh PJ. Repetitive and stereotyped behaviours in pervasive developmental disorders. J Child Psychol Psychiatry. 2006;47(6):573-81.

12.  Leekam S, Tandos J, McConachie H, et al. Repetitive behaviours in typically developing 2-year-olds. J Child Psychol Psychiatry2007 Nov;48(11):1131-8.

13.  Ghanizadeh A, Mohammadi MR, Akhondzadeh S, Shooshtari AA. Clinical symptoms of children with autism spectrum disorder, a clinical sample from Shiraz. Iran J Psychiatry (in Press).

14.  Martin SC, Wolters PL, Smith AC. Adaptive and maladaptive behavior in children with Smith-Magenis Syndrome. J Autism Dev Disord2006 May;36(4):541-52.

15.  Collins MS, Cornish K. A survey of the prevalence of stereotypy, self-injury and aggression in children and young adults with Cri du Chat syndrome. J Intellect Disabil Res2002 Feb;46(Pt 2):133-40.

16.  Gal E, Dyck MJ, Passmore A. The relationship between stereotyped movements and self-injurious behavior in children with developmental or sensory disabilities. Res Dev Disabil2009 Mar-Apr;30(2):342-52.

17.  MacDonald R, Green G, Mansfield R, et al. Stereotypy in young children with autism and typically developing children. Res Dev Disabil. 2007;28(3):266-77.

18.  Tan A, Salgado M, Fahn S. The characterization and outcome of stereotypical movements in nonautistic children. Mov Disord. 1997; 12(1):47-52.

19.  Mendez MF, Mirea A. Adult head-banging and stereotypic movement disorders. Mov Disord. 1998;13(5):825-8.

20.  Troster H. Prevalence and functions of stereotyped behaviors in nonhandicapped children in residential care. J Abnorm Child Psychol. 1994;22(1):79-97.

21.  Ghanizadeh A. Association of nail biting and psychiatric disorders in children and their parents in a psychiatrically referred sample of children. Child Adolesc Psychiatry Ment Health. 2008;2(1):13.

22.  McDougle CJ, Kresch LE, Goodman WK, et al. A case-controlled study of repetitive thoughts and behavior in adults with autistic disorder and obsessive-compulsive disorder. Am J Psychiatry. 1995;152(5):772-7.

23.  Mottron L, Mineau S, Martel G, et al. Lateral glances toward moving stimuli among young children with autism: Early regulation of locally oriented perception? Dev Psychopathol. 2007;19(1):23-36.

24.  Mancina C, Tankersley M, Kamps D, et al. Brief report: reduction of inappropriate vocalizations for a child with autism using a self-management treatment program. J Autism Dev Disord. 2000;30(6):599-606.

25.  Ghanizadeh A. Autism: is it all in the head? Altern Ther Health Med. 2009;15(2):8.

26.  Ghanizadeh A, Alishahi MJ, Ashkani H. Helping families for caring children with autistic spectrum disorders. Arch Iran Med. 2009; 12(5)478-82.

27.  Ghanizadeh A. A preliminary study on screening prevalence of pervasive developmental disorder in schoolchildren in Iran. J Autism Dev Disord. 2008;38(4):759-63.

28.  Ghanizadeh A. Should tactile sensation impairment be considered in pharmacotherapy of pervasive developmental disorders? A case report. Neuro Endocrinol Lett. 2008;29(6):877-8.

29.  Al-Jawadi AA, Abdul-Rhman S. Prevalence of childhood and early adolescence mental disorders among children attending primary health care centers in Mosul, Iraq: a cross-sectional study. BMC Public Health. 2007;7:274.

30.  McConachie H, Le Couteur A, Honey E. Can a diagnosis of Asperger syndrome be made in very young children with suspected autism spectrum disorder? J Autism Dev Disord2005 Apr;35(2):167-76.

31.  Harris KM, Mahone EM, Singer HS. Nonautistic motor stereotypies: clinical features and longitudinal follow-up. Pediatr Neurol. 2008; 38(4):267-72.

32.  Hartley SL, Sikora DM. Sex Differences in Autism Spectrum Disorder: An Examination of Developmental Functioning, Autistic Symptoms, and Coexisting Behavior Problems in Toddlers. J Autism Dev Disord. 2009.39(12):1715-22.

33.  Matson JL, Dempsey T, Fodstad JC. Stereotypies and repetitive/restrictive behaviours in infants with autism and pervasive developmental disorder. Dev Neurorehabil. 2009;12(3):122-7.

34.  Mooney EL, Gray KM, Tonge BJ. Early features of autism: Repetitive behaviours in young children. Eur Child Adolesc Psychiatry. 2006; 15(1):12-8.

35.  Kates WR, Lanham DC, Singer HS. Frontal white matter reductions in healthy males with complex stereotypies. Pediatr Neurol. 2005;  32(2):109-12.

36.  Miwa H, Morita S, Nakanishi I, et al. Stereotyped behaviors or punding after quetiapine administration in Parkinson's disease. Parkinsonism Relat Disord. 2004;10(3):177-80.

37.  Hollander E, Anagnostou E, Chaplin W, et al. Striatal volume on magnetic resonance imaging and repetitive behaviors in autism. Biol Psychiatry. 2005;58(3):226-32.

38.  Carter JC, Capone GT, Kaufmann WE. Neuroanatomic correlates of autism and stereotypy in children with Down syndrome. Neuroreport. 2008;19(6):653-6.

39.  Pierce K, Courchesne E. Evidence for a cerebellar role in reduced exploration and stereotyped behavior in autism. Biol Psychiatry. 2001;49(8):655-64.

40.  Temudo T, Oliveira P, Santos M, et al. Stereotypies in Rett syndrome: analysis of 83 patients with and without detected MECP2 mutations. Neurology. 2007;68(15):1183-7.

41.  Cuccaro ML, Nations L, Brinkley J, et al. A comparison of repetitive behaviors in Aspergers Disorder and high functioning autism. Child Psychiatry Hum Dev. 2007;37(4):347-60.

42.  Mandy WP, Skuse DH. Research review: What is the association between the social-communication element of autism and repetitive interests, behaviours and activities? J Child Psychol Psychiatry. 2008;49(8):795-808.

43.  Hollander E, Novotny S, Allen A, et al. The relationship between repetitive behaviors and growth hormone response to sumatriptan challenge in adult autistic disorder. Neuropsychopharmacology. 2000;22(2):163-7.

44.  Hollander E, Novotny S, Hanratty M, et al. Oxytocin infusion reduces repetitive behaviors in adults with autistic and Asperger's disorders. Neuropsychopharmacology. 2003;28(1):193-8.

45.  Lopez BR, Lincoln AJ, Ozonoff S, Lai Z. Examining the relationship between executive functions and restricted, repetitive symptoms of Autistic Disorder. J Autism Dev Disord. 2005;35(4):445-60.

46.  Bishop SL, Richler J, Lord C. Association between restricted and repetitive behaviors and nonverbal IQ in children with autism spectrum disorders. Child Neuropsychol. 2006;12(4-5):247-67.

47.  Schreck KA, Mulick JA, Smith AF. Sleep problems as possible predictors of intensified symptoms of autism. Res Dev Disabil. 2004; 25(1):57-66.

48.  Tang JC, Patterson TG, Kennedy CH. Identifying specific sensory modalities maintaining the stereotypy of students with multiple profound disabilities. Res Dev Disabil. 2003;24(6):433-51.

49.  Shprecher D, Kurlan R. The management of tics. Mov Disord. 2009;24(1):15-24.

50.  Gabriels RL, Cuccaro ML, Hill DE, Ivers BJ, Goldson E. Repetitive behaviors in autism: relationships with associated clinical features. Res Dev Disabil. 2005;26(2):169-81.

51.  Abramson RK, Ravan SA, Wright HH, et al. The relationship between restrictive and repetitive behaviors in individuals with autism and obsessive compulsive symptoms in parents. Child Psychiatry Hum Dev. 2005;36(2):155-65.

52.  Matson JL, Dempsey T, Lovullo SV, et al. The effects of intellectual functioning on the range of core symptoms of autism spectrum disorders. Res Dev Disabil. 2008;29(4):341-50.

53.  Matson JL, Wilkins J, Ancona M. Autism in adults with severe intellectual disability: an empirical study of symptom presentation. J Intellect Dev Disabil. 2008;33(1):36-42.

54.  Meilleur AA, Fombonne E. Regression of language and non-language skills in pervasive developmental disorders. J Intellect Disabil Res. 2009;53(2):115-24.

55.  Stoppelbein L, Greening L, Kakooza A. The importance of catatonia and stereotypies in autistic spectrum disorders. Int Rev Neurobiol. 2006;72:103-18.

56.  Zandt F, Prior M, Kyrios M. Repetitive behaviour in children with high functioning autism and obsessive compulsive disorder. J Autism Dev Disord. 2007;37(2):251-9.

57.  Matson JL, Hamilton M, Duncan D, et al. Characteristics of stereotypic movement disorder and self-injurious behavior assessed with the Diagnostic Assessment for the Severely Handicapped (DASH-II). Res Dev Disabil. 1997;18(6):457-69.

58.  Crosland KA, Zarcone JR, Schroeder S, et al. Use of an antecedent analysis and a force sensitive platform to compare stereotyped movements and motor tics. Am J Ment Retard. 2005;110(3):181-92.

59.  Singer HS. Motor stereotypies. Semin Pediatr Neurol. 2009;6(2)177-81.

60.  South M, Ozonoff S, McMahon WM. Repetitive behavior profiles in Asperger syndrome and high-functioning autism. J Autism Dev Disord2005 Apr;35(2):145-58.

61.  Fecteau S, Mottron L, Berthiaume C, et al. Developmental changes of autistic symptoms. Autism. 2003;7(3):255-68.

62.  Geschwind DH. Advances in autism. Annu Rev Med. 2009;60:367-80.

63.  Esbensen AJ, Seltzer MM, Lam KS, et al. Age-related differences in restricted repetitive behaviors in autism spectrum disorders. J Autism Dev Disord. 2009;39(1):57-66.

64.  Gritti A, Bove D, Di Sarno AM, et al. Stereotyped movements in a group of autistic children. Funct Neurol2003 Apr-Jun;18(2):89-94.

65.  Lam KS, Aman MG. The Repetitive Behavior Scale-Revised: independent validation in individuals with autism spectrum disorders. J Autism Dev Disord. 2007;37(5):855-66.

66.  Bourreau Y, Roux S, Gomot M, et al. Validation of the repetitive and restricted behaviour scale in autism spectrum disorders. Eur Child Adolesc Psychiatry. 2009;18(11):675-82.

67.  Lancioni GE, Singh NN, O'Reilly MF, et al. An overview of behavioral strategies for reducing hand-related stereotypies of persons with severe to profound intellectual and multiple disabilities: 1995-2007. Res Dev Disabil. 2009;30(1):20-43.

68.  Miller JM, Singer HS, Bridges DD, et al. Behavioral therapy for treatment of stereotypic movements in nonautistic children. J Child Neurol. 2006;21(2):119-25.

69.  Lundqvist LO, Andersson G, Viding J. Effects of vibroacoustic music on challenging behaviors in individuals with autism and developmental disabilities. Research in Autism Spectrum Disorders. 2009;3(2):390-400.

70.  Lee S, Odom SL, Loftin R. Social engagement with peers and stereotypic behavior of children with autism. Journal of Positive Behavior Interventions. 2007;9(2):67-79.

71.  Loftin RL, Odom SL, Lantz JF. Social interaction and repetitive motor behaviors. J Autism Dev Disord. 2008;38(6):1124-35.

72.  Malow BA, McGrew SG, Harvey M, Henderson LM, Stone WL. Impact of treating sleep apnea in a child with autism spectrum disorder. Pediatr Neurol. 2006;34(4):325-8.

73.  Symons F, Davis M. Instructional conditions and stereotyped behavior: the function of prompts. J Behav Ther Exp Psychiatry. 1994; 25(4):317-24.

74.  Smith LE, Greenberg JS, Seltzer MM, et al. Symptoms and behavior problems of adolescents and adults with autism: effects of mother-child relationship quality, warmth, and praise. Am J Ment Retard. 2008;113(5):387-402.

75.  Elliott RO, Dobbin AR, Rose GD, et al. Vigorous, aerobic exercise versus general motor training activities: effects on maladaptive and stereotypic behaviors of adults with both autism and mental retardation. J Autism Dev Disord. 1994;24(5):565-76.

76.  Escalona A, Field T, Singer-Strunck R, et al. Brief report: improvements in the behavior of children with autism following massage therapy. J Autism Dev Disord. 2001;31(5):513-6.

77.  Aman MG, McDougle CJ, Scahill L, et al. Medication and Parent Training in Children With Pervasive Developmental Disorders and Serious Behavior Problems: Results From a Randomized Clinical Trial. J Am Acad Child Adolesc Psychiatry. 2009. PMID: 19858761.

78.  Soorya L, Kiarashi J, Hollander E. Psychopharmacologic interventions for repetitive behaviors in autism spectrum disorders. Child Adolesc Psychiatr Clin N Am. 2008;17(4):753-71.

79.  Malone RP, Gratz SS, Delaney MA, et al. Advances in drug treatments for children and adolescents with autism and other pervasive developmental disorders. CNS Drugs. 2005;19(11):923-34.

80.  Ghanizadeh A. Does risperidone improve hyperacusia in children with autism? Psychopharmacol Bull. 2009;42(1):108-10.

81.  McDougle CJ, Scahill L, Aman MG, et al. Risperidone for the core symptom domains of autism: results from the study by the autism network of the research units on pediatric psychopharmacology. Am J Psychiatry. 2005;162(6):1142-8.

82.  McDougle CJ, Holmes JP, Carlson DC, et al. A double-blind, placebo-controlled study of risperidone in adults with autistic disorder and other pervasive developmental disorders. Arch Gen Psychiatry. 1998;55(7):633-41.

83.  Akhondzadeh S, Fallah J, Mohammadi MR, et al. Double-blind placebo-controlled trial of pentoxifylline added to risperidone: Effects on aberrant behavior in children with autism. Prog Neuropsychopharmacol Biol Psychiatry. 2010;34(1):32-6.

84.  Ghuman JK, Aman MG, Lecavalier L, et al. Randomized, Placebo-Controlled, Crossover Study of Methylphenidate for Attention-Deficit/Hyperactivity Disorder Symptoms in Preschoolers with Developmental Disorders. Journal of Child and Adolescent Psychopharmacology. 2009;19(4):329-39.

85.  Quintana H, Birmaher B, Stedge D, et al. Use of methylphenidate in the treatment of children with autistic disorder. J Autism Dev Disord. 1995;25(3):283-94.

86.  McDougle CJ, Kresch LE, Posey DJ. Repetitive thoughts and behavior in pervasive developmental disorders: treatment with serotonin reuptake inhibitors. J Autism Dev Disord. 2000;30(5):427-35.

87.  McDougle CJ, Brodkin ES, Naylor ST, et al. Sertraline in adults with pervasive developmental disorders: a prospective open-label investigation. J Clin Psycho­pharmacol. 1998;18(1):62-6.

88.  McDougle CJ, Naylor ST, Cohen DJ, et al. A double-blind, placebo-controlled study of fluvoxamine in adults with autistic disorder. Arch Gen Psychiatry. 1996;53(11):1001-8.

89.  King BH, Hollander E, Sikich L, et al. Lack of efficacy of citalopram in children with autism spectrum disorders and high levels of repetitive behavior: citalopram ineffective in children with autism. Arch Gen Psychiatry. 2009;66(6):583-90.

90.  Hollander E, Soorya L, Wasserman S, et al. Divalproex sodium vs. placebo in the treatment of repetitive behaviours in autism spectrum disorder. Int J Neuropsychopharmacol. 2006;9(2):209-13.

91.  Willemsen-Swinkels SH, Buitelaar JK, van Engeland H. The effects of chronic naltrexone treatment in young autistic children: a double-blind placebo-controlled crossover study. Biol Psychiatry. 1996;39(12):1023-31.

92.  Willemsen-Swinkels SH, Buitelaar JK, Nijhof GJ, et al. Failure of naltrexone hydrochloride to reduce self-injurious and autistic behavior in mentally retarded adults. Double-blind placebo-controlled studies. Arch Gen Psychiatry. 1995;52(9):766-73.

93.  Dhossche DM, Reti IM, Wachtel LE. Catatonia and autism: a historical review, with implications for electroconvulsive therapy. J ECT. 2009;25(1):19-22.

94.  Freeman RD, Soltanifar A, Baer S. Stereotypic movement disorder: easily missed. Dev Med Child Neurol. 2010. PMID: 20187883.