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J Clin Psychiatry. 2018 Mar/Apr;79(2). pii: 16m10889. doi: 10.4088/JCP.16m10889.

Relationships Between Self-Injurious Behaviors, Pain Reactivity, and β-Endorphin in Children and Adolescents With Autism.

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PHUPEA (Pôle Hospitalo-Universitaire de Psychiatrie de l'Enfant et de l'Adolescent), CHGR, Université de Rennes 1, 154 rue de Châtillon, Rennes 35000, France.
Hospital-University Department of Child and Adolescent Psychiatry, CHGR and University of Rennes 1, Rennes, France.
Laboratory of Psychology of Perception, CNRS UMR 8158, Paris, France.
Child Study Center, Yale University School of Medicine, New Haven, Connecticut, USA.
Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, Siena, Italy.
Hospital-University Department of Child and Adolescent Psychiatry, UBO, Brest, France.
University Paris 8, Saint Denis, France.
INSERM U 693, University Paris-South, School of Medicine Paris-South; AP-HP, CHU Bicêtre, Department of Molecular Genetics, Pharmacogenetics and Hormonology, Kremlin-Bicêtre, France.
Department of Child and Adolescent Psychiatry, AP-HP, GH Pitié-Salpétrière, CNRS FRE 2987, University Pierre and Marie Curie, Paris, France.
Aix Marseille University, CNRS, LPC, Marseille, France.
Laboratory of Public Health EA3279, School of Medicine of La Timone, Marseille, France.
Center of Excellence for Pervasive Developmental Disorders of the University of Montreal (CETEDUM), Rivières-des-Prairies Hospital, Montreal, Quebec, Canada.
Research Center of CIUSSS of the North of Montreal and Department of Psychiatry, University of Montreal, Montreal, Quebec, Canada.



Autism and certain associated behaviors including self-injurious behaviors (SIB) and atypical pain reactivity have been hypothesized to result from excessive opioid activity. The objective of this study was to examine the relationships between SIB, pain reactivity, and β-endorphin levels in autism.


Study participants were recruited between 2007 and 2012 from day care centers and included 74 children and adolescents diagnosed with autism (according to DSM-IV-TR, ICD-10, and CFTMEA) and intellectual disability. Behavioral pain reactivity and SIB were assessed in 3 observational situations (parents at home, 2 caregivers at day care center, a nurse and child psychiatrist during blood drawing) using validated quantitative and qualitative scales. Plasma β-endorphin concentrations were measured in 57 participants using 2 different immunoassay methods.


A high proportion of individuals with autism displayed SIB (50.0% and 70.3% according to parental and caregiver observation, respectively). The most frequent types of SIB were head banging and hand biting. An absence or decrease of overall behavioral pain reactivity was observed in 68.6% and 34.2% of individuals with autism according to parental and caregiver observation, respectively. Those individuals with hyporeactivity to daily life accidental painful stimuli displayed higher rates of self-biting (P < .01, parental evaluation). No significant correlations were observed between β-endorphin level and SIB or pain reactivity assessed in any of the 3 observational situations.


The absence of any observed relationships between β-endorphin level and SIB or pain reactivity and the conflicting results of prior opioid studies in autism tend to undermine support for the opioid theory of autism. New perspectives are discussed regarding the relationships found in this study between SIB and hyporeactivity to pain.

[Indexed for MEDLINE]

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