title: Plasma beta-endorphin concentrations in people with learning disability and self-injurious and/or autistic behaviour.
abstract: BACKGROUND
  It has been suggested that the key variable in reduced plasma immunoreactive beta-endorphin concentrations in autistic subjects may be concomitant self-injurious behaviour.
  
  
  METHODS
  We studied morning levels of plasma beta-endorphin in 33 learning disabled people with self-injurious and/or autistic behaviour.
  
  
  RESULTS
  The beta-endorphin level of the subjects with severe self-injurious behaviour proved to be significantly lower than of autistic subjects without severe self-injurious behaviour (3.6 (1.4) pmol/l v. 5.8 (4.3) pmol/l; t-test: P = 0.045. Replication: 3.7 (1.1) pmol/l v. 5.7 (3.8) pmol/l; t-test: P = 0.043). Individuals with mild and occasional self-injurious behaviour were found to have beta-endorphin levels comparable to those without self-injurious behaviour. Further, subjects being treated with neuroleptics and lower beta-endorphin levels than untreated subjects.
  
  
  CONCLUSIONS
  These results stress that in any study of opioid systems of learning disabled people, it is very important to differentiate between people with and without severe self-injurious behaviour. The results support the idea that severe self-injurious behaviour may be related to functional disturbances in the endogenous opioid system.
authors.affiliation: Rudolf Magnus Institute for Neurosciences, Department of Child and Adolescent Psychiatry, Utrecht University, The Netherlands.
authors.forename: S H
authors.initials: SH
authors.lastname: Willemsen-Swinkels
authors.forename: J K
authors.initials: JK
authors.lastname: Buitelaar
authors.forename: F G
authors.initials: FG
authors.lastname: Weijnen
authors.forename: J H
authors.initials: JH
authors.lastname: Thijssen
authors.forename: H
authors.initials: H
authors.lastname: Van Engeland
mesh_terms: D000328:Adult; D001321:Autistic Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D001921:Brain / Q000503:physiopathology; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D007859:Learning Disabilities / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D008297:Male; D011569:Psychiatric Status Rating Scales; D011957:Receptors, Opioid / Q000502:physiology; D016728:Self-Injurious Behavior / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D001615:beta-Endorphin / Q000097:blood*
chemical_list: D011957:Receptors, Opioid; D001615:beta-Endorphin