title: Apolipoprotein E ɛ4, Cognitive Function, and Pain Experience in Down Syndrome: A Pilot Study.
abstract: OBJECTIVE
  The presence of apolipoprotein E (ApoE) ɛ4 allele might be related to higher pain experience due to increased risk for potentially painful physical conditions and cognitive impairment (less efficient coping with pain). This hypothesis is clinically relevant to examine in adults with Down syndrome (DS) because they are at risk for painful physical conditions, their presence of ApoE ε4 is related to cognitive impairment, and their pain experience is unclear. The present pilot study addressed the associations between ApoE genotype, cognition, and pain in DS.
  
  
  METHODS
  DNA analysis of saliva, neuropsychological tests (assessing memory and executive functioning), and self-reporting pain scales (in rest and after movement) were used with a cross-sectional design in 146 adults with DS (mean age 39.1 years, mild to moderate intellectual disabilities, 46% men, 30% ApoE ɛ4 carrier).
  
  
  RESULTS
  The difference between ApoE ɛ4 carriers and noncarriers was not statistically significant for cognitive function, pain experience, and prevalence of potentially painful conditions. Among ɛ4 carriers, the presence of potentially painful conditions was associated with worse executive functioning (p = .022, r = .39).
  
  
  CONCLUSIONS
  The clinical implication of the results is that ApoE ɛ4 in DS may play a role in pain, although the theoretical explanation via associations with pain experience and cognition remains unclear. Further research should include a large sample of adults with DS selected on diagnosed painful conditions to obtain more insight into the possible role of ApoE genotype (and its association with cognition) in the pain experience of this target group.
authors.affiliation: Department of Clinical Neuropsychology, VU University, 1081 BT Amsterdam, The Netherlands nc.de.knegt@vu.nl.
authors.forename: Nanda C
authors.initials: NC
authors.lastname: de Knegt
authors.affiliation: Department of Clinical Child and Family Studies, VU University, 1081 BT Amsterdam, The Netherlands.
authors.forename: Carlo
authors.initials: C
authors.lastname: Schuengel
authors.affiliation: Department of General Practice, Erasmus MC University Medical Centre, 3015 CE Rotterdam, The Netherlands.
authors.forename: Heleen M
authors.initials: HM
authors.lastname: Evenhuis
authors.affiliation: Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam, 1081 LA Amsterdam, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Lobbezoo
authors.affiliation: Department of Clinical Neuropsychology, VU University, 1081 BT Amsterdam, The Netherlands.
authors.forename: Erik J A
authors.initials: EJ
authors.lastname: Scherder
mesh_terms: D000328:Adult; D000339:Affect; D053327:Apolipoprotein E4 / Q000235:genetics*; D003072:Cognition Disorders / Q000209:etiology* / Q000235:genetics; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics*; D005260:Female; D056726:Genetic Association Studies; D006801:Humans; D008607:Intellectual Disability / Q000209:etiology / Q000235:genetics; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000235:genetics; D008875:Middle Aged; D009483:Neuropsychological Tests; D010146:Pain / Q000209:etiology* / Q000235:genetics / Q000523:psychology; D010147:Pain Measurement; D010775:Photic Stimulation; D010865:Pilot Projects; D011569:Psychiatric Status Rating Scales; D057566:Self Report; D055815:Young Adult
chemical_list: D053327:Apolipoprotein E4
keywords: Chronic pain; Developmental and learning disabilities; Executive functions; Genotype studies