title: A more pessimistic life orientation is associated with experimental inducibility of a neuropathy-like pain pattern in healthy individuals.
abstract: The clinical pattern of neuropathic pain, diagnosed using the quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain), could be partly mimicked in healthy volunteers after topical capsaicin application. However, similar to clinical neuropathic pain that develops in only a subgroup of patients who have a neurologic lesion, this attempt to mimick a neuropathic pain pattern succeeded only in a small fraction (18%) of healthy individuals. In the present assessment, we pursued the hypothesis that the inducible subgroup differed from the other healthy participants with respect to their psychological phenotype. Therefore, in an observational study, participants were assessed using a comprehensive set of psychological variables comprising general psychological and pain-related cognitive-emotional mechanisms. The sum scores of the questionnaires were significantly linearly correlated with each other. Principal component analysis indicated that a major source of variance (46%) could be attributed to dispositional optimism examined via the Life Orientation Test (LOT). The LOT score significantly differed between the groups of participants, either those in whom a neuropathy-like pattern of pain assessed via QST could be partly (50-60% of the 11 QST parameters) induced (n = 20) or not (n = 90; P = .0375). It emerged again as the main selection criterion in a classification and regression tree predicting a participant's group assignment (inducible neuropathy-like QST pattern versus noninducible neuropathy-like QST pattern) at a cross-validated accuracy of 95.5 ± 2.1%. Thus, the few participants in a random sample of healthy volunteers who, after topical capsaicin application, partly resemble (to a degree of about 60%) the clinical pattern of neuropathic pain in the QST test battery, are preselectable on the basis of psychological factors, with a particular emphasis on pessimistic life attitudes.
  
  
  CONCLUSIONS
  In a small fraction of 18% of healthy volunteers, topical capsaicin application resulted in a neuropathy-like pattern in 50 to 60% of the components of a clinical test battery. These individuals displayed a more pessimistic life attitude as assessed by means of the LOT.
authors.affiliation: Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany.
authors.forename: Violeta
authors.initials: V
authors.lastname: Dimova
authors.affiliation: Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany.
authors.forename: Bruno G
authors.initials: BG
authors.lastname: Oertel
authors.affiliation: Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Gülden
authors.initials: G
authors.lastname: Kabakci
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Zimmermann
authors.affiliation: Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Hanneke
authors.initials: H
authors.lastname: Hermens
authors.affiliation: Physiological Psychology, Otto-Friedrich University Bamberg, Bamberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lautenbacher
authors.affiliation: DataBionics Research Group, University of Marburg, Marburg, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Ultsch
authors.affiliation: Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany. Electronic address: j.loetsch@em.uni-frankfurt.de.
authors.forename: Jörn
authors.initials: J
authors.lastname: Lötsch
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D002211:Capsaicin / Q000633:toxicity; D003072:Cognition Disorders / Q000209:etiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D019964:Mood Disorders / Q000209:etiology*; D009437:Neuralgia / Q000139:chemically induced / Q000150:complications* / Q000523:psychology*; D000067656:Optimism; D010147:Pain Measurement; D025341:Principal Component Analysis; D018689:Sensory System Agents / Q000633:toxicity; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D018689:Sensory System Agents; D002211:Capsaicin
keywords: Dispositional optimism; catastrophizing; experimental pain; healthy individuals; quantitative sensory testing