title: Can personality traits and gender predict the response to morphine? An experimental cold pain study.
abstract: The aim of the present study was to examine the possible role of personality traits, in accordance with Cloninger's theory, and gender, in the variability of responsiveness to opioids. Specifically, it was intended to test whether or not the three personality dimensions - harm avoidance (HA), reward dependence (RD) and novelty seeking (NS) - as suggested by Cloninger, can predict inter-personal differences in responsiveness to morphine after exposure to experimental cold pain. Thirty-four healthy volunteers (15 females, 19 males) were given the cold pressor test (CPT). Pain threshold, tolerance, and magnitude (VAS) were measured before and after (six measures, 30 min apart) the administration of either 0.5 mg/kg oral morphine sulphate (n=21) or 0.33 mg/kg oral active placebo (diphenhydramine) (n=13) in a randomized, double blind design. Assessment of the three personality traits, according to Cloninger's Tridimensional Personality Questionnaire, was performed before the CPT. A high HA score (but not RD, NS, or baseline values of the three pain parameters) predicted a significantly larger pain relief following the administration of morphine sulphate (but not of the placebo). Women exhibited a larger response in response to both treatments, as indicated by a significantly increased threshold and tolerance following morphine sulphate as well as significantly increased tolerance and decreased magnitude following placebo administration. The present study confirms the existence of individual differences in response to analgesic treatment. It suggests that high HA personality trait is associated with better responsiveness to morphine treatment, and that females respond better than men to both morphine and placebo.
authors.affiliation: Pain Relief Unit, Rambam Medical Center, Haifa, Israel. doritpud@research.haifa.ac.il
authors.forename: Dorit
authors.initials: D
authors.lastname: Pud
authors.forename: David
authors.initials: D
authors.lastname: Yarnitsky
authors.forename: Elliot
authors.initials: E
authors.lastname: Sprecher
authors.forename: Zeev
authors.initials: Z
authors.lastname: Rogowski
authors.forename: Rivka
authors.initials: R
authors.lastname: Adler
authors.forename: Elon
authors.initials: E
authors.lastname: Eisenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D001519:Behavior; D003080:Cold Temperature; D005106:Exploratory Behavior; D005260:Female; D006801:Humans; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D017288:Pain Threshold / Q000187:drug effects* / Q000523:psychology*; D010465:Perception; D010551:Personality; D010919:Placebos; D011237:Predictive Value of Tests; D012201:Reward; D012737:Sex Factors
chemical_list: D000701:Analgesics, Opioid; D010919:Placebos; D009020:Morphine