reptitiously reduced following the first cream application to produce condi- .... of analgesics were assessed before pain testing using a custom-built question-.
Abstracts
The Journal of Pain
S53
E12 Cognitive, Behavioural, and Clinical Neurosciences (Pain and Mood; Placebo/Nocebo)
(310) Sensitization to laboratory pain stimuli in healthy children and adolescents is associated with higher ratings of anxiety, pain intensity, and pain bother
(308) Optimism is not associated with the nociceptive flexion reflex (NFR), but is associated with placebo analgesia
L Seidman, K Lung, B Naliboff, L Zeltzer, and J Tsao; University of California, Los Angeles, Los Angeles, CA
€ereca, S Palit, and J Rhudy; The University of Tulsa, Tulsa, OK B Kuhn, Y Gu
Sensitization is defined as an increased response to repeated stimuli and is hypothesized to represent a behavioral marker of central pain processing. Few studies have analyzed sensitization to laboratory pain stimuli in children and adolescents. In this protocol, 137 healthy children and adolescents (51.8% girls, mean age=12.5 years) completed an Evoked Pressure (EP) task consisting of a series of 5-second pressure applications (10s between trials) to the thumbnail. Sequential pressure applications varied according to subjects’ prior response using a staircase procedure with a target threshold of moderate pain (ratings of 5-6 on a 0-10 numeric rating scale (NRS)). After the EP, a conditioned pain modulation (CPM) task beginning with a test stimulus (TS) of thumb pressure was administered. The amount of pressure applied as the TS matched the pressure participants had previously rated a 5-6 during the EP. Participants were grouped as habituators (n=47), consistent (n=53), or sensitizers (n=37) based on their response to the first TS, delivered 20 minutes following the EP (ratings of 0-4, 5-6, or 7-10, respectively). Participants also used the NRS to rate anticipatory anxiety prior to, and anxiety, pain intensity, and pain bother experienced during the CPM task. Univariate ANCOVAs controlling for age revealed significant group differences in all measures (F’s=4.43-14.43, all p’s .05), however, these variables were conservatively controled in the analyses. Left and right hippocampal volumes were compared between groups using a multivariate GLM with covariates of age and tGMV. Both left and right hippocampi showed volume reductions in FM independent of age and tGMV (p=.013, partial eta2 = .083; p=.007, partial eta2 = .096). Hippocampal dysfunction appears to be an important concomitant of the symptomology of FM. These volumetric reductions were hypothesized as a consequence of the disorder, however longitudinal studies are needed to clarify this relationship. The project described was supported by R01AR055160, and R01AR055160-S1 ARRA Supplement from the National Institute of Arthritis and Musculoskeletal and Skin Diseases, as well as R01AT001424-05 from the National Center for Complimentary and Alternative Medicine.
(311) Attitudes toward analgesic medications are associated with the degree of placebo analgesia: preliminary finding Y Guereca, B Kuhn, S Palit, and J Rhudy; The University of Tulsa, Tulsa, OK Placebo analgesia is pain reduction induced by a sham treatment and is mediated by at least two psychological factors: expectations for pain relief and classical conditioning (e.g., pairing an inert treatment with pain reduction). Although placebo analgesia is a replicable effect at the group level, there are tremendous individual differences in the degree to which individuals respond to a placebo manipulation. The present study evaluated whether attitudes about analgesics were associated with the magnitude of placebo responding. 65 healthy, pain-free individuals were randomly assigned to a natural history control group (NH, n=16), or one of three placebo manipulations: expectation-only (E, n=15), conditioning-only (C, n=18), or expectations and conditioning (E+C, n=16). Suprathreshold electric stimulations were delivered to the ankle to evoke pain before and after two inert cream applications. The E+C and E groups were told the cream was a powerful painkiller (Lidocaine) whereas the NH and C groups were told the cream was additional sensor gel. Following the first cream application, stimulus intensity was surreptitiously lowered in E+C and C to produce conditioning (ie, cream paired with pain relief). Stimulus intensity was not lowered after the second cream application; therefore, placebo response was defined as the change in pain associated with the second cream application. Negative attitudes about the importance of analgesics were assessed before pain testing using a custom-built questionnaire. To address problematic outliers greater than 2 standard deviations, variables were Winsorized (if necessary). Results indicated that negative attitudes about the importance of analgesic medications were associated with reduced placebo response (r=.26, p
