The influence of anxiety and pain sensitivity on experimental pain in man

TLDR

Experimental pain studies in humans often yield unreliable results due to various influencing factors. The study examined how aspirin, practice, baseline pain sensitivity, anxiety, coping, attitude, and personality affect experimental pain test outcomes. A randomized, double‑blind, cross‑over design with 32 healthy male volunteers performed an ischemic pain test and psychological assessments. Aspirin had no analgesic effect, pain sensitivity interacted with drug order, and anxiety markedly influenced results, making reliable experimental pain outcomes unlikely.

Abstract

A study was made of a number of factors that might be responsible for the unreliable results obtained in experimentally induced pain in man. In a randomised, double-blind, cross-over study on 32 healthy, male volunteers, the ischaemic pain test [14] and several psychological tests were performed. The influence of the following factors on the pain test results were examined: (a) ingestion of single, oral doses of 1000 mg aspirin (ASA) and placebo, (b) practice effect, (c) initial pain sensitivity, (d) anxiety, coping behaviour, attitude to the experiment and personality factors. The analgesic activity of ASA could not be demonstrated. An interaction between primary pain sensitivity and the sequence of drug administration was found. Furthermore, anxiety had a marked influence on the test results. Using experimental pain models reliable results are not to be expected as anxiety fluctuates intra- and interindividually in an unpredictable and uncontrollable manner.