Comment on article "Does pain confound interpretation of neuropsychological test results?"

Abstract

Nicholson, Martelli and Zasler conclude their review by stating “Future studies should be informed by an understanding of the psychology of chronic pain, as well as more rigorous neuropsychological methodology”. We can only agree with this conclusion because there has been a lack of rigour in past research, much of which has simply assumed that low test scores in patients are equivalent to cognitive impairment. It is possible that chronic pain does affect cognition but we cannot be sure of this until the effects of incomplete effort on tests have been controlled properly. In this review, Nicholson, Martelli and Zasler did not quote the study in which people with chronic complaints after whiplash injuries were given an effort test, the Amsterdam Short Term Memory Test (ASTM, Schmand, 1997). Based on their ASTM results, 61% of patients were found to be exaggerating their memory impairment on formal testing. Hence, their other ability test results would be presumed to be invalid. On the other hand, the latter study was quoted by Hart et al. [5], in a review of neuropsychological functioning in chronic pain patients. These authors concluded that tests of response bias and motivation should be used in evaluating chronic pain patients, who are involved in litigation or seeking wage replacement benefits. Logically, effort tests should be used not only in clinical cases but also in all group studies of chronic pain patients. If not, the results of any study of cognition and