Cognitive impairment in patients with chronic whiplash-associated disorder--a matched control study

Aim: To verify the occurrence of cognitive impairment in patients with chronic whiplash-associated disorder (WAD) and to provide a more detailed description of the impairment's character and context. Methods: Thirty (30) patients with chronic WAD and 30 matched healthy controls completed a cognitive test battery. Four computerised tests were used: a) two different types of cognitive tasks (reaction time vs. working memory) and b) two types of information processing (verbal vs. spatial). Before testing and after every randomised subtest, subjects rated their pain level on a visual analogue scale. Results: A worse overall performance among patients with WAD and, specifically, worse results concerning working memory tasks were found. Post-hoc testing revealed a statistically significant difference concerning the single variable "verbal reaction time". Pain intensity among patients increased significantly during testing. Pain intensity after the subtest for verbal mental reaction time (independent of test sequence) was significantly correlated with results in this subtest, the more pain, the more time was needed. Conclusion: Compared to healthy controls, patients performed worse overall. Concerning verbal reaction time, the impairment was correlated with pain intensity. The findings support the hypothesis that pain might be one important factor leading to cognitive impairment in patients with chronic WAD.