Performance on the CVLT-2 during induced pain

Objective: Chronic pain patients frequently report cognitive problems including learning and memory. However, recent research involving induced pain has demonstrated an absence of reliably detectable decrements on several standard cognitive measures, suggesting that factors other than pain likely explain perceived cognitive deficits in chronic pain patients. This study examined potential effects of induced pain on verbal learning and memory as measured by the California Verbal Learning Test (CVLT-2). Potential effects of self-reported pain intensity were also evaluated. Method: Participants (111 non-clinical undergraduate students in the Southwestern United States) completed one version (Standard or Alternate) of the CVLT-2 under normal conditions, and then were administered the other version (Alternate or Standard) either while experiencing cold pressor-induced pain (Pain condition) or non-painful warm water immersion (Control condition). Results: For the Pain condition decrements in performance across most CVLT-2 variables were observed, including a mean T-score decrease of 10.98 (SD = 10.99) for Trials 1-5, whereas the comparable decrease in the Control condition was an average of 1.5 words (SD = 8.27). Self-reported pain intensity was significantly correlated with the degree of Time 1 to Time 2 performance decrement for Short-Delay Free Recall (r = -.51, p < .050), but not for Trials 1-5 (r = -.37, p = .160). Conclusion: Induced pain produces detectable decrements in performance on a standard clinical measure of verbal learning and memory performance, suggesting that pain in clinical populations may contribute to learning and memory deficits apart from potential neurological conditions.