The effect of high versus low cognitive load on the development of nociceptive hypersensitivity: The roles of sympathetic arousal, sex and pain‐related fear

Abstract

Background: According to limited-capacity theories of attention, less attentional resources remain available when engaging in a high-versus a low-demanding cognitive task. This may reduce the perceived intensity and the evoked cortical responses of concomitant nociceptive stimuli. Whether and how the competition for limited attentional resources between a cognitive task and pain impacts the development of long-lasting hypersensitivity is unclear.Methods: Eighty-four healthy participants were randomized into a low or high cognitive load group. Low-frequency electrical stimulation (LFS) of the skin was used to induce secondary hypersensitivity. We hypothesized that performing the high-load task during LFS would reduce the development of hypersensitivity. We examined whether painfulness, nonpain-related sympathetic arousal, or sex related to hypersensitivity, by assessing intensity and unpleasantness of mechanical pinprick stimulation. During task execution, we recorded steady-state evoked potentials evoked by LFS and skin conductance level for sympathetic arousal.Afterwards, participants reported task difficulty and LFS-related fear. For the primary outcomes, we used mixed analysis of variances. Results:The results confirmed the difference in cognitive load. Although LFS successfully induced hypersensitivity, the high-load task did not reduce its development. Next, the steady-state evoked potentials did not differ between groups.Hypersensitivity correlated positively with pain-related fear and negatively with skin conductance level before LFS, despite the lack of group differences in skin conductance level. We did not find any sex differences in hypersensitivity.Conclusions: These results do not confirm that high cognitive load or sex modulate hypersensitivity, but show associations with pain-related fear and non-painrelated sympathetic arousal.Significance: Previous research has mainly focused on cognitive load effects on the perception of acute painful stimuli. Yet this study extends our understanding by investigating cognitive load effects on the development of long-lasting secondary hypersensitivity, a common aspect in numerous persistent pain conditions.As cognitive tasks are presented during a painful procedure inducing secondary

The impact of the social context on the development of secondary hyperalgesia: an experimental study

“…22,32,45,58,68 Importantly however, other recent studies that have used similar electrical stimulation protocols have found either modest or no modulation of SH. 4,18,48,66 This apparent difficulty may be due to the intense nature of the electrical stimulation and the large magnitude of SH that these procedures induce (eg, h p 2 5 0.47 in the current study). In addition, MFS stimulation induces the largest increase in perceived pinprick intensity compared with other frequencies.…”

“…Most studies that have attempted to modulate SH by attentional effects have focused on the stimulation period. 22,48,65 Any distraction caused by the presence of the partner during the stimulation may have been minimized since providing ratings for the MFS stimulation would have kept participants' attention focused on the stimulation. This, however, remains a possibility that cannot entirely be excluded.…”

Top-down Attention Does not Modulate Pain Sensitization: Insights from an Experimental Analysis

“…Progress in this field has been made by investigating how psychological factors affect pain sensitization [5,6,16,22,29,42,44,45,55,64,66,72] and the subsequent development of secondary hypersensitivity -characterized by a long-lasting increased mechanical pinprick sensitivity in the area surrounding an injured or inflamed site [30,32,52,63]. For instance, Torta et al [64] found that performing an n-back (working memory updating) task during the application of electrocutaneous stimulation reduced consecutive mechanical hypersensitivity, while performing a Flanker (inhibition) task resulted in its enhancement.…”

“…As the two tasks rely on different cognitive processes, it is challenging to directly compare the two solely based on their level of demand. To overcome this limitation, Meyers et al [45] compared two levels of difficulties of the n-back task (0-vs.2-back), but they did not observe a significant difference in secondary hypersensitivity. The same results were obtained in a follow-up study with a within-subjects design, including a control condition with no task [44].…”

“…This helped ensure that observed differences were due to attentional load, rather than task nature. Lastly, our between-subject design allowed us to test our hypothesis using a two-way interaction, which is an improvement over the conventional use of a three-way interaction (e.g., [45,64]). Higherorder interactions are difficult to interpret and greatly increase the sample size required to detect an effect, relative to a two-way interaction [27].…”