Timing and gender determine if acute pain impairs working memory performance

Temporal summation of second pain is affected by cognitive load

This work attempted to clarify the interaction of cognition and pain sensitization during a paradigm of Temporal Summation of Second Pain (TSSP). We analyzed pain ratings and electroencephalographic (EEG) activity obtained from 21 healthy participants during the presentation of four experimental conditions that differed in the manipulation of attention to painful stimuli or working memory load (Attention to hand & TSSP; 0-back & TSSP (low cognitive load); 2-back & TSSP (high cognitive load); 2-back (without pain)). We found that the TSSP was reduced when the attention was diverted and the cognitive load increased, and this reduction was accompanied by higher midfrontal theta activity and lower posterior alpha and central beta activity. Although it is well established that TSSP is a phenomenon that occurs at the spinal level, here we show that it is also affected by supraspinal attentional mechanisms. Delivery of painful repeated stimuli did not affect the performance of the 2-back task but was associated with smaller amplitudes of attentional event-related potentials (ERPs) after standard stimuli (not the target). The study of brain activity during TSSP allowed to clarify the role of top-down attentional modulation in pain sensitization processes. Results contribute to a better understanding of cognitive dysfunction in pain conditions and reinforce the use of therapeutic strategies based on distracting attention away from pain.

Neutral auditory words immediately followed by painful electric shock may show reduced next-day recollection

In this study, we investigated the effect of experimentally delivered acute pain on memory. Twenty-five participants participated in experimental sessions on consecutive days. The first session involved a categorization task to encourage memory encoding. There were two conditions, presented in randomized order, in which participants listened to a series of words, which were repeated three times. In one condition, one-third of the word items were immediately followed by a painful electrical shock. This word-shock pairing was consistent across repetition and the pain-paired items were presented unpredictably. In the other condition, all word items were not associated with pain. Response times over these repeated presentations were assessed for differences. Explicit memory was tested the following day, employing a Remember-Know assessment of word recognition, with no shocks employed. We found evidence that recollection may be reduced for pain-paired words, as the proportion of correct Remember responses (out of total correct responses) was significantly lower. There were no significant reductions in memory for non-pain items that followed painful stimulation after a period of several seconds. Consistent with the experience of pain consuming working memory resources, we theorize that painful shocks interrupt memory encoding for the immediately preceding experimental items, due to a shift in attention away from the word item.

Working Memory Performance, Pain and Associated Clinical Variables in Women With Fibromyalgia

Working memory (WM) is a critical process for cognitive functioning in which fibromyalgia (FM) patients could show cognitive disturbances. Dyscognition in FM has been explained by interference from pain processing, which shares the neural substrates involved in cognition and may capture neural resources required to perform cognitive tasks. However, there is not yet data about how pain is related to WM performance, neither the role that other clinical variables could have. The objectives of this study were (1) to clarify the WM status of patients with FM and its relationship with nociception, and (2) to determine the clinical variables associated to FM that best predict WM performance. To this end, 132 women with FM undertook a neuropsychological assessment of WM functioning (Digit span, Spatial span, ACT tests and a 2-Back task) and a complete clinical assessment (FSQ, FIQ-R, BDI-1A, HADS, PSQI, MFE-30 questionnaires), including determination of pain thresholds and tolerance by pressure algometry. Patients with FM seem to preserve their WM span and ability to maintain and manipulate information online for both visuospatial and verbal domains. However, up to one-third of patients showed impairment in tasks requiring more short-term memory load, divided attention, and information processing ability (measured by the ACT task). Cognitive performance was spuriously related to the level of pain experienced, finding only that pain measures are related to the ACT task. The results of the linear regression analyses suggest that sleep problems and fatigue were the variables that best predicted WM performance in FM patients. Future research should take these variables into account when evaluating dyscognition in FM and should include dynamic measures of pain modulation.

Pain Catastrophizing Mediates and Moderates the Link Between Acute Pain and Working Memory

The bidirectional relationship between pain and working memory (WM) deficits is well-documented but poorly understood. Pain catastrophizing-exaggerated, negative cognitive and emotional responses toward pain-may contribute to WM deficits by occupying finite, shared cognitive resources. The present study assessed the role of pain catastrophizing as both a state-level process and trait-level disposition in the link between acute pain and WM. Healthy, young adults were randomized to an experimentally-induced ischemic pain or control task, during which they completed verbal and non-verbal WM tests. Participants also completed measures of state- and trait-level pain catastrophizing. Simple mediation analyses indicated that participants in the pain group (vs. control) engaged in more state-level catastrophizing about pain, which led to worse verbal and non-verbal WM. Moderated mediation analyses indicated that the indirect (mediation) effect of state-level pain catastrophizing was moderated by trait-level pain catastrophizing for both verbal and non-verbal WM. Participants in the pain group who reported a greater trait-level tendency to catastrophize about pain experienced greater state-level catastrophizing about pain during the ischemic task, which led to worse verbal and non-verbal WM performance. These results provide evidence for pain catastrophizing as an important mechanism and moderating factor of WM deficits in acute pain. Future research should replicate these results in chronic pain samples, investigate other potential mechanisms (e.g., sleep disturbances), and determine if interventions that target pain catastrophizing directly can ameliorate cognitive deficits in people with pain. PERSPECTIVE: This article presents a laboratory study examining the relationships among pain, pain catastrophizing, and working memory in healthy participants. The results shed new light on these relationships and raise the possibility that interventions that reduce catastrophizing may lead to improved cognitive function among people with pain.

Pain memory in patients with chronic pain versus asymptomatic individuals: A prospective cohort study

BACKGROUND

The main objective of this study was to assess pain memory as well as long-term episodic memory, both in patients with chronic pain (CP) and in asymptomatic participants (AP).

METHODS

A prospective cohort study design was used. Sixty-eight participants were divided into two groups: CP (n = 34) and AP (n = 34). The protocol consisted of taking eight tests, four painful provocation tests and four distracting tests, and completing a memory test on the order of the tests at the end of the experiment and at 1-month post-experiment.

RESULTS

Patients with CP showed acceptable concordance in the classification, in ascending order from lower to higher pain perception, both post-experiment and 1-month post-experiment (κ = 0.41-0.60, p < .001). No differences were found regarding recall of the order of the tests, but differences were found in painful tests isolated only post-experiment in the CP group with a moderate effect size (p < .05, d = 0.77).

CONCLUSIONS

Patients with CP had a more reliable memory than AP in relation to the memory of the pain caused experimentally until at least 1 month after the experiment. Interspersing distraction tests appeared to result in increased complexity and difficulty in coding and decoding information in patients with CP, leading to similar reliable long-term memory consolidation in comparison with AP.

SIGNIFICANCE

Treatments directed towards chronic pain should consider the influence of painful memories and their establishment towards long-term explicit episodic memories in patients with chronic pain, as well as the influence of cognitive-evaluative and affective-motivational variables on memory. Not causing pain while implementing a treatment whose objective is to reduce pain could reduce the probability of developing new painful memories in patients with chronic pain.

Memory for non-painful auditory items is influenced by whether they are experienced in a context involving painful electrical stimulation

In this study, we sought to examine the effect of experimentally induced somatic pain on memory. Subjects heard a series of words and made categorization decisions in two different conditions. One condition included painful shocks administered just after presentation of some of the words; the other condition involved no shocks. For the condition that included painful stimulations, every other word was followed by a shock, and subjects were informed to expect this pattern. Word lists were repeated three times within each condition in randomized order, with different category judgments but consistent pain-word pairings. After a brief delay, recognition memory was assessed. Non-pain words from the pain condition were less strongly encoded than non-pain words from the completely pain-free condition. Recognition of pain-paired words was not significantly different than either subgroup of non-pain words. An important accompanying finding is that response times to repeated experimental items were slower for non-pain words from the pain condition, compared to non-pain words from the completely pain-free condition. This demonstrates that the effect of pain on memory may generalize to non-pain items experienced in the same experimental context.

Empathy skill-dependent modulation of working memory by painful scene

As an important online information retaining and processing function, working memory plays critical roles in many other cognitive functions. Several long-term factors, such as age, addiction and diseases, have been affirmed to impair working memory, but whether or how the short-term factors, like painful stimuli or emotions, regulate the human working memory ability is not well explored. Here we investigated the influences of empathic pain on upcoming working memory and existing working memory, by presenting human subjects with the pictures depicting painful or neutral scene. After separating the subjects into two groups, the more empathic group and relatively indifferent group, according to a well-accepted questionnaire (the Interpersonal Reactivity Index (IRI)), the modulatory effect emerged. Empathic pain might exerted either a facilitating effect or an impairing effect, which was closely correlated with the personal empathy skills. Meanwhile, different aspects of subjects’ empathy traits exerted distinct effects, and female subjects were more vulnerable than male subjects. Present study reveals a new modulatory manner of the working memory, via empathy skill-dependent painful experience.

Validating the factor structure and testing measurement invariance of modified Short-Form McGill Pain Questionnaire (Ortho-SF-MPQ) for orthodontic pain assessment

OBJECTIVE

To validate the factor structure of recently modified Short-Form McGill Pain Questionnaire (Ortho-SF-MPQ) to assess orthodontic pain; and to test its Measurement Invariance (MI) across gender.

METHODS

180 orthodontic patients were enrolled in this study. 0.016 inch Super-elastic NiTi arch wire was used in 0.022″ × 0.028″ slot pre-adjusted edgewise appliance. After initial arch wire placement, pain was assessed at T1 (24 hours), T2 (day 3), and T3 (day 7) by using the Ortho-SF-MPQ which consists of seven sensory (pressure, sore, aching, tight, throbbing, pulling, miserable) and four affective (uncomfortable, strange, frustrating, annoying) descriptors. Confirmatory factor analysis (CFA) models were fitted for analysis. Multiple-groups CFA (MG-CFA) approach was used for MI testing.

RESULTS

Data from 172 patients (85 male, 87 female) with mean age 14.2 years (SD 1.4) was analysed. CFA model fit indices value at T1 (RMSEA 0.048; CFI 0.995; TLI 0.995), T2 (RMSEA 0.051; CFI 0.998; TLI 0.997), and T3 (RMSEA 0.040; CFI 0.998; TLI 0.998) confirmed the validity of two-factor structure of Ortho-SF-MPQ in assessing orthodontic pain. MG-CFA model based non-significant scaled chi-square difference test (Satorra-Bentler method) for weak invariance (T1: χ² = 6.566, df = 9, p = 0.682; T2: χ² = 14.637, df = 9, p = 0.101; T3 (χ² = 14.248, df = 9, p = 0.114) and strong invariance (T1: χ² = 25.874, df = 20, p = 0.170; T2: χ² = 25.052, df = 20, p = 0.199; T3: χ² = 18.889, df = 20, p = 0.529) confirmed MI across male and female groups.

CONCLUSION

Two-factor structure (sensory and affective) of Ortho-SF-MPQ is structurally valid and invariant to measure pain in male and female orthodontic patents after initial arch wire placement.

Anxiety mediates the effect of acute stress on working memory performance when cortisol levels are high: a moderated mediation analysis

BACKGROUND

Anxiety is an aversive emotional state characterized by perceived uncontrollability and hypervigilance to threat that can frequently cause disruptions in higher-order cognitive processes like working memory. The attentional control theory (ACT) predicts that anxiety negatively affects the working memory system.

DESIGN

This study tested the association between anxiety and working memory after the addition of stress and measured the glucocorticoid, cortisol. To better understand this relationship, we utilized a moderated mediation model.

METHODS

Undergraduate students from a public university (N = 103) self-reported their anxiety levels. Participants first completed a short-term memory test. During and after a forehead cold pressor task (stress vs. control procedure) participants completed a working memory test. Salivary cortisol was taken at baseline and after the last working memory test.

RESULTS

Overall, acute stress had no effect on working memory. However, we found that anxiety levels mediated the influence of condition (stressed vs. control) on working memory, but only among those individuals who had high cortisol levels after exposure to acute stress, supporting a moderated mediation model.

CONCLUSIONS

These results imply that activation of the hypothalamic-pituitary-adrenal axis was necessary for working memory impairment in anxious individuals. These results provide support for the ACT.