Pain Processing in Older Age – Evidence from Event-Related Potentials

Scientific Conference (2021, June)

Aging is known to affect neurobiological and physiological aspects of pain perception and has been associated with reduced pain sensitivity and a deterioration of descending pain inhibitory mechanisms. To ... [more ▼]

Aging is known to affect neurobiological and physiological aspects of pain perception and has been associated with reduced pain sensitivity and a deterioration of descending pain inhibitory mechanisms. To investigate age differences in neural electrophysiological correlates of pain processing, we induced acute pain in healthy older (60 yrs+) and younger adults (18 to 35 yrs), using short transdermal electrical pulses administered to the inner forearm, with individually adjusted stimulation intensities. Participants received alternating blocks of painful and non-painful control stimulation and rated the intensity and unpleasantness of each stimulus on two visual analog scales. Pain-related evoked potentials were recorded with a 64-channel EEG. Preliminary results indicate that younger and older participants rated painful stimuli more intensive and unpleasant compared to the control stimulation, with older adults showing a slight habituation over time. In younger adults, ERP amplitudes (N2, P2 P3) of painful stimulation were enhanced compared to non- painful stimulation. In contrast, older participants showed generally reduced ERPs, no difference between pain and non-painful stimulation and by tendency longer latencies for painful stimulation. This suggests that nociceptive neural processing is altered in aging, while the reported pain perception is unaffected. Given that aging is also associated with a decline of cognitive functions and PFC volume and activity changes, this could have implications for the efficacy of cognitive pain modulation. Altogether, our results highlight the need for a deeper understanding of the mechanisms underlying pain processing in older adults, and how these age-related changes affect (cognitive) pain treatments in this population. [less ▲]

Distraction from Pain: An fMRI Study on the Role of Age-related Changes in Executive Functions

Scientific Conference (2021, June)

Even though aging is associated with increased and prolonged episodes of pain, little is known about potential age-related changes in the "top-down" modulation of pain, such as cognitive distraction from ... [more ▼]

Even though aging is associated with increased and prolonged episodes of pain, little is known about potential age-related changes in the "top-down" modulation of pain, such as cognitive distraction from pain. The hypoalgesic effect of distraction results from a competition for attentional and executive resources mediated by the prefrontal cortex (PFC). Given that age-related grey matter atrophy is particularly prominent in the PFC, older adults may benefit less from distraction to reduce pain than young adults. The aim of this study was to investigate the influence of aging on task-related hypoalgesia and its neural mechanisms, with a focus on the role of executive functions in distraction from pain. 64 participants (32 young adults: 26.69 ± 4.14 years; 32 older adults: 68.28 ± 7.00 years) first completed a battery of neuropsychological tests. In a second session, we administered a pain distraction paradigm while functional brain images were acquired. In this paradigm, participants completed a low (0-back) and a high (2-back) load condition of a working memory task while receiving either innocuous or painful heat stimuli to their lower arm. To control for age-related differences in sensitivity to pain and perceived task difficulty, stimulus intensity and task speed were individually calibrated. Both age groups showed significantly reduced activity in a network of regions involved in pain processing when performing the high compared to the low load distraction task; however, young adults showed a larger neural distraction effect in several of these regions, including the insula, caudate and midcingulate cortex. Moreover, in older adults, better executive functions – in particular inhibitory control abilities – were associated with a larger neural distraction effect in the insula, thalamus and primary somatosensory cortex, and with more activation in several prefrontal cortex regions during the high load task. These findings clearly demonstrate that the top-down control of pain is altered by age and could explain the higher vulnerability of older adults to developing chronic pain. Moreover, our findings suggest that the assessment of executive functions may be a useful tool for predicting the efficacy of cognitive pain modulation strategies in older adults. [less ▲]

Alterations in Neural Responses and Pain Perception in Older Adults During Distraction

in Psychosomatic Medicine (2020), 82

Age-Related Changes in Pain Perception Are Associated With Altered Functional Connectivity During Resting State

in Frontiers in Aging Neuroscience (2020), 12(116),

The role of executive functions in task-related analgesia

Poster (2019, March)

Introduction: Recent research suggests that weaker executive functions may be linked to a higher risk of pain chronicity. However, little is known about how executive functions affect the modulation of ... [more ▼]

Introduction: Recent research suggests that weaker executive functions may be linked to a higher risk of pain chronicity. However, little is known about how executive functions affect the modulation of acute pain. The present study aimed to investigate the impact of inhibitory control on the success of cognitive distraction from pain. Methods: Participants completed a battery of cognitive tasks (Go/NoGo, Color Stroop, Eriksen Flanker), assessing their cognitive inhibition and selective attention abilities. Additionally, self-report measures of pain catastrophizing and fear of pain were administered. In a pain distraction paradigm, participants completed either a cognitively demanding working memory task (2-back task) or a visually matched easy control task (target response task) while receiving warm or painful thermal stimuli to their left forearm. Nociceptive stimulus intensity was individually calibrated for each participant. Moreover, to maintain a similar level of task difficulty across participants, task speed was continuously adapted based on the participant's performance in the previous trials. Following each trial, participants rated the perceived intensity and unpleasantness of the thermal stimuli on visual analogue scales. Results: As expected, preliminary results indicate that the 2-back task, but not the target response task, successfully distracted participants from thermal pain, manifesting in significantly lower intensity and unpleasantness ratings. Importantly, the magnitude of the distraction effect was negatively associated with the Flanker effect. Discussion: In line with previous research, engaging in a cognitively demanding task led to significantly lower pain intensity and unpleasantness ratings when compared to an easy control task. Moreover, results indicate that better interference control abilities may predict greater task-related analgesia. Taken together, the results of the present study suggest that it is crucial to assess executive functions to develop a better understanding of the mechanisms behind cognitive distraction from pain. [less ▲]

Psychological, cognitive factors and contextual influences in pain and pain-related suffering as revealed by a combined qualitative and quantitative assessment approach

in PLoS ONE (2018)

Previous psychophysiological research suggests that pain measurement needs to go beyond the assessment of Pain Intensity and Unpleasantness by adding the evaluation of Pain-Related Suffering. Based on ... [more ▼]

Previous psychophysiological research suggests that pain measurement needs to go beyond the assessment of Pain Intensity and Unpleasantness by adding the evaluation of Pain-Related Suffering. Based on this three-dimensional approach, we attempted to elucidate who is more likely to suffer by identifying reasons that may lead individuals to report Pain and Pain-Related Suffering more than others. A sample of 24 healthy participants (age range 18±33) underwent four different sessions involving the evaluation of experimentally induced phasic and tonic pain. We applied two decision tree models to identify variables (selected from psychological questionnaires regarding pain and descriptors from post-session interviews) that provided a qualitative characterization of the degrees of Pain Intensity, Unpleasantness and Suffering and assessed the respective impact of contextual influences. The overall classification accuracy of the decision trees was 75% for Intensity, 77% for Unpleasantness and 78% for Pain-Related Suffering. The reporting of suffering was predominantly associated with fear of pain and active cognitive coping strategies, pain intensity with bodily competence conveying strength and resistance and unpleasantness with the degree of fear of pain and catastrophizing. These results indicate that the appraisal of the three pain dimensions was largely determined by stable psychological constructs. They also suggest that individuals manifesting higher active coping strategies may suffer less despite enhanced pain and those who fear pain may suffer even under low pain. The second decision tree model revealed that suffering did not depend on pain alone, but that the complex rating-related decision making can be shifted by situational factors (context, emotional and cognitive). The impact of coping and fear of pain on individual Pain-Related Suffering may highlight the importance of improving cognitive coping strategies in clinical settings. [less ▲]

The combination of postnatal maternal separation and social stress in young adulthood does not lead to enhanced inflammatory pain sensitivity and depressionrelated behavior in rats

in PLoS ONE (2018), 13(8), 0202599

Maternal separation stress leads to resilience against neuropathic pain in adulthood

in Neurobiology of Stress (2018), 8

Assessing suffering in experimental pain models: psychological and psychophysiological correlates

in Zeitschrift für Psychologie (2017), 225(1), 45-53

Although suffering is a central issue in pain, there is only little research on this topic. The aim of this study was to assess suffering in an experimental context using various stimulation methods and ... [more ▼]

Although suffering is a central issue in pain, there is only little research on this topic. The aim of this study was to assess suffering in an experimental context using various stimulation methods and durations, and to examine which psychological or psychophysiological measures covary with pain-related suffering. Twenty-one healthy volunteers participated in two experiments in which we used tonic thermal and phasic electric stimuli with short and long stimulus durations. The participants rated pain intensity, unpleasantness, and pain-related suffering on separate visual analog scales (VAS) and completed the Pictorial Representation of Illness and Self Measure (PRISM), originally developed to assess suffering in chronic illness. We measured heart rate, skin conductance responses (SCRs), and the electromyogram (EMG) of the musculus corrugator supercilii. For both heat and electric pain, we obtained high ratings on the suffering scale confirming that suffering can be evoked in experimental pain conditions. Whereas pain intensity and unpleasantness were highly correlated, both scales were less highly related to suffering, indicating that suffering is distinct from pain intensity and unpleasantness. Higher suffering ratings were associated with more pronounced fear of pain and increased private self-consciousness. Pain-related suffering was also related to high resting heart rate, increased SCR, and decreased EMG during painful stimulation. These results offer an approach to the assessment of suffering in an experimental setting using thermal and electric pain stimulation and shed light on its psychological and psychophysiological correlates. [less ▲]

The role of cognitive reappraisal in placebo analgesia: an fMRI study

in Social Cognitive and Affective Neuroscience (2017), (2017), 1-10

Placebo analgesia (PA) depends crucially on the prefrontal cortex (PFC), which is assumed to be responsible for initiating the analgesic response. Surprisingly little research has focused on the ... [more ▼]

Placebo analgesia (PA) depends crucially on the prefrontal cortex (PFC), which is assumed to be responsible for initiating the analgesic response. Surprisingly little research has focused on the psychological mechanisms mediated by the PFC and underlying PA. One increasingly accepted theory is that cognitive reappraisal—the reinterpretation of the meaning of adverse events—plays an important role, but no study has yet addressed the possible functional relationship with PA. We studied the influence of individual differences in reappraisal ability on PA and its prefrontal mediation. Participants completed a cognitive reappraisal ability task, which compared negative affect evoked by pictures in a reappraise versus a control condition. In a subsequent fMRI session, PA was induced using thermal noxious stimuli and an inert skin cream. We found a region in the left dorsolateral PFC, which showed a positive correlation between placebo-induced activation and (i) the reduction in participants’ pain intensity ratings; and (ii) cognitive reappraisal ability scores. Moreover, this region showed increased placebo-induced functional connectivity with the periaqueductal grey, indicating its involvement in descending nociceptive control. These initial findings thus suggest that cognitive reappraisal mechanisms mediated by the dorsolateral PFC may play a role in initiating pain inhibition in PA [less ▲]