Het geluid of beeld van iemand die zich krabt, kan jeuk oproepen bij de observator. Dit fenomeen noemen we besmettelijke jeuk. In andere besmettelijke gedragingen (zoals gapen) komt de rol van...Show moreHet geluid of beeld van iemand die zich krabt, kan jeuk oproepen bij de observator. Dit fenomeen noemen we besmettelijke jeuk. In andere besmettelijke gedragingen (zoals gapen) komt de rol van empathie naar voren. Er is nog niet veel onderzoek gedaan naar de mogelijke invloed van empathie op besmettelijke jeuk. Neurologische studies vinden activatie van hersengebieden tijdens besmettelijke jeuk, welke geassocieerd worden met affectiviteit. Eén eerder onderzoek toont aan dat er geen associatie is tussen empathie en besmettelijke jeuk. In deze scriptie wordt met een regressieanalyse getoetst of mensen met hogere mate van empathie meer jeuk ervaren na het zien van iemand met een huidaandoening, dan mensen met lagere mate van empathie. In het onderzoek werd de participanten een audiovisuele stimulus getoond, waarna een zelfrapportage van intensiteit van opgeroepen jeuk werd ingevuld. Empathie is berekend met de totaalscore van een vragenlijst. Uit de resultaten blijkt dat empathie geen significante voorspeller is van de mate van intensiteit van opgeroepen jeuk bij het zien van een huidaandoening. Echter bevat dit onderzoek wat limitaties zoals de relatief lage gemiddelde empathiescore van de steekproef. Mogelijk biedt verder onderzoek naar de eventuele invloed van empathie op besmettelijke jeuk bij bekenden, en de eventuele invloed van aparte dimensies van empathie, ruimte voor nieuwe inzichten.Show less
Placebo and nocebo effects are positive and negative treatment-like effects, respectively, that cannot be attributed to an active treatment component. They are caused by patients’ expectations of...Show morePlacebo and nocebo effects are positive and negative treatment-like effects, respectively, that cannot be attributed to an active treatment component. They are caused by patients’ expectations of symptom improvement or worsening. Both effects play a significant role in the treatment of itch. However, there is a great variability in their extent in healthy individuals and patient groups, which may be partly explained by genetic variants in specific neurotransmitter pathways. This study is the first to investigate genetic predictors of placebo and nocebo effects on itch. Based on research in pain, the genes COMT rs4680, FAAH rs324420, and OPRM1 rs1799971 were identified to investigate their potential role in the extent to which placebo and nocebo effects on itch were induced in healthy individuals. This cross-trial analysis included 58 in the placebo and 127 healthy genotyped participants in the nocebo analysis from three studies. Itch stimuli were elicited electrically or with histamine, and placebo and nocebo effects were induced with specific learning processes, i.e., conditioning with verbal suggestion, or antihistamine was classically conditioned. COMT met/met variants demonstrated significantly higher placebo effects on itch compared to val/val variants, 95% BCa CI [0.026, 1.263]. No other significant differences were found between the variants of COMT, FAAH and OPRM1 and placebo or nocebo effects on itch. Knowledge on genetic predictors of placebo and nocebo effects on itch could help to improve clinical trial design and allow clinicians to tailor itch-reducing treatments such that they optimize treatment efficacy. Future research should focus on a replication study with a larger cohort and homogenous itch-inducing methods as well as learning processes to verify the studied relationship.Show less
Background: People with type 1 diabetes (T1D) often experience problems with their glucose regulation (glucose variability and glucose control), sleep quality, and cognitive functioning. However,...Show moreBackground: People with type 1 diabetes (T1D) often experience problems with their glucose regulation (glucose variability and glucose control), sleep quality, and cognitive functioning. However, their interrelation has not often been investigated. The aim of this study was to investigate how sleep quality and cognitive functioning are associated with glucose regulation in people with T1D. Method: Continuous glucose monitoring (CGM) data was collected over two weeks, in 18 participants, while each day subjective sleep quality (once in the morning) and cognitive functioning (e.g., ability to concentrate, finding words) (up to five times during the day) was measured using ecological momentary assessments (EMAs). Based on the CGM data, glycemic parameters (glucose variability and glucose control) during the night and day were calculated and a mean value of cognitive functioning per day was composed. Linear mixed model analyses were used to test for 1) whether sleep quality was influenced by glycemic parameters during the night and 2) whether cognitive functioning during the day was influenced by sleep quality and whether cognitive functioning was associated with glycemic parameters during the day. In addition, an interaction effect between sleep quality and glucose variability on cognitive functioning was explored. Lastly, visual plots were used to explore the associations on an individual level. Results: No statistically significant main effects were found for either association. However, an interaction trend (ß = -2.07, p = .070) between sleep quality and glucose variability on cognitive functioning scores was found. For days with normal fluctuations in glucose levels, better sleep quality was associated with better cognitive functioning, whereas for days with high glucose variability, this association could not be found. Regarding the individual plots, both, positive and negative relationships between all mentioned variables were apparent, exemplifying important inter-individual differences. Conclusion: For people with T1D, the relationships between glucose parameters, sleep quality, and cognitive functioning, vary from person to person. This finding advocates for looking at the individual level when implementing possible treatment methods for increasing sleep quality and cognitive functioning. More research in a larger sample is warranted to further examine the inter-individual factors in these associations.Show less
Acute pain has the essential function of protecting organisms from harmful influences through painful signals that trigger protective behavioral responses. Chronic pain, however, has merely stress...Show moreAcute pain has the essential function of protecting organisms from harmful influences through painful signals that trigger protective behavioral responses. Chronic pain, however, has merely stress-inducing and disabling characteristics. To enable the development of treatment, understanding the mechanisms underlying pain experience is indispensable. Previous research has demonstrated how expectancy-induced nocebo effects (i.e., the worsening of a symptom caused by negative expectations) can provoke hyperalgesia, an increased sensitivity towards pain. The present study aimed to reproduce these findings and investigate the precise role of expectancies in the relationship between nocebo-inducing cues and the resulting pain experience. Within the context of expectancy, this study was further exploring the degree of awareness involved in the participants’ perception of their accuracy in predicting upcoming pain intensities. Sixty-nine healthy volunteers were divided between the experimental and the control condition, both of which received repeated electrical pain stimulation. Through verbal suggestion and conditioning, the experimental group learned to associate a specific color with high pain intensity and a second color with a medium intensity stimulus. In the control group, there were no instructions and the order of pain intensities and color cues was randomized. During the test phase, all color cues were accompanied by medium intensity pain to measure the magnitude of nocebo responses associated with the conditioned color as opposed to the control color. Pain expectancy and experience, as well as the extent to which they both matched, were measured through self-report scales after each stimulus-color pair. Nocebo conditioning produced the expected higher pain and expectancy ratings for the conditioned cue, as compared to the unconditioned cue in the nocebo group’s test data. Next, expectancies appeared to significantly mediate the effect of the nocebo-induction on pain experience in the experimental group. Finally, there was no significant indication that participants were aware of their degree of prediction accuracy. These findings confirm the significant involvement of expectation in pain experience and warrant further research on awareness in pain perception. Additional research is needed to provide deeper insight on the psychological processes underlying pain experience, as it will help optimize treatments for patients suffering from chronic pain.Show less
Pain-avoidance behavior has been associated with adverse pain outcomes. Past research has identified predictors for pain-avoidance behavior but the role of negative expectations in the avoidance of...Show morePain-avoidance behavior has been associated with adverse pain outcomes. Past research has identified predictors for pain-avoidance behavior but the role of negative expectations in the avoidance of pain has been largely undetermined. The present study aimed to fill the gap by investigating the relation between negative pain expectations and pain-avoidance behavior using a sample of healthy volunteers. Participants were randomly divided into control and experimental groups. In the experimental group, negative pain expectations were induced through verbal suggestion and conditioning of high and medium intensity electrical stimuli which were associated with two color cues. Participants in the control group received high and medium intensity electrical stimuli but no verbal suggestion or conditioning. During the pain-avoidance test, participants made a selection between two versions of the Tower of Hanoi game, differing in the level of difficulty. For the experimental group, hard and easy versions of the game were accompanied with color cues signifying medium and high intensity electrical stimulation, respectively. Based on the previous learning contingency, it was hypothesized that participants in the experimental group would choose to play the hard version of the game to avoid high intensity electrical stimuli. Results showed that verbal suggestion and conditioning are effective techniques at inducing negative pain expectations and nocebo effect on pain. The relationship between negative pain expectations and avoidance of pain was found to be nonsignificant, suggesting that learned negative pain expectations are insufficient at producing pain-avoidance behavior. Further research is needed to clarify predictors of pain-avoidance behavior in clinical populations.Show less
Chronic pain is a great hindrance in daily life. Treatments for chronic pain can unfortunately also have negative side effects, that a doctor has to inform patients of. It has been suggested that...Show moreChronic pain is a great hindrance in daily life. Treatments for chronic pain can unfortunately also have negative side effects, that a doctor has to inform patients of. It has been suggested that information about side effects could induce them in patients via a nocebo effect. A nocebo effect can also occur because of negative expectations, for example due to previous bad experiences with treatments. Nocebo hyperalgesia can be induced by a combination of verbal suggestions and conditioning. This paper verified whether this is possible in healthy adults. Participants (N = 27) were allocated in two groups; a nocebo and a control group. The experiment consisted of multiple phases. During the conditioning phase, participants received high and medium intensity electrical stimuli paired with color cues. In the nocebo group, one cue was conditioned. Participants were told it would activate a third electrode, making it more painful. In the control group, participants received electrical stimuli with randomized cues. During the testing phase, only medium intensity stimuli were given to both groups. In both phases, participants rated their pain after each stimulus. In the nocebo group, participants were expected to rate their conditioned cue as more painful. A 2x2 mixed ANOVA was performed of the testing phase, showing verbal suggestions and conditioning combined induced hyperalgesia in healthy adults. A large effect size was found. Further research should investigate nocebo hyperalgesia in clinical samples, to check if nocebo effects work in the same way and if there are ways to minimize nocebo hyperalgesia.Show less
Pain is a common complaint that can interfere with daily life severely. Expectations play a crucial role in pain perception. It has been found that fear of pain interacts with these expectations....Show morePain is a common complaint that can interfere with daily life severely. Expectations play a crucial role in pain perception. It has been found that fear of pain interacts with these expectations. Research investigating the influence of fear of pain on pain perception is sparse. The aim of the present study is to investigate whether increased pain sensitivity can be induced by conditioning and verbal suggestion of negative expectations. Moreover, the study investigated if fear of pain could predict increased sensitivity to pain. Data of 27 healthy young adults (22 females) was used in this study. Participants received induction of negative expectations regarding electrical pain. Fear of pain was measured prior to the induction of electrical pain by using the minor pain subscale of the Fear of Pain Questionnaire III. Pain was electrically induced and measured by numerical pain rating scales. The participants were randomized into an experimental (induction of negative expectations) or a control group (expectations not manipulated). The results show that the experimental group scored higher on increased sensitivity to pain than the control group. Therefore, it can be concluded that an increased sensitivity to pain can be induced by a negative expectation learning procedure. This effect is strong and can have a strong negative effect on treatment outcomes. Furthermore, it has been found that fear of pain cannot predict nocebo hyperalgesia. This may relate to the healthy sample. It is important to investigate the relation of expectations, increased pain sensitivity and fear of pain. Doing so optimizes treatment and therefore prevents patients with chronic pain to experience increased pain.Show less
Chronic pain is one of the most prominent medical conditions associated with significant limitations in various life aspects. Nocebo hyperalgesia which refers to increased pain perception due to...Show moreChronic pain is one of the most prominent medical conditions associated with significant limitations in various life aspects. Nocebo hyperalgesia which refers to increased pain perception due to negative expectations about pain plays crucial role in pain chronification. Nocebo effects have also been linked to dispositional characteristics. Studies investigating the role of fear of pain and nocebo hyperalgesia found inconsistent results. This study used conditioning and verbal suggestions hypothesizing that nocebo hyperalgesia will occur. We further investigated the association between fear of pain and nocebo hyperalgesia, expecting a positive relationship. In this study, 27 healthy individuals were randomly assigned to either a control group or a nocebo group in which negative expectancies about pain were induced. This was done by means of conditioning, through pairing electrically painful stimuli with color cues, and by giving negative verbal suggestions about an increase in pain related to a color cue and a sham electrode. Pain levels were rated on Numerical Rating Scale (NRS) and compared between groups. Dispositional fear of pain levels was measured using the fear of minor pain subscale of the Fear of Pain Questionnaire-III (FPQ-III). Nocebo hyperalgesia was successfully induced, as reflected by a significant difference (p =.005) in nocebo responding between the two groups. No significant relationship was found between FPQ-III scores and nocebo hyperalgesia. Findings are in line with previous research suggesting that conditioning and verbal suggestions can induce nocebo hyperalgesia. Since no association has been found between fear of pain and nocebo hyperalgesia, future research should investigate this relationship using other subscales of the FPQ-III.Show less
