Filling the glass: Effects of a positive psychology intervention on executive task performance in chronic pain patients.

BACKGROUND: Chronic pain is associated with emotional problems as well as difficulties in cognitive functioning. Prior experimental studies have shown that optimism, the tendency to expect that good things happen in the future, and positive emotions can counteract pain-induced task performance deficits in healthy participants. More specifically, induced optimism was found to buffer against the negative effects of experimental pain on executive functioning. This clinical experiment examined whether this beneficial effect can be extended to a chronic pain population. METHODS: Patients (N = 122) were randomized to a positive psychology Internet-based intervention (PPI; n = 74) or a waiting list control condition (WLC; n = 48). The PPI consisted of positive psychology exercises that particularly target optimism, positive emotions and self-compassion. RESULTS: Results demonstrated that patients in the PPI condition scored higher on happiness, optimism, positive future expectancies, positive affect, self-compassion and ability to live a desired life despite pain, and scored lower on pain catastrophizing, depression and anxiety compared to patients in the WLC condition. However, executive task performance did not improve following completion of the PPI, compared to the WLC condition. CONCLUSIONS: Despite the lack of evidence that positive emotions and optimism can improve executive task performance in chronic pain patients, this study did convincingly demonstrate that it is possible to increase positive emotions and optimism in chronic pain patients with an online positive psychology intervention. It is imperative to further explore amendable psychological factors that may reduce the negative impact of pain on executive functioning. SIGNIFICANCE: We demonstrated that an Internet-based positive psychology intervention strengthens optimism and positive emotions in chronic pain patients. These emotional improvements are not associated with improved executive task performance. As pain itself often cannot be relieved, it is imperative to have techniques to reduce the burden of living with chronic pain.

Are individual levels of pain anxiety related to negative interpretation bias? An examination using an ambiguous word priming task.

BACKGROUND: Cognitive processes like attentional and interpretation biases have been suggested to play a vital role in the onset and exacerbation of chronic pain. Research consistently supports the occurrence of interpretation bias (IB) in pain patients and healthy individuals high in pain anxiety. Nevertheless, studies on the indirect assessment of IB or the relation between IB and responses to pain are limited. The present studies examined the association between indirect assessed IB and pain anxiety, while Study 2 additionally examined IB as a mediator in the relation between pain anxiety and pain responses. METHOD: In Study 1 (N = 125) and Study 2 (N = 73), anxiety sensitivity, injury/illness sensitivity (IS) and pain catastrophizing were assessed with questionnaires. IB was indirectly derived from performance on an ambiguous word priming task. In Study 2, an experimental heat pain induction was used to assess pain responses (i.e. tolerance and subjective pain experience). RESULTS: Results showed a positive correlation between pain anxiety and IB, albeit that the strength of the observed associations differed between both studies. Furthermore, IB was inversely related to pain tolerance, and found to mediate the relation between IS and pain tolerance in Study 2. CONCLUSIONS: Current findings underscore the importance of interpretational processes in the context of physical health threat. Furthermore, the ambiguous word priming task is proposed as a suitable paradigm for further research on the indirect assessment of IB. Nevertheless, further research is warranted to deepen our understanding of IB and its contribution to the experience of (chronic) pain.

Role of the clock gene Bmal1 and the gastric ghrelin-secreting cell in the circadian regulation of the ghrelin-GOAT system.

As adequate food intake is crucial to survival, organisms have evolved endogenous circadian clocks to generate optimal temporal patterns of food-related behavior and physiology. The gastric ghrelin-secreting cell is thought to be part of this network of peripheral food-entrainable oscillators (FEOs), regulating the circadian release of this orexigenic peptide. This study aimed to determine the role of the core clock gene Bmal1 and the gastric ghrelin-secreting cell as an FEO in the circadian rhythmicity of ghrelin expression and secretion in vivo and in vitro. Bmal1-deficient mice not only lacked circadian rhythmicity in plasma ghrelin levels and food intake, but also showed decreased gastric mRNA expression of ghrelin and ghrelin O-acyltransferase (GOAT), the ghrelin activating enzyme. Furthermore, in the absence of the hypothalamic master clock, food-related stimuli entrained the molecular clock of gastric ghrelinoma cells to regulate the rhythmic release of ghrelin. Divergent responses in octanoyl and total ghrelin release towards different food cues were observed, suggesting that the FEO also regulates the circadian rhythmicity of GOAT. Collectively, these findings indicate that circadian rhythmicity of ghrelin signaling requires Bmal1 and is driven by a food-responsive clock in the gastric ghrelin-secreting cell that not only regulates ghrelin, but also GOAT activity.

Chemosensory signalling pathways involved in sensing of amino acids by the ghrelin cell.

Taste receptors on enteroendocrine cells sense nutrients and transmit signals that control gut hormone release. This study aimed to investigate the amino acid (AA) sensing mechanisms of the ghrelin cell in a gastric ghrelinoma cell line, tissue segments and mice. Peptone and specific classes of amino acids stimulate ghrelin secretion in the ghrelinoma cell line. Sensing of L-Phe occurs via the CaSR, monosodium glutamate via the TAS1R1-TAS1R3 while L-Ala and peptone act via 2 different amino acid taste receptors: CaSR &TAS1R1-TAS1R3 and CaSR &GPRC6A, respectively. The stimulatory effect of peptone on ghrelin release was mimicked ex vivo in gastric but not in jejunal tissue segments, where peptone inhibited ghrelin release. The latter effect could not be blocked by receptor antagonists for CCK, GLP-1 or somatostatin. In vivo, plasma ghrelin levels were reduced both upon intragastric (peptone or L-Phe) or intravenous (L-Phe) administration, indicating that AA- sensing is not polarized and is due to inhibition of ghrelin release from the stomach or duodenum respectively. In conclusion, functional AA taste receptors regulate AA-induced ghrelin release in vitro. The effects differ between stomach and jejunum but these local nutrient sensing mechanisms are overruled in vivo by indirect mechanisms inhibiting ghrelin release.

Attention allocation to ambiguous health/somatic threat cues.

BACKGROUND: An influential idea is that attentional bias to information related to pain or pain-related negative affect underlies persistent pain problems. Such information is however often ambiguous. If ambiguous input is perceived as pain or threat related, attention to this stimulus would be enhanced compared with stimuli with no (dominant) pain-/threat-related meaning. Attentional bias to ambiguous stimuli related to somatic/health threat was expected to be more pronounced with higher levels of pain catastrophizing. METHODS: University students performed a spatial cueing task including four types of word cues that were combinations of word content (somatic/health threat vs. non-threat), and word ambiguity (unambiguous vs. ambiguous), each presented for 500 or 750 ms. Attentional bias to somatic/health threat is reflected in larger cue validity effects for somatic/heath threat words than for non-threat words. RESULTS: In the 500-ms condition, cue validity effects were larger for threat than for non-threat words in participants reporting low catastrophizing, but did not depend on word content in participants reporting higher catastrophizing. In the 750-ms condition, cue validity effects did not depend on pain catastrophizing or word content. Cue validity effects did not significantly differ between unambiguous words and ambiguous homographs. CONCLUSIONS: Low catastrophizers demonstrated attentional bias to threat content. Participants reporting higher catastrophizing showed overall enhanced attentional orienting. There was no evidence for differences in (biased) attention to unambiguous and ambiguous words. Further research is needed to determine attentional bias for ambiguous pain-/threat-related stimuli in the context of consistent attentional bias for unambiguous pain-/threat-related stimuli.