Assessing the affective component of chronic pain: development of the Pain Discomfort Scale

Few methods exist to assess the affective or reactive dimension of chronic pain, and there are psychometric and practical limitations on the methods that do exist. The current paper reports on the development and validation of the Pain Discomfort Scale, a 10-item instrument designed to fill the need for a brief and psychometrically sound measure of pain affect. Preliminary evidence supports the reliability and validity of the measure. Its internal consistency and test-retest stability coefficients are high. In addition, the results of both correlational and factor analyses of the PDS with other measures support its distinctiveness (from measures of pain intensity) and construct validity (as indicated by its close association with other measures of pain affect). These results support the use of the PDS in situations where a measure of the affective response to chronic pain is needed.     

Coping with pain: A component analysis of Lamaze and cognitive-behavioral procedures

In this study an attempt was made to sort out the active ingredients of the Lamaze childbirth technique, and a possible improvement in the form of in-vivo emotive imagery was explored. Seventy female subjects were randomly assigned to one of seven treatment conditions in a 3 (levels of visual activity) × 2 (levels of respiratory activity)+ 1 (no treatment) design. Measures of pain threshold, pain endurance, and self-reported discomfort obtained in the cold pressor task were obtained before and after treatment. While no significant differences emerged on the respiratory activity factor, the imagery procedure was shown to be more effective than the visual procedure espoused by Lamaze for enhancing subjects' tolerance of ice-water discomfort. Implications of these findings for future research are discussed.     

Neural networks associated with the speed-accuracy tradeoff: evidence from the response signal method

This functional neuroimaging (fMRI) study examined the neural networks (spatial patterns of covarying neural activity) associated with the speed-accuracy tradeoff (SAT) in younger adults. The response signal method was used to systematically increase probe duration (125, 250, 500, 1000 and 2000 ms) in a nonverbal delayed-item recognition task. A covariance-based multivariate approach identified three networks that varied with probe duration—indicating that the SAT is driven by three distributed neural networks.     

Self-system therapy for distress associated with persistent low back pain: A randomized clinical trial

Objective: Persistent low back pain (PLBP) is associated with vulnerability to depression. PLBP frequently requires major changes in occupation and lifestyle, which can lead to a sense of failing to attain one’s personal goals (self-discrepancy). Method: We conducted a clinical trial to examine the efficacy of self-system therapy (SST), a brief structured therapy for depression based on self-discrepancy theory. A total of 101 patients with PLBP and clinically significant depressive symptoms were randomized either to SST, pain education, or standard care. Results: Patients receiving SST showed significantly greater improvement in depressive symptoms. Reduction in self-discrepancy predicted reduction in depressive symptoms only within the SST condition. Conclusions: Findings support the utility of SST for individuals facing persistent pain and associated depression.     

The feasibility of neuropsychological endophenotypes in the search for genes associated with bipolar affective disorder

OBJECTIVE: Efforts to identify genetic loci for bipolar disorder (BPD) have thus far proved elusive. The identification of processes mediating between genotype and phenotype (endophenotypes) may help resolve the carrier status of family members in genetic studies of polygenetic disorders with imperfect penetrance, such as BPD. We reviewed the literature to determine if neuropsychological measures could be used as effective endophenotypes to aid molecular genetic studies searching for genes predisposing to BPD. METHODS: Four prerequisites for endophenotypic markers are described, and a critical review of relevant literature was undertaken to determine if neurocognitive measures satisfy these four requirements in BPD. RESULTS: We found evidence that executive functions and declarative memory may be candidate neurocognitive endophenotypes for BPD. However, we cannot exclude other areas of cognition as being affected by BPD susceptibility genes, given the limits of the current knowledge of the neuropsychology of BPD. In particular, the paucity of studies measuring cognition in healthy relatives of BPD patient limits conclusion regarding familial aggregation of particular neurocognitive deficits (i.e. attention). Furthermore, the effects of clinical state and/or medication usage on cognitive functioning in BPD probands should be further explored. CONCLUSIONS: Molecular genetic studies of BPD may benefit from the application of select neuropsychological measures as endophenotypic markers. The use of these markers, once defined, may improve power for detecting genes predisposing to BPD and may help to better define diagnostic criteria.     

Independent component analysis of functional networks for response inhibition: Inter‐subject variation in stop signal reaction time

Cognitive control is a critical executive function. Many studies have combined general linear modeling and the stop signal task (SST) to delineate the component processes of cognitive control. For instance, by contrasting stop success (SS) and stop error (SE) trials in the SST, investigators examined regional responses to stop signal inhibition. In contrast to this parameterized approach, independent component analysis (ICA) elucidates brain networks subserving cognitive control. In our earlier work of 59 adults performing the SST during fMRI, we characterized six independent components (ICs). However, none of these ICs correlated with stop signal performance, raising questions about their behavioral validity. Here, in a larger sample (n = 100), we identified and explored 23 ICs for correlation with the stop signal reaction time (SSRT), a measure of the efficiency of response inhibition. At a corrected threshold (P < 0.0005), a paracentral lobule‐midcingulate network and a left inferior parietal‐supplementary motor‐somatomotor network showed a positive correlation between SE beta weight and SSRT. In contrast, a midline cerebellum–thalamus–pallidum network showed a negative correlation between SE beta weight and SSRT. These findings suggest that motor preparation and execution prolongs the SSRT, likely via an interaction between the go and stop processes as suggested by the race model. Behaviorally, consistent with this hypothesis, the difference in G and SE reaction times is positively correlated with SSRT across subjects. These new results highlight the importance of cognitive motor regions in response inhibition and support the utility of ICA in uncovering functional networks for cognitive control in the SST. Hum Brain Mapp 36:3289–3302, 2015. © 2015 Wiley Periodicals, Inc .     

A novel method of quantifying hemodynamic delays to improve hemodynamic response,and CVR estimates in CO2 challenge fMRI

Elevated carbon dioxide (CO2) in breathing air is widely used as a vasoactive stimulus to assess cerebrovascular functions under hypercapnia (i.e., “stress test” for the brain). Blood-oxygen-level-dependent (BOLD) is a contrast mechanism used in functional magnetic resonance imaging (fMRI). BOLD is used to study CO2-induced cerebrovascular reactivity (CVR), which is defined as the voxel-wise percentage BOLD signal change per mmHg change in the arterial partial pressure of CO2 (PaCO2). Besides the CVR, two additional important parameters reflecting the cerebrovascular functions are the arrival time of arterial CO2 at each voxel, and the waveform of the local BOLD signal. In this study, we developed a novel analytical method to accurately calculate the arrival time of elevated CO2 at each voxel using the systemic low frequency oscillations (sLFO: 0.01-0.1 Hz) extracted from the CO2 challenge data. In addition, 26 candidate hemodynamic response functions (HRF) were used to quantitatively describe the temporal brain reactions to a CO2 stimulus. We demonstrated that our approach improved the traditional method by allowing us to accurately map three perfusion-related parameters: the relative arrival time of blood, the hemodynamic response function, and CVR during a CO2 challenge.     

A simple method for quantitative electroencephalographic assessment of drugs with convulsant and anticonvulsant properties

A simple, inexpensive and reliable microcomputer-assisted method to detect and quantify abnormal EEG spiking is described. High frequency wave forms (20-40 Hz) with high amplitude are discriminated using a beta-2 bandpass filter and a threshold comparater. The spikes are then compiled and reported by an Apple II+ microcomputer. The method was validated by measuring seizures generated by intraperitoneal injection of pentylenetetrazol (PTZ), by microinjection of excitatory amino acids into the dorsal hippocampus, and by the antagonism of these seizures by diazepam and 2-amino-7-phosphono heptanoic acid, respectively.     

Empathy for social exclusion involves the sensory-discriminative component of pain: a within-subject fMRI study

Recent research has shown that experiencing events that represent a significant threat to social bonds activates a network of brain areas associated with the sensory-discriminative aspects of pain. In the present study, we investigated whether the same brain areas are involved when witnessing social exclusion threats experienced by others. Using a within-subject design, we show that an ecologically valid experience of social exclusion recruits areas coding the somatosensory components of physical pain (posterior insular cortex and secondary somatosensory cortex). Furthermore, we show that this pattern of activation not only holds for directly experienced social pain, but also during empathy for social pain. Finally, we report that subgenual cingulate cortex is the only brain area conjointly active during empathy for physical and social pain. This supports recent theories that affective processing and homeostatic regulation are at the core of empathic responses.     

A novel method for assessing distress intolerance: adaptation of a measure of willingness to pay

Background and ObjectivesDistress intolerance is a core element of many models of psychopathology and is related to a range of disorders and maladaptive behaviors. However, research on distress intolerance has been hampered by inconsistency in its assessment. Moreover, recent perspectives suggest that distress intolerance varies based on the domain of distress, highlighting the need for a measure that can capture intolerance across types of distress. This paper introduces a novel measure for distress intolerance: an adaptation of the willingness to pay (WTP) measure, which provides a consistent metric for assessing distress intolerance across domains of distress.MethodsThe WTP Distress Intolerance (WTP-DI) measure was administered to two samples of participants and feasibility and validity were evaluated.ResultsEvidence from unselected and clinical samples provide evidence for the feasibility and discriminant and concurrent validity of this measure.LimitationsTesting WTP-DI in larger samples and across additional domains of distress is needed.ConclusionsThe WTP-DI measure provides a new measure of distress intolerance that addresses the primary limitations of existing measures and has potential to serve as a cross domain measure to facilitate comparison across types of distress.