Setting empirical cut-offs on psychometric indicators of negative response bias: a methodological commentary with recommendations.

Malingering in neuropsychological assessment has been the subject of intense research for more than a decade and the detection methods arising from this work are diverse and sophisticated. However, the empirical findings are often presented in ways that limit the clinical utility of these techniques and may threaten their admissibility into legal proceedings. The purpose of this paper is to outline an approach for setting cut-offs on techniques designed to identify the presence of negative response bias. The use of this approach will result in the explicit specification of the error rate(s) of a given technique which can easily be applied by clinicians in the course of their practice and be admissible in court.     

Skill and selection bias has least influence on motor unit action potential firing rate/frequency

INTRODUCTION: Motor unit action potential (MUAP) rise time in quantitative electromyography (QEMG) using multi-MUAP analysis may influence neuromuscular disease diagnosis. OBJECTIVE: To demonstrate in QEMG that MUAP firing rate/frequency (FR) is the parameter least dependent on electrodiagnostician skill (EDXc) skill and selection bias. METHODS AND MATERIALS: During minimal contraction (< 6 MUAPs/4.8 s analysis period) of tibialis anterior, 20 MUAPs were selected for QEMG at each of the 3 insertion sites. There were three EDXcs (professor & two fellows), each an independent MUAP selector + EMG machine itself (EMGM), for a total of four independent MUAP selectors. EDXc and selector order variation at each site involved the following. At insertion site1, during EMG by EDXc 1, the MUAP selector order was EDXc 1, EMGM, EDXc 2 and EDXc 3. At the following two sites, the previous 1st selector was sequentially rotated to become the last selector during EMG by the subsequent EDXc. The protocol was repeated in two subjects. MUAP inclusion criteria by EDXcs was MUAP rise time < 1 ms by visual inspection and, by the EMGM, any and all MUAPs during the 4.8 s analysis period. RESULTS: The reproducibility of measurements between MUAP selectors for mean frequency was satisfactory (correlation coefficient for inter-EDXc was 0.57, and 0.66 between the most experienced EDXc and EMGM. Inter- EDXc correlation coefficient was poor for amplitude (0.10), duration (0.34), size index (0.35), phases (-0.13) and turns (-0.22). Of the MUAPs collected by EMGM, the mean amplitude was smaller and mean duration was longer than those collected by the other 3 selectors with no significant differences for the other parameters. CONCLUSIONS: FR was the only satisfactorily reproduced parameter from QEMG of MUAPs between selectors, and least dependent on skill and/or selection bias. From this, FR appears a relatively objective parameter, while other parameters appear unduly influenced by EDXc skill and/or MUAP selection bias.     

Psychogenic pain and depressive disorders: an empirical study

A sample of 31 patients of both sexes suffering from psychogenic pain disorder (DSM-III) were studied in order to test if their clinical and biological features as well as their response to antidepressant treatment support the hypothesis that relates this syndrome to depressive disorders. Biological variables were basal cortisol and dexamethasone suppression test, and treatment consisted of daily administration of 100-175 mg of imipramine for a period of 5 months. Mood state was evaluated by the Hamilton scale and pain was assessed through visual analogue scales immediately before starting treatment and 3 months later. There was a low prevalence of non-suppressors (9.6%) and all patients significantly improved in mood and pain after antidepressant treatment. However, general results support both the hypothesis linking psychogenic pain to depressive disorders and its possible understanding in terms of failed adjustment processes.     

Affective verbal learning in hostility: an increased primacy effect and bias for negative emotional material.

The current experiment examined the effects of hostility and a pain stressor on affective verbal learning. Participants were classified as high or low hostile and randomly assigned to a cold pressor or a non-cold pressor group. The subsequent effects on acquisition of the Auditory Affective Verbal Learning Test [AAVLT; Snyder, K. A., & Harrison, D. W. (1997). The Affective Verbal Learning Test. Archives of Clinical Neuropsychology, 12(5), 477-482] were measured. As expected, high hostiles learned negative emotional words significantly better than they learned positive words. Additionally, high hostiles were impaired in their acquisition of verbal material relative to low hostile participants. A significant primacy effect for negative emotional words and an overall better recall of negative information was also found. These results support the idea that high hostiles differ from low hostiles in a number of modalities and demonstrate the persistence of negative emotional material. Future work should address the implications these results have on high hostiles in daily interactions.     

Disagreement in primary study selection between systematic reviews on negative pressure wound therapy

Background  

Primary study selection between systematic reviews is inconsistent, and reviews on the same topic may reach different conclusions. Our main objective was to compare systematic reviews on negative pressure wound therapy (NPWT) regarding their agreement in primary study selection.     

Mouse strain differences in apomorphine-induced behavior: an empirical and methodological study

The behavioral response to 0.5-32.0 mg/kg apomorphine was evaluated in BALB/cJ, CBA/J, and C57BL/6J mice. Dose-response curves for each component of the drug-induced behavioral repertoire were derived, and ED50 (the dose at which 50% of the subjects meet or exceed a given rating) and slope were calculated for each. This method of analysis allows for a more quantitative estimate of drug sensitivity. Although some strain differences were observed in the qualitative characteristics of the response, differences in actual drug sensitivity (ED50s) were significant only at the higher ratings.     

Manipulation of feedback expectancy and valence induces negative and positive reward prediction error signals manifest in event-related brain potentials

The feedback-related negativity (FRN) has been hypothesized to be most sensitive to unexpected negative feedback. The present study investigated feedback expectancy and valence using a probabilistic gambling paradigm where subjects encountered expected or unexpected positive and negative feedback outcomes. In line with previous studies, FRN amplitude reflected a negative reward prediction error, but to a minor extent also a positive reward prediction error. Moreover, the P300 amplitude was largest after unexpected feedback, irrespective of valence. We propose to interpret the FRN in terms of a reinforcement learning signal which is detecting mismatch between internal and external representations indexed by the ACC to extract motivationally salient outcomes.     

A prospective multipractice study based on antecedent data. Reduced selection and behaviour bias.

A prospective multipractice study based on well-defined data collected by a number of general practitioners (GPs) over a period of time is often used in primary health care research. However, problems of research methodology such as selection bias are common in such studies when GPs either refuse to participate or interrupt their participation. A method is described whereby selection bias is avoided. In the present study, a medical laboratory made a daily record of all abnormal liver function tests requested by GPs over a period of six months. When mailing these results to the GPs, a questionnaire was enclosed in order to obtain a number of clinical data from them. Thirty of 31 possible GPs participated. During the study period, questionnaires concerning 134 patients were mailed, and 118 of these were returned without reminders. Following one reminder the response rate was 100%. Comparing the number of requested tests during the study period with the number requested during a control period before and after the study period (same six month periods of the year), no difference was seen in the pattern of requests. Thus, this method, unbiased with respect to both selection and request-behaviour, is recommended for similar studies.     

An empirical comparative study on biological age estimation algorithms with an application of Work Ability Index (WAI)

In this study, we described the characteristics of five different biological age (BA) estimation algorithms, including (i) multiple linear regression, (ii) principal component analysis, and somewhat unique methods developed by (iii) Hochschild, (iv) Klemera and Doubal, and (v) a variant of Klemera and Doubal's method. The objective of this study is to find the most appropriate method of BA estimation by examining the association between Work Ability Index (WAI) and the differences of each algorithm's estimates from chronological age (CA). The WAI was found to be a measure that reflects an individual's current health status rather than the deterioration caused by a serious dependency with the age. Experiments were conducted on 200 Korean male participants using a BA estimation system developed principally under the concept of non-invasive, simple to operate and human function-based. Using the empirical data, BA estimation as well as various analyses including correlation analysis and discriminant function analysis was performed. As a result, it had been confirmed by the empirical data that Klemera and Doubal's method with uncorrelated variables from principal component analysis produces relatively reliable and acceptable BA estimates.     

Dissociation, PTSD, and substance abuse: an empirical study

Few studies have examined the relationship between posttraumatic stress disorder (PTSD), substance use disorder, and dissociation. We studied 77 women with current PTSD and substance dependence, classified into high- versus low-dissociation groups per the Dissociative Experiences Scale. They were compared on trauma- and substance-related symptoms, cognitions, coping skills, social adjustment, trauma history, psychiatric symptoms, and self-harm/suicidal behaviors. We found the high-dissociation group consistently more impaired than the low-dissociation group. Also, the sample overall evidenced relatively high levels of dissociation, indicating that even in the presence of recent substance use, dissociation remains a major psychological phenomenon. Indeed, the high-dissociation group reported stronger expectation that substances could manage their psychiatric symptoms. The high-dissociation group also had more trauma-related symptoms and childhood histories of emotional abuse and physical neglect. The discussion addresses methodology, the "chemical dissociation" hypothesis, and the need for a more nuanced understanding of how substances are experienced in relation to dissociative phenomena.     

Multiple imputation for estimation of an occurrence rate in cohorts with attrition and discrete follow-up time points: a simulation study

Background  

In longitudinal cohort studies, subjects may be lost to follow-up at any time during the study. This leads to attrition and thus to a risk of inaccurate and biased estimations. The purpose of this paper is to show how multiple imputation can take advantage of all the information collected during follow-up in order to estimate the cumulative probability P(E) of an event E, when the first occurrence of this event is observed at t successive time points of a longitudinal study with attrition.     

Delusions and prediction error: re-examining the behavioural evidence for disrupted error signalling in delusion formation

Introduction. There is now significant evidence that prediction error signalling is mediated by dopamine in the midbrain, and that dopamine dysfunction is implicated in people experiencing psychotic symptoms, including delusions. There has also been significant theorizing and experimentation concerning the remaining link in this triad, namely that deviant prediction error signalling produces or maintains psychotic symptoms.

Methods. The research supporting the link between prediction error signalling and delusional symptoms was reviewed. Numerous studies indirectly support this link, but only one set of studies claim to directly test this hypothesis by combining three crucial elements: a patient sample, a manipulation of prediction error and neuroimaging. This particular set of studies were examined in detail.

Results. Important methodological limitations in these studies were observed, and a reinterpretation of their data was offered.

Conclusions. Methodological inconsistencies significantly weaken the claims made by these studies, but their data are consistent with current theorizing and they are instructive for future lines of inquiry in this field.     

Feature selection and classifier performance in computer-aided diagnosis: the effect of finite sample size

In computer-aided diagnosis (CAD), a frequently used approach for distinguishing normal and abnormal cases is first to extract potentially useful features for the classification task. Effective features are then selected from this entire pool of available features. Finally, a classifier is designed using the selected features. In this study, we investigated the effect of finite sample size on classification accuracy when classifier design involves stepwise feature selection in linear discriminant analysis, which is the most commonly used feature selection algorithm for linear classifiers. The feature selection and the classifier coefficient estimation steps were considered to be cascading stages in the classifier design process. We compared the performance of the classifier when feature selection was performed on the design samples alone and on the entire set of available samples, which consisted of design and test samples. The area Az under the receiver operating characteristic curve was used as our performance measure. After linear classifier coefficient estimation using the design samples, we studied the hold-out and resubstitution performance estimates. The two classes were assumed to have multidimensional Gaussian distributions, with a large number of features available for feature selection. We investigated the dependence of feature selection performance on the covariance matrices and means for the two classes, and examined the effects of sample size, number of available features, and parameters of stepwise feature selection on classifier bias. Our results indicated that the resubstitution estimate was always optimistically biased, except in cases where the parameters of stepwise feature selection were chosen such that too few features were selected by the stepwise procedure. When feature selection was performed using only the design samples, the hold-out estimate was always pessimistically biased. When feature selection was performed using the entire finite sample space, the hold-out estimates could be pessimistically or optimistically biased, depending on the number of features available for selection, the number of available samples, and their statistical distribution. For our simulation conditions, these estimates were always pessimistically (conservatively) biased if the ratio of the total number of available samples per class to the number of available features was greater than five.     

Emotional sensitization highlights the attentional bias in blood-injection-injury phobics: an ERP study

The presence of an attentional bias towards disorder-related stimuli has not been consistently demonstrated in blood phobics. The present study was aimed at investigating whether or not an attentional bias, as measured by event-related potentials (ERPs), could be highlighted in blood phobics by inducing cognitive-emotional sensitization through the repetitive presentation of different disorder-related pictures. The mean amplitudes of the N100, P200, P300 and late positive potentials to picture onset were assessed along with subjective ratings of valence and arousal in 13 blood phobics and 12 healthy controls. Blood phobics, but not controls, showed a linear increase of subjective arousal over time, suggesting that cognitive-emotional sensitization did occur. The analysis of cortical responses showed larger N100 and smaller late positive potentials in phobics than in controls in response to mutilations. These findings suggest that cognitive-emotional sensitization induced an attentional bias in blood phobics during picture viewing, involving early selective encoding and late cognitive avoidance of disorder-related stimuli depicting mutilations.     

Functional interactions between the cerebellum and the premotor cortex for error correction during the slow rate force production task: an fMRI study

Although neuroimaging studies indicate that functional magnetic resonance imaging (fMRI) signal changes in the cerebellum (CB) during the performance of a target movement reflect functions of error detection and correction, it is not well known how the CB intervenes in task-demanded movement attributes during automated on-line movement, i.e., how the CB simultaneously coordinates movement rate and error correction. The present study was undertaken to address this issue by recording fMRI signals during the performance of a task at two different movement rates (0.4 and 0.8 Hz). The results showed that movement errors increased with increasing movement rates. We also demonstrated that activation of the left CB increased with decreasing movement rates, whereas activation of the ipsilateral (right) premotor cortex (PMC) increased with increasing movement rates. Furthermore, there were significant relationships between individual movement errors and left CB activation at both movement rates, but these relationships were not observed in the ipsilateral PMC. Taken together, it is suggested that during the performance of automated and well-controlled slow force production tasks, the interactions between cortical (right PMC) and subcortical (left CB) motor circuits, i.e., a functional dissociation between PMC and CB, is exclusively dedicated to controlling movement rate and error correction. In particular, the present results showing significant relationships between individual force-control errors and CB activation might reflect functional differences of an individual’s internal model.     

Effects of cognitive remediation therapy on neurocognition and negative symptoms in schizophrenia: an Italian naturalistic study

Introduction: Cognitive remediation therapy (CRT) has been reported to positively affect neurocognitive processes among patients with schizophrenia; however, the degree to which changes in cognition is linked to improved clinical symptoms, remains poorly understood. The current study aimed to investigate whether cognitive gains were associated to improvements in negative symptoms’ severity in patients with schizophrenia living in two Italian psychiatric facilities.

Methods: Patients with a diagnosis of schizophrenia were consecutively assigned to CRT (n?=?33) and compared with an historical control group (n?=?28). Assessments were performed at baseline and post-treatment using a neuropsychological battery (Trail Making Test A and B, Self-Ordered Pointing Task, California Verbal Learning Test), along with clinical and functioning measures.

Results: Visual attention (TMT-A score change) was found as the only significant predictor of improvement in negative symptoms subscale of the Positive and Negative Syndrome Scale. Furthermore, a mediation path analysis confirmed that better performance in visual attention acts as mediator of the positive association between CRT intervention and lower post-treatment negative symptoms score.

Conclusions: CRT can have a positive impact on a measure of visual attention in patients with schizophrenia and on negative symptoms reduction that is mediated by this significant intervention effect.     

Engaging patients in health care: an empirical study of the role of engagement on attitudes and action

Objective

Identify the role of engaging people affected by cancer in service development in influencing healthcare professionals and service-users’ attitudes toward, and enactment of, engagement.

Methods

Focus group discussions with healthcare professionals and people affected by lung cancer, prior to and following an intervention where lung cancer teams were supported to engage with patients and family members.

Results

Staff and people affected by cancer who participated displayed more positive attitudes toward involvement than those who did not participate.

Conclusion

Progressing the involvement agenda requires the use of supported, small scale, projects where staff and patients/family members can develop their skills and knowledge of involvement.

Practice implications

Doing patient engagement work is a vital step toward changing attitudes and actions toward the involvement agenda.