Fred Rist

N2, P3 and the lateralized readiness potential in a nogo task involving selective response priming

Motor inhibition and its correlates in the event-related potential (ERP) are often studied in go/nogo tasks. However, go and nogo trials differ in their motor and their attentional requirements, rendering an interpretation of corresponding changes in ERP components difficult. As an alternative strategy to study motor inhibition, a hybrid choice-reaction go/nogo procedure involving selective response priming was used. Eighteen subjects performed the task. Response time (RT) and error measures as well as the lateralized readiness potential (LRP) indicated that responses were primed by flanker stimuli that were associated with one of the two possible responses. In nogo trials, selective response priming influenced the N2 amplitude whereas the P3 amplitude was unaffected. Because the N2 appeared irrespective of whether an erroneous response was correctable (in go trials) or not (in nogo trials), we conclude that the N2 reflects either the detection or the inhibition of an inappropriate tendency to respond.

Long-term cognitive and emotional consequences of mild traumatic brain injury.

BACKGROUND The objective of this study was to investigate long-term cognitive and emotional sequelae of mild traumatic brain injury (mTBI), as previous research has remained inconclusive with respect to their prevalence and extent. METHOD Thirty-three individuals who had sustained mTBI on average 6 years prior to the study and 33 healthy control subjects were matched according to age, gender and education. Structural brain damage at time of testing was excluded by magnetic resonance imaging (MRI). A comprehensive neuropsychological test battery was conducted to assess learning, recall, working memory, attention and executive function. Psychiatric symptoms were assessed by the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) and the Beck Depression Inventory (BDI). Possible negative response bias was ruled out by implementing the Word Memory Test (WMT). RESULTS The mTBI individuals had significant impairments in all cognitive domains compared to the healthy control subjects. Effect sizes of cognitive deficits were medium to large, and could not be accounted for by self-perceived deficits, depression, compensation claims or negative response bias. BDI scores were significantly higher in the patient group, and three patients fulfilled DSM-IV criteria for a mild episode of major depression. CONCLUSIONS Primarily, well-recovered individuals who had sustained a minor trauma more than half a decade ago continue to have long-term cognitive and emotional sequelae relevant for everyday social and professional life. mTBI may lead to a lasting disruption of neurofunctional circuits not detectable by standard structural MRI and needs to be taken seriously in clinical and forensic evaluations.

An event-related brain potential substrate of disturbed response monitoring in paranoid schizophrenic patients.

Response monitoring in schizophrenic patients and healthy controls was assessed by measuring performance and event-related brain potentials in the flanker priming task. Three visual-context conditions were construed: Flankers and targets pointed either into the same direction or into different directions. Stimuli without any response assignment were used as flankers in the neutral context condition. The schizophrenic patients were further subdivided into paranoid (n = 19) and nonparanoid (n = 10) patients and compared with healthy controls (n = 18). Performance scores revealed that the flankers induced a similar degree of distraction by visual context in all 3 groups. Although the schizophrenic patients showed normal error correction performance, the error negativity (NE) was significantly reduced in paranoid schizophrenic patients. The attenuation of the NE possibly reflects disturbed response monitoring in these patients.

Evidence for overlap between idiopathic environmental intolerance and somatoform disorders.

Objective: Idiopathic environmental intolerance (IEI), also known as multiple chemical sensitivity, is a chronic, polysymptomatic condition that cannot be explained by an organic disease. Physical and psychological complaints are believed to be sustained by low levels of chemically unrelated substances in the environment. At present, it is unclear whether IEI is an environmental illness or a variant of somatoform disorders (SFD). This study examined whether IEI can be distinguished from SFD with respect to self-reported symptoms, trait anxiety, body-related cognitions, and symptom attributions. Methods: We compared 54 subjects with IEI, 54 subjects with SFD but without IEI, and 44 subjects with neither IEI nor SFD on symptom scales, psychological questionnaires, and structured interviews for IEI, depression, anxiety, and SFD. Results: More than half of the IEI subjects met Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria of SFD. This group shared both symptoms and psychological features of somatization with the SFD group. IEI subjects who did not fulfill criteria for a specific SFD were less impaired by their chemical sensitivity but differed nevertheless from nonsomatoform controls by significantly higher symptom scores, higher trait anxiety, a focus on autonomic sensations, and more pronounced somatic symptom attributions. These psychological features were significantly associated with the burden of somatic symptoms in both SFD and IEI. Furthermore, self-reported allergy but not total immunoglobulin E correlated with symptom burden in the total sample. Conclusions: The similarity of IEI and SFD regarding symptoms and psychological features of somatization support the hypothesis that IEI is a variant of SFD. IEI = idiopathic environmental intolerance; SFD = somatoform disorder; ESQ = Environmental Sensitivity Questionnaire; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, fourth edition; ANOVA = analysis of variance; SIQ = Symptom Interpretation Questionnaire; PHQ-9 = Patient Health Questionnaire depressive symptom severity scale; PHQ-15 = Patient Health Questionnaire somatic symptom severity scale; SOMS = screening for somatoform symptoms; STAI = State Trait Anxiety Inventory; COSS = Chemical Odor Sensitivity Scale; SCID = Structured Clinical Interview for DSM-IV; ACQ = Agoraphobic Cognition Questionnaire; CABAH = Cognitions about Body and Health Questionnaire.

Influence of alcohol on the processing of emotional facial expressions in individuals with social phobia

OBJECTIVES Individuals with social phobia are at an increased risk to develop alcohol problems. However, the mechanism responsible for this association is unclear. It has been suggested that alcohol reduces anxiety by impairing initial appraisal of threatening stimuli. Information that is especially threatening, however, may be resistant to such an effect of alcohol. We tested the influence of alcohol on the appraisal of five emotional facial expressions. METHODS 40 social phobia patients and 40 controls performed a dot probe task, after drinking either alcohol or orange juice. Stimuli were faces with happy, angry, neutral and also two ambiguous expressions that were formed by blending angry or happy faces and neutral faces. Stimuli were presented for either 175 or 600 ms. RESULT Sober patients showed an attentional bias towards angry faces, indicating preferential processing of threat stimuli. Alcohol significantly reduced this bias. Only in sober participants, this attentional bias correlated with measures of social anxiety. In controls, no biases were observed. CONCLUSIONS Alcohol seems to attenuate the impact of threatening social stimuli on social phobia patients, which may negatively reinforce the consumption of alcohol and at least partially explain the heightened comorbidity with alcohol related problems known from epidemiological studies. The dot probe task with short stimulus presentation times seems to provide an adequate method to demonstrate alcohol effects on information processing.

Syndrome stability and psychological predictors of symptom severity in idiopathic environmental intolerance and somatoform disorders.

BACKGROUND Previous studies suggest that idiopathic environmental intolerance (IEI) is a variant of somatoform disorders (SFDs) or the so-called functional somatic syndromes. Little is known, however, about the stability and the psychological predictors of IEI. METHOD This prospective study examined the 1-year stability of somatic symptoms and IEI features in three diagnostic groups: 49 subjects with IEI, 43 subjects with SFD but without IEI, and 54 subjects (control group, CG) with neither IEI nor SFD. The predictive value of typical psychological predictors for somatization was tested using zero-order correlations and multiple linear regression analyses. RESULTS Somatic symptoms and IEI features proved to be temporally stable over the 1-year follow-up period. The SFD and IEI groups scored significantly higher than CG on all measures of somatic symptoms and on questionnaires assessing psychological predictors for somatization. Measures of trait negative affectivity (NA), somatic symptom attribution and somatosensory amplification predicted somatic symptom severity within the IEI and SFD groups, both at baseline and 1 year later. The strongest predictors of IEI complaints in the IEI group were somatic attributions, followed by prominent cognitions of environmental threat and a tendency to focus on unpleasant bodily sensations and to consider them as pathological. CONCLUSIONS IEI and SFD are highly stable conditions. In both SFD and IEI, NA and the processes of symptom perception, interpretation and attribution contribute substantially to the persistence of typically somatoform symptoms and IEI complaints. Treatment of IEI and SFD should address these psychological factors and mechanisms.

Superior Perception of Phasic Physiological Arousal and the Detrimental Consequences of the Conviction to Be Aroused on Worrying and Metacognitions in GAD

Although people suffering from generalized anxiety disorder (GAD) often report arousal symptoms, psychophysiological studies show no evidence of autonomic hyperarousal. Hypersensitivity toward and catastrophic interpretation of phasic arousal cues may explain this discrepancy. The authors tested (a) whether GAD sufferers perceive nonspecific skin conductance fluctuations (NSCFs), an indicator of phasic autonomic arousal, better than controls do and (b) whether the conviction to be aroused contributes to the maintenance of worrying and metacognitive beliefs about worrying. Thirty-three GAD sufferers and 34 healthy controls participated in 2 experiments. In Experiment 1, participants were asked to detect their own NSCFs during a signal detection task. GAD sufferers accurately detected more of their NSCFs than did controls, who tended to miss NSCFs. In Experiment 2, participants were instructed to relax following worry induction. While relaxing, they received nonveridical feedback indicating either arousal or relaxation. Arousal feedback conserved negative metacognitive beliefs regarding worrying and also maintained negative mood and worry exclusively in GAD participants. These findings suggest that superior perception of phasic arousal cues and their catastrophic misinterpretation increases worrying, negative metacognitive beliefs about worrying, and anxious mood in GAD.

Psychological Predictors of Short- and Medium Term Outcome in Individuals with Idiopathic Environmental Intolerance (IEI) and Individuals with Somatoform Disorders

Idiopathic environmental intolerance (IEI), also known as multiple chemical sensitivity (MCS), is defined as a chronic polysymptomatic condition that cannot be explained by an organic disease. Previous studies suggest that IEI may be a variant of somatoform disorders (SFD), because both disorders overlap with respect to symptoms and psychological features of somatization. However, little is known about the short- and medium-term outcome of IEI and psychological outcome predictors. Two clinical groups (IEI and SFD) and a comparison group (CG) were followed through 32 mo to assess both the outcome, and the extent to which trait anxiety and somatic symptom attribution (assessed at first examination) predict outcome presented 12 and 32 mo later. Outcome measures were the number of self-reported IEI symptoms, IEI triggers, IEI-associated functional impairments, and the number of somatoform symptoms. In addition, the course of the 2 syndromes over the 32-mo follow-up period was investigated with standardized screening scales. The 3 diagnostic groups consisted of 46 subjects with IEI, 38 subjects with SFD but without IEI, and 46 subjects (CG) with neither IEI nor SFD. Syndrome stability was high over the 32-mo follow-up period, and at both follow-ups IEI and non-IEI subjects differed on all IEI outcome measures (symptoms, triggers, functional impairments). Both trait anxiety and somatic attribution (the tendency to attribute common somatic complaints to an illness) predicted outcome. In addition, somatic attribution was found to partially mediate the effect of trait anxiety on outcome in the IEI group. In conclusion, these results suggest that IEI is a chronic and disabling condition and that trait anxiety contributes to the maintenance of the disorder via somatic attributions.

Modern health worries and idiopathic environmental intolerance

OBJECTIVE We conducted two studies to test whether modern health worries (MHWs) were associated with central features of a condition called idiopathic environmental intolerance (IEI) and medical care utilization. METHODS In Study 1, 474 Internet users completed an Internet-based questionnaire that assessed MHWs, IEI features, and medical care utilization. In Study 2, the diagnostic specificity of MHWs was investigated by comparing the level of MHWs of three diagnostic groups: 46 people with IEI, 38 people with somatoform disorder but without IEI, and 46 people with neither IEI nor somatoform disorder. RESULTS The good psychometric properties of the MHW scale were confirmed. MHWs were related to various features of IEI, and people who met IEI case criteria showed consistently higher levels of MHWs compared with people without IEI. The link between MHWs and number of doctor visits was mediated by perceived IEI complaints. In Study 2, the MHW scale effectively discriminated the IEI group from the non-IEI groups. CONCLUSIONS These results suggest that MHWs may contribute to the development of IEI. However, only prospective longitudinal studies will enable us to determine the predictive importance of MHWs for later development of IEI.

The Alcohol Use Disorders Identification Test revisited: Establishing its structure using nonlinear factor analysis and identifying subgroups of respondents using latent class factor analysis

BACKGROUND Previous research used principal components as well as exploratory and confirmatory factor analysis to establish continuous dimensions underlying answers to the 10-items of the Alcohol Use Disorders Identification Test (AUDIT). The majority of these studies conclude that one consumption dimension and an adverse consequences dimension explain the answers to the AUDIT sufficiently. However, most of the methods used presuppose normal answer distributions and linear relations between indicators and constructs, which are unrealistic assumptions for AUDIT answer. OBJECTIVES First, to investigate the continuous factor analytic structure underlying the answers to all AUDIT items. Second and third, to assess the impact of consumption as well as age and gender on AUDIT consequences dimension. Fourth and fifth, to categorize respondents into subgroups based on the AUDIT consequences items and adjusting the subgroups for differences in consumption, age and gender. Sixth, to describe the subgroups with respect to further adverse consequences of drinking. METHODS Nonlinear factor and latent class factor analyses models were applied to the AUDIT answers of N=6259 patients of 26 general practitioners in a city area in Germany. Consumption items as well as age and gender were included as predictors of answers to the AUDIT consequences items. RESULTS Nonlinear factor analyses suggested two continuous correlated factors reflecting the adverse consequences of alcohol use: (1) harmful alcohol use, (2) alcohol dependence (aim 1). Consumption items did not prove to be reasonable construct indicators, but adverse consequences were predicted by consumption (aim 2), and also by age and gender (aim 3). Latent class factor analysis identified four subgroups based on the AUDIT consequences items (aim 4): one not affected (66%), and three subgroups defined by either harmful (15%) or dependent (9%), or combined harmful and dependent use (10%). These groups differed also with respect to further alcohol use consequences. Adjusting the subgroups for differences in consumption, age and gender (aim 5) reduced the non-affected subgroup and increased the subgroup with harmful and dependent use. CONCLUSIONS The AUDIT items cover three separable domains, i.e. consumption, harmful and dependent use, as originally intended. Hence, assessment of alcohol use does not substitute for assessing adverse consequences, as assumed in short versions of the AUDIT comprising only the AUDIT consumption items. Further, the dimensional as well as the LCFA subgroup solution imply that the respondents cannot be ordered along a single severity dimension without loss of information.