Interference control and resource allocation in adults with Attention-Deficit/Hyperactivity Disorder : an evaluation of response variability and error compensation

Thesis (Ph. D.)--University of Rochester. Dept. of Clinical and Social Sciences in Psychology, 2012.This research investigated intrasubject variability in reaction time, interference control, and error compensation during a flanker task in 37 adults with Attention-Deficit/Hyperactivity Disorder (ADHD; 20 Combined subtype, 17 Predominantly Inattentive subtype) and 26 healthy controls. I hypothesized that, similar to children with ADHD, adults with the disorder would demonstrate: (a) greater interference control deficits than control subjects, as reflected in greater effects of incongruent flankers on accuracy, reaction time, and intrasubject variability; and (b) less post-error slowing than controls, indicating difficulties with error compensation associated with resource allocation deficits. Intrasubject variability was assessed using the ex-Gaussian distributional model and the deviation from the mode method. Across task conditions, similar to pediatric samples, adults with ADHD demonstrated greater intrasubject variability involving greater sigma, reflecting relatively faster reaction times in the normal portion of the curve, and greater tau, indicating greater variability in the positive skew of the distribution. These results suggest that the portion of the RT distribution affected in patients with ADHD is consistent across the lifespan. Variability in child and adult ADHD may be explained by the default-mode hypothesis, which emphasizes the role of attentional lapses in performance. In contrast to prediction, performance measures did not implicate a specific deficit in interference control among adults with ADHD. In fact, controls were more adversely affected by incongruent arrays with respect to the proportion of correct responses, directional errors, and nonresponses to targets. Only for false alarms was there a greater interference effect among adults with ADHD. However, whereas previous studies have not found an elevated flanker effect on intrasubject variability of patients with ADHD, the present results indicated that adults with ADHD exhibited increased variability with greater demands for interference control. Intrasubject variability in adults with ADHD involved greater sigma during flanker incongruent compared to congruent trials, reflecting increased variability in the normal portion of the RT distribution. In addition, adults with ADHD exhibited diminished post-error slowing, a result consistent with previous findings for children with the disorder. This deficit in executive functioning is present in individuals with ADHD throughout development and can be explained by the resource allocation hypothesis

Long-term cognitive modulation of event related potentials to affective stimuli as a function of trait anxiety

Thesis (Ph. D.)--University of Rochester. Department of Clinical and Social Sciences in Psychology, 2013.The present work aimed to test the adaptive role of reconsolidation as a window of opportunity to modify emotional memories by pairing an experimentally specified meaning to aversive emotional stimuli and measuring the change with event-related potentials (ERPs). The present hypothesis was that this cognitive intervention during the reconsolidation window would impact the acquisition and consolidation of emotional memories. This result would have important implications for the treatment of anxiety disorders. The proposed research examined (a) differences in responses to negative affective stimuli in individuals with and without elevated anxiety during passive viewing of negative and affectively neutral slides, and (b) the effectiveness of a brief cognitive intervention to reduce responses to negative affective stimuli, especially in anxious persons. Participants were 81 young adults with varying levels of trait anxiety. Task participation occurred across two laboratory sessions, held 5 -10 days apart. Session 1 consisted of two blocks of 160 presentations of affective slides (Passive Viewing and Emotional Regulation) and Session 2 (Follow Up) involved one block of the same 160 affective slides. In both sessions, ERPs were measured. Findings indicating differences in cognitive processing of emotional stimuli were found as early as ERPs peaking at 100 ms through 2 seconds. Results for Passive Viewing showed that ERPs evoked by affectively negative images reflect more processing of emotional compared to neutral stimuli; notably, Late Positive Potential amplitude to aversive slides was enhanced among anxious persons. In addition, the attendant amplitude modulations observed for the earlier and later ERP components replicated previous work in this area. Results during Emotion Regulation involving specific reappraisal conditions yielded mixed results. ERPs evoked by affectively negative images suggest that emotional memories are in fact malleable and modifiable, but not in the intended direction. Specifically, images that did not have any descriptions evoked higher ERP amplitudes than aversive slides preceded by a description, whether positively or negatively framed. However, the malleability of emotional memories during the reconsolidation window was demonstrated by increased amplitude of ERPs in the Follow Up block for selected conditions. Ratings of valence and arousal were generally consistent with hypotheses, but differed from ERP results. Specifically, individuals viewed images preceded by a negatively framed description (Enhancing condition) as most unpleasant, followed by images not preceded by a description (No Description Condition); the lowest unpleasantness was attributed to those images preceded by a positively framed description (Attenuating condition). Finally, higher levels of trait anxiety magnified the overall changes in ERP amplitude between blocks, a pattern that is consistent with a greater bias for affectively negative stimuli in anxious persons

Fluctuations of perceived stress and fatigue impact in patients with relapsing remitting multiple sclerosis and the moderating role of coping mechanisms : a diary study

Thesis (Ph. D.)--University of Rochester. Department of Clinical and Social Sciences in Psychology, 2013.Fatigue is one of the most common and time enduring symptom in patients with relapsing-remitting multiple sclerosis and has a profound impact on their quality of life and well-being. Previous research has shown a relation between objective stress (stressful life events) and disease exacerbation manifested by various symptoms, including fatigue. The subjective component of stress and its temporal fluctuations were not studied in relation to fatigue in these patients. The present study explored the hypothesis that weekly fluctuations of perceived stress influence the weekly fluctuations of fatigue impact in patients with relapsing-remitting multiple sclerosis. In addition, the researcher explored whether the relation between perceived stress and fatigue impact may be moderated by factors such as disease duration and coping mechanisms. Seventy-eight patients with relapsing-remitting multiple sclerosis offered weekly self-report data on perceived stress and fatigue impact over the course of a year. Hierarchical linear models were used to test the study hypotheses. Results revealed that perceived stress has an influence on the same week, as well as following week, fatigue impact. Further, only the relation between perceived stress and following week fatigue impact was found to be moderated by the disease duration and coping mechanisms. The findings suggest that perceived stress is a contributing factor to fatigue in individuals with multiple sclerosis. Clinical implications and directions for future research are discussed

Temporospatial components of brain ERPs as biomarkers for Alzheimers disease.

INTRODUCTION: Developing biomarkers that distinguish individuals with Alzheimers disease (AD) from those with normal cognition remains a crucial goal for improving the health of older adults. We investigated adding brain spatial information to temporal event-related potentials (ERPs) to increase AD identification accuracy over temporal ERPs alone. METHODS: With two-step principal components analysis, we applied multivariate analyses that incorporated temporal and spatial ERP information from a cognitive task. Discriminant analysis used temporospatial ERP scores to classify participants as belonging to either the AD or healthy control group. RESULTS: Temporospatial ERPs produced a cross-validated area under the curve of 0.84. Adding spatial information through a formal procedure significantly improves classification accuracy. DISCUSSION: A weighted combination of temporospatial ERP markers performs well in detecting AD. Because ERPs are noninvasive and inexpensive, they may be promising biomarkers for AD that can add functional information to other biomarker systems while providing the individuals probability of correct classification

Temporospatial components of brain ERPs as biomarkers for Alzheimer's disease.

IntroductionDeveloping biomarkers that distinguish individuals with Alzheimer's disease (AD) from those with normal cognition remains a crucial goal for improving the health of older adults. We investigated adding brain spatial information to temporal event-related potentials (ERPs) to increase AD identification accuracy over temporal ERPs alone.MethodsWith two-step principal components analysis, we applied multivariate analyses that incorporated temporal and spatial ERP information from a cognitive task. Discriminant analysis used temporospatial ERP scores to classify participants as belonging to either the AD or healthy control group.ResultsTemporospatial ERPs produced a cross-validated area under the curve of 0.84. Adding spatial information through a formal procedure significantly improves classification accuracy.DiscussionA weighted combination of temporospatial ERP markers performs well in detecting AD. Because ERPs are noninvasive and inexpensive, they may be promising biomarkers for AD that can add functional information to other biomarker systems while providing the individual's probability of correct classification