Biomedical subjects

Julie C Stout

Publications and source records attributed to Julie C Stout.

16 recordsLinked to original sources

PubMed2007

Specific psychiatric manifestations among preclinical Huntington disease mutation carriers.

BACKGROUND: Despite the need for significant clinical intervention owing to the psychiatric manifestations of Huntington disease (HD), there has been a paucity of studies specifically designed to evaluate these symptoms prior to disease diagnosis. OBJECTIVES: To investigate whether the Symptom Checklist 90-Revised (SCL-90-R) and the Center for Epidemiological Studies Depression Scale can be used to detect psychiatric manifestations among preclinical mutation carriers with absent or minimal motor signs of HD. DESIGN, SETTING, AND PARTICIPANTS: Individuals at risk for or recently diagnosed with HD were recruited and then evaluated at Indiana University School of Medicine, Indianapolis. All of the subjects completed a uniform clinical evaluation that included the Unified Huntington's Disease Rating Scale-99, molecular testing to determine HD mutation status, the SCL-90-R, and the Center for Epidemiological Studies Depression Scale. The sample was divided into 4 study groups: 171 individuals in the nonmutation carrier group; 29 with minimal, if any, motor signs of HD in the preclinical mutation carrier group 1; 20 with motor abnormalities suggestive of HD in the preclinical mutation carrier group 2; and 34 in the manifest HD group. MAIN OUTCOME MEASURES: Scores on the SCL-90-R and Center for Epidemiological Studies Depression Scale were compared. RESULTS: Five SCL-90-R symptom dimensions (obsessive-compulsive, interpersonal sensitivity, anxiety, paranoid ideation, and psychoticism) demonstrated a significant group effect (P < or = .04). The preclinical mutation carrier group 2 and the manifest HD group scored significantly higher on all 5 dimensions as compared with the nonmutation carrier group. The preclinical mutation carrier group 2 scored significantly higher than the nonmutation carrier group for 3 of the SCL-90-R symptom dimensions (anxiety, paranoid ideation, and psychoticism). A significant group effect was found on the Center for Epidemiological Studies Depression Scale (P = .04). The frequency of depressive symptoms was significantly higher in the manifest HD group and the preclinical mutation carrier group 2 as compared with the nonmutation carrier group. CONCLUSION: This study identified specific psychiatric symptom dimensions that differentiate nonmutation carriers from individuals in the early preclinical stages of HD who are either symptom free or have minor nonspecific motor abnormalities.

Adult↗

PubMed2006

Preparing for preventive clinical trials: the Predict-HD study.

BACKGROUND: The optimal design and outcome measures for preventive clinical trials in neurodegenerative diseases are unknown. OBJECTIVE: To examine measures that may be associated with disease in the largest cohort ever recruited of prediagnosed individuals carrying the gene expansion for Huntington disease (HD). DESIGN: The Predict-HD study is a multicenter observational research study in progress at 17 sites in the United States, 4 in Canada, and 3 in Australia. SETTING: Genetics and HD outpatient clinics. PARTICIPANTS: Five hundred five at-risk individuals who had previously undergone elective DNA analyses for the CAG expansion in the HD gene (predictive testing) and did not currently have a clinical diagnosis of HD. MAIN OUTCOME MEASURES: Basal ganglia volumes on magnetic resonance images, estimated probability of diagnosis (based on CAG repeat length), performances on 21 standardized cognitive tasks, total scores on 3 scales of psychiatric distress, and motor diagnosis based on the Unified Huntington's Disease Rating Scale. RESULTS: Several variables showed progressive decline as the diagnostic ratings advanced toward manifest disease. Estimated probability of diagnosis was associated with Unified Huntington's Disease Rating Scale prediagnostic stages and varied from 15% in persons with no motor abnormalities to nearly 40% in those with abnormalities suggestive of probable disease. Striatal volumes, cognitive performances, and even psychiatric ratings declined significantly with motor manifestations of disease. CONCLUSIONS: The documentation of biological and refined clinical markers suggests several clinical end points for preventive clinical trials. Longitudinal study is critical to further validate possible markers for prediagnosed HD.

Adult↗

PubMed2006

Motivational processes and autonomic responsivity in Asperger's disorder: evidence from the Iowa Gambling Task.

Asperger's disorder (ASP), like other autism spectrum disorders, is associated with altered responsiveness to social stimuli. This study investigated learning and responsiveness to nonsocial, but motivational, stimuli in ASP. We examined choice behavior and galvanic skin conductance responses (SCRs) during the Iowa Gambling Task (IGT; Bechara et al., 1994) in 15 adolescents and young adults with ASP and 14 comparison subjects. We examined aspects of learning, attention to wins and losses, and response style with a formal cognitive model, the Expectancy-Valence Learning model (Busemeyer & Stout, 2002). The ASP group did not differ from the comparison group in proportions of selections from advantageous decks. However, ASP participants showed a distinct pattern of selection characterized by frequent shifts between the four IGT decks, whereas comparison participants developed clear deck preferences. SCR results showed some evidence of reduced responsiveness in the ASP group during the IGT. Results from the cognitive model indicated that, in contrast to the comparison group, the ASP group's selections were less consistent with the motivational significance they assigned to decks. Findings are discussed in the context of the neurobiological substrates associated with IGT performance.

Adolescent↗

PubMed2005

Activation of conflicting responses in Parkinson's disease: evidence for degrading and facilitating effects on response time.

Response selection often occurs in a context of competition among conflicting responses. According to recent models, the basal ganglia may play an integral role in resolving this competition by focusing the selection and inhibition of responses. We hypothesized that basal ganglia dysfunction produced by Parkinson's disease (PD) disrupts selection among conflicting responses. Using a version of the Eriksen flanker task, we tested the specific prediction that individuals with PD would experience greater response interference when distractors in the visual field activate a response that conflicts with the target response. In addition, we investigated whether greater response interference induced by these distractors could actually reduce normal response time costs in PD when the task required production of the response opposite the target. Compared to 16 healthy controls (HC), 16 individuals with PD showed an exacerbated slowing when target and distracting stimuli corresponded to conflicting responses. No group differences occurred when targets and distractors corresponded to the same response. Furthermore, the slowing induced by the distractors was reduced in both groups, but more so in PD, when execution of a response opposite the target response (i.e. incompatible response) was required. Moreover, among individuals with PD, the magnitude of the interference produced by the distractors was related to clinical ratings of bradykinesia. These findings are consistent with the hypothesis that basal ganglia dysfunction due to Parkinson's disease disrupts processes that resolve response conflict.

Aged↗

PubMed2005

Cognitive impairment and dementia in basal ganglia disorders.

We present an update focusing on research from the past 2 years on cognitive impairment and dementia in basal ganglia disorders, including Huntington's disease, progressive supranuclear palsy, Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies. In addition to the many recent papers that aim to refine descriptions of the cognitive phenotypes in the basal ganglia disorders, the current literature addresses the use of cognitive assessment in differential diagnosis of clinically overlapping disorders, the effects of surgical and pharmacologic treatments on cognitive functions, and the relationship between cognitive impairment and functional disability. We also discuss opportunities for enhancing the understanding of cognition in basal ganglia disorders through the use of improved study design and assessment strategies.

Animals↗

PubMed2005

Neurocognitive insights into substance abuse.

Cognitive studies are revealing key aspects of how drug abusers monitor and respond to negative feedback differently from non-abusers, and in doing so are adding an important piece to the conceptual puzzle that must be solved to understand, treat, and prevent drug abuse. In this review, we bring together two quite different lines of research, one addressing the selection of gambles in a risky decision task, and the other focused on imaging neural systems related to the detection and processing of errors. We suggest that diminished behavioural control, which is a cardinal feature of drug abuse, may be linked to alterations in the psychological and neural mechanisms that detect error signals and which, in turn, lead to optimization of behavioural responses.

Brain Mapping↗

PubMed2005

Psychological processes underlying risky decisions in drug abusers.

Decision-making deficits are considered to be a significant contributing factor for drug abuse. Drug abusers performed poorly on a simulated gambling task (A. Bechara, H. Damasio, D. Tranel, & S. Anderson, 1994); however, the psychological processes that contribute to these deficits are unknown. The authors used cognitive decision models with a simulated gambling task (SGT) to examine underlying processes of decision making in 66 drug abusers and 58 control participants. As expected, male drug abusers performed more poorly than male controls, and model results showed that male drug abusers placed greater emphasis on wins. The findings for women were less clear because control women performed at chance level on the SGT. Additional studies of gender differences on the SGT are needed to clarify these findings of discrepant performance in the control women.

Adolescent↗

PubMed2005

Using cognitive models to map relations between neuropsychological disorders and human decision-making deficits.

Findings from a complex decision-making task (the Iowa gambling task) show that individuals with neuropsychological disorders are characterized by decision-making deficits that lead to maladaptive risk-taking behavior. This article describes a cognitive model that distills performance in this task into three different underlying psychological components: the relative impact of rewards and punishments on evaluations of options, the rate that the contingent payoffs are learned, and the consistency between learning and responding. Findings from 10 studies are organized by distilling the observed decision deficits into the three basic components and locating the neuropsychological disorders in this component space. The results reveal a cluster of populations characterized by making risky choices despite high attention to losses, perhaps because of difficulties in creating emotive representations. These findings demonstrate the potential contribution of cognitive models in building bridges between neuroscience and behavior.

Cognition Disorders↗

PubMed2004

Reduced autonomic responsiveness to gambling task losses in Huntington's disease.

We examined the possible role of autonomic activity in Huntington's disease (HD) during a risky decision making task. Skin conductance responses (SCRs) of 15 HD participants and 16 healthy controls were measured while they performed a computerized version of the Simulated Gambling Task (SGT). The results replicated our previous finding of a performance decrement in HD, and showed that HD was associated with an altered pattern of SCRs during the risky decision task. Specifically, the healthy controls produced increased SCRs following selections from the disadvantageous decks and following losing selections. In contrast, the SCRs of the HD group did not differentiate between wins and losses. These findings indicate a reduced impact of loss on decision-making processes under risky conditions in HD.

Autonomic Nervous System Diseases↗

PubMed2004

Cognitive modeling analysis of decision-making processes in cocaine abusers.

This article examines the theoretical basis of decision-making deficits exhibited by cocaine abusers in a laboratory decision-making task first described by Bechara, Damasio, Damasio, and Anderson (1994). A total of 12 male cocaine abusers and 14 comparison subjects performed the task, and the cocaine group performed significantly worse than the comparison group. A cognitive modeling analysis (Busemeyer & Stout, 2002) was used to estimate three parameters that measure importance of the cognitive, motivational, and response processes for determining the observed performance deficit. The results of this analysis indicated, for the first time, that motivational and choice consistency factors, but not learning/memory were mainly responsible for the decision-making deficit of the cocaine abusers in this task.

Adult↗

PubMed2003

Visual function in Huntington's disease patients and presymptomatic gene carriers.

Disturbances of visual cognition, visuomotor performance, and visual memory have been described frequently in Huntington's disease (HD). Early stage visual abnormalities could contribute to these deficits. We evaluated visual processing in 20 control subjects who were non-gene carriers at risk for HD, nine presymptomatic gene-positive subjects, and eight subjects with a recent diagnosis of Huntington's disease. Visual perceptual tests of contrast sensitivity and motion discrimination were used to probe early stage visual processing. Extraocular movements were evaluated in a neurologic examination, and the Digit Symbol test was used to test visual motor performance. Contrast sensitivity did not differ among the three groups. Motion discrimination was impaired in HD subjects but not in the presymptomatic gene carriers when compared to gene noncarriers. Among gene carriers, impaired motion discrimination performance was associated with poorer Digit Symbol performance and extraocular abnormalities. These findings suggest that the early stages of HD are associated with disturbances of motion perception as well as disruptions of visual motor and ocular motor performance.

Adult↗

PubMed2003

Factor analysis of the frontal systems behavior scale (FrSBe).

The Frontal Systems Behavior Scale (FrSBe), formerly called the Frontal Lobe Personality Scale (FLOPS), is a brief behavior rating scale with demonstrated validity for the assessment of behavior disturbances associated with damage to the frontal-subcortical brain circuits. The authors report an exploratory principal factor analysis of the FrSBe-Family Version in a sample including 324 neurological patients and research participants, of which about 63% were diagnosed with neurodegenerative diseases (Huntington's, Parkinson's, and Alzheimer's diseases). The three-factor solution accounted for a modest level of variance (41%) and confirmed a factor structure consistent with the three subscales proposed on the theoretical basis of the frontal systems. Most items (83%)from the FrSBe subscales of Apathy, Disinhibition, and Executive Dysfunction loaded saliently on three corresponding factors. The FrSBe factor structure supports its utility for assessing both the severity of the three frontal syndromes in aggregate and separately.

Alzheimer Disease↗

PubMed2002

Divergent findings regarding negative priming in Parkinson's disease: A comment on Filoteo et al. (2002) and Wylie and Stout (2002).

This commentary discusses divergent findings in 2 articles published in this issue of Neuropsychology. The studies used negative priming (NP) to probe the associations between basal ganglia function and cognition in Parkinson's disease (PD) and tested different predictions about NP in PD. Different NP tasks were used, and although the subject samples appeared to have similar clinical features, results were quite different. This commentary, written jointly by the authors of the 2 studies (J. V. Filoteo, L. M. Rilling, & D. L. Strayer, 2002; S. A. Wylie & J. C. Stout, 2002), describes a process by which their disparate results may be used to facilitate the design of new studies that may determine how specific features of NP tasks lead to different findings in PD. The results are a more systematic account of how task features, such as specific response demands, interact with the response selection processes that are implemented by the basal ganglia.

Basal Ganglia↗

PubMed2002

A contribution of cognitive decision models to clinical assessment: decomposing performance on the Bechara gambling task.

The Bechara simulated gambling task is a popular method of examining decision-making deficits exhibited by people with brain damage, psychopathology, antisocial personality, or drug abuse problems. However, performance on this task is confounded by complex interdependencies between cognitive, motivational, and response processes, making it difficult to sort out and identify the specific processes responsible for the observed behavioral deficits. The authors compare 3 competing cognitive decision models of the Bechara task in terms of their ability to explain the performance deficits observed in Huntington's disease patients as compared with healthy populations and people with Parkinson's disease. The parameters of the best fitting model are used to decompose the observed performance deficit of the Huntington patients into cognitive, motivational, and response sources.

Brain Damage, Chronic↗

PubMed2002

Enhanced negative priming in Parkinson's disease.

In the ignored repetition paradigm, negative priming (NP) is defined as the increase in response time that occurs when the current target stimulus served as a distractor stimulus in the previous trial. In this study, 25 Parkinson's disease (PD) participants and 17 age-matched healthy controls (HCs) were tested using a touchscreen version of the ignored repetition task that allowed response time to be partitioned into response initiation and response execution segments. In both groups, NP effects were stronger in the response execution than in the response initiation segments. The most striking result was that the PD group showed larger NP effects overall than the HC group. In PD, clinical ratings of bradykinesia, but not tremor, were related to larger NP effects. Results indicate that in PD, disruption of dopamine neuromodulation diminishes response efficiency when action must be directed toward previously ignored information.

Cognition↗

PubMedDate not supplied

Frontal behavioral syndromes and functional status in probable Alzheimer disease.

OBJECTIVE: / METHOD: The authors used the Frontal Systems Behavior Scale (FrSBe) to determine the frequency of frontal behavioral syndromes in 49 subjects with mild-to-moderate dementia and 23 subjects with severe dementia of Alzheimer disease (AD) and 23 healthy control (HC) participants. RESULTS: / CONCLUSIONS: Frontal behavior syndromes occurred with higher frequency in AD. Apathy and executive dysfunction were elevated both in mild-to-moderate and severe AD. Disinhibition was elevated only in severe AD. In AD, apathy was associated with difficulty in basic activities of daily living (ADL), whereas executive dysfunction was related to impairment in instrumental ADLs.

Activities of Daily Living↗