Biomedical subjects

Byron P Rourke

Publications and source records attributed to Byron P Rourke.

10 recordsLinked to original sources

PubMed2005

Rules for the classification of younger children with nonverbal learning disabilities and basic phonological processing disabilities.

Rules for the classification of Nonverbal Learning Disabilities (NLD) and Basic Phonological Processing Disabilities (BPPD) that had been generated and tested on older children (ages 9-15) were applied to younger children (ages 7-8). The goal was to evaluate the applicability of these classification rules for a younger population with NLD and BPPD, and to make revisions if necessary. These rules were used to differentiate these two subtypes of learning disabilities using levels and patterns of performance on motor/psychomotor, tactile/perceptual, visual-spatial, auditory-perceptual, problem solving, and language measures. An experienced child-clinical neuropsychologist classified each child. Only those children who received a classification of NLD or BPPD by the neuropsychologist and those who met criteria for definite or probable NLD and BPPD as defined by the rules were used in this study. Revisions were made to these rules for younger children. Revised rules allow for their use as a source of information to assist a clinician in deciding whether a comprehensive neuropsychological evaluation would be valuable. They may also be useful for research purposes.

Articulation Disorders↗

PubMed2004

Verbal fluency patterns in two subgroups of patients with Alzheimer's disease.

Previous research has identified two subgroups of patients with Alzheimer's disease (AD) based on performance discrepancies on semantic and visual-constructional measures: Left AD (LAD) and Right AD (RAD). In this study, verbal fluency performances (Animal Fluency [AF] and Letter Fluency [FAS]) of these two subgroups were examined. It was hypothesized that LAD patients would perform worse on AF compared to FAS, due to an underlying breakdown of left-hemisphere semantic networks. On the other hand, the RAD group, which theoretically has a relatively preserved semantic system, yet difficulties retrieving overlearned information, was not expected to differ on the two fluency tasks. These predictions were based on the notion that the AF task requires intact retrieval and semantic processes, whereas the FAS task is reliant on retrieval processes alone. Patients were classified into subgroups on the basis of performance discrepancies on the Boston Naming Test (BNT) and Copy tasks: LAD (BNT < Copy); RAD (BNT > Copy). A split-plot ANOVA using demographically corrected standard T-scores revealed a significant main effect for fluency task, and a significant subgroup x fluency task interaction. LAD patients performed poorer on AF compared to FAS; there was no fluency task difference for the RAD group. Analysis of within-subcategory response clustering on AF revealed more instances of serial subclass exemplar responses by RAD members. These results support the loss theory in explaining the semantic deficit of LAD, and suggest that retrieval difficulties underlie the fluency problems of RAD.

Aged↗

PubMed2003

Reduced thalamic volume in high-functioning individuals with autism.

BACKGROUND: In this study, specific consideration is given to a role for the thalamus in autism. METHODS: A volumetric analysis of the thalamus was conducted using magnetic resonance imaging, based on segmentation of continuous 1.2 mm(3) coronal images. The sample consisted of 12 high-functioning individuals with autism, mean age of 21.0 years (SD = 10.4) and mean IQ of 106.4 (SD = 18.3). Normal control subjects were selected to match this group; the mean age was 18.1 years (SD = 6.3); mean IQ was 108.8 (SD = 15.6). RESULTS: Unadjusted mean thalamic volume was not significantly different; however, there were significant differences in the relationship between thalamic volume and total brain volume (TBV). The correlation was strong and positive in the control group but statistically nonsignificant in the autism group. Group differences were found when adjustments were made for TBV, achieved by grouping subjects' measurements on this variable using a split median procedure. Mean thalamic volume was significantly reduced in the autism group relative to normal control subjects, specifically within the high TBV group. CONCLUSION: The increase in thalamic volume with increase in TBV was not seen in autism, suggesting underdeveloped connections between cortical and subcortical regions and indicating a need to examine this structure further.

Adolescent↗

PubMed2003

Theoretically derived CVLT subtypes in HIV-1 infection: internal and external validation.

The present study sought to delineate empirically derived memory subtypes using the California Verbal Learning Test (CVLT; Delis et al., 1987) in a sample of adults with HIV-1 infection (N = 154). Confirmatory factor analysis was used to evaluate eight models of the CVLT structure suggested by Wiegner and Donders (1999). A four-factor model, consisting of Attention Span, Learning Efficiency, Delayed Recall, and Inaccurate Recall appeared to be the best fitting model. Variables with the highest factor loadings from the model were entered in a two-stage cluster analysis. Four reliable CVLT clusters or subtypes were identified: Normal, Atypical, Subsyndromal, and Frontal-striatal. Internal and external validation of subtypes demonstrated that clusters were stable and clinically interpretable. Subtypes were meaningfully related to neuropsychological functioning, and to some extent, depressive symptomatology. Subtypes did not differ significantly with respect to subjective neurocognitive complaints and markers of HIV-1 disease. The present findings highlight the heterogeneity of memory profiles in HIV-1 infection and support a frontal-striatal conceptualization of verbal memory performance. The identification of robust HIV-1 memory subtypes may have important implications for the clinical management of adults infected with HIV-1 infection.

Adult↗

PubMed2003

Psychosocial status after pediatric traumatic brain injury: a subtype analysis using the Child Behavior Checklist.

This study identified subtypes of psychosocial functioning in children who had sustained traumatic brain injury (TBI). Child Behavior Checklist (CBCL) profiles for 92 participants, aged 12 to 18 years, who had sustained a mild, moderate, or severe TBI were subjected to Q-Factor analysis. Sixty-four of the participants (75%) were classified into a four-category psychosocial typology labelled Normal (n = 32), Attention (n = 14), Delinquent (n = 10), and Withdrawn-Somatic (n = 8). This typology was found to overlap in part with previous TBI psychosocial typology (Butler et al., 1997), and with three of the clinical profile types derived by Achenbach (1993) for the CBCL. The majority of participants, including those who sustained severe TBI, were assigned to the Normal subtype and the overall level of psychosocial deviance was relatively mild in the other three subtypes. The results of this study support previous typology efforts and confirm the heterogeneous presentation of social and emotional functioning following TBI.

Adaptation, Psychological↗

PubMed2003

Cognitive complaints, depression, medical symptoms, and their association with neuropsychological functioning in HIV infection: a structural equation model analysis.

The main objective of this study was to use structural equation modeling (SEM) to clarify the relationship between subjective cognitive complaints and neuropsychological functioning in 160 adults with HIV infection. Participants completed questionnaires assessing cognitive complaints, symptoms of depression, and HIV-related medical symptoms. Neuropsychological tests included measures of attention, verbal fluency, psychomotor skills, learning, memory, and executive skills. SEM was used to test models of the relationships among cognitive complaints, mood, and medical symptoms with neuropsychological functioning. The model indicated that although depressed mood (beta = 0.32, p < .01) and medical symptoms (beta = 0.31, p < .01) influenced cognitive complaints, cognitive complaints were independently associated with poorer neuropsychological performance (beta = 0.39, p < .01). Mood and medical symptoms were significantly correlated but were not significantly associated with neuropsychological skills.

Adult↗

PubMed2003

Comparison of the psychosocial typology of children with below average IQ to that of children with learning disabilities.

This study investigates the subtypal patterns of psychosocial functioning of children with below average IQ (BAIQ) using the application of both Q-factor analysis and profile-matching. The results suggest that the psychosocial dimensions of children with BAIQ are quite similar to those of children with LD in a general sense. Many of the same subtypes were derived, and the proportions of children displaying normal, mild, and severe levels of psychopathology were not significantly different from those of children with LD. There were some minor differences, however: For example, children with BAIQ exhibited a greater tendency to display psychopathology with internalizing features. Consistent with previous research involving children with LD, there were no changes in either type or severity of psychopathology with advancing years.

Adolescent↗

PubMed2003

Learning-disabled brains: a review of the literature.

In this paper, we review the literature investigating the neurophysiological correlates of learning disabilities (LD). The focus is placed on the developmental presentations of LD and not on learning difficulties that arise as a result of some form of acquired neurological insult. Following a brief historical overview of research in this area, we examine evidence from investigations of brain morphology and of functional brain systems in individuals with LD. The studies reviewed include those that have employed postmortem examinations, neuroimaging techniques, or electrophysiological procedures. We summarize the major morphological and functional distinctions between individuals with LD and nonimpaired individuals. Finally, we make recommendations for future studies in this area, including the adoption of more widespread methodological conventions, and a greater consideration of nosological/classification and developmental issues.

Brain↗

PubMed2003

Subtypes of emotional and behavioural sequelae in patients with traumatic brain injury.

This study examined patterns of emotional and behavioural sequelae in 300 individuals who sustained a traumatic brain injury (TBI). Participants were obtained through the Adult Acquired Brain Injury Program at Chedoke Hospital in Hamilton, Ontario, based on the following inclusionary criteria: (1) single incident of TBI; (2) no history of additional neurological diseases; (3) time postinjury < or =8.5 years; (4) WAIS-R FSIQ >85 and/or estimated reading skills above grade 5 level; and (5) valid Minnesota Multiphasic Personality Inventory (MMPI) profiles (i.e., F<90, L<66, and K<66). MMPI profiles of these individuals, in randomly split samples of 150 per group, were subjected to a three-step cluster analytic approach. A six-cluster solution was adequately replicated across samples and across clustering techniques. The identified subtypes included profiles indicative of: (1) no concerns or normal functioning; (2) mild somatic and pain concerns; (3) mild internalizing difficulties; (4) marked disinhibition and externalizing behavioural difficulties; (5) marked internalizing difficulties; and (6) marked somatic, internalizing, and externalizing behavioural disturbances. Members of the Externalized subtype were significantly younger in age than those in the other five subtypes, and more likely to be single than those in the Internalized subtype. Individuals in the Internalized subtype tended to be married, have longer times postaccident, and lower WAIS-R Verbal Intelligence Quotients than those comprising the Normal subtype.

Adolescent↗

PubMed1986

Adolescent chronic pain: the ability to cope.

The study investigated differences in mother-child interaction, child personality, and family characteristics between adolescents who were coping with chronic benign intractable pain and adolescents who were not. Both groups experienced a similar amount and intensity of pain. Behavioural observations indicated that non-copers engaged in significantly more negative behaviour than the copers. In addition, non-copers tended to express more pain and were on-task less often than the copers. Mothers of non-copers more frequently discouraged coping behaviour. No differences between the two groups were evident on the family or personality measures. The data are consistent with clinical impressions that parental behaviour interacts with child coping.

Activities of Daily Living↗