Biomedical subjects

D C Theberge

Publications and source records attributed to D C Theberge.

5 recordsLinked to original sources

PubMed1999

Declarative and procedural memory in bipolar disorder.

BACKGROUND: Memory function is an important but under researched area for neuropsychological investigation in persons with bipolar disorder. Previous studies have reported cognitive deficits on tasks of declarative memory in bipolar patients in the euthymic state. METHODS: This study extended these findings by investigating declarative as well as procedural learning and memory in bipolar patients (with and without alcohol abuse) who were examined in the euthymic state. The California Verbal Learning Test, Star Mirror Tracing Task, Pursuit Rotor Task, American National Adult Reading Test, and the Vocabulary Subtest of the WAIS-R, were administered to bipolar patients and control subjects by researchers who were blind to the subject's group. RESULTS: Bipolar patients performed worse than control subjects on a measure of declarative memory (California Verbal Learning Test) but did not differ from the performance of control subjects on either of the two procedural learning tasks (Pursuit Rotor Task and Star Mirror Task). CONCLUSIONS: These results suggest disturbed function of temporal lobe, but not basal ganglia, structures in persons with bipolar disorder.

Adult↗

PubMed1999

Normalizing hematocrit in dialysis patients improves brain function.

Recombinant human erythropoietin (rHuEPO) treatment has been shown to improve brain and cognitive function in anemic dialysis patients. Significant debate continues, however, regarding the appropriate target hematocrit (Hct) that will lead to the greatest benefits while considering possible side effects and costs of rHuEPO. Current practice results in an Hct averaging only 31% to 32% in dialysis patients, a level less than that achieved in the initial clinical trials and well less than normal. This study was designed to evaluate dialysis patients at the current practice Hct levels versus normal Hct levels (40% to 45%) to see if improvement in brain function resulted. Twenty patients with end-stage renal disease (ESRD) currently being treated with rHuEPO (mean Hct, 31.6%) were administered additional rHuEPO to reach normal Hct levels (mean, 42. 8%). Electroencephalogram (EEG) frequency analysis showed a significant decrease in EEG slowing at greater Hct values, and the auditory oddball and Continuous Performance Task tasks yielded significant electrode and time-by-electrode effects for P300 amplitude. Changes in P300 latency significantly correlated with increased Hct in the auditory oddball task. These findings suggest that further correction of anemia to normal Hct levels may result in continued improvement in neurocognitive function by improving the ability to sustain attention in easier tasks and by enhancing the ability to recognize, discriminate, and hold stimuli in memory for more difficult tasks.

Anemia↗

PubMed1998

Cognitive impairment in euthymic bipolar patients with and without prior alcohol dependence. A preliminary study.

BACKGROUND: Few studies of the neurocognitive performance of patients with bipolar disorder have been performed while patients are in the euthymic state. METHODS: Twenty-five euthymic bipolar patients (12 with and 13 without a history of alcohol dependence) were compared with 22 normal control subjects on a neuropsychological test battery assessing a range of cognitive domains. The relationship between subjects' neurocognitive performance and the course-of-illness variables (lifetime episodes and duration of mania, depression, or both), as well as current lithium level, was determined. RESULTS: The results indicated differences across the groups, with the bipolar patients with and without alcohol dependence performing more poorly than controls on tests of verbal memory. Furthermore, bipolar subjects with a history of alcohol dependence had additional decrements in executive (i.e., frontal lobe) functions when compared with controls. For subjects in the bipolar group, lifetime months of mania and depression were negatively correlated with performance in verbal memory and several executive function measures. CONCLUSIONS: Our findings support the presence of persistent neurocognitive difficulties in patients with long-standing bipolar disorder who are not in the psychiatrically acute state or who are suffering the effects of alcohol abuse and suggest that there may be an aggregate negative effect of lifetime duration of bipolar illness on memory and frontal or executive systems.

Alcoholism↗

PubMed1996

Callosal transfer of finger localization information in phonologically dyslexic adults.

Dyslexia, particularly phonological dyslexia, has been hypothesized to be associated with deficits in interhemispheric interactions mediated by the corpus callosum. Twenty-one dyslexic subjects were compared to 21 controls on the Finger Localization Test in order to observe patterns of tactile-motor integration and interhemispheric collaboration. When compared to control subjects, dyslexics showed consistent deficits in finger localization, particularly when more complex trials had to be completed. When subjects were re-grouped according to phonological processing ability (regardless of diagnostic group membership), subjects with lower phonological processing scores were found to perform poorly on complex trials of finger localization, particularly on those trials which reflect callosal transfer of finger localization information from one hemisphere (hand) to the other. These results suggest that interhemispheric transfer of information is critical to efficient phonological processing.

Adolescent↗

PubMed1995

Bimanual coordination in dyslexic adults.

Various types of dyslexia have been associated with tactile-motor coordination deficits and inefficient transfer of information between the two cerebral hemispheres. Twenty-one dyslexic adults were compared to 21 controls on the Bimanual Coordination Task, a test of tactile-motor coordination and interhemispheric collaboration. When compared to control subjects, dyslexics showed a consistent pattern of deficits in bimanual motor coordination, both with and without visual feedback. In particular, dyslexics had greater difficulty relative to normals when the left hand had to move faster than the right, and when the hands had to make opposite (mirror-image) movements, suggesting problems with interhemispheric modulation of visuomotor control. In addition, accuracy on this bimanual coordination task was significantly correlated with the Block Design subtest of the WAIS--R, but not with a rhyme fluency task, suggesting some contribution of right hemisphere controlled visuospatial skill to performance.

Adolescent↗