Neil Pliskin

Thalamic integrity underlies executive dysfunction in traumatic brain injury

Objective: To quantify the effects of traumatic brain injury on integrity of thalamocortical projection fibers and to evaluate whether damage to these fibers accounts for impairments in executive function in chronic traumatic brain injury. Methods: High-resolution (voxel size: 0.78 mm × 0.78 mm × 3 mm3) diffusion tensor MRI of the thalamus was conducted on 24 patients with a history of single, closed-head traumatic brain injury (TBI) (12 each of mild TBI and moderate to severe TBI) and 12 age- and education-matched controls. Detailed neuropsychological testing with an emphasis on executive function was also conducted. Fractional anisotropy was extracted from 12 regions of interest in cortical and corpus callosum structures and 7 subcortical regions of interest (anterior, ventral anterior, ventral lateral, dorsomedial, ventral posterior lateral, ventral posterior medial, and pulvinar thalamic nuclei). Results: Relative to controls, patients with a history of brain injury showed reductions in fractional anisotropy in both the anterior and posterior corona radiata, forceps major, the body of the corpus callosum, and fibers identified from seed voxels in the anterior and ventral anterior thalamic nuclei. Fractional anisotropy from cortico-cortico and corpus callosum regions of interest did not account for significant variance in neuropsychological function. However, fractional anisotropy from the thalamic seed voxels did account for variance in executive function, attention, and memory. Conclusions: The data provide preliminary evidence that traumatic brain injury and resulting diffuse axonal injury results in damage to the thalamic projection fibers and is of clinical relevance to cognition.

Improved delayed visual reproduction test performance in multiple sclerosis patients receiving interferon beta-1b

We assessed neuropsychological function longitudinally in 30 MS patients who participated in the pivotal trial of interferon beta-1b (IFN-beta-1b). Nine patients received high-dose IFN-beta-1b (8.0 million units), eight low-dose IFN-beta-1b (1.6 MIU), and 13 placebo. There was significant improvement in Wechsler Memory Scale Visual Reproduction-Delayed Recall scores between years 2 and 4 of the trial in MS subjects receiving high-dose IFN-beta-1b. Motoric performance, MRI lesion area, and depression rating scores did not correlate with this finding. Comparison of MRI at baseline and at years 2 and 4 revealed significant changes over time for the total cohort (p < 0.02). Mean lesion area in the high-dose group did not change over time, whereas the low-dose and placebo groups had increases in total lesion area of 28 and 36%, respectively, at year 4. Expanded disability status scale scores did not change significantly between years 2 and 4 of the trial, nor did they correlate with MRI lesion area at any assessment point. We conclude that high-dose IFN-beta-1b improves delayed visual reproduction test performance in MS patients, a finding unlikely to be explained by practice effects or brain lesion area. NEUROLOGY 1996;47: 1463-1468

Neurocognitive effects of repetitive transcranial magnetic stimulation in severe major depression.

OBJECTIVE Repetitive transcranial magnetic stimulation (rTMS) is being investigated as a potential treatment for depression. Few studies have addressed the neurocognitive effects of a course of rTMS in severely depressed patients. We evaluated neurocognitive effects of a 1-4 week course (mean 3 weeks) of rTMS using an aggressive set of parameters, in 15 severely depressed subjects. METHODS A battery of neurocognitive tests relevant to attention, working memory-executive function, objective memory and motor speed were administered to 15 subjects with treatment-resistant major depression (unipolar and bipolar), before and after a course of rTMS. Mean z scores were computed for each of 4 cognitive domains and analyzed using repeated measures multivariate analysis of covariance. Significant interactions were further clarified using univariate analysis of variance. RESULTS There was no worsening of performance on any of the cognitive domains over the baseline-post rTMS period. On the contrary, evidence of modest but statistically significant improvement in performance was noted in working memory-executive function, objective memory and fine motor speed domains over the rTMS treatment period. CONCLUSIONS There was no evidence of adverse neurocognitive changes over the baseline-post rTMS period in 15 treatment-resistant depressed subjects undergoing a 3 week (mean) trial of rTMS. Significant improvements in several domains observed over the rTMS treatment period could not be explained by improved mood. Practice effects as well as other factors potentially contributing to these findings are discussed. SIGNIFICANCE rTMS is being increasingly studied as a neurophysiological probe as well as for its potential antidepressive effects. The effects on neuronal function raise appropriate questions of safety of its use at varying stimulus parameters and durations. This study contributes to the small body of evidence of the cognitive effects of rTMS in severely depressed patients.

Official Position of the Military TBI Task Force on the Role of Neuropsychology and Rehabilitation Psychology in the Evaluation, Management, and Research of Military Veterans with Traumatic Brain Injury

This Position Statement is a summary of the literature and learning regarding current issues raised by the occurrence, treatment, and study of traumatic brain injury in military service members and veterans. The Report has been approved by the American Academy of Clinical Neuropsychology (AACN), Divisions 40 (Neuropsychology) and 22 (Rehabilitation Psychology) of the American Psychological Association (APA), and the National Academy of Neuropsychology (NAN), with the goal of providing information of relevance on an important public policy matter within their respective areas of expertise. The Report is not intended to establish guidelines or standards for the professional practice of psychology, nor has it been adopted as official policy by the American Psychological Association or any other division or subunit of APA.

Verbal learning differences in chronic mild traumatic brain injury

Following mild traumatic brain injury (TBI), a percentage of individuals report chronic memory and attention difficulties. Traditional neuropsychological assessments often fail to find evidence for such complaints. We hypothesized that mild TBI patients may, in fact, experience subtle cognitive deficits that reflect diminished initial acquisition that can be explained by changes in cerebral white matter microstructure. In the data presented here, a sample of nonlitigating and gainfully employed mild TBI patients demonstrated statistically significant differences from age and education matched control participants in performance on the first trial of a verbal learning task. Performance on this trial was associated with reduced fractional anisotropy in the uncinate fasciculus and the superior longitudinal fasciculus providing an anatomical correlate for the cognitive findings. Mild TBI patients were not impaired relative to control participants on total learning or memory composite variables. Performance on the first learning trial was not related to any psychological variables including mood. We concluded that patients with mild TBI demonstrate diminished verbal learning that is not often interpreted in standard neuropsychological assessment.

Safety of human MRI at static fields above the FDA 8T guideline: Sodium imaging at 9.4T does not affect vital signs or cognitive ability

To assess whether exposure to a 9.4T static magnetic field during sodium imaging at 105.92 MHz affects human vital signs and cognitive function.

Neuropsychological Symptom Presentation after Electrical Injury

OBJECTIVE This study explored the relationship of neuropsychological complaints to accident- and injury-related characteristics, affective state, and work status in a group of electrical injury (EI) patients. METHODS Sixty-three EI patients and 22 electricians with no history of electrical shock completed the Neuropsychological Symptom Checklist and the Beck Depression Inventory as part of an extensive neuropsychological evaluation. RESULTS The EI group endorsed significantly more physical, cognitive, and emotional symptoms than did the controls. Symptom complaints were not related to injury parameters or litigation status. Only the time interval between injury and assessment accounted for differences in symptom presentation, with patients in the postacute stages of recovery showing the most cognitive and emotional complaints. CONCLUSION The neuropsychological syndrome of electrical injury survival includes physical, cognitive, and emotional complaints. Considering that most electrically injured patients are treated within the acute medical setting, greater attention needs to be directed early in the course of treatment toward addressing neuropsychologic and psychiatric issues.

Vital signs and cognitive function are not affected by 23-sodium and 17-oxygen magnetic resonance imaging of the human brain at 9.4 T.

To evaluate the effect of 23‐sodium (23Na) and 17‐oxygen (17O) magnetic resonance imaging (MRI) at 9.4 (T) on vital signs and cognitive function of the human brain.

Neuropsychological changes following electrical injury

The clinical presentation of electrical injury commonly involves physical, cognitive, and emotional complaints. Neuropsychological studies, including case reports, have indicated that electrical injury (EI) survivors may experience a broad range of impaired neuropsychological functions, although this has not been clarified through controlled investigation. In this study, we describe the neuropsychological test findings in a series of 29 EI patients carefully screened and matched to a group of 29 demographically similar healthy electricians. Participants were matched by their estimated premorbid intellectual ability. Multivariate analysis of variance was used to assess group differences in the following neuropsychological domains: attention and mental speed, working memory, verbal memory, visual memory, and motor skills. EI patients performed significantly worse on composite measures of attention/mental speed and motor skills, which could not be explained by demographic differences, injury parameters, litigation status, or mood disturbance. Results suggest that cognitive changes do occur in patients suffering from electrical injury.

The effects of long-term interferon-beta-1b treatment on cognitive functioning in multiple sclerosis: a 16-year longitudinal study.

Background: Multiple sclerosis (MS) is a progressive disease of the central nervous system that affects cognition. Short-term treatment with interferon-beta-1b (IFN-b-1b) has been shown to have beneficial effects on cognition. Objective: The objective of this paper is to evaluate the effects of IFN-b-1b on cognitive functioning in patients with MS over the course of 16 years. Methods: Sixteen subjects with relapsing–remitting MS participated in the study. Nine of these subjects received IFN-b-1b, while seven received placebo treatment in the pivotal MS trial. After five years, all subjects were switched to IFN-b-1b treatment. At two and four years into the study, all subjects underwent a brief neuropsychological test battery, magnetic resonance imaging (MRI), and neurologic ratings; measures were repeated at 16 years. Results: Across the total cohort, cognitive functioning remained relatively stable over the course of 16 years. The placebo/IFN-b-b group exhibited increased visual memory performance relative to the IFN-b-1b treatment group, but had a greater decline in verbal memory. Initial MRI lesion load demonstrated a significant, negative correlation with overall cognitive performance at 16 years (p = 0.00). Conclusion: We conclude that IFN-b-1b has beneficial effects on long-term cognition outcomes in MS.