Biomedical subjects

J A Fields

Publications and source records attributed to J A Fields.

At least 19 recordsLinked to original sources

PubMed2003

Neuropsychological and quality of life outcomes 12 months after unilateral thalamic stimulation for essential tremor.

OBJECTIVES: To evaluate the one year cognitive, mood state, and quality of life (QoL) outcomes of unilateral thalamic deep brain stimulation (DBS) for essential tremor (ET). METHODS: 40 patients diagnosed with ET completed comprehensive neuropsychological assessments about one month before and three and 12 months after DBS electrode implantation. Data were subjected to multivariate analyses, and significant results were further analysed using univariate techniques. RESULTS: Analyses revealed statistically significant improvements on a cognitive screening measure and in aspects of fine visuomotor and visuoperceptual functions, verbal memory, mood state, and QoL. No group-wise declines in cognition were observed, but more patients showed declines than improvements on language and visual memory tests. Semantic verbal fluency declined significantly in four (10%) of the patients. In these four patients, diminished lexical verbal fluency was present at baseline. CONCLUSION: Cognitive, mood, and QoL outcomes after one year of DBS for ET are favourable; there were no overall deleterious effects on cognition, and DBS was accompanied by a significant reduction in anxiety and improvements in quality of life. However, preoperative verbal fluency diminution may predispose to further fluency declines after DBS.

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PubMed2002

Neuropsychological deficits in essential tremor: an expression of cerebello-thalamo-cortical pathophysiology?

Few studies have been published regarding the neuropsychological characteristics of patients with essential tremor (ET), but preliminary findings suggest that mild attentional and executive dysfunction accompany the disorder. A consecutive series of 101 patients with ET referred for thalamotomy and/or thalamic deep brain stimulation candidacy work-up also underwent neuropsychological evaluation. Average neuropsychological test scores were calculated, along with the proportions of subjects whose scores fell within or more than one SD above or below the mean (using demographically corrected normative data). Significantly lower than average (T-score of 50) scores were evident on measures of complex auditory attention, visual attention and response inhibition, recall of a word list, verbal fluency, and visual confrontation naming. A significantly greater proportion of patients (ranging from about 34 to 60%) than might be expected on the basis of a normal distribution obtained scores more than one SD below the normative mean on select measures of attention, verbal fluency, immediate word list recall, semantic encoding, and facial matching. Consistent with prior research, notable, albeit clinically subtle, deficits in attention and select executive functions are evident in patients with ET. Although not specific to ET or cerebellar dysfunction, the observed pattern of cognitive deficits is consistent with cerebello-thalamo-cortical circuit dysfunction.

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PubMed2001

Neuropsychological and quality of life changes following unilateral thalamic deep brain stimulation in Parkinson's disease: a one-year follow-up.

BACKGROUND: The long-term neuropsychological and quality of life (QOL) outcomes of unilateral thalamic deep brain stimulation (DBS) in patients with intractable Parkinson's disease (PD) have not heretofore been described. METHOD: Six patients diagnosed with PD underwent unilateral DBS implantation into a verified thalamic VIM nucleus target. Participants completed presurgical neuropsychological evaluation and follow-up assessment at approximately one year postsurgery. FINDINGS: Compared to their presurgical scores, PD patients exhibited significant improvement on measures of conceptualization, verbal memory, emotional adjustment, and QOL at one-year follow-up. A few nominal declines were observed across the battery of tests. INTERPRETATION: These data provide preliminary support for the long-term neurocognitive safety and QOL improvements following thalamic stimulation in patients with PD.

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PubMed2000

Identification of dyes on ancient Chinese paper samples using the subtracted shifted Raman spectroscopy method.

The Stein Collection in the British Library contains the Diamond Sutra, the world's oldest, dated, printed document. The paper of the Diamond Sutra and other documents from the Stein collection is believed to be dyed yellow by a natural extract, called huangbo, from the bark of Phellodendron amurense, which contains three major yellow chromophores: berberine, palmatine, and jatrorrhizine. Conservation of these documents requires definite information on the chemical composition of the dyes but no suitable, completely noninvasive analytical method is known. Here we report resonance Raman studies of a series of pure dyes, of plant materials and extracts, and of dyed ancient and modern paper samples. Resonance Raman spectroscopy is used to enhance the spectra of the dyes over the signals from the paper matrixes in which they are held. The samples all give resonance Raman spectra which are dominated by intense fluorescence, but by using SSRS (subtracted shifted Raman spectroscopy) we have obtained reliable spectra of the pure dyes, native bark from the Phellodendron amurense, modern paper dyed with huangbo extracted from this bark, and ancient paper samples. For both ancient paper samples whose pigment bands were detected, the relative intensities of the bands due to berberine and palmatine suggest that the ancient paper is richer in berberine than its modern counterpart. This is the first nondestructive in situ method for detection of these pigments in manuscripts, and as such has considerable potential benefit for the treatment of irreplaceable documents that are believed to be dyed with huangbo but documents on which conservation work cannot proceed without definite identification of the chemical compounds that they contain.

Luminescent Measurements↗

PubMed2000

Cognitive outcomes after deep brain stimulation for Parkinson's disease: a review of initial studies and recommendations for future research.

Modern ablative surgery for movement disorders probably results in less frequent and severe cognitive morbidity than seen in early surgical series. Nonetheless, recent studies indicate that neurobehavioral functions commonly compromised in Parkinson's disease (PD) (e.g., executive functions, verbal fluency, and memory) are negatively impacted in some patients by lesion placement. The potential reversibility of cognitive dysfunction after chronic electrical deep brain stimulation (DBS) for PD has lead some to favor this treatment modality over ablation. This paper reviews the initial studies of the cognitive effects of thalamic, pallidal, and subthalamic DBS. These studies suggest that DBS is relatively safe from a cognitive standpoint and that the benefits of motor improvements probably outweigh the cost of minimal cognitive morbidity. This conclusion must be offered with caution, however, given the small numbers of studies to date and their methodological limitations. Neurobehavioral research has yet to adequately address (1) outcome relative to appropriate control groups; (2) effects of electrode placement versus stimulation; (3) laterality- and site-specific effects of DBS; (4) long-term effects of DBS; (5) effects of stimulation parameters; (6) risk factors for cognitive dysfunction with DBS; (7) whether cognitive dysfunction associated with DBS is reversible; and (8) comparative neurobehavioral outcome after DBS and ablation. DBS affords an exciting opportunity to clarify the neurobehavioral role of the basal ganglia.

Brain↗

PubMed2000

Health-related quality of life in Parkinson's disease after pallidotomy and deep brain stimulation.

This study explored the multidimensional outcome of three neurosurgical interventions for Parkinson's disease (PD): pallidotomy (N = 23), pallidal deep brain stimulation (DBS) (N = 9), and thalamic DBS (N = 7). All patients completed the Sickness Impact Profile (SIP) and the Beck Depression Inventory. Pallidotomy patients also completed the Profile of Mood States, the Beck Anxiety Inventory, and a disease-specific quality of life (QOL) measure, the Parkinson's Disease Questionnaire (PDQ-39). Three months after surgery, all neurosurgical groups showed significant improvements in mood and function, including physical, psychosocial, and overall functioning. Pallidal DBS and pallidotomy patients who completed additional QOL measures reported decreased anxiety and tension, increased vigor, improved mobility and ability to perform activities of daily living, and decreased perceived stigma. Psychosocial dysfunction scores from the SIP were related to depressed mood both at baseline (r = .42) and at followup (r = .45), but the physical dysfunction subscale was not related to mood at either time point, suggesting that disruption of social relationships due to PD may have more impact on affective distress than physical symptoms alone. Results suggest that neurosurgical interventions for PD improve disabling PD motor symptoms and also improve several domains of quality of life.

Activities of Daily Living↗

PubMed1999

Neuropsychological and quality of life outcome after thalamic stimulation for essential tremor.

OBJECTIVE: To evaluate short-term effects of unilateral thalamic deep brain stimulation (DBS) on cognition, mood state, and quality of life in patients with essential tremor (ET). BACKGROUND: Unilateral thalamotomy and thalamic DBS are effective in alleviating refractory tremor contralateral to the side of surgery. Thalamotomy can lead to cognitive morbidity, and DBS might be a preferable surgical intervention given potential avoidance or reversibility of such morbidity. Although unilateral thalamic DBS is cognitively safe and leads to quality of life improvement in PD, its neurobehavioral effects in ET are unknown. METHODS: Forty patients with ET were administered a broad neuropsychological test battery, measures of mood state, and generic and disease-specific quality of life measures approximately 1 month before and 3 months after surgery (left hemisphere, 38 patients). RESULTS: Unilateral thalamic DBS was associated with significant improvements in tremor and dominant-hand fine visuomotor coordination. Statistically significant but clinically modest gains were observed on tasks of visuoperceptual and constructional ability, visual attention, delayed word list recognition, and prose recall. Only lexical verbal fluency declined significantly after surgery. Patients rated themselves as less anxious after surgery, and they perceived their quality of life as improved significantly. In particular, patients reported improved quality of life with respect to activities of daily living, stigma, emotional well-being, and communication. CONCLUSIONS: Unilateral thalamic DBS for ET is cognitively safe and associated with improvements in anxiety and quality of life in the near term and in the absence of operative complications. Patients were better able to carry out activities of daily living after surgery, and they reported improvement in several psychosocial domains of quality of life.

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PubMed1999

Action (verb naming) fluency as an executive function measure: convergent and divergent evidence of validity.

Numerous studies have demonstrated dissociable neuroanatomic underpinnings for the retrieval of grammatical classes of words such as nouns and verbs. Whereas retrieval of common and proper nouns is primarily mediated by posterior and anterior temporal regions, respectively, verb retrieval is primarily mediated by frontal regions. The majority of studies evaluating verb production have utilized tasks requiring subjects to name a graphically depicted action (i.e. action naming), leaving tests of verb generation in the absence of prompting stimuli (i.e. action fluency) largely unexamined. In a recent study, Piatt, Fields, Paolo, Koller and Tröster (in press) found that an action fluency task discriminated demented Parkinson's disease (PD) patients from non-demented PD patients and healthy control subjects, whereas lexical and categorical fluency tasks did not. These authors suggested that action fluency was sensitive to the fronto-striatal pathophysiology associated with PD dementia, and thus, that action fluency might serve as an indicator of executive functioning. This study was undertaken to evaluate the construct validity of action fluency as an executive function measure in a group of healthy elderly control subjects. Findings revealed modest to moderate relationships between action fluency and several putative executive measures. Action fluency was unrelated to indices of semantic and episodic memory. Results support the construct validity of action fluency as an executive function measure and suggest that this task may provide some unique information not tapped by traditional executive function tasks.

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PubMed1999

Cognitive outcome following staged bilateral pallidal stimulation for the treatment of Parkinson's disease.

As neurosurgical treatment of parkinsonian symptoms has become increasingly popular, concern about the cognitive morbidity which may result from such interventions has risen proportionately. Previous reports of cognitive difficulties associated with pallidotomy and thalamotomy, especially in bilateral cases, have provided the impetus for research into chronic electrical deep brain stimulation procedures which are believed to be safer than ablation. Given the lack of neurobehavioral research following bilateral deep brain stimulation procedures, this preliminary study of six Parkinson's disease patients undergoing staged bilateral pallidal stimulation was undertaken. A battery of tests assessing attention, executive function, visuomotor coordination, language, visuoperceptual function, learning memory and mood revealed no significant change in overall level of cognitive functioning after either unilateral or bilateral pallidal deep brain stimulation. No significant declines were observed about three months following bilateral stimulation, and in fact, significant gains in delayed recall and relief of anxiety symptoms were noted. It was concluded from this preliminary data that bilateral pallidal stimulation for the treatment of Parkinson's disease, at least in the absence of operative complications, offers a cognitively safe alternative to ablation.

Cognition↗

PubMed1999

Lexical, semantic, and action verbal fluency in Parkinson's disease with and without dementia.

Previous research suggests that lexical and semantic verbal fluency are differentially sensitive to the effects of cortical and subcortical dementias, but little is known about action fluency performance in dementias. The present study compared lexical, semantic, and action fluency in groups of patients with Parkinson's disease (PD) with and without dementia and an elderly control group. Findings revealed an interaction between fluency type and subject group. Although the demented PD (PDD) group performed significantly more poorly than their non-demented counterparts and normal controls on all three fluency tasks, a disproportionate disparity in scores was noted on the action fluency task. The findings suggest that action fluency may be particularly sensitive to PD-associated dementia and may be an early indicator of the conversion from PD to PDD. As reported elsewhere, PD without dementia was not associated with significant impairment on any of the fluency tasks.

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PubMed1998

Chronic electrical stimulation of the left ventrointermediate (Vim) thalamic nucleus for the treatment of pharmacotherapy-resistant Parkinson's disease: a differential impact on access to semantic and episodic memory?

Thalamotomy for medically refractory Parkinson's disease (PD) is considered to be efficacious and relatively safe. Because a minority of patients experience decrements in language and memory (often mild and transient) after thalamotomy, chronic thalamic deep brain stimulation (DBS) might be a safer treatment given its reversibility and the modifiability of stimulation parameters. Two preliminary studies support the relative cognitive safety of unilateral DBS of the ventral intermediate (Vim) thalamic nucleus, but it is unclear whether possibly subtle changes in language and memory represent effects of "microthalamotomy" or of stimulation per se. This report provides preliminary data concerning effects of left thalamic stimulation on information processing speed, semantic memory (verbal fluency and visual confrontation naming), and verbal episodic memory in a patient with PD. In addition to being evaluated before and 3 and 6 months after surgery, the patient was tested 18 months after surgery either on or off medications and with the stimulator turned either on or off (order counterbalanced across medication conditions). Test performance differences between the stimulation conditions were attenuated "off" as compared to "on" medication. Vim stimulation consistently, albeit subtly, improved semantic verbal fluency but interfered with immediate recall of word lists. Parallels to findings from acute, intraoperative thalamic stimulation studies are explored. The hypothesis is offered that left Vim stimulation might facilitate access to semantic memory, but interfere with episodic memory processes.

Adult↗

PubMed1998

Cortical and subcortical influences on clustering and switching in the performance of verbal fluency tasks.

Impairments on lexical and semantic fluency tasks occur in both cortical and subcortical dementia. Recent reports that the average size of phonemic and semantic clusters is reduced in Alzheimer's disease (AD), but not in Parkinson's disease (PD) could support the hypothesis that in AD verbal fluency deficits arise from degraded memory storage while in PD the same impairments result from defective retrieval. In the present study, patients with AD, PD with dementia, or Huntington's disease produced fewer words, fewer switching responses and smaller semantic cluster sizes. Patients with multiple sclerosis, regardless of whether or not they were demented, produced fewer words and switching responses, but normal size clusters, and patients with PD without dementia performed normally on all fluency measures. These results indicate that reductions in cluster size on verbal fluency tests are best interpreted as changes in the efficiency of access to lexical and semantic memory stores. The findings are also consistent with the idea that patterns of cognitive impairment may differ among diseases that result in subcortical dementia.

Adult↗

PubMed1998

Innovation, public choice and public control in the market for health insurance.

Innovation, public choice and public control in the market for health insurance/benefits in the United States are largely dependent upon the ability of the various stakeholders to successfully argue their positions with legislators, regulators, providers, purchasers and third party beneficiaries. Given the public/private nature of health benefits, these relationships are examined in a Stigler/Posner/Peltzman public choice framework. Conflicts among various stakeholders and their ability to influence innovation in the market for health benefits are discussed.

Choice Behavior↗

PubMed1997

Unilateral pallidal stimulation for Parkinson's disease: neurobehavioral functioning before and 3 months after electrode implantation.

Unilateral pallidotomy is thought to have a low risk for cognitive morbidity. Nonetheless, recent research suggests that some patients experience declines in memory and language and that pallidal stimulation might be a safer treatment for Parkinson's disease (PD). We investigated the neurobehavioral effects of unilateral pallidal stimulation. Nine consecutive PD patients undergoing unilateral deep brain-stimulating electrode implantation in the globus pallidus interna were evaluated with a neuropsychological test battery approximately 1 month before and 3 months after surgery. Patients reported significantly fewer symptoms of anxiety and greater vigor after surgery. There was a trend toward fewer depressive symptoms. Semantic verbal fluency and visuoconstructional test scores declined significantly after surgery. However, among five patients showing declines in semantic verbal fluency, only one patient's score declined by more than 2 SD. No patient showed significant decline or improvement in the overall level of cognitive functioning. This study supports the relative safety, in terms of cognitive function, of unilateral pallidal stimulation in PD.

Adult↗

PubMed1997

Collectively bargained public health benefit plans.

The marketplace for health benefits for public sector employees is large and complex with a great variety of approaches for providing care and a difficult patchwork of regulatory and collective bargaining regulation to deal with in designing a plan. Public sector workers' plans are subject to an additional constraint provided by the political nature of the process. The products sold to public sector plans are not regulated as ERISA plans, given the exclusion of government plans and the differential regulation of collectively bargained plans under the HMO act. This article attempts to guide the reader through some of the difficulties of this marketplace, pointing out pitfalls and opportunities where they appear.

Collective Bargaining↗

PubMed1996

Regulating health insurance: the challenges of managed networks.

The role of the regulator in health insurance is examined in the context of the change in nature of regulatory oversight necessary to monitor the activities of the regulated parties. Health insurance to this point has been largely regulated by insurance departments that have historically focused on monitoring the solvency and meeting the contractually required reimbursements for indemnity carriers. Now as the indemnity carrier has either migrated to managed care or faced a declining book of business, the historic role of regulation must change to match the new environment. This article examines the role of the health insurance/managed care regulator department under this new paradigm and identifies where and how the regulator can exert influence in such a system.

Bankruptcy↗

PubMed1995

Neuropsychological impairment in Parkinson's disease with and without depression.

OBJECTIVES: To compare quantitative and qualitative aspects of neuropsychological test performance in patients with Parkinson's disease who currently had depression (PDD) and those without depression (PDN) so as to evaluate the influence of depression on cognition in Parkinson's disease. DESIGN: Cross-sectional comparisons among PDN, PDD, and normal control (NC) groups. The setting was a neurodegenerative disease research center in a teaching hospital. Groups consisted of 44 patients with PDN and 44 patients with PDD matched for age, education, gender, age at onset of disease, disease duration, and disease severity; a group of 44 NC subjects matched for age, education, and gender; and a second set of comparisons between 15 patients with PDN and 15 patients with PDD also matched for overall severity of cognitive impairment. MEASURES: The neuropsychological measures used were the Mattis Dementia Rating Scale, Beck Depression Inventory, Wisconsin Card Sorting Test, Controlled Oral Word Association Test, Logical Memory subtest of the Wechsler Memory Scale-Revised, Digit Span subtest of the Wechsler Adult Intelligence Scale-Revised, and the Boston Diagnostic Aphasia Examination's Animal Naming test and Boston Naming Test. RESULTS: Relative to the NC group, both PDN and PDD groups demonstrated impairments in immediate and delayed verbal recall, semantic fluency, and problem solving. When PDN and PDD groups were matched for demographic and disease variables, only the PDD group evidenced impairment relative to NC in visual confrontation naming, and in lexical and semantic fluency. In addition, impairments on immediate recall and semantic fluency in the PDD group were more pronounced than those in the PDN group. However, when PDN and PDD groups were also matched for overall severity of cognitive impairment, no significant differences emerged among the two groups' neuropsychological test performances. CONCLUSIONS: Depression exacerbates some memory and language impairments associated with PD, even when the PDN and PDD groups are matched for demographic and disease variables. However, the extent and pattern of cognitive impairment is similar in PDN and PDD when the groups are also matched also for overall severity of cognitive impairment. Depression influences the quantity rather than the quality of cognitive impairment associated with Parkinson's disease.

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PubMed1994

Single payer: the California referendum.

The California Health Security Act is likely to appear on the November 1994 ballot. The bill would provide universal coverage to California residents and assign the state as the single payer for all medical care provided, financed with funding for programs already in place, employer payroll taxes, individual income taxes and taxes on tobacco products.

California↗