Kathleen Poston, MD, MS

All Publications

• Dopamine-Related Dissociation of Cortical and Subcortical Brain Activations in Cognitively Unimpaired Parkinson's Disease Patients OFF and ON Medications. Neuropsychologia Kim, J., Zhang, K., Cai, W., YorkWilliams, S., I Ua Cruadhlaoich, M. A., Llanes, S., Menon, V., Poston, K. L. 2018

  Abstract

  BACKGROUND: Despite dopaminergic depletion that is severe enough to cause the motor symptoms of Parkinson's disease (PD), many patients remain cognitively unimpaired. Little is known about brain mechanisms underlying such preserved cognitive abilities and their alteration by dopaminergic medications.OBJECTIVES: We investigated brain activations underlying dopamine-related differences in cognitive function using a unique experimental design with PD patients off and on dopaminergic medications. We tested the dopamine overdose hypothesis, which posits that the excess of exogenous dopamine in the frontal cortical regions can impair cognition.METHODS: We used a two-choice forced response Choice Reaction Time (CRT) task to probe cognitive processes underlying response selection and execution. Functional magnetic resonance imaging data were acquired from 16 cognitively unimpaired (Level-II) PD participants and 15 well-matched healthy controls (HC). We compared task performance (i.e. reaction time and accuracy) and brain activation of PD participants off dopaminergic medications (PD_OFF) in comparison with HC, and PD_OFF participants with those on dopaminergic medications (PD_ON).RESULTS: PD_OFF and PD_ON groups did not differ from each other, or from the HC group, in reaction time or accuracy. Compared to HC, PD_OFF activated the bilateral putamen less, and this was compensated by higher activation of the anterior insula. No such differences were observed in the PD_ON group, compared to HC. Compared to both HC and PD_OFF, PD_ON participants showed dopamine-related hyperactivation in the frontal cortical regions and hypoactivation in the amygdala.CONCLUSION: Our data provide further evidence that PD_OFF and PD_ON participants engage different cortical and subcortical systems to achieve similar levels of cognitive performance as HC. Crucially, our findings demonstrate dopamine-related dissociation in brain activation between cortical and subcortical regions, and provide novel support for the dopamine overdose hypothesis.

  View details for DOI 10.1016/j.neuropsychologia.2018.07.024

  View details for PubMedID 30040957

• Longitudinal Change of Clinical and Biological Measures in Early Parkinson's Disease: Parkinson's Progression Markers Initiative Cohort MOVEMENT DISORDERS Simuni, T., Siderowf, A., Lasch, S., Coffey, C. S., Caspell-Garcia, C., Jennings, D., Tanner, C. M., Trojanowski, J. Q., Shaw, L. M., Seibyl, J., Schuff, N., Singleton, A., Kieburtz, K., Toga, A. W., Mollenhauer, B., Galasko, D., Chahine, L. M., Weintraub, D., Foroud, T., Tosun, D., Poston, K., Arnedo, V., Frasier, M., Sherer, T., Chowdhury, S., Marek, K., Parkinson's Progression Marker Ini 2018; 33 (5): 771–82

  Abstract

  The objective of this study was to assess longitudinal change in clinical and dopamine transporter imaging outcomes in early, untreated PD.We describe 5-year longitudinal change of the MDS-UPDRS and other clinical measures using results from the Parkinson's Progression Markers Initiative, a longitudinal cohort study of early Parkinson's disease (PD) participants untreated at baseline. We also provide data on the longitudinal change in dopamine transporter 123-I Ioflupane striatal binding and correlation between the 2 measures.A total of 423 PD participants were recruited, and 358 remain in the study at year 5. Baseline MDS-UPDRS total score was 32.4 (standard deviation 13.1), and the average annual change (assessed medications OFF for the treated participants) was 7.45 (11.6), 3.11 (11.7), 4(11.9), 4.7 (11.1), and 1.74(11.9) for years 1, 2, 3, 4, and 5, respectively (P < .0001 for the change over time), with a steeper change in year 1. Dopaminergic therapy had a significant effect on the change of MDS-UPDRS. There was a significant longitudinal change in dopamine transporter binding in all striatal regions (P < .001). There was a significant but weak correlation between MDS-UPDRS and dopamine transporter binding at baseline and years 1, 2, and 4, but no correlation between the rate of change of the 2 variables.We present 5-year longitudinal data on the change of the MDS-UPDRS and other clinical and dopamine transporter imaging outcome measures in early PD. These data can be used for sample size estimates for interventional studies in the de novo PD population. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

  View details for DOI 10.1002/mds.27361

  View details for Web of Science ID 000434152700018

  View details for PubMedID 29572948

  View details for PubMedCentralID PMC6001458

• Sex differences in progression to mild cognitive impairment and dementia in Parkinson's disease. Parkinsonism & related disorders Cholerton, B., Johnson, C. O., Fish, B., Quinn, J. F., Chung, K. A., Peterson-Hiller, A. L., Rosenthal, L. S., Dawson, T. M., Albert, M. S., Hu, S., Mata, I. F., Leverenz, J. B., Poston, K. L., Montine, T. J., Zabetian, C. P., Edwards, K. L. 2018

  Abstract

  INTRODUCTION: Identification of factors associated with progression of cognitive symptoms in Parkinson's disease (PD) is important for treatment planning, clinical care, and design of future clinical trials. The current study sought to identify whether prediction of cognitive progression is aided by examining baseline cognitive features, and whether this differs according to stage of cognitive disease.METHODS: Participants with PD in the Pacific Udall Center Clinical Consortium who had longitudinal data available and were nondemented at baseline were included in the study (n = 418). Logistic and Cox regression models were utilized to examine the relationship between cognitive, demographic, and clinical variables with risk and time to progression from no cognitive impairment to mild cognitive impairment (PD-MCI) or dementia (PDD), and from PD-MCI to PDD.RESULTS: Processing speed (OR = 1.05, p = 0.009) and working memory (OR = 1.01, p = 0.03) were associated with conversion to PDD among those with PD-MCI at baseline, over and above demographic variables. Conversely, the primary predictive factor in the transition from no cognitive impairment to PD-MCI or PDD was male sex (OR = 4.47, p = 0.004), and males progressed more rapidly than females (p = 0.01). Further, among females with shorter disease duration, progression was slower than for their male counterparts, and poor baseline performance on semantic verbal fluency was associated with shorter time to cognitive impairment in females but not in males.CONCLUSIONS: This study provides evidence for sex differences in the progression to cognitive impairment in PD, while specific cognitive features become more important indicators of progression with impending conversion to PDD.

  View details for DOI 10.1016/j.parkreldis.2018.02.007

  View details for PubMedID 29478836

• 7T MRI subthalamic nucleus atlas for use with 3T MRI JOURNAL OF MEDICAL IMAGING Milchenko, M., Norris, S. A., Poston, K., Campbell, M. C., Ushe, M., Perlmutter, J. S., Snyder, A. Z. 2018; 5 (1): 015002

  Abstract

  Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces motor symptoms in most patients with Parkinson disease (PD), yet may produce untoward effects. Investigation of DBS effects requires accurate localization of the STN, which can be difficult to identify on magnetic resonance images collected with clinically available 3T scanners. The goal of this study is to develop a high-quality STN atlas that can be applied to standard 3T images. We created a high-definition STN atlas derived from seven older participants imaged at 7T. This atlas was nonlinearly registered to a standard template representing 56 patients with PD imaged at 3T. This process required development of methodology for nonlinear multimodal image registration. We demonstrate mm-scale STN localization accuracy by comparison of our 3T atlas with a publicly available 7T atlas. We also demonstrate less agreement with an earlier histological atlas. STN localization error in the 56 patients imaged at 3T was less than 1 mm on average. Our methodology enables accurate STN localization in individuals imaged at 3T. The STN atlas and underlying 3T average template in MNI space are freely available to the research community. The image registration methodology developed in the course of this work may be generally applicable to other datasets.

  View details for DOI 10.1117/1.JMI.5.1.015002

  View details for Web of Science ID 000429258000047

  View details for PubMedID 29340288

  View details for PubMedCentralID PMC5757662

• Distinct alterations in Parkinson's medication-state and disease-state connectivity NEUROIMAGE-CLINICAL Ng, B., Varoquaux, G., Poline, J., Thirion, B., Greicius, M. D., Poston, K. L. 2017; 16: 575–85

  Abstract

  Altered brain connectivity has been described in people with Parkinson's disease and in response to dopaminergic medications. However, it is unclear whether dopaminergic medications primarily 'normalize' disease related connectivity changes or if they induce unique alterations in brain connectivity. Further, it is unclear how these disease- and medication-associated changes in brain connectivity relate differently to specific motor manifestations of disease, such as bradykinesia/rigidity and tremor. In this study, we applied a novel covariance projection approach in combination with a bootstrapped permutation test to resting state functional MRI data from 57 Parkinson's disease and 20 healthy control participants to determine the Parkinson's medication-state and disease-state connectivity changes associated with different motor manifestations of disease. First, we identified brain connections that best classified Parkinson's disease ON versus OFF dopamine and Parkinson's disease versus healthy controls, achieving 96.9 ± 5.9% and 72.7 ± 12.4% classification accuracy, respectively. Second, we investigated the connections that significantly contribute to the classifications. We found that the connections greater in Parkinson's disease OFF compared to ON dopamine are primarily between motor (cerebellum and putamen) and posterior cortical regions, such as the posterior cingulate cortex. By contrast, connections that are greater in ON compared to OFF dopamine are between the right and left medial prefrontal cortex. We also identified the connections that are greater in healthy control compared to Parkinson's disease and found the most significant connections are associated with primary motor regions, such as the striatum and the supplementary motor area. Notably, these are different connections than those identified in Parkinson's disease OFF compared to ON. Third, we determined which of the Parkinson's medication-state and disease-state connections are associated with the severity of different motor symptoms. We found two connections correlate with both bradykinesia/rigidity severity and tremor severity, whereas four connections correlate with only bradykinesia/rigidity severity, and five connections correlate with only tremor severity. Connections that correlate with only tremor severity are anchored by the cerebellum and the supplemental motor area, but only those connections that include the supplemental motor area predict dopaminergic improvement in tremor. Our results suggest that dopaminergic medications do not simply 'normalize' abnormal brain connectivity associated with Parkinson's disease, but rather dopamine drives distinct connectivity changes, only some of which are associated with improved motor symptoms. In addition, the dissociation between of connections related to severity of bradykinesia/rigidity versus tremor highlights the distinct abnormalities in brain circuitry underlying these specific motor symptoms.

  View details for DOI 10.1016/j.nicl.2017.09.004

  View details for Web of Science ID 000413235100061

  View details for PubMedID 28971008

  View details for PubMedCentralID PMC5608603

• Compensatory neural mechanisms in cognitively unimpaired Parkinson disease. Annals of neurology Poston, K. L., YorkWilliams, S., Zhang, K., Cai, W., Everling, D., Tayim, F. M., Llanes, S., Menon, V. 2016; 79 (3): 448-463

  Abstract

  Cognitive impairments in Parkinson's disease (PD) are thought to be caused in part by dopamine dysregulation. However, even when nigrostriatal dopamine neuron loss is severe enough to cause motor symptoms, many patients remain cognitively unimpaired. It is unclear what brain mechanisms allow these patients to remain cognitively unimpaired despite substantial dopamine dysregulation.31 cognitively unimpaired PD participants OFF dopaminergic-medications were scanned using fMRI while they performed a working memory task, along with 23 controls. We first compared the PD_OFF medication group with controls to determine whether PD participants engage compensatory frontostriatal mechanisms during working memory. We then studied the same PD participants ON dopaminergic-medications to determine whether these compensatory brain changes are altered with dopamine.Controls and PD showed working memory load-dependent activation in the bilateral putamen, anterior-dorsal insula, supplementary motor area, and anterior cingulate cortex. Compared to controls, PD_OFF showed compensatory hyper-activation of bilateral putamen and posterior insula, and machine learning algorithms identified robust differences in putamen activation patterns. Compared to PD_OFF, PD_ON showed reduced compensatory activation in the putamen. Loss of compensatory hyper-activation ON dopaminergic-medication correlated with slower performance on the working memory task and slower cognitive speed on the Symbol Digit Modality Test.Our results provide novel evidence that PD patients maintain normal cognitive performance through compensatory hyper-activation of the putamen. Dopaminergic-medication down-regulates this hyper-activation and the degree of down-regulation predicts behavior. Identifying cognitive compensatory mechanisms in PD is important for understanding how some patients maintain intact cognitive performance, despite nigrostriatal dopamine loss. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/ana.24585

  View details for PubMedID 26696272

• Do CSF Biomarkers Predict Progression to Cognitive Impairment in Parkinson's disease patients? A Systematic Review. Neuropsychology review Leaver, K., Poston, K. L. 2015; 25 (4): 411-423

  Abstract

  Many patients with Parkinson's disease (PD) will develop cognitive impairment. Cross-sectional studies have shown that certain protein levels are altered in the cerebrospinal fluid (CSF) of PD patients with dementia and are thought to represent potential biomarkers of underlying pathogenesis. Recent studies suggest that CSF biomarker levels may be predictive of future risk of cognitive decline in non-demented PD patients. However, the strength of this evidence and difference between specific CSF biomarkers is not well delineated. We therefore performed a systematic review to assess if levels of specific CSF protein biomarkers are predictive of progression to cognitive impairment. Nine articles were identified that met inclusion criteria for the review. Findings from the review suggest a convergence of evidence that a low baseline Aβ42 in the CSF of non-demented PD patients predicts development of cognitive impairment over time. Conversely, there is limited evidence that CSF levels of tau, either total tau or phosphorylated tau, is a useful predictive biomarker. There are mixed results for other CSF biomarkers such as α-synuclein, Neurofilament light chain, and Heart fatty acid-binding protein. Overall the results of this review show that certain CSF biomarkers have better predictive ability to identify PD patients who are at risk for developing cognitive impairment. Given the interest in developing disease-modifying therapies, identifying this group will be important for clinical trials as initiation of therapy prior to the onset of cognitive decline is likely to be more efficacious.

  View details for DOI 10.1007/s11065-015-9307-8

  View details for PubMedID 26626621

  View details for PubMedCentralID PMC5152566

• Differential diagnosis of parkinsonism: a metabolic imaging study using pattern analysis LANCET NEUROLOGY Tang, C. C., Poston, K. L., Eckert, T., Feigin, A., Frucht, S., Gudesblatt, M., Dhawan, V., Lesser, M., Vonsattel, J., Fahn, S., Eidelberg, D. 2010; 9 (2): 149-158

  Abstract

  Idiopathic Parkinson's disease can present with symptoms similar to those of multiple system atrophy or progressive supranuclear palsy. We aimed to assess whether metabolic brain imaging combined with spatial covariance analysis could accurately discriminate patients with parkinsonism who had different underlying disorders.Between January, 1998, and December, 2006, patients from the New York area who had parkinsonian features but uncertain clinical diagnosis had fluorine-18-labelled-fluorodeoxyglucose-PET at The Feinstein Institute for Medical Research. We developed an automated image-based classification procedure to differentiate individual patients with idiopathic Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy. For each patient, the likelihood of having each of the three diseases was calculated by use of multiple disease-related patterns with logistic regression and leave-one-out cross-validation. Each patient was classified according to criteria defined by receiver-operating-characteristic analysis. After imaging, patients were assessed by blinded movement disorders specialists for a mean of 2.6 years before a final clinical diagnosis was made. The accuracy of the initial image-based classification was assessed by comparison with the final clinical diagnosis.167 patients were assessed. Image-based classification for idiopathic Parkinson's disease had 84% sensitivity, 97% specificity, 98% positive predictive value (PPV), and 82% negative predictive value (NPV). Imaging classifications were also accurate for multiple system atrophy (85% sensitivity, 96% specificity, 97% PPV, and 83% NPV) and progressive supranuclear palsy (88% sensitivity, 94% specificity, 91% PPV, and 92% NPV).Automated image-based classification has high specificity in distinguishing between parkinsonian disorders and could help in selecting treatment for early-stage patients and identifying participants for clinical trials.National Institutes of Health and General Clinical Research Center at The Feinstein Institute for Medical Research.

  View details for DOI 10.1016/S1474-4422(10)70002-8

  View details for Web of Science ID 000273922000012

  View details for PubMedID 20061183

• Further study of the Montreal Cognitive Assessment's domain-specific metrics could allow for international data comparison and collaboration PARKINSONISM & RELATED DISORDERS Hendershott, T. R., Poston, K. L. 2018; 48: 101

  View details for DOI 10.1016/j.parkreldis.2017.11.336

  View details for Web of Science ID 000428010200018

  View details for PubMedID 29221675

• Slower saccadic reading in Parkinson's disease PLOS ONE Jehangir, N., Yu, C., Song, J., Shariati, M., Binder, S., Beyer, J., Santini, V., Poston, K., Liao, Y. 2018; 13 (1): e0191005

  Abstract

  Idiopathic Parkinson's Disease (PD) is characterized by degeneration of dopaminergic and other neurons, leading to motor and non-motor deficits. Abnormal eye movements in PD, including fixations, saccades, and convergence, are well described. However, saccadic reading, which requires serial and alternating saccades and fixations, is not well studied, despite its obvious impact on the quality of life. In this study, we assessed saccadic reading using variations of the King-Devick (KD) test, a rapid single digit number naming test, as a way to assess the ability to make serial left-to-right ocular motor movements necessary for reading. We recruited 42 treated PD patients and 80 age-matched controls and compared their reading times with a variety of measures, including age, duration of disease, Unified Parkinson's Disease Rating Scale (UPDRS), the National Eye Institute 25-Item Visual Functioning Questionnaire 25 (VFQ-25), and Montreal Cognitive assessment (MoCA) test. The subjects performed 4 trials of reading 120 single digit numbers aloud as fast as possible without making errors. In each trial, they read 3 pages (KD1, KD2, and KD3), and each page contained 40 numbers per page in 8 lines with 5 numbers/line. We found that PD patients read about 20% slower than controls on all tests (KD1, 2, and 3 tests) (p < 0.02), and both groups read irregularly spaced numbers slower than regularly spaced numbers. Having lines between numbers to guide reading (KD1 tests) did not impact reading time in both PD and controls, but increased visual crowding as a result of decreased spacing between numbers (KD3 tests) was associated with significantly slower reading times in both PD and control groups. Our study revealed that saccadic reading is slower in PD, but controls and PD patients are both impacted by visuospatial planning challenges posed by increased visual crowding and irregularity of number spacing. Reading time did not correlate with UPDRS or MoCA scores in PD patients but significantly correlated with age, duration of disease, and VFQ-25 scores. The presence of convergence insufficiency did not significantly correlate with reading time in PD patients, although on average there was slower reading time in those with convergence insufficiency by 8 s (p = 0.2613). We propose that a simple reading task using 120 single-digit numbers can be used as a screening tool in the clinical setting to assess functional ocular motor difficulties in Parkinson's disease that can have a profound impact on quality of life.

  View details for DOI 10.1371/journal.pone.0191005

  View details for Web of Science ID 000423412500032

  View details for PubMedID 29364897

  View details for PubMedCentralID PMC5783375

• FREQUENCY-DEPENDENT DIFFERENCES IN BRAIN SIGNAL OSCILLATIONS: RELATION TO HIV INFECTION, PARKINSON'S DISEASE, AND ALCOHOL Muller-Oehring, E. M., Hong, J. Y., Bronte-Stewart, H. M., Poston, K. L., Pfefferbaum, A., Sullivan, E. V., Schulte, T. WILEY. 2017: 68A

  View details for Web of Science ID 000402419600203

• gene therapy trial for Parkinson's disease. JCI insight Niethammer, M., Tang, C. C., LeWitt, P. A., Rezai, A. R., Leehey, M. A., Ojemann, S. G., Flaherty, A. W., Eskandar, E. N., Kostyk, S. K., Sarkar, A., Siddiqui, M. S., Tatter, S. B., Schwalb, J. M., Poston, K. L., Henderson, J. M., Kurlan, R. M., Richard, I. H., Sapan, C. V., Eidelberg, D., During, M. J., Kaplitt, M. G., Feigin, A. 2017; 2 (7)

  Abstract

  BACKGROUND. We report the 12-month clinical and imaging data on the effects of bilateral delivery of the glutamic acid decarboxylase gene into the subthalamic nuclei (STN) of advanced Parkinson's disease (PD) patients. METHODS. 45 PD patients were enrolled in a 6-month double-blind randomized trial of bilateral AAV2-GAD delivery into the STN compared with sham surgery and were followed for 12 months in open-label fashion. Subjects were assessed with clinical outcome measures and (18)F-fluorodeoxyglucose (FDG) PET imaging. RESULTS. Improvements under the blind in Unified Parkinson's Disease Rating Scale (UPDRS) motor scores in the AAV2-GAD group compared with the sham group continued at 12 months [time effect: F(4,138) = 11.55, P < 0.001; group effect: F(1,35) = 5.45, P < 0.03; repeated-measures ANOVA (RMANOVA)]. Daily duration of levodopa-induced dyskinesias significantly declined at 12 months in the AAV2-GAD group (P = 0.03; post-hoc Bonferroni test), while the sham group was unchanged. Analysis of all FDG PET images over 12 months revealed significant metabolic declines (P < 0.001; statistical parametric mapping RMANOVA) in the thalamus, striatum, and prefrontal, anterior cingulate, and orbitofrontal cortices in the AAV2-GAD group compared with the sham group. Across all time points, changes in regional metabolism differed for the two groups in all areas, with significant declines only in the AAV2-GAD group (P < 0.005; post-hoc Bonferroni tests). Furthermore, baseline metabolism in the prefrontal cortex (PFC) correlated with changes in motor UPDRS scores; the higher the baseline PFC metabolism, the better the clinical outcome. CONCLUSION. These findings show that clinical benefits after gene therapy with STN AAV2-GAD in PD patients persist at 12 months. TRIAL REGISTRATION. ClinicalTrials.gov NCT00643890. FUNDING. Neurologix Inc.

  View details for DOI 10.1172/jci.insight.90133

  View details for PubMedID 28405611

• Early uptake Amyloid PET imaging correlates strongly with cerebral blood flow based on arterial spin labeling MRI: a simultaneous PET/MRI study Zaharchuk, G., Fan, A., Gulaka, P., Guo, J., Poston, K., Greicius, M., Sha, S., Vasanawala, M., Zeineh, M. SAGE PUBLICATIONS INC. 2017: 224–25

  View details for Web of Science ID 000400157400329

• Domain-specific accuracy of the Montreal Cognitive Assessment subsections in Parkinson's disease. Parkinsonism & related disorders Hendershott, T. R., Zhu, D., Llanes, S., Poston, K. L. 2017

  Abstract

  The Montreal Cognitive Assessment (MoCA) is among the most widely adopted screening tools for cognitive impairment because it includes tests in multiple domains and is available in 55 languages. The MoCA is often the only formal cognitive assessment available when comprehensive neuropsychological testing is not practical, such as rural clinical settings or large retrospective and multi-lingual research settings. However, the MoCA domain-specific subsections have never been formally assessed for sensitivity or specificity. Therefore, in Parkinson's disease, we examined whether the subsections of the MoCA could identify cognitive impairment within specific cognitive domains.We administered a comprehensive neuropsychological battery to 85 Parkinson's disease participants, who were then categorized as with or without cognitive impairment, with respect to global cognition and in five cognitive domains. We then assessed the domain-specific categorization of the MoCA subsections compared to the full neuropsychology battery.All MoCA subsections predicted impairment in their respective cognitive domain. However, the executive subsection showed the highest sensitivity and specificity (89.3% and 82.5%, respectively), followed by visuospatial (93.3% and 45.7%, respectively) and memory (84.6% and 56.5%, respectively).The MoCA is a useful screening tool for PD global cognitive and executive functions. The MoCA is also highly sensitive to visuospatial and memory impairment, but with limited specificity and accuracy these subsections should be interpreted with caution.

  View details for DOI 10.1016/j.parkreldis.2017.02.008

  View details for PubMedID 28215728

  View details for PubMedCentralID PMC5400012

• Abnormal eye movement behavior during reading in Parkinson's disease PARKINSONISM & RELATED DISORDERS Yu, C. Y., Lee, T., Shariati, A., Santini, V., Poston, K., Liao, Y. 2016; 32: 130–32

  Abstract

  Reading difficulties are common in Parkinson's disease (PD) but not well studied. We report a case of reading difficulties in a 40-year-old man with 6-year history of PD on dopamine replacement therapy.We performed detailed neuro-ophthalmic examination and assessment of reading with and without infrared oculography.Clinical examination revealed visual acuity of 20/20, no evidence of vision loss, and normal eye movement and ocular alignment with normal saccades, pursuit, and normal convergence. During King-Devick test, a rapid number reading task performed on a book, patient had normal number reading speed. More detailed study of number and word reading using infrared oculography revealed that while this patient had normal speed and eye movement behavior during number reading, he had dramatic slowing and eye movement abnormality during word reading. The slower reading speed during word reading was due to increased number of progressive saccades, smaller saccade amplitudes, increased number of regressive saccades, and longer fixation durations.This case nicely illustrated the importance of comprehensive neuro-ophthalmic evaluations in Parkinson's disease and shows that reading difficulties can arise even when there is good visual acuity, ocular motor abilities necessary to read, and accommodation. In this case, reading difficulty was due to higher order ocular motor planning or cognitive abilities involved in word reading since the patient had no difficulty with ocular motor planning while reading numbers. These findings may have important implications towards our understanding of PD and can serve to spark further research in this important area.

  View details for DOI 10.1016/j.parkreldis.2016.08.008

  View details for Web of Science ID 000388777000022

  View details for PubMedID 27592009

• Effects of Dopaminergic Medication on Working Memory in Patients with Parkinson's Disease with and without Mild Cognitive Impairment Sherman, E., Zhang, K., Everling, D., Marshall, A., YorkWilliams, S., Menon, V., Poston, K. LIPPINCOTT WILLIAMS & WILKINS. 2016

  View details for Web of Science ID 000411328601278

• The effects of dopamine on digit span in Parkinson's disease. Journal of clinical movement disorders Warden, C., Hwang, J., Marshall, A., Fenesy, M., Poston, K. L. 2016; 3: 5-?

  Abstract

  Parkinson's disease patients are at an elevated risk of developing cognitive impairment. Although cognitive impairment is one of the strongest predictors of quality of life, dopaminergic anti-parkinsonian medications are designed to target motor symptoms. However, there is substantial evidence that dopamine also impacts cognition, in particular working memory. It is therefore critical for movement disorders physicians to understand the potential dopaminergic effects on working memory when prescribing these medications. Verbal digit span tasks offer a potentially straightforward and quick assessment of baseline working memory. Moreover, Digit Span Backward was recently validated as a screening tool for mild cognitive impairment in Parkinson's disease when participants were medicated. Research indicates that the interaction between dopamine and working memory follows an Inverted-U shaped curve, but the effect of dopamine on Digit Span has not been well studied. Our study seeks to: (1) determine the validity of verbal Digit Spans for detecting cognitive impairment in Parkinson's disease patients both ON and OFF medications; and (2) ascertain the effects of dopaminergic medications on verbal Digit Span.We recruited 64 Parkinson's disease patients and 22 age-and education-matched controls. Parkinson's patients completed Digit Span Backward and Digit Span Forward ON and OFF medications, while healthy controls completed them once. All participants were categorized by cognitive diagnosis using level-II consensus criteria.Digit Span Backward successfully identified mild cognitive impairment in Parkinson's disease, both ON and OFF medications. Combining patients with and without cognitive impairment, we found that dopamine significantly improved performance on Digit Span Backward, but not Forward. In a secondary analysis, we found this dopaminergic improvement was restricted to the Low baseline working memory group; the High baseline working memory group was unaffected.This study provides evidence for Digit Span Backward as a screening tool for working memory impairment in Parkinson's disease and for its utility in measuring baseline working memory. Moreover, it reveals a partial beneficial effect of dopamine on Digit Span in Parkinson's disease patients.

  View details for DOI 10.1186/s40734-016-0033-z

  View details for PubMedID 26955482

  View details for PubMedCentralID PMC4780147

• Task-rest modulation of basal ganglia connectivity in mild to moderate Parkinson's disease BRAIN IMAGING AND BEHAVIOR Mueller-Oehring, E. M., Sullivan, E. V., Pfefferbaum, A., Huang, N. C., Poston, K. L., Bronte-Stewart, H. M., Schulte, T. 2015; 9 (3): 619-638

  Abstract

  Parkinson's disease (PD) is associated with abnormal synchronization in basal ganglia-thalamo-cortical loops. We tested whether early PD patients without demonstrable cognitive impairment exhibit abnormal modulation of functional connectivity at rest, while engaged in a task, or both. PD and healthy controls underwent two functional MRI scans: a resting-state scan and a Stroop Match-to-Sample task scan. Rest-task modulation of basal ganglia (BG) connectivity was tested using seed-to-voxel connectivity analysis with task and rest time series as conditions. Despite substantial overlap of BG-cortical connectivity patterns in both groups, connectivity differences between groups had clinical and behavioral correlates. During rest, stronger putamen-medial parietal and pallidum-occipital connectivity in PD than controls was associated with worse task performance and more severe PD symptoms suggesting that abnormalities in resting-state connectivity denote neural network dedifferentiation. During the executive task, PD patients showed weaker BG-cortical connectivity than controls, i.e., between caudate-supramarginal gyrus and pallidum-inferior prefrontal regions, that was related to more severe PD symptoms and worse task performance. Yet, task processing also evoked stronger striatal-cortical connectivity, specifically between caudate-prefrontal, caudate-precuneus, and putamen-motor/premotor regions in PD relative to controls, which was related to less severe PD symptoms and better performance on the Stroop task. Thus, stronger task-evoked striatal connectivity in PD demonstrated compensatory neural network enhancement to meet task demands and improve performance levels. fMRI-based network analysis revealed that despite resting-state BG network compromise in PD, BG connectivity to prefrontal, premotor, and precuneus regions can be adequately invoked during executive control demands enabling near normal task performance.

  View details for DOI 10.1007/s11682-014-9317-9

  View details for Web of Science ID 000361604300021

  View details for PubMedCentralID PMC4385510

• Task-rest modulation of basal ganglia connectivity in mild to moderate Parkinson's disease. Brain imaging and behavior Müller-Oehring, E. M., Sullivan, E. V., Pfefferbaum, A., Huang, N. C., Poston, K. L., Bronte-Stewart, H. M., Schulte, T. 2015; 9 (3): 619-638

  Abstract

  Parkinson's disease (PD) is associated with abnormal synchronization in basal ganglia-thalamo-cortical loops. We tested whether early PD patients without demonstrable cognitive impairment exhibit abnormal modulation of functional connectivity at rest, while engaged in a task, or both. PD and healthy controls underwent two functional MRI scans: a resting-state scan and a Stroop Match-to-Sample task scan. Rest-task modulation of basal ganglia (BG) connectivity was tested using seed-to-voxel connectivity analysis with task and rest time series as conditions. Despite substantial overlap of BG-cortical connectivity patterns in both groups, connectivity differences between groups had clinical and behavioral correlates. During rest, stronger putamen-medial parietal and pallidum-occipital connectivity in PD than controls was associated with worse task performance and more severe PD symptoms suggesting that abnormalities in resting-state connectivity denote neural network dedifferentiation. During the executive task, PD patients showed weaker BG-cortical connectivity than controls, i.e., between caudate-supramarginal gyrus and pallidum-inferior prefrontal regions, that was related to more severe PD symptoms and worse task performance. Yet, task processing also evoked stronger striatal-cortical connectivity, specifically between caudate-prefrontal, caudate-precuneus, and putamen-motor/premotor regions in PD relative to controls, which was related to less severe PD symptoms and better performance on the Stroop task. Thus, stronger task-evoked striatal connectivity in PD demonstrated compensatory neural network enhancement to meet task demands and improve performance levels. fMRI-based network analysis revealed that despite resting-state BG network compromise in PD, BG connectivity to prefrontal, premotor, and precuneus regions can be adequately invoked during executive control demands enabling near normal task performance.

  View details for DOI 10.1007/s11682-014-9317-9

  View details for PubMedID 25280970

• Gene delivery of neurturin to putamen and substantia nigra in Parkinson disease: A double-blind, randomized, controlled trial ANNALS OF NEUROLOGY Olanow, C. W., Bartus, R. T., Baumann, T. L., Factor, S., Boulis, N., Stacy, M., Turner, D. A., Marks, W., Larson, P., Starr, P. A., Jankovic, J., Simpson, R., Watts, R., Guthrie, B., Poston, K., Henderson, J. M., Stern, M., Baltuch, G., Goetz, C. G., Herzog, C., Kordower, J. H., Alterman, R., Lozano, A. M., Lang, A. E. 2015; 78 (2): 248-257

  Abstract

  A 12-month double-blind sham-surgery-controlled trial assessing adeno-associated virus type 2 (AAV2)-neurturin injected into the putamen bilaterally failed to meet its primary endpoint, but showed positive results for the primary endpoint in the subgroup of subjects followed for 18 months and for several secondary endpoints. Analysis of postmortem tissue suggested impaired axonal transport of neurturin from putamen to substantia nigra. In the present study, we tested the safety and efficacy of AAV2-neurturin delivered to putamen and substantia nigra.We performed a 15- to 24-month, multicenter, double-blind trial in patients with advanced Parkinson disease (PD) who were randomly assigned to receive bilateral AAV2-neurturin injected bilaterally into the substantia nigra (2.0 × 10(11) vector genomes) and putamen (1.0 × 10(12) vector genomes) or sham surgery. The primary endpoint was change from baseline to final visit performed at the time the last enrolled subject completed the 15-month evaluation in the motor subscore of the Unified Parkinson's Disease Rating Scale in the practically defined off state.Fifty-one patients were enrolled in the trial. There was no significant difference between groups in the primary endpoint (change from baseline: AAV2-neurturin, -7.0 ± 9.92; sham, -5.2 ± 10.01; p = 0.515) or in most secondary endpoints. Two subjects had cerebral hemorrhages with transient symptoms. No clinically meaningful adverse events were attributed to AAV2-neurturin.AAV2-neurturin delivery to the putamen and substantia nigra bilaterally in PD was not superior to sham surgery. The procedure was well tolerated, and there were no clinically significant adverse events related to AAV2-neurturin. Ann Neurol 2015;78:248-257.

  View details for DOI 10.1002/ana.24436

  View details for Web of Science ID 000358501600009

• A disease-specific metabolic brain network associated with corticobasal degeneration BRAIN Niethammer, M., Tang, C. C., Feigin, A., Allen, P. J., Heinen, L., Hellwig, S., Amtage, F., Hanspal, E., Vonsattel, J. P., Poston, K. L., Meyer, P. T., Leenders, K. L., Eidelberg, D. 2014; 137: 3036-3046

  Abstract

  Corticobasal degeneration is an uncommon parkinsonian variant condition that is diagnosed mainly on clinical examination. To facilitate the differential diagnosis of this disorder, we used metabolic brain imaging to characterize a specific network that can be used to discriminate corticobasal degeneration from other atypical parkinsonian syndromes. Ten non-demented patients (eight females/two males; age 73.9 ± 5.7 years) underwent metabolic brain imaging with (18)F-fluorodeoxyglucose positron emission tomography for atypical parkinsonism. These individuals were diagnosed clinically with probable corticobasal degeneration. This diagnosis was confirmed in the three subjects who additionally underwent post-mortem examination. Ten age-matched healthy subjects (five females/five males; age 71.7 ± 6.7 years) served as controls for the imaging studies. Spatial covariance analysis was applied to scan data from the combined group to identify a significant corticobasal degeneration-related metabolic pattern that discriminated (P < 0.001) the patients from the healthy control group. This pattern was characterized by bilateral, asymmetric metabolic reductions involving frontal and parietal cortex, thalamus, and caudate nucleus. These pattern-related changes were greater in magnitude in the cerebral hemisphere opposite the more clinically affected body side. The presence of this corticobasal degeneration-related metabolic topography was confirmed in two independent testing sets of patient and control scans, with elevated pattern expression (P < 0.001) in both disease groups relative to corresponding normal values. We next determined whether prospectively computed expression values for this pattern accurately discriminated corticobasal degeneration from multiple system atrophy and progressive supranuclear palsy (the two most common atypical parkinsonian syndromes) on a single case basis. Based upon this measure, corticobasal degeneration was successfully distinguished from multiple system atrophy (P < 0.001) but not progressive supranuclear palsy, presumably because of the overlap (∼ 24%) that existed between the corticobasal degeneration- and the progressive supranuclear palsy-related metabolic topographies. Nonetheless, excellent discrimination between these disease entities was achieved by computing hemispheric asymmetry scores for the corticobasal degeneration-related pattern on a prospective single scan basis. Indeed, a logistic algorithm based on the asymmetry scores combined with separately computed expression values for a previously validated progressive supranuclear palsy-related pattern provided excellent specificity (corticobasal degeneration: 92.7%; progressive supranuclear palsy: 94.1%) in classifying 58 testing subjects. In conclusion, corticobasal degeneration is associated with a reproducible disease-related metabolic covariance pattern that may help to distinguish this disorder from other atypical parkinsonian syndromes.

  View details for DOI 10.1093/brain/awu256

  View details for Web of Science ID 000346760900025

  View details for PubMedID 25208922

  View details for PubMedCentralID PMC4208467

• Dissociated Effect of Dopamine on Cognitive Resting State Networks in PD Poston, K. L., Price, C., YorkWilliams, S., Everling, D., Fenesy, M., Marshall, A., Cruadhlaoich, M., Menon, V., Greicius, M. D. WILEY-BLACKWELL. 2014: S45–S46

  View details for Web of Science ID 000343766400085

• What light have resting state fMRI studies shed on cognition and mood in Parkinson's disease? Journal of clinical movement disorders YorkWilliams, S., Poston, K. L. 2014; 1: 4-?

  Abstract

  Much remains unknown about non-motor symptoms of Parkinson's disease (PD), which have variable occurrence, progression, and severity among patients. The existing suite of neuroimaging tools has yielded insight that cannot be garnered by traditional methods such as behavioral and post-mortem assessment. They provide information on brain activity and structure that is invaluable to understanding abnormalities associated with neurodegeneration in PD. Among these tools, functional magnetic resonance imaging (fMRI) is often favored for its safety and spatial resolution. Resting state fMRI research capitalizes on the wealth of information that the brain offers when a person is not performing a motor or cognitive task. It is also a good means to study impaired and heterogeneous populations, such as people with PD. The present article reviews research that applies resting state fMRI to the ongoing hunt for biomarkers of PD non-motor symptoms. Thus far, research in this subfield has focused on two of the most common and significant non-motor symptoms: cognitive impairment and depression. These studies support resting state fMRI as a valid and practical tool for the study of these symptoms, but discrepancies among findings highlight the importance of further research with standardized procedures.

  View details for DOI 10.1186/2054-7072-1-4

  View details for PubMedID 26788330

  View details for PubMedCentralID PMC4677732

• DOPAMINERGIC MODULATION OF WORKING MEMORY IN PARKINSON'S DISEASE PATIENTS Poston, K., Tayim, F., YorkWilliams, S., Lambert, J., Menon, V. MIT PRESS. 2013: 192

  View details for Web of Science ID 000317030501092

• Functional brain networks and abnormal connectivity in the movement disorders NEUROIMAGE Poston, K. L., Eidelberg, D. 2012; 62 (4): 2261-2270

  Abstract

  Clinical manifestations of movement disorders, such as Parkinson's disease (PD) and dystonia, arise from neurophysiological changes within the cortico-striato-pallidothalamocortical (CSPTC) and cerebello-thalamo-cortical (CbTC) circuits. Neuroimaging techniques that probe connectivity within these circuits can be used to understand how these disorders develop as well as identify potential targets for medical and surgical therapies. Indeed, network analysis of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has identified abnormal metabolic networks associated with the cardinal motor symptoms of PD, such as akinesia and tremor, as well as PD-related cognitive dysfunction. More recent task-based and resting state functional magnetic resonance imaging studies have reproduced several of the altered connectivity patterns identified in these abnormal PD-related networks. A similar network analysis approach in dystonia revealed abnormal disease related metabolic patterns in both manifesting and non-manifesting carriers of dystonia mutations. Other multimodal imaging approaches using magnetic resonance diffusion tensor imaging in patients with primary genetic dystonia suggest abnormal connectivity within the CbTC circuits mediate the clinical manifestations of this inherited neurodevelopmental disorder. Ongoing developments in functional imaging and future studies in early patients are likely to enhance our understanding of these movement disorders and guide novel targets for future therapies.

  View details for DOI 10.1016/j.neuroimage.2011.12.021

  View details for Web of Science ID 000308265200010

  View details for PubMedID 22206967

  View details for PubMedCentralID PMC3489159

• Network correlates of disease severity in multiple system atrophy NEUROLOGY Poston, K. L., Tang, C. C., Eckert, T., Dhawan, V., Frucht, S., Vonsattel, J., Fahn, S., Eidelberg, D. 2012; 78 (16): 1237-1244

  Abstract

  Multiple system atrophy (MSA), the most common of the atypical parkinsonian disorders, is characterized by the presence of an abnormal spatial covariance pattern in resting state metabolic brain images from patients with this disease. Nonetheless, the potential utility of this pattern as a MSA biomarker is contingent upon its specificity for this disorder and its relationship to clinical disability in individual patients.We used [(18)F]fluorodeoxyglucose PET to study 33 patients with MSA, 20 age- and severity-matched patients with idiopathic Parkinson disease (PD), and 15 healthy volunteers. For each subject, we computed the expression of the previously characterized metabolic covariance patterns for MSA and PD (termed MSARP and PDRP, respectively) on a prospective single-case basis. The resulting network values for the individual patients were correlated with clinical motor ratings and disease duration.In the MSA group, disease-related pattern (MSARP) values were elevated relative to the control and PD groups (p < 0.001 for both comparisons). In this group, MSARP values correlated with clinical ratings of motor disability (r = 0.57, p = 0.0008) and with disease duration (r = -0.376, p = 0.03). By contrast, MSARP expression in the PD group did not differ from control values (p = 1.0). In this group, motor ratings correlated with PDRP (r = 0.60, p = 0.006) but not with MSARP values (p = 0.88).MSA is associated with elevated expression of a specific disease-related metabolic pattern. Moreover, differences in the expression of this pattern in patients with MSA correlate with clinical disability. The findings suggest that the MSARP may be a useful biomarker in trials of new therapies for this disorder.

  View details for DOI 10.1212/WNL.0b013e318250d7fd

  View details for Web of Science ID 000302933200010

  View details for PubMedID 22491861

  View details for PubMedCentralID PMC3324319

• Dopaminergic Modulation of Basal Ganglia Connectivity in Parkinson's Disease Poston, K. L., Shire, W., Joseph, R., Menon, V., Greicius, M. WILEY-BLACKWELL. 2012: S138–S139

  View details for Web of Science ID 000312938700537

• AAV2-GAD gene therapy for advanced Parkinson's disease: a double-blind, sham-surgery controlled, randomised trial LANCET NEUROLOGY LeWitt, P. A., Rezai, A. R., Leehey, M. A., Ojemann, S. G., Flaherty, A. W., Eskandar, E. N., Kostyk, S. K., Thomas, K., Sarkar, A., Siddiqui, M. S., Tatter, S. B., Schwalb, J. M., Poston, K. L., Henderson, J. M., Kurlan, R. M., Richard, I. H., Van Meter, L., Sapan, C. V., During, M. J., Kaplitt, M. G., Feigin, A. 2011; 10 (4): 309-319

  Abstract

  Gene transfer of glutamic acid decarboxylase (GAD) and other methods that modulate production of GABA in the subthalamic nucleus improve basal ganglia function in parkinsonism in animal models. We aimed to assess the effect of bilateral delivery of AAV2-GAD in the subthalamic nucleus compared with sham surgery in patients with advanced Parkinson's disease.Patients aged 30-75 years who had progressive levodopa-responsive Parkinson's disease and an overnight off-medication unified Parkinson's disease rating scale (UPDRS) motor score of 25 or more were enrolled into this double-blind, phase 2, randomised controlled trial, which took place at seven centres in the USA between Nov 17, 2008, and May 11, 2010. Infusion failure or catheter tip location beyond a predefined target zone led to exclusion of patients before unmasking for the efficacy analysis. The primary outcome measure was the 6-month change from baseline in double-blind assessment of off-medication UPDRS motor scores. This trial is registered with ClinicalTrials.gov, NCT00643890.Of 66 patients assessed for eligibility, 23 were randomly assigned to sham surgery and 22 to AAV2-GAD infusions; of those, 21 and 16, respectively, were analysed. At the 6-month endpoint, UPDRS score for the AAV2-GAD group decreased by 8·1 points (SD 1·7, 23·1%; p<0·0001) and by 4·7 points in the sham group (1·5, 12·7%; p=0·003). The AAV2-GAD group showed a significantly greater improvement from baseline in UPDRS scores compared with the sham group over the 6-month course of the study (RMANOVA, p=0·04). One serious adverse event occurred within 6 months of surgery; this case of bowel obstruction occurred in the AAV2-GAD group, was not attributed to treatment or the surgical procedure, and fully resolved. Other adverse events were mild or moderate, likely related to surgery and resolved; the most common were headache (seven patients in the AAV2-GAD group vs two in the sham group) and nausea (six vs two).The efficacy and safety of bilateral infusion of AAV2-GAD in the subthalamic nucleus supports its further development for Parkinson's disease and shows the promise for gene therapy for neurological disorders.Neurologix.

  View details for DOI 10.1016/S1474-4422(11)70039-4

  View details for Web of Science ID 000289185000014

  View details for PubMedID 21419704

• Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) with Myoclonus MOVEMENT DISORDERS Poston, K. L., McGovern, R. A., Goldman, J. S., Caccappolo, E., Mazzoni, P. 2010; 25 (4): 514-516

  View details for DOI 10.1002/mds.22929

  View details for Web of Science ID 000276337400027

  View details for PubMedID 20063436

• Abnormalities in Metabolic Network Activity Precede the Onset of Motor Symptoms in Parkinson's Disease JOURNAL OF NEUROSCIENCE Tang, C. C., Poston, K. L., Dhawan, V., Eidelberg, D. 2010; 30 (3): 1049-1056

  Abstract

  Imaging studies show that Parkinson's disease (PD) alters the activity of motor- and cognition-related metabolic brain networks. However, it is not known whether the network changes appear at or before symptom onset. In this study, we examined 15 hemiparkinsonian patients who underwent serial metabolic imaging with [(18)F]-fluorodeoxyglucose (FDG) PET at baseline and again 2.1 +/- 0.6 (mean +/- SD) and 3.9 +/- 0.7 years later. We assessed longitudinal changes in network activity in each cerebral hemisphere, focusing specifically on the "presymptomatic" hemisphere--ipsilateral to the initially involved body side. At the network level, the activity of the PD motor-related pattern (PDRP) increased symmetrically in both hemispheres over time (p < 0.001), with significant bilateral elevations at each of the three time points. Hemispheric expression of the PD cognition-related pattern likewise increased symmetrically (p < 0.001), although significant elevations were not evident on either side until 4 years. At the regional level, putamen metabolism contralateral to the initially affected body side was elevated at all three time points, without longitudinal change. In contrast, in the initially presymptomatic hemisphere, putamen metabolic activity increased steadily over time, reaching abnormal levels only at 4 years. Metabolic activity in the contralateral precuneus fell to subnormal levels by the final time point. These findings suggest that abnormal PDRP activity antecedes the appearance of motor signs by approximately 2 years. The timing and laterality of symptom onset relates to focal asymmetric metabolic changes at the putamenal node of this network.

  View details for DOI 10.1523/JNEUROSCI.4188-09.2010

  View details for Web of Science ID 000273779200026

  View details for PubMedID 20089913

  View details for PubMedCentralID PMC2866050

• FDG PET in the Evaluation of Parkinson's Disease. PET clinics 2010; 5 (1): 55–64

  Abstract

  Network analysis of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is an innovative approach for the study of in movement disorders, such as Parkinson's disease (PD). Spatial covariance analysis of imaging data acquired from PD patients has revealed characteristic regional patterns associated with the motor and cognitive features of disease. Quantification of pattern expression in individual patients can be used for diagnosis, assessment of disease severity, and evaluation of novel medical and surgical therapies. Identification of disease-specific patterns in other parkinsonian syndromes, such as multiple system atrophy and progressive supranuclear palsy, has improved diagnostic accuracy in patients with difficult to diagnose parkinsonism. Further developments of these techniques are likely to enhance the role of functional imaging in investigating underlying abnormalities and potential new therapies in these neurodegenerative diseases.

  View details for DOI 10.1016/j.cpet.2009.12.004

  View details for PubMedID 20689674

  View details for PubMedCentralID PMC2913894

• Action tremor of the legs in essential tremor: Prevalence, clinical correlates, and comparison with age-matched controls PARKINSONISM & RELATED DISORDERS Poston, K. L., Rios, E., Louis, E. D. 2009; 15 (8): 602-605

  Abstract

  The hallmark feature of essential tremor (ET) is action tremor of the arms. Leg tremor may also occur yet it has not been the central focus of previous studies. Its prevalence has only rarely been reported, its clinical correlates have yet to be explored. Our aims were to report the prevalence and analyze the clinical correlates of leg action tremor in patients with ET and, given the propensity for normal elderly individuals to manifest mild limb tremors, compare the prevalence with that in age-matched controls. Kinetic leg tremor rated > or =1 occurred in 28/63 (44.4%) ET cases and in only 9/63 (14.3%) controls (p<0.001); moderate leg tremor occurred in 14.3% of cases. Leg tremor severity modestly correlated with disease duration (r=0.31, p=0.02). However, the severity and laterality of leg tremor did not correlate with those of arm tremor. The pathophysiological implications of this finding deserve further exploration.

  View details for DOI 10.1016/j.parkreldis.2008.11.006

  View details for Web of Science ID 000270122500011

  View details for PubMedID 19103506

• Network biomarkers for the diagnosis and treatment of movement disorders NEUROBIOLOGY OF DISEASE Poston, K. L., Eidelberg, D. 2009; 35 (2): 141-147

  Abstract

  Functional brain networks provide a set of useful biomarkers for the assessment of movement disorders such as Parkinson's disease (PD). Spatial covariance analysis of imaging data from PD patients has led to the identification of abnormal metabolic patterns associated with the motor and cognitive features of this disease. Measurements of pattern expression have been used for diagnosis, assessment of rates of disease progression, and objective evaluation of the efficacy of therapeutic interventions. For instance, the recent identification of new disease-specific patterns for Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) has improved diagnostic accuracy in patients with parkinsonian syndromes. Further, disease-related networks have been found to be modulated by novel treatment strategies such as gene therapy. Finally, the application of network analysis to the study of inherited movement disorders such as Huntington's disease can aid in the assessment of disease-modifying therapies in pre-symptomatic gene mutation carriers.

  View details for DOI 10.1016/j.nbd.2008.09.026

  View details for Web of Science ID 000268078300004

  View details for PubMedID 19013242

• Movement disorder emergencies 16th Symposium on the Treatment of Parkinsons Disease Poston, K. L., Frucht, S. J. SPRINGER HEIDELBERG. 2008: 2–13

  Abstract

  Movement disorder emergencies include any movement disorder which evolves over hours to days, in which failure to appropriately diagnose and manage can result in patient morbidity or mortality. It is crucial that doctors recognize these emergencies with accuracy and speed by obtaining the proper history and by being familiar with the phenomenology of frequently encountered movements. These disorders will be discussed based on the most common associated involuntary movement, either parkinsonism, dystonia, chorea, tics or myoclonus, and, when available, review the workup and treatment options based on the current literature.

  View details for DOI 10.1007/s00415-008-4002-9

  View details for Web of Science ID 000259034000002

  View details for PubMedID 18821080

• Zydis selegilline in the management of Parkinson's disease EXPERT OPINION ON PHARMACOTHERAPY Poston, K. L., Waters, C. 2007; 8 (15): 2615-2624

  Abstract

  Selegiline, a selective monoamine oxidase-B inhibitor, has been used for decades in the treatment of Parkinson's disease. The recent development of an orally disintegrating dosage form using Zydis technology allows pregastric drug absorption and, thus, greatly improving the pharmacodynamic and pharmacokinetic drug profiles. This new formulation provides higher drug bioavailability and a substantially reduced concentration of active metabolites. As an adjunct to levodopa, Zydis selegiline is shown to be a safe and effective therapy in patients with motor fluctuations and wearing off. This review outlines the advantages of a Zydis formulation in Parkinson's disease and the evidence supporting the use of Zydis selegiline for motor fluctuations.

  View details for DOI 10.1517/14656566.8.15.2615

  View details for Web of Science ID 000250426000014

  View details for PubMedID 17931095