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Phillips JS, Da Re F, Dratch L, Xie SX, Irwin DJ, McMillan CT, Vaishnavi SN, Ferrarese C, Lee EB, Shaw LM, Trojanowski JQ, Wolk DA, Grossman M. Neocortical origin and progression of gray matter atrophy in nonamnestic Alzheimer's disease. Neurobiol Aging 2017; 63:75-87. [PMID: 29223682 DOI: 10.1016/j.neurobiolaging.2017.11.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 10/27/2017] [Accepted: 11/15/2017] [Indexed: 12/12/2022]
Abstract
Amnestic Alzheimer's disease (AD) is characterized by early atrophy of the hippocampus and medial temporal lobes before spreading to the neocortex. In contrast, nonamnestic Alzheimer's patients have relative sparing of the hippocampus, but the pattern in which the disease spreads is unclear. We examined spreading disease in nonamnestic AD using a novel magnetic resonance imaging-based analysis adapted from pathologic staging studies, applied here to cross-sectional imaging data. We selected 240 T1-weighted scans from 129 patients with pathology confirmed by autopsy or cerebrospinal fluid, and atrophy maps were computed relative to 238 scans from 115 elderly controls. For each phenotype, the frequency of atrophy in 116 brain regions was used to infer the anatomical origin of disease and its progression across 4 phases of atrophy. Results from the amnestic cohort were used to determine appropriate parameter settings for the phase assignment algorithm, based on correspondence to Braak pathology staging. Phase 1 regions, which represent the origin of disease, included the hippocampus for the amnestic group (comprising 33 scans); left lateral temporal lobe for logopenic-variant primary progressive aphasia (88 scans); occipitoparietal cortex for posterior cortical atrophy (51 scans); temporoparietal cortex for corticobasal syndrome (31 scans); and frontotemporal cortex for behavioral/dysexecutive variant AD (37 scans). In nonamnestic patients, atrophy spread to other neocortical areas in later phases, but the hippocampus exhibited only late-phase atrophy in posterior cortical atrophy and corticobasal syndrome. Region-specific phase values were also associated with regional measures of tau, beta amyloid, neuronal loss, and gliosis for the subset of patients (n = 17) with neuropathology findings; this comparison represented a first validation of the phase assignment algorithm. We subsequently assigned a phase to each patient scan based on the similarity of regional atrophy patterns with atrophy predicted for the corresponding phenotype at each phase. Scan-specific phases were correlated with disease duration as well as global and domain-specific cognition, supporting these phase values as global estimates of patients' disease progression. Logistic regression models based on spatial overlap with model-predicted atrophy patterns reliably discriminated nonamnestic phenotypes from each other and from amnestic AD. The frequency-based phase assignment algorithm used in the present study thus represents a promising approach for studying the neocortical origin and spread of disease in nonamnestic AD.
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Fleisher JE, Dahodwala NA, Xie SX, Mayo M, Weintraub D, Chodosh J, Shea JA. Development and Validation of the Parkinson's Disease Medication Beliefs Scale (PD-Rx). JOURNAL OF PARKINSONS DISEASE 2017; 6:383-92. [PMID: 27061070 DOI: 10.3233/jpd-150765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Medication non-adherence is common in Parkinson's disease (PD) and is associated with increased disability and healthcare costs. Individuals' beliefs regarding their medical conditions and treatments impact medication adherence. While instruments exist to measure patients' beliefs about medications in general, no such tool exists for PD. OBJECTIVES Create an instrument eliciting medication beliefs of persons with PD; identify demographic and clinical characteristics associated with beliefs; and examine whether beliefs are associated with dopaminergic therapy adherence. METHODS We developed the Parkinson's Disease Medication Beliefs Scale (PD-Rx) in four phases: focus groups of patients and caregivers to generate items, scale development, expert and patient revision of items, and a cross-sectional validation sample (n = 75). Adherence was calculated using two approaches incorporating self-reported medication lists. RESULTS The PD-Rx consists of 11 items covering benefits and risks of PD pharmacotherapies. The scale covers motor improvement, current adverse effects, and future concerns. Higher scores indicate more positive beliefs. Internal consistency was acceptable (Cronbach's alpha = 0.67). Test-retest reliability was 0.47. Quality of life was associated with PD-Rx scores, and lower scores were associated with non-adherence. CONCLUSIONS Negative beliefs about PD treatments are associated with lower quality of life and may be related to medication non-adherence. Further study of any causal relationship between beliefs and medication non-adherence in PD will inform the design of future patient-centered interventions to improve adherence.
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Rennert L, Xie SX. Cox regression model with doubly truncated data. Biometrics 2017; 74:725-733. [PMID: 29073330 DOI: 10.1111/biom.12809] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/01/2017] [Accepted: 09/01/2017] [Indexed: 11/29/2022]
Abstract
Truncation is a well-known phenomenon that may be present in observational studies of time-to-event data. While many methods exist to adjust for either left or right truncation, there are very few methods that adjust for simultaneous left and right truncation, also known as double truncation. We propose a Cox regression model to adjust for this double truncation using a weighted estimating equation approach, where the weights are estimated from the data both parametrically and nonparametrically, and are inversely proportional to the probability that a subject is observed. The resulting weighted estimators of the hazard ratio are consistent. The parametric weighted estimator is asymptotically normal and a consistent estimator of the asymptotic variance is provided. For the nonparametric weighted estimator, we apply the bootstrap technique to estimate the variance and confidence intervals. We demonstrate through extensive simulations that the proposed estimators greatly reduce the bias compared to the unweighted Cox regression estimator which ignores truncation. We illustrate our approach in an analysis of autopsy-confirmed Alzheimer's disease patients to assess the effect of education on survival.
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Fullard ME, Xie SX, Marek K, Stern M, Jennings D, Siderowf A, Willis AW, Chen-Plotkin AS. Vitamin D in the Parkinson Associated Risk Syndrome (PARS) study. Mov Disord 2017; 32:1636-1640. [PMID: 28906025 DOI: 10.1002/mds.27127] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/02/2017] [Accepted: 06/18/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Lower vitamin D levels have been associated with manifest Parkinson's disease, prompting the hypothesis that vitamin D insufficiency or deficiency may increase risk for PD. OBJECTIVES To evaluate vitamin D levels in a population at risk for developing PD. METHODS Plasma vitamin D levels were measured in the Parkinson Associated Risk Syndrome Study, a cohort of asymptomatic individuals, some of whom are at high risk for PD. Vitamin D levels were compared between subjects at high risk for PD (hyposmia and dopamine transporter scan deficit) versus all others and examined for correlations with dopaminergic system integrity. RESULTS Mean vitamin D levels did not differ between groups, with a level of 27.8 ng/mL (standard deviation = 12.0) in the high-risk group versus 24.7 ng/mL (standard deviation = 9.0) in all others (P = 0.09). Vitamin D levels did not associate with putaminal dopamine transporter uptake. CONCLUSIONS Our data from the asymptomatic Parkinson Associated Risk Syndrome cohort do not support the hypothesis that chronic vitamin D insufficiency threatens dopaminergic system integrity, contributing to PD pathogenesis. © 2017 International Parkinson and Movement Disorder Society.
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Kovacs GG, Xie SX, Lee EB, Robinson JL, Caswell C, Irwin DJ, Toledo JB, Johnson VE, Smith DH, Alafuzoff I, Attems J, Bencze J, Bieniek KF, Bigio EH, Bodi I, Budka H, Dickson DW, Dugger BN, Duyckaerts C, Ferrer I, Forrest SL, Gelpi E, Gentleman SM, Giaccone G, Grinberg LT, Halliday GM, Hatanpaa KJ, Hof PR, Hofer M, Hortobágyi T, Ironside JW, King A, Kofler J, Kövari E, Kril JJ, Love S, Mackenzie IR, Mao Q, Matej R, McLean C, Munoz DG, Murray ME, Neltner J, Nelson PT, Ritchie D, Rodriguez RD, Rohan Z, Rozemuller A, Sakai K, Schultz C, Seilhean D, Smith V, Tacik P, Takahashi H, Takao M, Rudolf Thal D, Weis S, Wharton SB, White CL, Woulfe JM, Yamada M, Trojanowski JQ. Multisite Assessment of Aging-Related Tau Astrogliopathy (ARTAG). J Neuropathol Exp Neurol 2017; 76:605-619. [PMID: 28591867 DOI: 10.1093/jnen/nlx041] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Aging-related tau astrogliopathy (ARTAG) is a recently introduced terminology. To facilitate the consistent identification of ARTAG and to distinguish it from astroglial tau pathologies observed in the primary frontotemporal lobar degeneration tauopathies we evaluated how consistently neuropathologists recognize (1) different astroglial tau immunoreactivities, including those of ARTAG and those associated with primary tauopathies (Study 1); (2) ARTAG types (Study 2A); and (3) ARTAG severity (Study 2B). Microphotographs and scanned sections immunostained for phosphorylated tau (AT8) were made available for download and preview. Percentage of agreement and kappa values with 95% confidence interval (CI) were calculated for each evaluation. The overall agreement for Study 1 was >60% with a kappa value of 0.55 (95% CI 0.433-0.645). Moderate agreement (>90%, kappa 0.48, 95% CI 0.457-0.900) was reached in Study 2A for the identification of ARTAG pathology for each ARTAG subtype (kappa 0.37-0.72), whereas fair agreement (kappa 0.40, 95% CI 0.341-0.445) was reached for the evaluation of ARTAG severity. The overall assessment of ARTAG showed moderate agreement (kappa 0.60, 95% CI 0.534-0.653) among raters. Our study supports the application of the current harmonized evaluation strategy for ARTAG with a slight modification of the evaluation of its severity.
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Yousef A, Robinson JL, Irwin DJ, Byrne MD, Kwong LK, Lee EB, Xu Y, Xie SX, Rennert L, Suh E, Van Deerlin VM, Grossman M, Lee VMY, Trojanowski JQ. Neuron loss and degeneration in the progression of TDP-43 in frontotemporal lobar degeneration. Acta Neuropathol Commun 2017; 5:68. [PMID: 28877758 PMCID: PMC5586052 DOI: 10.1186/s40478-017-0471-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 08/28/2017] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) is associated with the accumulation of pathological neuronal and glial intracytoplasmic inclusions as well as accompanying neuron loss. We explored if cortical neurons detected by NeuN decreased with increasing TDP-43 inclusion pathology in the postmortem brains of 63 patients with sporadic and familial FTLD-TDP. Semi-automated quantitative algorithms to quantify histology in tissue sections stained with antibodies specific for pathological or phosphorylated TDP-43 (pTDP-43) and NeuN were developed and validated in affected (cerebral cortex) and minimally affected (cerebellar cortex) brain regions of FTLD-TDP cases. Immunohistochemistry (IHC) for NeuN and other neuronal markers found numerous neurons lacking reactivity, suggesting NeuN may reflect neuron health rather than neuron loss in FTLD. We found three patterns of NeuN and pTDP-43 reactivity in our sample of cortical tissue representing three intracortical region-specific stages of FTLD-TDP progression: Group 1 showed low levels of pathological pTDP-43 and high levels NeuN, while Group 2 showed increased levels of pTDP-43, and Group 3 tissues were characterized by reduced staining for both pTDP-43 and NeuN. Comparison of non-C9orf72/GRN FTLD-TDP with cases linked to both GRN mutations and C9orf72 expansions showed a significantly increased frequency of Group 3 histopathology in the latter cases, suggesting more advanced cortical disease. Hence, we propose that IHC profiles of pTDP-43 and NeuN reflect the burden of pTDP-43 and its deleterious effects on neuron health.
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Irwin DJ, Lleó A, Xie SX, McMillan CT, Wolk DA, Lee EB, Van Deerlin VM, Shaw LM, Trojanowski JQ, Grossman M. Ante mortem cerebrospinal fluid tau levels correlate with postmortem tau pathology in frontotemporal lobar degeneration. Ann Neurol 2017; 82:247-258. [PMID: 28719018 DOI: 10.1002/ana.24996] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 07/07/2017] [Accepted: 07/12/2017] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To test the hypotheses that (1) antemortem cerebrospinal fluid (CSF) tau levels correlate with postmortem tau pathology in frontotemporal lobar degeneration (FTLD) and (2) tauopathy patients have higher phosphorylated-tau levels compared to transactivation response element DNA-binding protein 43 (TDP-43) proteinopathy patients while accounting for Alzheimer's disease (AD) copathology. METHODS Patients had autopsy-confirmed FTLD with tauopathy (n = 31), TDP-43 proteinopathy (n = 49), or AD (n = 26) with antemortem CSF. CSF tau levels were compared between groups and correlated with digital histology measurement of postmortem tau pathology averaged from three cerebral regions (angular gyrus, mid-frontal cortex, and anterior cingulate gyrus). Multivariate linear regression tested the association of ante mortem CSF tau levels with postmortem tau pathology adjusting for demographics. RESULTS Multivariate regression found an independent association of ante mortem CSF phosphorylated tau levels with postmortem cerebral tau pathology in FTLD (Beta = 1.3; 95% confidence interval = 0.2-2.4; p < 0.02). After excluding patients with coincident AD-associated tau pathology accompanying sporadic FTLD, we found lower CSF phosphorylated tau levels in the TDP-43 group (median = 7.4pg/ml; interquartile range [IQR] = 6.0, 12.3; n = 26) compared to the tauopathy group (median = 12.5pg/ml; IQR = 10.7, 15.0; n = 23; Z = 2.6; p < 0.01). INTERPRETATION CSF phosphorylated-tau levels are positively associated with cerebral tau burden in FTLD. In vivo detection of AD copathology in sporadic FTLD patients may help stratify clinical cohorts with pure neuropathology in which low CSF phosphorylated-tau levels may have diagnostic utility to distinguish TDP-43 proteinopathy from tauopathy. Autopsy-confirmed samples are critical for FTLD biomarker development and validation. Ann Neurol 2017;82:247-258.
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Kovacs GG, Robinson JL, Xie SX, Lee EB, Grossman M, Wolk DA, Irwin DJ, Weintraub D, Kim CF, Schuck T, Yousef A, Wagner ST, Suh E, Van Deerlin VM, Lee VMY, Trojanowski JQ. Evaluating the Patterns of Aging-Related Tau Astrogliopathy Unravels Novel Insights Into Brain Aging and Neurodegenerative Diseases. J Neuropathol Exp Neurol 2017; 76:270-288. [PMID: 28340083 DOI: 10.1093/jnen/nlx007] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The term "aging-related tau astrogliopathy" (ARTAG) describes pathological accumulation of abnormally phosphorylated tau protein in astrocytes. We evaluated the correlates of ARTAG types (i.e., subpial, subependymal, white and gray matter, and perivascular) in different neuroanatomical regions. Clinical, neuropathological, and genetic (eg, APOE ε4 allele, MAPT H1/H2 haplotype) data from 628 postmortem brains from subjects were investigated; most of the patients had been longitudinally followed at the University of Pennsylvania. We found that (i) the amygdala is a hotspot for all ARTAG types; (ii) age at death, male sex, and presence of primary frontotemporal lobar degeneration (FTLD) tauopathy are significantly associated with ARTAG; (iii) age at death, greater degree of brain atrophy, ventricular enlargement, and Alzheimer disease (AD)-related variables are associated with subpial, white matter, and perivascular ARTAG types; (iv) AD-related variables are associated particularly with lobar white matter ARTAG; and (v) gray matter ARTAG in primary FTLD-tauopathies appears in areas without neuronal tau pathology. We provide a reference map of ARTAG types and propose at least 5 constellations of ARTAG. Furthermore, we propose a conceptual link between primary FTLD-tauopathy and ARTAG-related astrocytic tau pathologies. Our observations serve as a basis for etiological stratification and definition of progression patterns of ARTAG.
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Akhtar RS, Xie SX, Chen YJ, Rick J, Gross RG, Nasrallah IM, Van Deerlin VM, Trojanowski JQ, Chen-Plotkin AS, Hurtig HI, Siderowf AD, Dubroff JG, Weintraub D. Regional brain amyloid-β accumulation associates with domain-specific cognitive performance in Parkinson disease without dementia. PLoS One 2017; 12:e0177924. [PMID: 28542444 PMCID: PMC5444629 DOI: 10.1371/journal.pone.0177924] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 05/05/2017] [Indexed: 01/31/2023] Open
Abstract
Parkinson disease patients develop clinically significant cognitive impairment at variable times over their disease course, which is often preceded by milder deficits in memory, visuo-spatial, and executive domains. The significance of amyloid-β accumulation to these problems is unclear. We hypothesized that amyloid-β PET imaging by 18F-florbetapir, a radiotracer that detects fibrillar amyloid-β plaque deposits, would identify subjects with global cognitive impairment or poor performance in individual cognitive domains in non-demented Parkinson disease patients. We assessed 61 non-demented Parkinson disease patients with detailed cognitive assessments and 18F-florbetapir PET brain imaging. Scans were interpreted qualitatively (positive or negative) by two independent nuclear medicine physicians blinded to clinical data, and quantitatively by a novel volume-weighted method. The presence of mild cognitive impairment was determined through an expert consensus process using Level 1 criteria from the Movement Disorder Society. Nineteen participants (31.2%) were diagnosed with mild cognitive impairment and the remainder had normal cognition. Qualitative 18F-florbetapir PET imaging was positive in 15 participants (24.6%). Increasing age and presence of an APOE ε4 allele were associated with higher composite 18F-florbetapir binding. In multivariable models, an abnormal 18F-florbetapir scan by expert rating was not associated with a diagnosis of mild cognitive impairment. However, 18F-florbetapir retention values in the posterior cingulate gyrus inversely correlated with verbal memory performance. Retention values in the frontal cortex, precuneus, and anterior cingulate gyrus retention values inversely correlated with naming performance. Regional cortical amyloid-β amyloid, as measured by 18F-florbetapir PET, may be a biomarker of specific cognitive deficits in non-demented Parkinson disease patients.
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Deck BL, Rick J, Xie SX, Chen-Plotkin A, Duda JE, Morley JF, Chahine LM, Dahodwala N, Trojanowski JQ, Weintraub D. Statins and Cognition in Parkinson's Disease. JOURNAL OF PARKINSON'S DISEASE 2017; 7:661-667. [PMID: 28922167 PMCID: PMC5675567 DOI: 10.3233/jpd-171113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND The relationship between statins and cognition in Parkinson's disease (PD) is poorly understood. OBJECTIVES Analyses were performed to determine associations between statin use and cross-sectional and longitudinal cognitive performance in PD. METHODS Neuropsychological tests, medication logs, and ratings of functional abilities were collected from 313 PD participants longitudinally. RESULTS At baseline, statin users (SU; N = 129) were older, more likely male, and had shorter PD duration than non-statin users (NSU; N = 184). In Cross-sectional analysis, SU performed better on global cognition, Trails B, semantic fluency, and phonemic fluency tasks. Rate of long-term global cognitive (Dementia Rating Scale-2 and MoCA) decline was significantly less in SU.
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Brennan L, Devlin KM, Xie SX, Mechanic-Hamilton D, Tran B, Hurtig HH, Chen-Plotkin A, Chahine LM, Morley JF, Duda JE, Roalf DR, Dahodwala N, Rick J, Trojanowski JQ, Moberg PJ, Weintraub D. Neuropsychological Subgroups in Non-Demented Parkinson's Disease: A Latent Class Analysis. JOURNAL OF PARKINSON'S DISEASE 2017; 7:385-395. [PMID: 28387684 PMCID: PMC5548408 DOI: 10.3233/jpd-171081] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Methods to detect early cognitive decline and account for heterogeneity of deficits in Parkinson's disease (PD) are needed. Quantitative methods such as latent class analysis (LCA) offer an objective approach to delineate discrete phenotypes of impairment. OBJECTIVE To identify discrete neurocognitive phenotypes in PD patients without dementia. METHODS LCA was applied to a battery of 8 neuropsychological measures to identify cognitive subtypes in a cohort of 199 non-demented PD patients. Two measures were analyzed from each of four domains: executive functioning, memory, visuospatial abilities, and language. Additional analyses compared groups on clinical characteristics and cognitive diagnosis. RESULTS LCA identified 3 distinct groups of PD patients: an intact cognition group (54.8%), an amnestic group (32.2%), and a mixed impairment group with dysexecutive, visuospatial and lexical retrieval deficits (13.1%). The two impairment groups had significantly lower instrumental activities of daily living ratings and greater motor symptoms than the intact group. Of those diagnosed as cognitively normal according to MDS criteria, LCA classified 23.2% patients as amnestic and 9.9% as mixed cognitive impairment. CONCLUSIONS Non-demented PD patients exhibit distinct neuropsychological profiles. One-third of patients with LCA-determined impairment were diagnosed as cognitively intact by expert consensus, indicating that classification using a statistical algorithm may improve detection of initial and subtle cognitive decline. This study also demonstrates that memory impairment is common in non-demented PD even when cognitive impairment is not clinically apparent. This study has implications for predicting eventual emergence of significant cognitive decline, and treatment trials for cognitive dysfunction in PD.
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White MT, Shaw LM, Xie SX. Evaluation of Cerebrospinal Fluid Assay Variability in Alzheimer's Disease. J Alzheimers Dis 2016; 51:463-70. [PMID: 26890778 DOI: 10.3233/jad-151045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Studies of cerebrospinal fluid (CSF) biomarkers in Alzheimer's disease (AD) have indicated that much of the variability observed in the biomarkers may be due to measurement error. Biomarkers are often obtained with measurement error, which may make the diagnostic biomarker appear less effective than it truly is. In the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, technical replicates of CSF biomarkers are available; the National Alzheimer's Coordinating Center database contains longitudinal replicates of CSF biomarkers. We focus on the area under the receiver operating characteristic curve (AUC) as the measure of diagnostic effectiveness for differentiating AD from normal cognition using CSF biomarkers and compare AUC estimates obtained by a more standard, naïve method (which uses a single observation per subject and ignores measurement error) to a maximum likelihood (ML) based method (which uses all replicates per subject and adjusts for measurement error). The choice of analysis method depends upon the noise to signal ratio (i.e., the magnitude of the measurement error variability relative to the true biomarker variability); moderate to high ratios may significantly bias the naïve AUC estimate, and the ML-based method would be preferred. The noise to signal ratios were low for the ADNI biomarkers but high for the tTau and pTau biomarkers in NACC. Correspondingly, the naïve and ML-based AUC estimates were nearly identical in the ADNI data but dissimilar for the tTau and pTau biomarkers in the NACC data. Therefore, using the naïve method is adequate for analysis of CSF biomarkers in the ADNI study, but the ML method is recommended for the NACC data.
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Mao JJ, Xie SX, Keefe JR, Soeller I, Li QS, Amsterdam JD. Long-term chamomile (Matricaria chamomilla L.) treatment for generalized anxiety disorder: A randomized clinical trial. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2016; 23:1735-1742. [PMID: 27912875 PMCID: PMC5646235 DOI: 10.1016/j.phymed.2016.10.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/28/2016] [Accepted: 10/23/2016] [Indexed: 05/22/2023]
Abstract
BACKGROUND Generalized Anxiety Disorder (GAD) is one of the most common anxiety disorders treated in primary care, yet current therapies have limited efficacy and substantial side effects. PURPOSE To evaluate long-term chamomile (Matricaria chamomilla L.) use for prevention of GAD symptom relapse. METHODS Outpatients from primary care practices and local communities with a primary diagnosis of moderate-to-severe GAD were enrolled for this two-phase study at a large US academic medical center. During Phase 1, eligible participants received 12 weeks of open-label therapy with chamomile pharmaceutical grade extract 1500mg (500mg capsule 3 times daily). During Phase 2, treatment responders were randomized to either 26 weeks of continuation chamomile therapy or placebo in a double-blinded, placebo-substitution design. The primary outcome was time to relapse during continuation therapy, analyzed using Cox proportional hazards. Secondary outcomes included the proportion who relapsed, treatment-emergent adverse events, and vital sign changes. This study is registered at ClinicalTrials.gov, identifier NCT01072344. RESULTS Between March 1, 2010, and June 30, 2015, we enrolled 179 participants. Of those, 93 (51.9%) were responders and agreed to continue in the double-blind randomized controlled trial. A numerically greater number of placebo-switched (n=12/47; 25.5%) versus chamomile-continuation (n = 7/46; 15.2%) participants relapsed during follow-up. Mean time to relapse was 11.4 ± 8.4 weeks for chamomile and 6.3 ± 3.9 weeks for placebo. Hazard of relapse was non-significantly lower for chamomile (hazard ratio, 0.52; 95% CI, 0.20-1.33; P = 0.16). During follow-up, chamomile participants maintained significantly lower GAD symptoms than placebo (P = 0.0032), with significant reductions in body weight (P = 0.046) and mean arterial blood pressure (P = 0.0063). Both treatments had similar low adverse event rates. CONCLUSIONS Long-term chamomile was safe and significantly reduced moderate-to-severe GAD symptoms, but did not significantly reduce rate of relapse. Our limited sample size and lower than expected rate of placebo group relapse likely contributed to the non-significant primary outcome finding. Possible chamomile superiority over placebo requires further examination in large-scale studies.
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Cooper CA, Jain N, Gallagher MD, Weintraub D, Xie SX, Berlyand Y, Espay AJ, Quinn J, Edwards KL, Montine T, Van Deerlin VM, Trojanowski J, Zabetian CP, Chen-Plotkin AS. Common variant rs356182 near SNCA defines a Parkinson's disease endophenotype. Ann Clin Transl Neurol 2016; 4:15-25. [PMID: 28078311 PMCID: PMC5221454 DOI: 10.1002/acn3.371] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 10/04/2016] [Indexed: 01/11/2023] Open
Abstract
Objective Parkinson's disease (PD) presents clinically with several motor subtypes that exhibit variable treatment response and prognosis. Here, we investigated genetic variants for their potential association with PD motor phenotype and progression. Methods We screened 10 SNPs, previously associated with PD risk, for association with tremor‐dominant (TD) versus postural‐instability gait disorder (PIGD) motor subtypes. SNPs that correlated with the TD/PIGD ratio in a discovery cohort of 251 PD patients were then evaluated in a multi‐site replication cohort of 559 PD patients. SNPs associated with motor phenotype in both cross‐sectional cohorts were next evaluated for association with (1) rates of motor progression in a longitudinal subgroup of 230 PD patients and (2) brain alpha‐synuclein (SNCA) expression in the GTEx (Genotype‐Tissue Expression project) consortium database. Results Genotype at rs356182, near SNCA, correlated with the TD/PIGD ratio in both the discovery (Bonferroni‐corrected P = 0.04) and replication cohorts (P = 0.02). The rs356182 GG genotype was associated with a more tremor‐predominant phenotype and predicted a slower rate of motor progression (1‐point difference in annual rate of UPDRS‐III motor score change, P = 0.01). The rs356182 genotype was associated with SNCA expression in the cerebellum (P = 0.005). Interpretation Our study demonstrates that the GG genotype at rs356182 provides molecular definition for a clinically important endophenotype associated with (1) more tremor‐predominant motor phenomenology, (2) slower rates of motor progression, and (3) decreased brain expression of SNCA. Such molecularly defined endophenotyping in PD may benefit both clinical trial design and tailoring of clinical care as we enter the era of precision medicine.
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Zhang C, Xie SX, Wang WX, Xi N, Wang YC, Liu LQ. Bio-syncretic tweezers actuated by microorganisms: modeling and analysis. SOFT MATTER 2016; 12:7485-7494. [PMID: 27432020 DOI: 10.1039/c6sm01055e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Advancements in micro-/nano-technology have led to the development of micro-manipulators. However, some challenges remain; for instance, the efficiency, precision and flexibility of micro-manipulators restrain their applications. This paper proposes a bio-tweezer system to flexibly manipulate micro-objects with bio-actuation via local light-induced high-concentration microorganisms in two different manipulation modes: light-spot induced mode and geometric shape-induced mode. Depending on the shape of micro-objects, either 2-dimensional translation or 1-dimensional rotation can be achieved. Based on the Langevin equation, a mathematical model considering both hydrodynamics and mimicked Brownian motion is proposed to analyze the bio-manipulation performance of the microorganisms; the model was validated by experiments to translate micro-particles in a two-dimensional plane and to rotate a micro-gear structure around its axis. This paper will aid in the development of micro-manipulators and the quantitative understanding of micro-/nano-manipulation actuated by microorganisms.
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Bilello M, Doshi J, Nabavizadeh SA, Toledo JB, Erus G, Xie SX, Trojanowski JQ, Han X, Davatzikos C. Correlating Cognitive Decline with White Matter Lesion and Brain Atrophy Magnetic Resonance Imaging Measurements in Alzheimer's Disease. J Alzheimers Dis 2016; 48:987-94. [PMID: 26402108 DOI: 10.3233/jad-150400] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Vascular risk factors are increasingly recognized as risks factors for Alzheimer's disease (AD) and early conversion from mild cognitive impairment (MCI) to dementia. While neuroimaging research in AD has focused on brain atrophy, metabolic function, or amyloid deposition, little attention has been paid to the effect of cerebrovascular disease to cognitive decline. OBJECTIVE To investigate the correlation of brain atrophy and white matter lesions with cognitive decline in AD, MCI, and control subjects. METHODS Patients with AD and MCI, and healthy subjects were included in this study. Subjects had a baseline MRI scan, and baseline and follow-up neuropsychological battery (CERAD). Regional volumes were measured, and white matter lesion segmentation was performed. Correlations between rate of CERAD score decline and white matter lesion load and brain structure volume were evaluated. In addition, voxel-based correlations between baseline CERAD scores and atrophy and white matter lesion measures were computed. RESULTS CERAD rate of decline was most significantly associated with lesion loads located in the fornices. Several temporal lobe ROI volumes were significantly associated with CERAD decline. Voxel-based analysis demonstrated strong correlation between baseline CERAD scores and atrophy measures in the anterior temporal lobes. Correlation of baseline CERAD scores with white matter lesion volumes achieved significance in multilobar subcortical white matter. CONCLUSION Both baseline and declines in CERAD scores correlate with white matter lesion load and gray matter atrophy. Results of this study highlight the dominant effect of volume loss, and underscore the importance of small vessel disease as a contributor to cognitive decline in the elderly.
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Smith KM, Xie SX, Weintraub D. Incident impulse control disorder symptoms and dopamine transporter imaging in Parkinson disease. J Neurol Neurosurg Psychiatry 2016; 87:864-70. [PMID: 26534930 PMCID: PMC4854795 DOI: 10.1136/jnnp-2015-311827] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/02/2015] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To describe the incidence of, and clinical and neurobiological risk factors for, new-onset impulse control disorder (ICD) symptoms and related behaviours in early Parkinson disease (PD). METHODS The Parkinson's Progression Markers Initiative is an international, multicenter, prospective study of de novo patients with PD untreated at baseline and assessed annually, including serial dopamine transporter imaging (DAT-SPECT) and ICD assessment (Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease short form, QUIP). Participants were included if they screened negative on the QUIP at baseline. Kaplan-Meier curves and generalised estimating equations examined frequency and predictors of incident ICD symptoms. RESULTS Participants were seen at baseline (n=320), year 1 (n=284), year 2 (n=217) and year 3 (n=96). Estimated cumulative incident rates of ICD symptoms and related behaviours were 8% (year 1), 18% (year 2) and 25% (year 3) and increased each year in those on dopamine replacement therapy (DRT) and decreased in those not on DRT. In participants on DRT, risk factors for incident ICD symptoms were younger age (OR=0.97, p=0.05), a greater decrease in right caudate (OR=4.03, p=0.01) and mean striatal (OR=6.90, p=0.04) DAT availability over the first year, and lower right putamen (OR=0.06, p=0.01) and mean total striatal (OR=0.25, p=0.04) DAT availability at any post-baseline visit. CONCLUSIONS The rate of incident ICD symptoms increases with time and initiation of DRT in early PD. In this preliminary study, a greater decrease or lower DAT binding over time increases risk of incident ICD symptoms, conferring additional risk to those taking DRT. CLINICAL TRIAL REGISTRATION NCT01141023.
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Chahine LM, Xie SX, Simuni T, Tran B, Postuma R, Amara A, Oertel WH, Iranzo A, Scordia C, Fullard M, Linder C, Purri R, Darin A, Rennert L, Videnovic A, Del Riva P, Weintraub D. Longitudinal changes in cognition in early Parkinson's disease patients with REM sleep behavior disorder. Parkinsonism Relat Disord 2016; 27:102-6. [PMID: 27010070 PMCID: PMC5031362 DOI: 10.1016/j.parkreldis.2016.03.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/13/2016] [Accepted: 03/10/2016] [Indexed: 10/22/2022]
Abstract
INTRODUCTION Cognitive decline is common in Parkinson's disease (PD), and identifying patients at highest risk for it is essential. We aimed to examine the effect of possible REM sleep behavior disorder (pRBD) on rate of cognitive decline in early PD, for both global cognition and in specific cognitive domains. METHODS Parkinson's Progression Markers Initiative (PPMI) is a multi-site, international study of PD patients untreated at enrollment. pRBD was assessed with the REM sleep behavior disorder questionnaire (RBDSQ). Global cognition was assessed at baseline and annually using the Montreal Cognitive Assessment (MoCA) and a cognitive battery. Linear mixed effects models were used to examine the relationship between pRBD (RBDSQ≥6) and rate of change in cognitive variables. Age, sex, years of education, and baseline motor and cognitive scores were included as covariates. RESULTS The baseline sample consisted of 423 individuals with PD, mean age 61.7 years and 65.5% male. Data was available on 389, 366, and 196 participants at 1-year, 2-year, and 3-year follow-up respectively. Possible RBD occurred in 108 (25.5%) at baseline. In multivariate analyses, baseline RBD was associated with greater annual rate of decline in MoCA score (β = -0.34, 95%CI -0.54, -0.13, p < 0.001), Symbol Digit Modalities Test (β = -0.69, 95%CI -1.3, -0.09, p = 0.024), and Hopkins Verbal Learning Test-Revised, delayed free recall (β = -0.21, 95%CI -0.41, -0.013, p = 0.037). CONCLUSIONS Possible RBD is common in early PD and predicts future cognitive decline, particularly in attention and memory domains.
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Brennan L, Siderowf A, Rubright JD, Rick J, Dahodwala N, Duda JE, Hurtig H, Stern M, Xie SX, Rennert L, Karlawish J, Shea JA, Trojanowski JQ, Weintraub D. The Penn Parkinson's Daily Activities Questionnaire-15: Psychometric properties of a brief assessment of cognitive instrumental activities of daily living in Parkinson's disease. Parkinsonism Relat Disord 2016; 25:21-6. [PMID: 26923524 PMCID: PMC4818172 DOI: 10.1016/j.parkreldis.2016.02.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 02/04/2016] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
Abstract
INTRODUCTION To describe the psychometric properties of the Penn Parkinson's Daily Activities Questionnaire-15 (PDAQ-15), a 15-item measure of cognitive instrumental activities of daily living for Parkinson's disease (PD) patients derived from the original 50-item PDAQ. METHODS PDAQ-15 items were chosen by expert consensus. Knowledgeable informants of PD participants (n = 161) completed the PDAQ-15. Knowledgeable informants were defined as an individual having regular contact with the PD participant. PD participants were assigned a diagnosis of normal cognition, mild cognitive impairment, or dementia based on expert consensus. RESULTS PDAQ-15 scores correlated strongly with global cognition (Dementia Rating Scale-2, r = 0.71, p < 0.001) and a performance-based functional measure (Direct Assessment of Functional Status, r = 0.83; p < 0.001). PDAQ-15 scores accurately discriminated between non-demented PD participants (normal cognition/mild cognitive impairment) and PD with dementia (ROC curve area = 0.91), participants with and without any cognitive impairment (normal cognition versus mild cognitive impairment/dementia, ROC curve area = 0.85) and between participants with mild cognitive impairment and dementia (ROC curve area = 0.84). CONCLUSIONS The PDAQ-15 shows good discriminant validity across cognitive stages, correlates highly with global cognitive performance, and appears suitable to assess daily cognitive functioning in PD.
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Lim NS, Swanson CR, Cherng HR, Unger TL, Xie SX, Weintraub D, Marek K, Stern MB, Siderowf A, Trojanowski JQ, Chen-Plotkin AS. Plasma EGF and cognitive decline in Parkinson's disease and Alzheimer's disease. Ann Clin Transl Neurol 2016; 3:346-55. [PMID: 27231704 PMCID: PMC4863747 DOI: 10.1002/acn3.299] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 02/17/2016] [Accepted: 02/18/2016] [Indexed: 01/17/2023] Open
Abstract
Objective Cognitive decline occurs in multiple neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). Shared underlying mechanisms may exist and manifest as shared biomarker signatures. Previously, we nominated plasma epidermal growth factor (EGF) as a biomarker predicting cognitive decline in patients with established PD. Here, we investigate EGF as a predictive biomarker in prodromal PD, as well as AD. Methods A cohort of PD patients (n = 236) was recruited to replicate our finding that low baseline EGF levels predict future cognitive decline. Additionally, plasma EGF and cognitive outcome measures were obtained from individuals with normal cognition (NC, n = 58), amnestic mild cognitive impairment (AD‐MCI, n = 396), and Alzheimer's disease (AD, n = 112) in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort to investigate whether low EGF levels correlate with cognitive status and outcome in AD‐MCI and AD. Third, plasma EGF and cognitive measures were evaluated in the high‐risk asymptomatic Parkinson's Associated Risk Study (PARS) cohort (n = 165) to investigate the association of EGF and cognitive performance in a PD prodromal context. Results In both PD and AD‐MCI, low baseline plasma EGF predicted poorer long‐term cognitive outcomes. In asymptomatic individuals at highest risk for developing PD from the PARS cohort, low baseline plasma EGF associated with poorer performance in the visuospatial domain but not in other cognitive domains. Interpretation Low plasma EGF at baseline predicts cognitive decline in both AD and PD. Evidence for this signal may exist in prodromal stages of both diseases.
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Garland SN, Gehrman P, Barg FK, Xie SX, Mao JJ. CHoosing Options for Insomnia in Cancer Effectively (CHOICE): Design of a patient centered comparative effectiveness trial of acupuncture and cognitive behavior therapy for insomnia. Contemp Clin Trials 2016; 47:349-55. [DOI: 10.1016/j.cct.2016.02.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 02/21/2016] [Accepted: 02/28/2016] [Indexed: 10/22/2022]
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Fullard ME, Tran B, Xie SX, Toledo JB, Scordia C, Linder C, Purri R, Weintraub D, Duda JE, Chahine LM, Morley JF. Olfactory impairment predicts cognitive decline in early Parkinson's disease. Parkinsonism Relat Disord 2016; 25:45-51. [PMID: 26923521 DOI: 10.1016/j.parkreldis.2016.02.013] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/30/2016] [Accepted: 02/14/2016] [Indexed: 12/22/2022]
Abstract
OBJECTIVE To evaluate the association between baseline olfaction and both cross-sectional and longitudinal cognitive assessments, motor symptoms, non-motor symptoms (NMS), and CSF biomarkers in early Parkinson's disease (PD). METHODS Parkinson's Progression Marker's Initiative (PPMI) participants underwent baseline olfactory testing with the University of Pennsylvania Smell Identification Test (UPSIT). Serial assessments included measures of motor symptoms, NMS, neuropsychological assessment, and CSF biomarkers. Up to three years follow-up data were included. RESULTS At baseline, worse olfaction (lowest tertile) was associated with more severe NMS, including anxiety and autonomic symptoms. Those in the lowest olfactory tertile were more likely to report cognitive impairment (37.4%) compared to those in the middle (24.4%) and highest olfactory tertiles (14.2%, p < 0.001). Aβ1-42 was significantly lower, and tau/Aβ1-42 ratio was higher in those with worse olfaction. In longitudinal analyses, lower UPSIT score was associated with greater decline in MoCA score (β = 0.02 [0.01, 0.03], p = 0.001) over time, as were composite measures of UPSIT score and either Aβ1-42 or tau/Aβ1-42 ratio. In a Cox proportional hazards model, a composite measure of olfaction and Aβ1-42 was a significant predictor of conversion from normal cognition to mild cognitive impairment (MCI; i.e., MoCA < 26), with subjects most impaired on both measures being 87% more likely to develop incident MCI (HR = 1.87 [1.16, 3.01], p = 0.01). CONCLUSIONS Worse baseline olfaction is associated with long-term cognitive decline. The addition of AD CSF biomarkers to olfactory testing may increase the likelihood of identifying those at highest risk for cognitive decline and progression to MCI.
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Moelter ST, Weintraub D, Mace L, Cary M, Sullo E, Xie SX, Karlawish J. Research consent capacity varies with executive function and memory in Parkinson's disease. Mov Disord 2016; 31:414-7. [PMID: 26861463 DOI: 10.1002/mds.26469] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 10/01/2015] [Accepted: 10/05/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We examined the association between cognitive domains and research consent capacity in PD. Our hypothesis was that research consent capacity is best predicted by executive function. METHODS A cohort of 90 PD patients and 30 healthy older adults were administered the MacArthur Competence Assessment Tool for Clinical Research, Dementia Rating Scale-2, and the MoCA. Experts classified patients as either "capable" or "not capable" of providing informed consent to participate in two clinical trials. RESULTS MacArthur Competence Assessment Tool for Clinical Research Reasoning scores for both clinical trial types were most associated with executive functions and delayed recall. As scores on these domains improved, the odds of an expert rating of "capable of consent" increased. CONCLUSIONS These results extend our previous findings by demonstrating that memory and executive abilities appear closely associated with capacity when evaluated using either a structured interview or expert judgment of that interview.
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Berlyand Y, Weintraub D, Xie SX, Mellis IA, Doshi J, Rick J, McBride J, Davatzikos C, Shaw LM, Hurtig H, Trojanowski JQ, Chen-Plotkin AS. An Alzheimer's Disease-Derived Biomarker Signature Identifies Parkinson's Disease Patients with Dementia. PLoS One 2016; 11:e0147319. [PMID: 26812251 PMCID: PMC4727929 DOI: 10.1371/journal.pone.0147319] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/31/2015] [Indexed: 12/23/2022] Open
Abstract
Biomarkers from multiple modalities have been shown to correlate with cognition in Parkinson's disease (PD) and in Alzheimer's disease (AD). However, the relationships of these markers with each other, and the use of multiple markers in concert to predict an outcome of interest, are areas that are much less explored. Our objectives in this study were (1) to evaluate relationships among 17 biomarkers previously reported to associate with cognition in PD or AD and (2) to test performance of a five-biomarker classifier trained to recognize AD in identifying PD with dementia (PDD). To do this, we evaluated a cross-sectional cohort of PD patients (n = 75) across a spectrum of cognitive abilities. All PD participants had 17 baseline biomarkers from clinical, genetic, biochemical, and imaging modalities measured, and correlations among biomarkers were assessed by Spearman's rho and by hierarchical clustering. We found that internal correlation among all 17 candidate biomarkers was modest, showing a maximum pairwise correlation coefficient of 0.51. However, a five-marker subset panel derived from AD (CSF total tau, CSF phosphorylated tau, CSF amyloid beta 42, APOE genotype, and SPARE-AD imaging score) discriminated cognitively normal PD patients vs. PDD patients with 80% accuracy, when employed in a classifier originally trained to recognize AD. Thus, an AD-derived biomarker signature may identify PDD patients with moderately high accuracy, suggesting mechanisms shared with AD in some PDD patients. Based on five measures readily obtained during life, this AD-derived signature may prove useful in identifying PDD patients most likely to respond to AD-based crossover therapies.
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Akhtar RS, Xie SX, Brennan L, Pontecorvo MJ, Hurtig HI, Trojanowski JQ, Weintraub D, Siderowf AD. Amyloid-Beta Positron Emission Tomography Imaging of Alzheimer's Pathology in Parkinson's Disease Dementia. Mov Disord Clin Pract 2016; 3:367-375. [PMID: 27500181 DOI: 10.1002/mdc3.12290] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Neuronal loss and α-synuclein (α-syn) pathology are diagnostic of PD in the appropriate clinical context. However, some PD patients have co-morbid Alzheimer's disease (AD) pathology on autopsy, including amyloid-β (Aβ) plaques and neurofibrillary tangles. Florbetapir(18F) is a PET ligand that detects Aβ pathology. We hypothesized that florbetapir(18F) imaging could detect Aβ pathology in Parkinson disease dementia (PDD) patients prior to death. OBJECTIVE To determine the utility of florbetapir(18F) PET imaging in detecting Aβ pathology in patients with autopsy-confirmed PDD. METHODS Five participants with PDD had florbetapir(18F) PET imaging prior to death as a part of a longitudinal research study of cognitive decline in PD. PET scans were evaluated by expert raters blinded to clinical and neuropathological information. At autopsy, all five participants underwent semi-quantitative assessments of regional Aβ and tau immunohistochemistry. RESULTS All participants met neuropathological criteria for PD. Two had both positive florbetapir(18F) scans and Aβ-positive plaques in multiple brain regions. Regional florbetapir(18F) binding correlated with regional semi-quantitative Aβ pathology in these cases. Three cases had negative florbetapir(18F) scans. Two of these had significant tau pathology without Aβ pathology, consistent with progressive supranuclear palsy (PSP) in one case and argyrophilic grain disease (AGD) in the other. The last case had a low level of AD neuropathological change. CONCLUSIONS Florbetapir(18F) Aβ imaging can detect the presence of Aβ neuropathology in patients with PDD. This imaging technique may aid the clinical evaluation of PDD patients to determine if cognitive decline is occurring in the setting of Aβ accumulation.
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