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Viswanathan, Anand

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Viswanathan

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Anand

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Viswanathan, Anand
Author's Publications: search.filters.isAuthorOfPublication.907578ee-4c18-462c-a560-5ccb3bbe02a0

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Now showing 1 - 7 of 7
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    Brain hemorrhage recurrence, small vessel disease type, and cerebral microbleeds: A meta-analysis
    (Lippincott Williams & Wilkins, 2017) Charidimou, Andreas; Imaizumi, Toshio; Moulin, Solene; Biffi, Alexandro; Samarasekera, Neshika; Yakushiji, Yusuke; Peeters, Andre; Vandermeeren, Yves; Laloux, Patrice; Baron, Jean-Claude; Hernandez-Guillamon, Mar; Montaner, Joan; Casolla, Barbara; Gregoire, Simone M.; Kang, Dong-Wha; Kim, Jong S.; Naka, H.; Smith, Eric E.; Viswanathan, Anand; Jäger, Hans R.; Al-Shahi Salman, Rustam; Greenberg, Steven; Cordonnier, Charlotte; Werring, David J.
    Objective: We evaluated recurrent intracerebral hemorrhage (ICH) risk in ICH survivors, stratified by the presence, distribution, and number of cerebral microbleeds (CMBs) on MRI (i.e., the presumed causal underlying small vessel disease and its severity). Methods: This was a meta-analysis of prospective cohorts following ICH, with blood-sensitive brain MRI soon after ICH. We estimated annualized recurrent symptomatic ICH rates for each study and compared pooled odds ratios (ORs) of recurrent ICH by CMB presence/absence and presumed etiology based on CMB distribution (strictly lobar CMBs related to probable or possible cerebral amyloid angiopathy [CAA] vs non-CAA) and burden (1, 2–4, 5–10, and >10 CMBs), using random effects models. Results: We pooled data from 10 studies including 1,306 patients: 325 with CAA-related and 981 CAA-unrelated ICH. The annual recurrent ICH risk was higher in CAA-related ICH vs CAA-unrelated ICH (7.4%, 95% confidence interval [CI] 3.2–12.6 vs 1.1%, 95% CI 0.5–1.7 per year, respectively; p = 0.01). In CAA-related ICH, multiple baseline CMBs (versus none) were associated with ICH recurrence during follow-up (range 1–3 years): OR 3.1 (95% CI 1.4–6.8; p = 0.006), 4.3 (95% CI 1.8–10.3; p = 0.001), and 3.4 (95% CI 1.4–8.3; p = 0.007) for 2–4, 5–10, and >10 CMBs, respectively. In CAA-unrelated ICH, only >10 CMBs (versus none) were associated with recurrent ICH (OR 5.6, 95% CI 2.1–15; p = 0.001). The presence of 1 CMB (versus none) was not associated with recurrent ICH in CAA-related or CAA-unrelated cohorts. Conclusions: CMB burden and distribution on MRI identify subgroups of ICH survivors with higher ICH recurrence risk, which may help to predict ICH prognosis with relevance for clinical practice and treatment trials.
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    Impaired memory is more closely associated with brain beta-amyloid than leukoaraiosis in hypertensive patients with cognitive symptoms
    (Public Library of Science, 2018) Smith, Eric E.; Muzikansky, Alona; McCreary, Cheryl R.; Batool, Saima; Viswanathan, Anand; Dickerson, Bradford; Johnson, Keith; Greenberg, Steven; Blacker, Deborah
    Background: Hypertension is the strongest modifiable risk factor for subcortical ischemic changes and is also a risk factor for Alzheimer’s dementia. We used neuroimaging to investigate the pathological basis of early cognitive symptoms in patients with hypertension. Methods: In this cross-sectional cohort study 67 patients age >60 years with hypertension and Clinical Dementia Rating scale score of 0.5 without dementia, and without history of symptomatic stroke, underwent MRI for measurement of subcortical vascular changes and positron emission tomography (PET) scan with Pittsburgh Compound B (PiB-PET) to detect beta-amyloid deposition. These imaging measures were related to neuropsychological tests of memory, executive function and processing speed. Results: Mean age was 75.0 (standard deviation, SD, 7.3). Mean neuropsychological Z scores were: episodic memory -0.63 (SD 1.23), executive function -0.40 (SD 1.10), processing speed -0.24 (SD 0.88); 22 of the 67 subjects met criteria for mild cognitive impairment (MCI) and the remaining 45 subjects had subjective cognitive concerns only. In multivariable models adjusting for age and years of education, each 0.1 unit increase in mean cortical PiB-PET binding was associated with 0.14 lower mean Z score for episodic memory (95% CI -0.28 to -0.01). This means that for every 0.1 unit increase in mean cortical PiB-PET, episodic memory was 0.14 standard deviations lower. White matter hyperintensity volume, silent brain infarcts and microbleeds were not associated with neuropsychological test scores. Conclusions: Episodic memory was prominently affected in hypertensive participants with MCI or subjective cognitive concerns, and was associated with PiB-PET binding. This suggests a prominent role for Alzheimer pathology in cognitive impairment even in hypertensive participants at elevated risk for vascular cognitive impairment.
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    Multiple neuropathologies and dementia in the aging brain: A key role for cerebrovascular disease?
    (Elsevier, 2016) Charidimou, Andreas; Viswanathan, Anand
    This short perspective discusses the conclusions of a Research Roundtable meeting held in October in 2014 within the overall theme of understanding the role of additional/comorbid pathologies in the aging brain and their potential interaction with clinical Alzheimer's disease and other dementia phenotypes. We specifically examine the key role of for cerebrovascular small vessel disease in this context and highlight future directions.
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    The TeleStroke Mimic (TM)‐Score: A Prediction Rule for Identifying Stroke Mimics Evaluated in a Telestroke Network
    (Blackwell Publishing Ltd, 2014) Ali, Syed F.; Viswanathan, Anand; Singhal, Aneesh; Rost, Natalia S.; Forducey, Pamela G.; Davis, Lawrence W.; Schindler, Joseph; Likosky, William; Schlegel, Sherene; Solenski, Nina; Schwamm, Lee
    Background: Up to 30% of acute stroke evaluations are deemed stroke mimics (SM). As telestroke consultation expands across the world, increasing numbers of SM patients are likely being evaluated via Telestroke. We developed a model to prospectively identify ischemic SMs during Telestroke evaluation. Methods and Results: We analyzed 829 consecutive patients from January 2004 to April 2013 in our internal New England–based Partners TeleStroke Network for a derivation cohort, and 332 cases for internal validation. External validation was performed on 226 cases from January 2008 to August 2012 in the Partners National TeleStroke Network. A predictive score was developed using stepwise logistic regression, and its performance was assessed using receiver‐operating characteristic (ROC) curve analysis. There were 23% SM in the derivation, 24% in the internal, and 22% in external validation cohorts based on final clinical diagnosis. Compared to those with ischemic cerebrovascular disease (iCVD), SM had lower mean age, fewer vascular risk factors, more frequent prior seizure, and a different profile of presenting symptoms. The TeleStroke Mimic Score (TM‐Score) was based on factors independently associated with SM status including age, medical history (atrial fibrillation, hypertension, seizures), facial weakness, and National Institutes of Health Stroke Scale >14. The TM‐Score performed well on ROC curve analysis (derivation cohort AUC=0.75, internal validation AUC=0.71, external validation AUC=0.77). Conclusions: SMs differ substantially from their iCVD counterparts in their vascular risk profiles and other characteristics. Decision‐support tools based on predictive models, such as our TM Score, may help clinicians consider alternate diagnosis and potentially detect SMs during complex, time‐critical telestroke evaluations.
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    A call for comparative effectiveness research to learn whether routine clinical care decisions can protect from dementia and cognitive decline
    (BioMed Central, 2016) Dacks, Penny A.; Armstrong, Joshua J.; Brannan, Stephen K.; Carman, Aaron J.; Green, Allan M.; Kirkman, M. Sue; Krakoff, Lawrence R.; Kuller, Lewis H.; Launer, Lenore J.; Lovestone, Simon; Merikle, Elizabeth; Neumann, Peter J.; Rockwood, Kenneth; Shineman, Diana W.; Stefanacci, Richard G.; Velentgas, Priscilla; Viswanathan, Anand; Whitmer, Rachel A.; Williamson, Jeff D.; Fillit, Howard M.
    Common diseases like diabetes, hypertension, and atrial fibrillation are probable risk factors for dementia, suggesting that their treatments may influence the risk and rate of cognitive and functional decline. Moreover, specific therapies and medications may affect long-term brain health through mechanisms that are independent of their primary indication. While surgery, benzodiazepines, and anti-cholinergic drugs may accelerate decline or even raise the risk of dementia, other medications act directly on the brain to potentially slow the pathology that underlies Alzheimer’s and other dementia. In other words, the functional and cognitive decline in vulnerable patients may be influenced by the choice of treatments for other medical conditions. Despite the importance of these questions, very little research is available. The Alzheimer’s Drug Discovery Foundation convened an advisory panel to discuss the existing evidence and to recommend strategies to accelerate the development of comparative effectiveness research on how choices in the clinical care of common chronic diseases may protect from cognitive decline and dementia.
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    Reduced vascular amyloid burden at microhemorrhage sites in cerebral amyloid angiopathy
    (Springer Berlin Heidelberg, 2016) Van Veluw, Susanne; Kuijf, Hugo J.; Charidimou, Andreas; Viswanathan, Anand; Biessels, Geert Jan; Rozemuller, Annemieke J. M.; Frosch, Matthew; Greenberg, Steven
    Microhemorrhages are strongly associated with advanced cerebral amyloid angiopathy (CAA). Although it has been frequently proposed that the deposition of Aβ in the walls of cortical vessels directly causes microhemorrhages, this has not been studied in great detail, mainly because the ruptured vessels are often missed on routine histopathologic examination. Here, we examined histopathological data from studies targeting microhemorrhages with high-resolution ex vivo 7 T MRI in nine cases with moderate-to-severe CAA, and assessed the presence of Aβ in the walls of involved vessels. We also assessed the density of Aβ positive cortical vessels in areas surrounding microhemorrhages compared to control areas. In seven out of 19 microhemorrhages, the presumed involved vessel could be identified on the histopathological section. Only one of these vessels was positive for Aβ at the site of rupture. Moreover, the density of Aβ positive cortical vessels was lower (1.0 per mm2) within a range of 315 µm surrounding the microhemorrhage, compared to control areas (2.0 per mm2; p < 0.05). These findings question the widely held assumption that the deposition of Aβ in the walls of cortical vessels directly causes microhemorrhages. Electronic supplementary material The online version of this article (doi:10.1007/s00401-016-1635-0) contains supplementary material, which is available to authorized users.
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    Variability in the Perception of Informed Consent for IV-tPA during Telestroke Consultation
    (Frontiers Research Foundation, 2012) Thomas, Lisa E.; Viswanathan, Anand; Cochrane, Thomas I.; Johnson, John; O’Brien, Janice; McMahon, Marilyn; Santimauro, Janine Marie; Schwamm, Lee
    Objective: To study the perception of informed consent among various raters for thrombolysis in acute ischemic stroke patients receiving intravenous tissue plasminogen activator (IV-tPA). Methods: Twenty randomly selected videotaped telestroke consultations of acute stroke patients administered IV-tPA were retrospectively reviewed. Adequacy of informed consent was reviewed by five raters: a neurologist and emergency physician who routinely treat stroke, a medical risk management paralegal, a bioethicist, and a lay person. Raters assessed the quality of the informed consent presentation by the treating physician and the degree of understanding demonstrated by the patient/family authorizing consent. Factors associated with adequacy of consent were analyzed. Results: Consent was rated as adequately understood by the patient-family in 78.6% cases. Agreement between all five raters with regard to the patient-family understanding of consent was poor and also between the subgroups of non-physician and physician (all k < 0.20). Similarly, the quality of the physician consent process was poor for agreement between all five raters (k = 0.07) or between the subgroup of the three non-physician raters (k = −0.06) and fair between the two physician raters (k = 0.24). The legal reviewer and the bioethicist rated the physician consent process as being of lower quality than did the two physicians and the layperson. Conclusion: Despite high variability in the perception of informed consent among raters in this time-sensitive clinical situation, almost 80% of patients were rated by all reviewers as having adequate understanding of risks and benefits of tPA. This suggests the need for a standardized but brief tPA consent process that includes patient/family demonstration of understanding.