Works by van der Flier, Wiesje M.

Results: 714

Atrophy subtypes in prodromal Alzheimer's disease are associated with cognitive decline.

Published in:

2018

By:

Kate, Mara ten;
Dicks, Ellen;
Visser, Pieter Jelle;
Flier, Wiesje M van der;
Teunissen, Charlotte E;
Barkhof, Frederik;
Scheltens, Philip;
Tijms, Betty M;
Initiative, Alzheimer's Disease Neuroimaging;
Ten Kate, Mara;
van der Flier, Wiesje M;
Alzheimer’s Disease Neuroimaging Initiative

Publication type:

journal article

A clinical-radiological framework of the right temporal variant of frontotemporal dementia.

Published in:

2020

By:

Erkoyun, Hulya Ulugut;
Groot, Colin;
Heilbron, Ronja;
Nelissen, Anne;
Rossum, Jonathan van;
Jutten, Roos;
Koene, Ted;
Flier, Wiesje M van der;
Wattjes, Mike P;
Scheltens, Philip;
Ossenkoppele, Rik;
Barkhof, Frederik;
Pijnenburg, Yolande;
Ulugut Erkoyun, Hulya;
van Rossum, Jonathan;
van der Flier, Wiesje M

Publication type:

journal article

Deciding on genetic testing for familial dementia: Perspectives of patients and families.

Published in:

Alzheimer's & Dementia: The Journal of the Alzheimer's Association, 2025, v. 21, n. 4, p. 1, doi. 10.1002/alz.70140

By:

van der Schaar, Jetske;
van der Lee, Sven J.;
Asscher, Eva C. A.;
Pijnenburg, Yolande A. L.;
de Geus, Christa M.;
Bredenoord, Annelien L.;
van der Flier, Wiesje M.;
van den Hoven, Mariette A.;
Smets, Ellen M. A.;
Visser, Leonie N. C.

Publication type:

Article

Characterizing visual read tau‐PET‐negative participants with Alzheimer's disease dementia.

Published in:

Alzheimer's & Dementia: The Journal of the Alzheimer's Association, 2025, v. 21, n. 4, p. 1, doi. 10.1002/alz.14423

By:

Rikken, Roos M.;
Coomans, Emma M.;
de Koning, Lotte A.;
Visser, Denise;
Neutelings, Eline;
den Braber, Anouk;
Collij, Lyduine E.;
Golla, Sandeep S. V.;
Barkhof, Frederik;
Visser, Pieter Jelle;
Scheltens, Philip;
van der Flier, Wiesje M.;
Boellaard, Ronald;
Ossenkoppele, Rik;
Vijverberg, Everard G. B.;
van de Giessen, Elsmarieke

Publication type:

Article

Enlarged cavum septum pellucidum as a neuroimaging signature of head impact exposure.

Published in:

Brain Communications, 2025, v. 7, n. 2, p. 1, doi. 10.1093/braincomms/fcaf085

By:

Kamps, Suzie;
Hempel, Hugo L;
Amerongen, Suzan van;
Bruin, Hannah de;
Linden, Fleur H C van der;
Venkatraghavan, Vikram;
Flier, Wiesje M van der;
Pijnenburg, Yolande A L;
Barkhof, Frederik;
Scheltens, Philip;
Ossenkoppele, Rik;
Vijverberg, Everard G B

Publication type:

Article

Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease.

Published in:

2009

By:

Sluimer JD;
van der Flier WM;
Karas GB;
van Schijndel R;
Barnes J;
Boyes RG;
Cover KS;
Olabarriaga SD;
Fox NC;
Scheltens P;
Vrenken H;
Barkhof F;
Sluimer, Jasper D;
van der Flier, Wiesje M;
Karas, Giorgos B;
van Schijndel, Ronald;
Barnes, Josephine;
Boyes, Richard G;
Cover, Keith S;
Olabarriaga, Sílvia D

Publication type:

journal article

Grey matter network markers identify individuals with prodromal Alzheimer's disease who will show rapid clinical decline.

Published in:

Brain Communications, 2022, v. 4, n. 2, p. 1, doi. 10.1093/braincomms/fcac026

By:

Pelkmans, Wiesje;
Vromen, Ellen M.;
Dicks, Ellen;
Scheltens, Philip;
Teunissen, Charlotte E.;
Barkhof, Frederik;
van der Flier, Wiesje M.;
Tijms, Betty M.

Publication type:

Article

Time Trend in Persistent Cognitive Decline: Results From the Longitudinal Aging Study Amsterdam.

Published in:

Journals of Gerontology Series B: Psychological Sciences & Social Sciences, 2018, v. 73, p. S57, doi. 10.1093/geronb/gbx151

By:

van den Kommer, Tessa N.;
Deeg, Dorly J. H.;
van der Flier, Wiesje M.;
Comijs, Hannie C.

Publication type:

Article

APOE Genotype in the Era of Disease-Modifying Treatment With Monoclonal Antibodies Against Amyloid-β.

Published in:

2023

By:

Ossenkoppele, Rik;
van der Flier, Wiesje M.

Publication type:

Opinion

Framework for Clinical Trials in Cerebral Small Vessel Disease (FINESSE): A Review.

Published in:

JAMA Neurology, 2022, v. 79, n. 11, p. 1187, doi. 10.1001/jamaneurol.2022.2262

By:

Markus, Hugh S.;
van Der Flier, Wiesje M.;
Smith, Eric E.;
Bath, Philip;
Biessels, Geert Jan;
Briceno, Emily;
Brodtman, Amy;
Chabriat, Hugues;
Chen, Christopher;
de Leeuw, Frank-Erik;
Egle, Marco;
Ganesh, Aravind;
Georgakis, Marios K.;
Gottesman, Rebecca F.;
Kwon, Sun;
Launer, Lenore;
Mok, Vincent;
O'Brien, John;
Ottenhoff, Lois;
Pendlebury, Sarah

Publication type:

Article

The ATN Framework—Moving Preclinical Alzheimer Disease to Clinical Relevance.

Published in:

2022

By:

van der Flier, Wiesje M.;
Scheltens, Philip

Publication type:

Opinion

Global Prevalence of Young-Onset Dementia: A Systematic Review and Meta-analysis.

Published in:

JAMA Neurology, 2021, v. 78, n. 9, p. 1080, doi. 10.1001/jamaneurol.2021.2161

By:

Hendriks, Stevie;
Peetoom, Kirsten;
Bakker, Christian;
van der Flier, Wiesje M.;
Papma, Janne M.;
Koopmans, Raymond;
Verhey, Frans R. J.;
de Vugt, Marjolein;
Köhler, Sebastian;
Withall, Adrienne;
Parlevliet, Juliette L.;
Uysal-Bozkir, Özgül;
Gibson, Roger C.;
Neita, Susanne M.;
Nielsen, Thomas Rune;
Salem, Lise C.;
Nyberg, Jenny;
Lopes, Marcos Antonio;
Dominguez, Jacqueline C.;
De Guzman, Ma Fe

Publication type:

Article

Association of Amyloid Positron Emission Tomography With Changes in Diagnosis and Patient Treatment in an Unselected Memory Clinic Cohort: The ABIDE Project.

Published in:

JAMA Neurology, 2018, v. 75, n. 9, p. 1062, doi. 10.1001/jamaneurol.2018.1346

By:

de Wilde, Arno;
van der Flier, Wiesje M.;
Pelkmans, Wiesje;
Bouwman, Femke;
Verwer, Jurre;
Groot, Colin;
van Buchem, Marieke M.;
Zwan, Marissa;
Ossenkoppele, Rik;
Yaqub, Maqsood;
Kunneman, Marleen;
Smets, Ellen M. A.;
Barkhof, Frederik;
Lammertsma, Adriaan A.;
Stephens, Andrew;
van Lier, Erik;
Biessels, Geert Jan;
van Berckel, Bart N.;
Scheltens, Philip

Publication type:

Article

Interpreting Biomarker Results in Individual Patients With Mild Cognitive Impairment in the Alzheimer's Biomarkers in Daily Practice (ABIDE) Project.

Published in:

JAMA Neurology, 2017, v. 74, n. 12, p. 1481, doi. 10.1001/jamaneurol.2017.2712

By:

van Maurik, Ingrid S.;
Zwan, Marissa D.;
Tijms, Betty M.;
Bouwman, Femke H.;
Teunissen, Charlotte E.;
Scheltens, Philip;
Wattjes, Mike P.;
Barkhof, Frederik;
Berkhof, Johannes;
van der Flier, Wiesje M.

Publication type:

Article

Neurogranin as a Cerebrospinal Fluid Biomarker for Synaptic Loss in Symptomatic Alzheimer Disease.

Published in:

JAMA Neurology, 2015, v. 72, n. 11, p. 1275, doi. 10.1001/jamaneurol.2015.1867

By:

Kester, Maartje I.;
Teunissen, Charlotte E.;
Crimmins, Daniel L.;
Herries, Elizabeth M.;
Ladenson, Jack. H.;
Scheltens, Philip;
van der Flier, Wiesje M.;
Morris, John C.;
Holtzman, David M.;
Fagan, Anne M.

Publication type:

Article

Microbleeds, Mortality, and Stroke in Alzheimer Disease.

Published in:

JAMA Neurology, 2015, v. 72, n. 5, p. 539, doi. 10.1001/jamaneurol.2015.14

By:

Benedictus, Marije R.;
Prins, Niels D.;
Goos, Jeroen D. C.;
Scheltens, Philip;
Barkhof, Frederik;
van der Flier, Wiesje M.

Publication type:

Article

Associations Between Cerebral Small-Vessel Disease and Alzheimer Disease Pathology as Measured by Cerebrospinal Fluid Biomarkers.

Published in:

JAMA Neurology, 2014, v. 71, n. 7, p. 855, doi. 10.1001/jamaneurol.2014.754

By:

Kester, Maartje I.;
Goos, Jeroen D. C.;
Teunissen, Charlotte E.;
Benedictus, Marije R.;
Bouwman, Femke H.;
Wattjes, Mike P.;
Barkhof, Frederik;
Scheltens, Philip;
van der Flier, Wiesje M.

Publication type:

Article

Head-to-head comparison of relative cerebral blood flow derived from dynamic [18F]florbetapir and [18F]flortaucipir PET in subjects with subjective cognitive decline.

Published in:

EJNMMI Research, 2023, v. 13, n. 1, p. 1, doi. 10.1186/s13550-023-01041-x

By:

Tuncel, Hayel;
Visser, Denise;
Timmers, Tessa;
Wolters, Emma E.;
Ossenkoppele, Rik;
van der Flier, Wiesje M.;
van Berckel, Bart N. M.;
Boellaard, Ronald;
Golla, Sandeep S. V.

Publication type:

Article

CSF proteome profiling reveals biomarkers to discriminate dementia with Lewy bodies from Alzheimer´s disease.

Published in:

Nature Communications, 2023, v. 14, n. 1, p. 1, doi. 10.1038/s41467-023-41122-y

By:

del Campo, Marta;
Vermunt, Lisa;
Peeters, Carel F. W.;
Sieben, Anne;
Hok-A-Hin, Yanaika S.;
Lleó, Alberto;
Alcolea, Daniel;
van Nee, Mirrelijn;
Engelborghs, Sebastiaan;
van Alphen, Juliette L.;
Arezoumandan, Sanaz;
Chen-Plotkin, Alice;
Irwin, David J.;
van der Flier, Wiesje M.;
Lemstra, Afina W.;
Teunissen, Charlotte E.

Publication type:

Article

MRI Visual Ratings of Brain Atrophy and White Matter Hyperintensities across the Spectrum of Cognitive Decline Are Differently Affected by Age and Diagnosis.

Published in:

Frontiers in Aging Neuroscience, 2017, p. 1, doi. 10.3389/fnagi.2017.00117

By:

Rhodius-Meester, Hanneke F. M.;
Benedictus, Marije R.;
Wattjes, Mike P.;
Barkhof, Frederik;
Scheltens, Philip;
Muller, Majon;
van der Flier, Wiesje M.

Publication type:

Article

Integrative EEG biomarkers predict progression to Alzheimer's disease at the MCI stage.

Published in:

Frontiers in Aging Neuroscience, 2013, v. 5, p. 1, doi. 10.3389/fnagi.2013.00058

By:

Poil, Simon-Shlomo;
de Haan, Willem;
van der Flier, Wiesje M.;
Mansvelder, Huibert D.;
Scheltens, Philip;
Linkenkaer-Hansen, Klaus

Publication type:

Article

Computerized decision support is an effective approach to select memory clinic patients for amyloid-PET.

Published in:

PLoS ONE, 2024, v. 19, n. 5, p. 1, doi. 10.1371/journal.pone.0303111

By:

Rhodius-Meester, Hanneke F. M.;
van Maurik, Ingrid S.;
Collij, Lyduine E.;
van Gils, Aniek M.;
Koikkalainen, Juha;
Tolonen, Antti;
Pijnenburg, Yolande A. L.;
Berkhof, Johannes;
Barkhof, Frederik;
van de Giessen, Elsmarieke;
Lötjönen, Jyrki;
van der Flier, Wiesje M.

Publication type:

Article

What does heritability of Alzheimer's disease represent?

Published in:

PLoS ONE, 2023, v. 18, n. 4, p. 1, doi. 10.1371/journal.pone.0281440

By:

Baker, Emily;
Leonenko, Ganna;
Schmidt, Karl Michael;
Hill, Matthew;
Myers, Amanda J.;
Shoai, Maryam;
de Rojas, Itziar;
Tesi, Niccoló;
Holstege, Henne;
van der Flier, Wiesje M.;
Pijnenburg, Yolande A. L.;
Ruiz, Agustin;
Hardy, John;
van der Lee, Sven;
Escott-Price, Valentina

Publication type:

Article

Reply to "Usefulness of Plasma Amyloid as Prescreener of the Earliest Alzheimer Pathological Changes Depends on the Study Population".

Published in:

Annals of Neurology, 2020, v. 87, n. 1, p. 155, doi. 10.1002/ana.25633

By:

Verberk, Inge M. W.;
Teunissen, Charlotte E.;
Van der Flier, Wiesje. M.

Publication type:

Article

Reply to "Usefulness of Plasma Amyloid as Prescreener of the Earliest Alzheimer Pathological Changes Depends on the Study Population".

Published in:

2019

By:

Verberk, Inge M W;
Teunissen, Charlotte E;
Van der Flier, Wiesje M

Publication type:

Letter

Plasma Amyloid as Prescreener for the Earliest Alzheimer Pathological Changes.

Published in:

2018

By:

Verberk, Inge M. W.;
Slot, Rosalinde E.;
Verfaillie, Sander C. J.;
Heijst, Hans;
Prins, Niels D.;
van Berckel, Bart N. M.;
Scheltens, Philip;
Teunissen, Charlotte E.;
van der Flier, Wiesje M.

Publication type:

journal article

Prevalence of amyloid-β pathology in distinct variants of primary progressive aphasia.

Published in:

2018

By:

Bergeron, David;
Gorno‐Tempini, Maria L.;
Rabinovici, Gil D.;
Santos‐Santos, Miguel A.;
Seeley, William;
Miller, Bruce L.;
Pijnenburg, Yolande;
Keulen, M. Antoinette;
Groot, Colin;
van Berckel, Bart N. M.;
van der Flier, Wiesje M.;
Scheltens, Philip;
Rohrer, Jonathan D.;
Warren, Jason D.;
Schott, Jonathan M.;
Fox, Nick C.;
Sanchez‐Valle, Raquel;
Grau‐Rivera, Oriol;
Gelpi, Ellen;
Seelaar, Harro

Publication type:

journal article

Low normal cerebrospinal fluid Aβ42 levels predict clinical progression in nondemented subjects.

Published in:

2017

By:

Tijms, Betty M.;
Bertens, Daniela;
Slot, Rosalinde E.;
Gouw, Alida A.;
Teunissen, Charlotte E.;
Scheltens, Philip;
van der Flier, Wiesje M.;
Visser, Pieter Jelle

Publication type:

journal article

EEG abnormalities in early- and late-onset Alzheimer's disease: Evidence for the existence of subtypes

Published in:

2010

By:

de Waal, Hanneke;
Stam, Cornelis J.;
Blankenstein, Marinus A.;
Pijnenburg, Yolande A.L.;
Scheltens, Philip;
van der Flier, Wiesje M.

Publication type:

Abstract

Predictors of time to AD diagnosis in subjects with MCI

Published in:

2010

By:

van Rossum, Ineke A.;
Visser, Pieter Jelle;
van der Flier, Wiesje M.;
Blankenstein, Marinus A.;
Scheltens, Philip

Publication type:

Abstract

First ever longitudinal [11C]PIB and [18F]FDDNP PET studies in patients with Alzheimer's disease or mild cognitive impairment and healthy controls

Published in:

2010

By:

Ossenkoppele, Rik;
Tolboom, Nelleke;
Foster-Dingley, Jessica;
Boellaard, Ronald;
Yaqub, Maqsood;
Windhorst, Albert D.;
van der Flier, Wiesje M.;
Barkhof, Frederik;
Lammertsma, Adriaan A.;
Scheltens, Philip;
van Berckel, Bart N.M.

Publication type:

Abstract

CSF biomarkers predict cognitive decline in Alzheimer's disease

Published in:

2009

By:

Kester, Maartje I.;
Van Der Vlies, Annelies E.;
Blankenstein, Marinus A.;
Pijnenburg, Yolande A.L.;
Van Elk, Evert J.;
Scheltens, Philip;
Van Der Flier, Wiesje M.

Publication type:

Abstract

Relationship of cerebrospinal fluid biomarkers with in vivo [11C]PIB and [18F]FDDNP binding

Published in:

2009

By:

van Berckel, Bart N.M.;
Tolboom, Nelleke;
van der Flier, Wiesje M.;
Yaqub, Maqsood;
Boellaard, Ronald;
Verwey, Nicolaas A.;
Blankenstein, Marinus A.;
Luurtsema, Gert;
Windhorst, Albert D.;
Lammertsma, Adriaan A.;
Scheltens, Philip

Publication type:

Abstract

Most rapid cognitive decline in APOE4 negative Alzheimer's disease with early onset

Published in:

2009

By:

van der Flier, Wiesje M.;
van der Vlies, Annelies E.;
Koedam, Esther L.;
Pijnenburg, Yolande A.L.;
Twisk, Jos W.R.;
Scheltens, Philip

Publication type:

Abstract

P3-100: Variability in longitudinal CSF Tau and phosporylated Tau measurements

Published in:

2008

By:

Verwey, Nicolaas A.;
Bouwman, Femke H.;
Veerhuis, Robert;
Scheltens, Philip;
Van der Flier, Wiesje M.;
Blankenstein, Marinus A.

Publication type:

Abstract

P3-098: Whole-brain atrophy rate and CSF biomarker levels in mild cognitive impairment and Alzheimer's disease: A longitudinal study

Published in:

2008

By:

Van der Flier, Wiesje M.;
Sluimer, Jasper;
Bouwman, Femke H.;
Vrenken, Hugo;
Blankenstein, Marinus A.;
Barkhof, Frederik;
Scheltens, Philip

Publication type:

Abstract

P3-079: CSF biomarker levels, APOE genotype and the effect of aging

Published in:

2008

By:

Kester, Maartje I.;
Bouwman, Femke H.;
van Elk, Evert J.;
Blankenstein, Marinus A.;
Scheltens, Philip;
van der Flier, Wiesje M.

Publication type:

Abstract

P3-023: Comparison of mortality risk between early- and late-onset dementia

Published in:

2008

By:

Koedam, Esther L.G.E.;
Pijnenburg, Yolande A.L.;
Baak, Merel M.E.;
van der Vlies, Annelies E.;
Scheltens, Philip;
van der Flier, Wiesje M.

Publication type:

Abstract

P1-371: New research criteria for the diagnosis of Alzheimer's disease applied in a memory clinic population

Published in:

2008

By:

Bouwman, Femke H.;
Verwey, Nicolaas A.;
Klein, Martin;
Pijnenburg, Yolande A.L.;
Kok, Astrid;
Blankenstein, Marinus A.;
Sluimer, Jasper D.;
Barkhof, Frederik;
Van der Flier, Wiesje M.;
Scheltens, Philip

Publication type:

Abstract

P1-307: Assessment of global cortical atrophy and medial temporal lobe atrophy in suspected and definite dementia: Comparison of magnetic resonance imaging and 64 multidetector row computed tomography

Published in:

2008

By:

Wattjes, Mike P.;
Vrenken, Hugo;
van der Flier, Wiesje M.;
Geurts, Jeroen J.J.G.;
Gillissen, Freek;
Romkes, Rolinka;
Scheltens, Philip;
Barkhof, Frederik

Publication type:

Abstract

P1-302: Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

Published in:

2008

By:

van der Flier, Wiesje M.;
Sluimer, Jasper;
Karas, Giorgos B.;
van Schijndel, Ronald;
Barnes, Josephine;
Boyes, Richard;
Cover, Keith;
Olabarriaga, Silvia;
Fox, Nick C.;
Scheltens, Philip;
Vrenken, Hugo;
Barkhof, Frederik

Publication type:

Abstract

P1-300: Imaging Alzheimer pathology in vivo: Quantitative comparison of [11C]PIB and [18F]FDDNP

Published in:

2008

By:

Tolboom, Nelleke;
Yaqub, Maqsood;
Van der Flier, Wiesje M.;
Boellaard, Ronald;
Luurtsema, Gert;
Windhorst, Albert D.;
Barkhof, Frederik;
Scheltens, Philip;
Lammertsma, Adriaan A.;
Van Berckel, Bart N.M.

Publication type:

Abstract

P1-248: Diagnostic utility of cross-sectional and longitudinal hippocampal volumetry in memory clinic patients

Published in:

2008

By:

Henneman, Wouter J.P.;
Vrenken, Hugo;
Barnes, Josephine;
Sluimer, Jasper D.;
Van der Flier, Wiesje M.;
Fox, Nick C.;
Scheltens, Philip;
Barkhof, Frederik

Publication type:

Abstract

P1-246: White matter hyperintensities in Alzheimer patients and non-demented elderly: Postmortem quantitative MRI and neuropathological characteristics

Published in:

2008

By:

Gouw, Alida A.;
Seewann, Alexandra;
Vrenken, Hugo;
van der Flier, Wiesje M.;
Rozemuller, Annemieke M.;
Barkhof, Frederik;
Scheltens, Philip;
Geurts, Jeroen J.G.

Publication type:

Abstract

P1-235: An automated method for measuring longitudinal volume changes of the ventricular system

Published in:

2008

By:

Vries, Rehana de;
Vos, Eline K.;
van der Flier, Wiesje M.;
Sluimer, Ingrid C.;
Knol, Dirk L.;
Scheltens, Philip;
Barkhof, Frederik;
Vrenken, Hugo

Publication type:

Abstract

O1-05-01: Biomarker profiles and their relationship to cognitive and other clinical variables in Alzheimer's disease

Published in:

2008

By:

van der Vlies, Annelies E.;
Verwey, Niek N.;
Bouwman, Femke H.;
Blankenstein, Marinus A.;
Klein, Martin;
Scheltens, Philip;
van der Flier, Wiesje M.

Publication type:

Abstract

O1-02-01: Progression of mild cognitive impairment to dementia: The contribution of atrophy and vascular disease

Published in:

2008

By:

Staekenborg, Salka S.;
Koedam, Esther L.G.E.;
Henneman, Wouter;
Stokman, Pauline;
Scheltens, Philip;
Barkhof, Frederik;
van der Flier, Wiesje M.

Publication type:

Abstract

IC-P3-229: Assessment of global cortical atrophy and medial temporal lobe atrophy in suspected and definite dementia: Comparison of magnetic resonance imaging and 64 multi-detector row computed tomography

Published in:

2008

By:

Wattjes, Mike P.;
Vrenken, Hugo;
van der Flier, Wiesje M.;
Geurts, Jeroen J.J.G.;
Gillissen, Freek;
Romkes, Rolinka;
Scheltens, Philip;
Barkhof, Frederik

Publication type:

Abstract

IC-P3-177: An automated method for measuring longitudinal volume changes of the ventricular system

Published in:

2008

By:

de Vries, Rehana;
Vos, Eline K.;
van der Flier, Wiesje M.;
Sluimer, Ingrid C.;
Knol, Dirk L.;
Scheltens, Philip;
Barkhof, Frederik;
Vrenken, Hugo

Publication type:

Abstract

IC-P2-145: Whole-brain atrophy rate and CSF biomarker levels in MCI and AD: A longitudinal study

Published in:

2008

By:

van der Flier, Wiesje M.;
Sluimer, Jasper;
Bouwman, Femke;
Vrenken, Hugo;
Blankenstein, Marinus A.;
Barkhof, Frederik;
Scheltens, Philip

Publication type:

Abstract