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CDR System
Please visit this website for more information about the instrument: CDR System
The Cognitive Drug Research (CDR) System is owned by Signant Health who license it for use in clinical trials.
Supplemental: Parkinson's Disease (PD)
Short Description of Instrument
Purpose: The Cognitive Drug Research computerized cognitive assessment system (CDR System) is an integrated set of cognitive tasks, developed in the 1980s to provide a practical, sensitive, reliable and repeatable method of assessing core aspects of cognitive function in healthy volunteers and any patient population. Responses are made via a simple YES/NO button box, and early work established that patients with Parkinson's disease could reliably use the apparatus (Simpson et al., 1991). ECogPro is a new system that utilizes the same validated and widely used tests as the earlier Cognitive Drug Research system, but with enhanced programming to further improve the sensitivity of the milli sec reaction time capture. It has proven utility, reliability, sensitivity, and validity, as well as reliable sensitivity to change over time (Brooker et al., 2020).
Overview: The 9 core tests assess attention, information processing, executive control, working memory (articulatory & spatial) and episodic memory (verbal & visual). It does not require specialist administration and can be completed within 20 minutes, with the data being stored and processed automatically. There are over 60 parallel forms of all tasks, and it is available in over 50 languages. The System is modular, allowing subsets of tests to be employed. It has been widely used in a variety of trials in PD (see references). The System includes a pattern separation task, sensitive to neurogenesis in the dentate gyrus, which has provided the first behavioral data of neurogenesis deficits in PD (Wesnes & Burn, 2013).
Comments/Special Instructions
There is also a CDR System version for use with patients with Parkinson's disease dementia (PDD), which contains the same tasks but fewer stimuli. This version has been successfully used in clinical trials with rivastigmine, donepezil and memantine to demonstrate treatment related improvements in cognitive function, particularly to attention. Further, in a population of 451 PDD patients when compared to other tests (ADAS-cog, MMSE and Delis Kaplan Verbal Fluency), the CDR attention tests were the single strongest cognitive predictor of ADL status, matching the strength of motor disability (Bronnick et al., 2005). CDR was used in combination with standard tests to diagnose mild cognitive impairment (MCI) in the ICICLE study (Yarnall et al., 2014).
Scoring and Psychometric Properties
Scoring: The accuracy (% correct) and speed (ms) of each response in every task is automatically captured. These are transferred electronically to Bracket, where the various scores for each task are calculated using in-house software. These summary scores are provided in pre-agreed formats, together with a range of core domain scores derived from the various test scores. These domain scores have been validated by factor analysis, and cover major aspects of attention, information processing, working and episodic memory. Age and gender matched normative data are available from the extensive Bracket databases, including a large population of healthy volunteers as well as a wide range of clinical conditions including PD and all of the major dementias.
Psychometric Properties:  Normative data reportedly exist but hold by the company and not publicly available. No psychometric data exist for PD.
The CDR System is the embodiment of the advantages of automated testing over pencil and paper procedures. Test administration is standardized, and the automatic capture and scoring of data overcomes the majority of the problems experienced in clinical trials with non-automated tests. The precise measurement of the speed of information processing in attentional tasks confers a strong advantage to the CDR System. The system can identify a characteristic profile of attentional impairment in PD, even in recently diagnosed untreated patients (Moon et al., 2003). In a population of 484 PD patients, using the 2012 MDS task force Diagnostic Criteria for PD-MCI Level II, data from the system identified attentional PD-MCI in 59%, amnestic in 15% and visuospatial in 51% of patients (Wesnes & Burn, 2013). This contrasted sharply to an analysis using the same criteria of 1,346 patients from 8 cohorts which identified attentional PD-MCI in 10%, amnesic in 13% and visuospatial in 11% of patients (Aarsland et al., 2010). Further, the CDR System attention tests predict cognitive decline over 3 years in PD (Taylor et al., 2008), as well as the frequency of falls (Allcock et al., 2009). Finally, deep brain stimulation has been found to improve speed on CDR System tests of attention in PD (Thevathasan et al., 2010).
Strengths: Computerized, homebased system, easy to use, includes reaction time, has been used in PD and PDD trials.
Weaknesses: No cut-off or reference values publicly available, not widely used outside UK. There are very few recent studies using the system in PD.
Key References:
CDR System publications containing data from PD patients:
Allcock LM, Rowan EN, Steen IN, Wesnes K, Kenny RA, Burn DJ. Impaired attention predicts falling in Parkinson's disease. Parkinsonism Relat Disord. 2009 Feb;15(2):110-5.
Ballard CG, Aarsland D, McKeith I, O'Brien J, Gray A, Cormack F, Burn D, Cassidy T, Starfeldt R, Larsen JP, Brown R, Tovee M. Fluctuations in attention: PD dementia vs DLB with parkinsonism. Neurology. 2002 Dec 10;59(11):1714-20.
Brooker H, Williams G, Hampshire A, Corbett A, Aarsland D, Cummings J, Molinuevo JL, Atri A, Ismail Z, Creese B, Fladby T, Thim-Hansen C, Wesnes K, Ballard C. FLAME: A computerized neuropsychological composite for trials in early dementia. Alzheimers Dement (Amst). 2020 Oct 14;12(1):e12098.
Molloy SA, Rowan EN, O'Brien JT, McKeith IG, Wesnes K, Burn DJ. Effect of levodopa on cognitive function in Parkinson's disease with and without dementia and dementia with Lewy bodies. J Neurol Neurosurg Psychiatry. 2006 Dec;77(12):1323-8.
Moon G, Wesnes KA, Manktelow TC. Cognitive deficits in recently diagnosed untreated patients with Parkinson's disease. J Psychopharmacol. 2002;16(suppl):A31.
Simpson, P.M., Surmon, D.J., Wesnes, K.A. and Wilcock, G.K. (1991), The cognitive drug research computerized assessment system for demented patients: A validation study. Int. J. Geriat. Psychiatry, 6: 95-102.
Taylor JP, Rowan EN, Lett D, O'Brien JT, McKeith IG, Burn DJ. Poor attentional function predicts cognitive decline in patients with non-demented Parkinson's disease independent of motor phenotype. J Neurol Neurosurg Psychiatry. 2008 Dec;79(12):1318-23.
Thevathasan W, Silburn PA, Brooker H, Coyne TJ, Khan S, Gill SS, Aziz TZ, Brown P. The impact of low-frequency stimulation of the pedunculopontine nucleus region on reaction time in parkinsonism. J Neurol Neurosurg Psychiatry. 2010 Oct;81(10):1099-104.
Wesnes KA, Burn DJ. Compromised object pattern separation performance in Parkinson's disease suggests dentate gyrus neurogenesis may be compromised in the condition. J Alzheim Dis Parkinsonism 2013;3:131.
Wesnes KA, Burn DJ. The frequency of Mild Cognitive Impairment in Parkinson's disease as assessed with automated cognitive tests. Paper selected for Blue Ribbon Highlights Session at: 17th International Congress of Parkinson's Disease and Movement Disorders, Sydney, Australia, June 2013.
Yarnall AJ, Breen DP, Duncan GW, Khoo TK, Coleman SY, Firbank MJ, Nombela C, Winder-Rhodes S, Evans JR, Rowe JB, Mollenhauer B, Kruse N, Hudson G, Chinnery PF, O'Brien JT, Robbins TW, Wesnes K, Brooks DJ, Barker RA, Burn DJ; ICICLE-PD Study Group. Characterizing mild cognitive impairment in incident Parkinson disease: the ICICLE-PD study. Neurology. 2014 Jan 28;82(4):308-16.
Additional Papers with CDR System data in PDD patients:
Bronnick K, Ehrt U, Emre M, De Deyn PP, Wesnes K, Tekin S, Aarsland D. Attentional deficits affect activities of daily living in dementia-associated with Parkinson's disease. J Neurol Neurosurg Psychiatry. 2006 Oct;77(10):1136-42.
Emre M, Aarsland D, Albanese A, Byrne EJ, Deuschl G, De Deyn PP, Durif F, Kulisevsky J, van Laar T, Lees A, Poewe W, Robillard A, Rosa MM, Wolters E, Quarg P, Tekin S, Lane R. Rivastigmine for dementia associated with Parkinson's disease. N Engl J Med. 2004 Dec 9;351(24):2509-18.
Papers commenting upon or using CDR System Data in PD or PD Dementia:
Aarsland D, Bronnick K, Williams-Gray C, Weintraub D, Marder K, Kulisevsky J, Burn D, Barone P, Pagonabarraga J, Allcock L, Santangelo G, Foltynie T, Janvin C, Larsen JP, Barker RA, Emre M. Mild cognitive impairment in Parkinson disease: a multicenter pooled analysis. Neurology. 2010 Sep 21;75(12):1062-9.
Document last updated August 2022