It is now over four years since I found myself under pressure from a local GP to expand my diagnosis of Alzheimer’s disease to include people who were not found to have symptoms of dementia:
I spent a considerable amount of time examining the evidence behind current guidance which I was following and explained this to Dr Houston but he persisted:
I then reminded Dr Houston that pharmacological options are licensed for the ‘treatment of mild to moderate dementia in Alzheimer’s disease.’ The SIGN and NICE guidelines are also for dementia. I had previously sent him the evidence that these drugs do not prevent the development of dementia in any patients. I also reiterated that the provision of support is not dependent on any diagnosis but determined by the needs of any individual patient.
Dr Houston was a local advocate for CANTABmobile and wrote to me describing it as:
"a very sensitive test for Alzheimer's disease."
Following this I felt it important for patient safety to establish the evidence behind this test.
Posted below are the written communications I made and received about CANTABmobile
Sent: 20 October 2012 21:25
I am writing to ask if you know anything about CANTABmobile which one of our local GP practices is piloting.
The company can be found here: http://www.cantabmobile.com/
The company, Cambridge Cognition have been promoting locally and I think also UK wide?
The CANTABmobile film states: ‘early detection makes the journey easier’ and the promotional videos say it is ‘highly sensitive and specific’. I have been unable to find further data about this screening test though I do know CANTAB has a long history in pharmaceutical studies. It might be a perfectly reasonable and robust test but I would like to know far more about it. My concerns are heightened as conceptually early memory loss is difficult.
Just wondered if you knew anymore about CANTABmobile?
NHS Psychiatrist for Older Adults
From: David Hart [David.Hart@camcog.com]
Sent: 25 October 2012 17:36
Thank you for your email.
Please find attached (above) the science rationale document for the CANTABmobile system.
Additional details are also online at www.cantabmobile.com including an FAQ section at http://www.cantabmobile.com/support.asp concerning the key features, applications and background science relating to MCI and Alzheimer’s disease.
I hope this is helpful. Please call me on 01223 810 722 if you have any additional queries or would like to discuss any aspects of our work in more detail over the telephone.
With best wishes
Senior Business Development Manager
Cambridge Cognition Ltd.
Daily Mail, front page, 5 November 2012:
To: David Hart,
Senior Business Development Manager,
Cambridge Cognition Ltd, Tunbridge Court,
Tunbridge Lane, Bottisham, Cambridge, CB25 9TU
Tuesday 27th November 2012
I am really grateful to you for sending on the paper (NMI-008) ‘The use of CANTAB PAL in Alzheimer’s disease’ by Dr Andrew Blackwell, Chief Scientific Officer for Cambridge Cognition. I have now had a chance to read this and to read all the FAQ on your promotional website. I also watched your promotional films which I thought were well put together.
CANTABmobile is an exciting technology with an established base, over many years in research, rather than in clinically based medicine. I can see a role for it. However I have some further questions and some specific concerns. If you do not mind, I shall set these out below?
Your homepage displays the headline “A new touch screen for dementia.” This is, at best, misleading. CANTAB is one single domain (PAL) of neuropsychological tests and is sensitive for MCI not dementia. In fact you state this in your FAQ: “PAL is not a diagnostic test, and a diagnosis of dementia can only be made by a qualified physician.” So why do you not state this clearly on your homepage?
The sub-headline on your homepage carries this quote: “Is my memory normal, doctor?” This would suggest you are promoting your test as a screening test. In lines of the WHO you are offering what they term ‘Selective Screening’ defined by them as:
“We use this term for the screening of selected high-risk groups in the population. It may still be large scale, and can be considered as one form of population screening.”
As I understand it, there is no evidence-base to support cognitive screening and it is not supported by any professional guideline. I note that you avoid the term ‘screening’. Perhaps anticipating concern about screening, you do add the caveat: “available only to GPs / healthcare professionals.” The trouble I have, which does not reassure me, is that many GP’s and healthcare professionals have not heard of MCI.
The World Health Organisation, offer ten criteria for screening and it is quite clear to me that at least two of these criteria are not met for screening/early detection of dementia:
Firstly we have “The natural history of the condition, including development from latent to declared disease should be adequately understood.” Mild cognitive impairment and early dementia overlap and both the patho-physiology and natural histories are ill-understood and beyond simplification. As Allen Frances has stated, the risk of false-positive diagnoses of dementia becomes extremely high the earlier one tries to detect memory loss. There has been much recent debate about screening and in particular the harms and benefits associated with breast-screening. This debate has revealed that most people had not heard of DCIS (Ductal carcinoma in-situ) before the debate about the harms of breast-screening reached the wider press; I am sure that most people have not heard of mild cognitive impairment. The parallels are obvious.
Worldwide, large scale RCT’s, have reproduced the finding, that at very worst, no more than 50% of those with ‘amnesic MCI’ go on to develop dementia. Those in this large group of our elderly, generally have mild static loss that sometimes gets better. This is 50% of the patients testing positive on CANTABmobile. Your promotional material makes no mention of this anywhere.
In this context you paradoxically promote that CANTABmobile will help the ‘worried well.’ Your test though, given your headline messages, is likely to worry a large group of our elderly who have non-progressive mild memory loss. The consequences of a false-positive diagnosis of dementia can be life-changing and suicide is a potential risk.
I agree with Dr Margaret McCartney that “The screening of people for disease causes enormous problems which don’t often get acknowledged – not even to the people having the tests.” In your promotional material there is not one reference to potential for harm. Ethical considerations are at the heart of good medical practice and apply to all interventions however well intended they may be. Our elderly cannot be truly informed if Cambridge Cognition presents only benefits and certainties. It is a legitimate question to ask if there are potential harms with CANTABmobile?
I support the science you offer but insist that a lot of unknowns remain. To be fair to our elderly these need to be acknowledged. Given these unknowns, I would like your evidence base to include properly piloted studies of CANTABmobile as a screening tool in primary care. It is this evidence base that is vital along with epidemiological and ethical considerations. Meantime your test has been promoted in my local NHS area and one GP practice is already using it.
One possible consequence, counter to actual intention, is that such screening will increase the fear of ‘Alzheimer’s’. There is also the potential to re-define what we mean by Alzheimer’s disease by wide application of a screening test i.e. a cultural change in diagnosis. Not to be ignored is the inadvertent risk of heightening stigma in our elderly (where cognition becomes all defining) – what Stephen Post calls a ‘hypercognitive culture.’
David, having reviewed the literature you have provided and considered it carefully in the context of my interest in ethics, medical humanities and the neuroscience of Alzheimer’s disease I am concerned that technology like the CANTABmobile is being promoted before its full place in widespread clinical settings is properly understood.
Finally, I am concerned that ‘informed consent,’ based on your promotion, is impossible.
We all want to pick up progressive memory loss that leads to dementia and give as much support to this group as we possibly can. But early memory loss is a most complicated area. It needs a very careful approach. There are a great deal of unknowns, and just as many misunderstandings: my apprehension is that this is the sort of milieu that has the potential to make society disproportionately fearful of ageing.
Dr Peter J. Gordon
From: Gordon Peter
To: Grassroot doctors
Sent: 08 December 2012
I thought you might be interested in this.
The first screenshot is of the homepage, headline advert for CANTABmobile as on the web (date 24 Nov)
The second screenshot is from today (date 8 Dec)
Previously I sent you a copy of the letter I sent to Cambridge Cognition which I sent on the 27th November.
You will notice that CANTABmobile have changed their headline from “a new touch screen test for dementia“ to “a new touch screen test for memory impairment.”
Am I alone to be worried about this? This company has widely promoted a test for “piloting” across the UK but they seem not to know or are undecided what their test actually tests? Especially as primary care doctors are implementing a screening test that they are ‘educated’ about by the promotion of the company,
Yours sincerely, Peter
From: David Hart [David.Hart@camcog.com]
Sent: 10 December 2012
To: Gordon Peter
Dear Dr Gordon,
Many thanks for taking the time to give us your feedback about CANTABmobile.
You are quite right that screening for dementia is a thorny issue – we are very aware of the debate and as a result we do not promote nor recommend the use of CANTABmobile for general population screening. Our intention is that CANTABmobile is used to aid referral decisions by allowing doctors to make an objective assessment of memory in patients who are seeking help for memory complaints. I accept that our position with respect to screening was perhaps not clear enough on our website, and we have now added an FAQ to explicitly address this point.
We have also changed the wording on the website to clarify that CANTABmobile is a test of memory impairment, not dementia per se.
Thank you again for your interest in CANTABmobile.
The letter below was published in the BMJ the 15th October 2013:
I have been reflecting that it may have been the claims initially promoted by Cambridge Cognition which made Dr Houston so reluctant to accept the evidence that I presented him:
This surprises me as Dr Houston has been National Clinical Lead for Safety Improvement in Primary Care, Healthcare Improvement Scotland:
 Wilson J. M. G, & Junger, G Principles and Practice of Screening for Disease. World Health Organization 1968
 Frances, A. Psychology Today. Published 16 February, 2012
 Brian Draper, Carmelle Peisah, John Snowdon, Henry Brodat Early dementia diagnosis and the risk of suicide and euthanasia Alzheimer’s & Dementia 6 (2010) 75–82. New South Wales, Australia
 McCartney, M. The Patient Paradox 2012. Pinter & martin Ltd. p6