September 10, 2013

expert reaction to dementia screening

Writing in the British Medical Journal, a group of UK and Australian experts said a political drive to screen older people for minor memory changes is leading to unnecessary investigation and potentially harmful treatment, claiming up to 23% of non-demented older people could labelled with dementia. 

Prof John Starr, Director of the Alzheimer Scotland Dementia Research Centre, University of Edinburgh, said:

“At present less than half the people with dementia in the UK are diagnosed. For any other serious condition – cancer, stroke, diabetes – this would be unacceptable. Screening per se may not be an effective strategy to identify those with dementia with high specificity and high sensitivity due to the poor performance of standard screening tools, but that is not to say that measuring cognitive function in older adults should be discouraged. Indeed, having a baseline measure of cognition greatly facilitates future diagnosis. There is likely to be little harm arising from brief cognitive tests, but labeling people with ‘mild cognitive impairment’ may be less benign. Such labels may be helpful to patients and families seeking understanding of their symptoms if carefully explained, but most clinicians would acknowledge that a cut-off of 1.5 standard deviations below the mean is entirely arbitrary.

“Early diagnosis of dementia, on the other hand, is generally beneficial. Not only for symptomatic drug therapy, which with non-proprietary donepezil is only around £30 per year, but to enable people with dementia to plan their futures such as putting in place powers of attorney etc. The point of diagnosis and subsequent post-diagnostic support provides an opportunity to reflect on priorities and facilitates discussion with family and other close ones. Something which is much more difficult when diagnosis is delayed.”

Prof Klaus Ebmeier, Foundation Professor of Old Age Psychiatry, University of Oxford, said:

“In my experience, UK GPs tend to make sure that only patients are referred who are actually in clinical need of such support.  If memory clinics give a boost to dementia care (including physical care, picking up vascular risk factors and alternative causes of poor memory, including depression, getting advice on practical issues, such as benefits, community, residential care, moral support for carers) that can only be good.”

Prof David Nutt, Edmond J Safra Professor of Neuropsychopharmacology and director of the Neuropsychopharmacology Unit in the Division of Brain Sciences, Imperial College London, said:

“Screening for dementia may cause more harm than good as the tests aren’t yet robust enough. For example, MRI measures brain shrinkage, which occurs in dementias but is often not sufficient to make a categorical diagnosis. Other techniques like Positron Emission Tomography (PET) can measure biomarkers in the brain, such as amyloid, which is thought to be associated with Alzheimer’s. However, amyloid tracers are probably not going to be that useful because removing amyloid doesn’t seem to help anyway and therefore it may not be that useful to monitor.

“We need to develop more proximal biomarkers, ideally ones that tell us what’s going wrong in the brain and that can monitor real treatment progress. We therefore need to develop tracers for other aspects of the disorder, such as inflammation and chemical changes, e.g. in the cholinergic system which is down-regulated, and for neuroinflammation which seems to be a major element in the progression of Alzheimer’s and Lewy body dementias. We should be investing in new PET technology to get mechanistic studies going that will enable us to address these issues and monitor progression of the illness. This would then allow us to see how treatment interventions work in a much more objective fashion.”

Prof Derek Hill, Professor of Medical Imaging Science, UCL and CEO of IXICO medical imaging company, said:

“At the moment, a significant minority – or in some countries a majority – of dementia sufferers do not receive a diagnosis, and many that do receive that diagnosis late in the disease. While there are no cures for the most common diseases that cause dementia, there are drugs that have been shown to be effective (e.g. cholinesterase inhibitors for mild or moderate Alzheimer’s Disease) and as the UK NHS points out in its “Living well with dementia” strategy, diagnosis can enable patients and their families to access care and support that can help them live well with the disease.

“This analysis is, as the title emphasises, critical of screening for pre-dementia. The paper risks being misinterpreted to mean that all dementia diagnosis is a bad thing and that would be an unfortunate conclusion as it would deny many sufferers and their families from the treatment and support they need.

“Increasing diagnosis rates of dementia is tricky because of its slow, gradual onset. It is quite a different challenge from diagnosing people with many diseases that have sudden onset of symptoms. Therefore, healthcare providers such as the UK NHS argue that the diagnosis process should be proactive.  But proactively identifying patients with symptoms is not the same as population screening – and criticism of screening should not be interpreted to mean that diagnosis of symptomatic patients is a bad thing. There is a need for improving the way that this proactive diagnosis is done, and joining that diagnosis up so that it is at the right time to improve outcomes, and also that it is joined up with subsequent care and support, so patients can be served better.

“Pre-dementia is a term that means people who don’t yet meet the diagnostic criteria for dementia, but have either mild symptoms, or maybe no symptoms but molecular markers of the disease. While many research scientists believe successful treatment of diseases such as Alzheimer’s may eventually require treatment at this pre-dementia stage, such treatments remain in the research domain.”

Toby Williamson, Head of Development and Later Life, Mental Health Foundation, said:

“We agree that screening for “pre-dementia” runs the risk of incorrectly diagnosing some people who have mild cognitive impairment (symptoms similar to early stages of Alzheimer’s disease but not proof of it) as having dementia – with all the negative consequences for them and their families that this is likely to cause. Because screening tools lack the necessary precision there is quite widespread agreement that they are not the way forward in the UK, although that may be different in other countries with different health funding systems (e.g. USA).

“However we would be concerned that members of the public (and indeed professionals) may get confused between this debate and the importance of seeking and receiving a good assessment if they have concerns about their memory or other problems which might indicate a dementia, or a relative or close friend is experiencing these problems. Still only around 40% of people in England who have dementia receive a diagnosis but those that do generally find it much more helpful to know what is happening to them and to plan accordingly, than to be unaware of what is happening, with the confusion and distress this may cause. It is possible to “live well” with dementia, a diagnosis doesn’t automatically result in a lower quality of life or decline in wellbeing, and we know many people with dementia who continue to lead active lives in their communities, and to be able to speak about living with dementia.”

Prof Robert Howard, Professor of Old Age Psychiatry and Psychopathology, Institute of Psychiatry, King’s College London and Consultant Old Age Psychiatrist, South London and Maudsley NHS Foundation Trust, said:

“The first issue is should we be trying to make a reliable diagnosis of Alzheimer’s disease as early as possible in patients who want to know whether or not they have dementia? It is easy to argue that information about diagnosis is useful in terms of planning for the future and accessing the (admittedly modest) benefits that the current dementia drugs offer. On the downside, this is a devastating diagnosis to receive and we do not currently have any effective therapies that can slow down or stop the progressive decline in cognition and function.

The second – and much more difficult to argue for in terms of benefits to individual patients – issue is that of should we be making diagnoses of the various “pre-Alzheimer” states? Most important of these is Mild Cognitive Impairment and it is really hard to see the usefulness for a patient of receiving this diagnosis. My own view is that Memory Clinics should not be making this diagnosis because it is so unhelpful and should instead be focussing their attention on making the diagnosis of Alzheimer’s disease with better precision and confidence. I do worry that they sometimes use MCI as a kind of “get out of jail free card” when they are unskilled or unconfident in making the AD diagnosis. The only justification for diagnosing MCI is for research – in particular identifying participants for the current clinical trials of potential disease modifying drugs. When we have drugs to slow the progress of AD we will want to use them at the earliest stages.”

Prof Tom Dening, Professor of Dementia Research, Institute of Mental Health, University of Nottingham, said:

“There is no hard evidence of public enthusiasm for dementia screening as demonstrated by a systematic review undertaken with funding from Bupa and the Alzheimer’s Society by my colleagues from Cambridge. A meeting was held in June by Professor Alistair Burns (National Clinical Director for NHS England) and the BMA on this issue and reached a consensus that timely diagnosis was appropriate but earlier (e.g. presymptomatic) diagnosis and screening were not. (Further information available upon request)

“One problem is that there are huge vested interests in medicalising this issue, e.g. people developing biomarkers and potential treatments, but there is not yet any evidence of any benefits. Indeed, the only decent trial of treatment for mild cognitive impairment (an at-risk state for dementia) was negative probably because of the heterogeneity of this group of people – it is far from certain that most of them will develop dementia in the longer run. Enthusiasts for an early aggressive approach to diagnosis also tend to gloss over the harms that will result from the inevitable misdiagnoses and unwarranted treatment.”

‘Political drive to screen for pre-dementia: not evidence based and ignores the harms of diagnosis’ by Le Couteur et al., published in British Medical Journal on Tuesday 10th September.