How we risk getting it wrong in cognitive screening too

Reply to: How we got it wrong with breast screening: http://www.bmj.com/content/344/bmj.e3450

Dr Peter J Gordon’s reply was published in the BMJ as a letter; Published 12 June 2012 as:BMJ2012;344:e4043: http://www.bmj.com/content/344/bmj.e4043

How we risk getting it wrong in cognitive screening too
This is an interesting review by Professor Klim McPherson[1] and it has left me wondering that if in ten years time we may be asking a similar question of cognitive screening?

Klim McPherson is a professor in public health epidemiology and I would suggest that we give this discipline due weight in the consideration of cognitive screening in our elderly. Robust, repeated world wide epidemiological findings show that more than half of our elderly with mild early memory loss do not progress to clinical dementia[2]. This group needs consideration as well as the group who actually go on to develop dementia. A diagnosis of dementia is a life-changing event: we cannot simply ignore the potential for false-positive diagnoses. This is perhaps especially true for a vulnerable group like this whose voice has not been sought.

Fears have been expressed that screening based on the proposed DSM-V category of ‘minor neurocognitive disorder’ may potentially have this group classified as suffering from early dementia[3]. Yet, seen from a clinical and epidemiological perspective this group actually do not have dementia: they have mild memory loss that is static (occasionally reversible) with no significant functional loss.

I support my professional colleagues in seeking a timely diagnosis of dementia and agree that this is a challenge that deserves serious thinking. But specialties such as mine must not ignore the wider, real-world sociology of ageing alongside robust epidemiological evidence. Furthermore perhaps we need to consider lessons learnt through other early screening programmes such as this[4]. Otherwise in ten years time we might be asking: How we got it wrong with cognitive screening?

This letter was published last summer in the BMJ. Since that time the Grassroots GP have been carefully considering cognitive screening as proposed by the Department of Health. The narrative of this is beautifully summarised here:
http://grassrootsgp.org/dementia-screening/

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[1] McPherson, K. Review: How we got it wrong with breast screening. Published 17 May 2012. BMJ2012;344:e3450

[2] Palmer, K., Backman, L., Winblad, B., Fratiglioni, L., 2008. Mild cognitive impairment in the general population: occurrence and progression to Alzheimer disease. Am. J. Geriatr. Psychiatry 16, 603–611.

[3] Frances, A. DSM 5 Minor Neurocognitive Disorder. Psychology Today. 16 Feb 2012

[4] Gøtzsche, Peter C. Mammography Screening: Truth, Lies and Controversies

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