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Unreliable tests miss signs of dementia

By Daniel Cressey

Patients with early signs of dementia are missing out on diagnosis because current testing procedures are unreliable, new research warns.

The study suggests GPs cannot necessarily be reassured if their patients receive the all-clear from memory clinics.

The evaluation of 166 GP referrals to a memory clinic found a significant proportion who were normal by standard testing actually had mild cognitive impairment.

The research comes amid fierce debate over the treatment of early dementia and with GPs expected to draw up registers of the disease under the new QOF.

The study, published early online by Psychological Medicine, evaluated 124 patients who did not have established dementia or depression.

Some 58 per cent tested positive for mild cognitive impairment using the well-established mini-mental state examination.

But when verbal and non-verbal memory performance tests were used, the figure rose to 73 per cent, suggesting a significant proportion of patients were missing out on diagnosis.

There was also wide variation between different memory tests, with only 27 per cent of patients showing up as impaired on all three of those evaluated.

Study leader Professor John Hodges, professor of behavioural neurology at the University of Cambridge, said: 'Definition of mild cognitive impairment varies considerably dependent on the tests used for case definition. It is likely this variability has implications for the long-term fate of individual subjects.'

Dr Chris Manning, chief executive of Primary Care Mental Health and Education, said there were significant problems with the diagnosis of dementia. 'We have got people who are currently ignored whose wheels are falling off and they are not even being picked up.'

But he added: 'I'm not so sure I want to go down the road of MCI, if it means that we find we end up having to ''treat'' the whole nation.'

Professor Chris Drinkwater, head of the primary care development centre at the University of Northumbria, said there could be implications for the new GP dementia registers. 'There will be people who score between one and nine on these registers. This paper is saying it won't necessarily pick up all the people with MCI.'

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