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Distant memory – new dementia test allows international comparisons

It is difficult to diagnose dementia in societies with limited education. So comparison of levels of the condition in different countries may not be valid. A study involving the UK Institute of Psychiatry aimed to develop and assess a culturally and educationally unbiased test for dementia.

Patients can receive a diagnosis of dementia if their condition has two of the following features:

There is a decline in two domains of cognitive ability, including memory.
It interferes with social or occupational function.
There is no other explanation, such as depression.

In developing countries, low levels of education, literacy and numeracy make it hard to detect dementia. Use of the wrong tests can lead to an over-diagnosis. We need a new test that does not require mathematical, reading or writing skills. The researchers developed a new tool, which includes elements from three other tests:

the popular ‘geriatric mental state’ test
the ‘community screening instrument for dementia’
the ‘modified CERAD ten-word list-learning task’.

They interviewed 2 885 people aged 60 years and older in 25 centres in: India (760 people), China and south-east Asia (367), Latin America and the Caribbean (1 682) and Nigeria (76). 729 have dementia and of the rest, 702 have depression, 694 have high education levels and 760 have low education levels. They found that:

The combined test is a great improvement on each test used alone – it correctly identifies 94 per cent of dementia cases.
False-positive rates are fifteen, three and six percent in the depression, high education and low education groups, respectively.
It is most accurate in China, south-east Asia and India and least accurate in Latin America.

Although 15 per cent of depression cases are wrongly classified as dementia by the test, this is still acceptable for use in population-based research. It is especially suited to studies in low education populations in the developing world, or those designed to make comparisons across countries and cultures. It can be given by non-health workers after only a few days of training. The researchers conclude that it is possible to develop a one-stage culturally and educationally sensitive dementia test. However, the three measures give different results depending on the region, so it may be a challenge to develop a completely culture-free test.

Source(s):
‘Dementia diagnosis in developing countries: a cross-cultural validation study’, The Lancet 361: 909-917, by M. Prince, et al, 2003 Full document.

Funded by: Alzheimer’s Disease International; Friends of Alzheimer’s Disease International; FAPESP; CNPq; National Science Council of Taiwan; World Health Organisation

id21 Research Highlight: 4 November 2003

Further Information:
Martin Prince
Institute of Psychiatry
De Crespigny Park
London SE5 8AF
UK

Tel: +44 (0) 20 7848 0136
Fax: +44 (0) 20 7277 0283
Contact the contributor: m.prince@iop.kcl.ac.uk

Institute of Psychiatry, UK

10/66 Dementia Research Group, UK

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