The need for research on dementia in developing countries.

Dementia is one of the commonest and most disabling late-life mental disorders. Its prevalence and incidence have been assessed in developed countries, and show little geographical variation between countries and regions. Although most older people live in developing countries, little research has been carried out in those settings. There is some evidence that age-specific prevalence rates for dementia in developing countries may be relatively low. More research is needed to allow developing countries to estimate the current extent, type and cost of medical and social service provision, and to make confident predictions of future need. Research in different cultures with different levels of economic and industrial development will also increase the variance of environmental exposure, facilitating the identification of environmental risk factors and gene-environment interactions for dementia. Research methodologies need to be adapted to the different circumstances of developing countries, with implications for sampling, cognitive screening and definitive dementia diagnosis.