Previous estimates of levels of dementia in the developing world may have substantially underestimated the problem, according to research published today. The findings suggest that policymakers in low-income and middle-income countries may need to re-examine the burden and impact that dementia places on their health services.
As the average age of the global population increases, dementia and other age-related illnesses are increasing in prevalence. Recent estimates have suggested that over 24 million people live with dementia worldwide, with 4.6 million new cases every year. However, a number of studies have suggested that the prevalence of dementia in the developing world is between a quarter and a fifth of that typically recorded in developed countries.
Now, research announced at the International Conference on Alzheimer's Disease and published online today in the journal The Lancet suggests that this figure has been underestimated and that levels of dementia in the developing world may be much closer to those in the developed world.
The research was conducted by the 10/66 Dementia Research Group, an international collaboration whose funders include the Wellcome Trust. The 10/66 Dementia Research Group is part of Alzheimer's Disease International. The group is so named because less than one tenth of all population-based dementia research has been directed towards the two-thirds or more of all people with dementia who live in developing parts of the world. It aims to provide by far the most extensive source of information regarding dementia in low and middle income countries.
Professor Martin Prince from the Institute of Psychiatry, King's College London, who leads the group, believes that a number of factors may have led to researchers failing to identify a significant proportion of cases of dementia.
"It's likely that cultural differences may be partly responsible for researchers missing cases of dementia," says Professor Prince. "Our evidence suggests that relatives in developing world countries are less likely to perceive or report that their elders are experiencing difficulties, even in the presence of clear evidence of disability and memory impairment."
The research group assessed almost 15,000 people over the age of 65 in eleven countries, including India, China, Cuba and Peru. The assessment consisted of interviews with the participant and, typically, a family member, as well as a physical examination and a blood test. The criteria used by the 10/66 researchers were developed and validated cross-culturally across Latin America, Africa, South and South East Asia in an attempt to enable valid comparisons to be made between different countries and cultures even when a high proportion of older people had had little or no education.
According to the study, prevalence of dementia in urban settings in Latin America is comparable with rates in Europe and the US, though the prevalence in China and India is lower.