A new study has found that the incidence of dementia in middle-income countries could be double that previously thought, and suggests that education, literacy, and verbal ability could play a role in reducing the risk of the condition. The findings are published online on 22 May in the journal Lancet.
The population-based cohort study recruited 12,887 volunteers over the age of 65 from Cuba, the Dominican Republic, Venezuela, Peru, Mexico, China and India. The volunteers were assessed for dementia using new criteria, adjusted to make it more suitable for assessing people in low to middle-income countries.
Of the original volunteers, 8,137 were dementia free at the start of the study and were followed up and re-assessed after an average of four years. The study found that the incidence rates reported using the new criteria were 1.5-2.5 times higher than those previously reported, bringing them more in line with the incidence rates in higher-income countries.
The participants were also asked to complete a questionnaire outlining their age, sex, education, occupation, level of literacy, verbal fluency and the household assets they own, including cars, televisions and mains water. The researchers found that older age, fewer years in education, illiteracy and lower verbal fluency scores were all associated with a higher incidence of dementia.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said:
“This study provides a stark reminder of the burden of dementia across the world and highlights the need for dementia tests to be sensitive to different cultural settings. As well as being one of the largest studies of dementia incidence, the findings suggest the potential influence of early-year factors such as education on protecting our brains from dementia later in life.
"The findings sound the alarm about the urgent need for more funding for dementia research. With an ageing population across the world, the number of people affected by dementia will only continue to rise. There is an urgent need for answers and research is the only solution.”